Agroécologie, INRAE Audrey Labonté
email: labonte.audrey@hotmail.com

Lucie S Monticelli

Mélinda Turpin

Emeline Felten

Emilien Laurent

Annick Matejicek

Luc Biju-Duval

Chantal Ducourtieux

Eric Vieren

Violaine Deytieux

| Luc Biju-Duval

| Chantal Ducourtieux

Stéphane Cordeau

| David Bohan

Adam J Vanbergen

Individual flowering phenology shapes plant-pollinator interactions across ecological scales affecting plant reproduction

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

respond to spatio-temporal heterogeneity arising from agroecological management affecting wild plant species reproduction. The interplay of pollinator interactions within and between ecological scales affecting seed set implies a co-occurrence of pollinator-mediated facilitative and competitive interactions among plant species and individuals.

K E Y W O R D S

agroecological infrastructure, Centaurea, network structure, plant-insect community, seed set, spatio-temporal heterogeneity

| INTRODUC TI ON

Sexual reproduction in outcrossing plant species contributes to genetically diverse populations and reduces inbreeding risks [START_REF] Eckert | Plant mating systems in a changing world[END_REF]. Seed set is one component of plant reproductive success that results from the plant's physiological state and efficient conspecific pollen (= genes) transfer, which is facilitated by foraging insects in many flowering plant species [START_REF] Ollerton | How many flowering plants are pollinated by animals?[END_REF].

Physiological investment in reproduction by the plant individual (flowers and seeds) relies on the availability of water, energy, and nutrients, with any deficit likely to affect the physiological capacity for seed production [START_REF] Akter | Water stress and nitrogen supply affect floral traits and pollination of the white mustard, Sinapis alba (Brassicaceae)[END_REF][START_REF] Guilioni | High temperature and water deficit may reduce seed number in field pea purely by decreasing plant growth rate[END_REF]. Furthermore, intra-and interspecific plant competition for these abiotic resources can divert investment from sexual reproduction and modify the size of floral displays used to attract the pollinators needed for cross-pollination [START_REF] Akter | Water stress and nitrogen supply affect floral traits and pollination of the white mustard, Sinapis alba (Brassicaceae)[END_REF].

Plants may also compete for insect pollination because plantpollinator interactions typically occur in multi-species assemblages [START_REF] Bascompte | Plant-animal mutualistic networks: The architecture of biodiversity[END_REF]. Indirect plant-plant interactions through pollinator sharing can reduce seed set due to interspecific pollen transfer that disrupts conspecific pollination [START_REF] Arceo-Gómez | Coflowering community context influences female fitness and alters the adaptive value of flower longevity in Mimulus guttatus[END_REF][START_REF] Morales | Interspecific pollen transfer: Magnitude, prevalence and consequences for plant fitness[END_REF]. Conversely, facilitation of plant reproductive success can also occur in diverse co-flowering assemblages when greater pollinator densities or diversity increase flower visitation rates or provide complementarity and redundancy in pollination services [START_REF] Blüthgen | Functional complementarity and specialisation: The role of biodiversity in plant-pollinator interactions[END_REF][START_REF] Ghazoul | Floral diversity and the facilitation of pollination[END_REF][START_REF] Hegland | Floral neighbourhood effects on pollination success in red clover are scale-dependent[END_REF]. Moreover, pollinator foraging behaviors vary with the relative quality, abundance, and accessibility of pollen or nectar due to the spatio-temporal turnover in flowering plant assemblages [START_REF] Gallagher | Pollinator visitation rate and effectiveness vary with flowering phenology[END_REF][START_REF] Jha | Resource diversity and landscape-level homogeneity drive native bee foraging[END_REF][START_REF] Lázaro | Co-flowering neighbors influence the diversity and identity of pollinator groups visiting plant species[END_REF]. This combination of foraging plasticity and spatio-temporal floral heterogeneity can determine the level of pollination competition or facilitation among plant individuals and species to alter plant reproductive outcomes. This complexity of multispecies interactions and ecological processes influencing plant reproduction can be understood as a plant-pollinator network [START_REF] Bascompte | Plant-animal mutualistic networks: The architecture of biodiversity[END_REF]. Variation in the organization and strength of species interactions in a network reflects community composition, species coevolution, and ecological processes like competition and resource partitioning [START_REF] Junker | Specialization on traits as basis for the niche-breadth of flower visitors and as structuring mechanism of ecological networks[END_REF][START_REF] Magrach | Niche complementarity among pollinators increases community-level plant reproductive success[END_REF][START_REF] Vázquez | Uniting pattern and process in plant-animal mutualistic networks: A review[END_REF].

Greater network linkage density (encompassing the overall species richness and frequency of interactions) might affect pollination processes by increasing overall flower visitation rates [START_REF] Akter | Effects of small-scale clustering of flowers on pollinator foraging behaviour and flower visitation rate[END_REF] or by offering potential complementarity or redundancy in pollinators [START_REF] Blüthgen | Functional complementarity and specialisation: The role of biodiversity in plant-pollinator interactions[END_REF][START_REF] Ghazoul | Floral diversity and the facilitation of pollination[END_REF][START_REF] Magrach | Niche complementarity among pollinators increases community-level plant reproductive success[END_REF][START_REF] Venjakob | Plant diversity increases spatio-temporal niche complementarity in plant-pollinator interactions[END_REF]. A high level of plant species specialization in pollinator interactions (d′- [START_REF] Blüthgen | Measuring specialization in species interaction networks[END_REF][START_REF] Blüthgen | What do interaction network metrics tell us about specialization and biological traits?[END_REF][START_REF] Dormann | Indices, graphs and null models: Analyzing bipartite ecological networks[END_REF] implies that pollen transfer relies on relatively few pollinator species in the multispecies network, which, under adaptive foraging, may dictate the potential for floral constancy, conspecific pollen transfer, and subsequent seed set [START_REF] Valdovinos | Adaptive foraging allows the maintenance of biodiversity of pollination networks[END_REF]. This potential would be greatest where there is a strong mutual dependence between pollinator and plant species in the network re-enforcing conspecific pollen transfer [START_REF] Bascompte | Asymmetric coevolutionary networks facilitate biodiversity maintenance[END_REF][START_REF] Vázquez | Species abundance and asymmetric interaction strength in ecological networks[END_REF]. However, an insect species dominating visitation to a particular plant species but with lower dependence because it forages on an array of forage plant species may dilute conspecific pollen deposition and interfere with plant reproduction through heterospecific pollen deposition [START_REF] Arceo-Gómez | Coflowering community context influences female fitness and alters the adaptive value of flower longevity in Mimulus guttatus[END_REF][START_REF] Morales | Interspecific pollen transfer: Magnitude, prevalence and consequences for plant fitness[END_REF]. Consequently, variation in plant-pollinator network structure has the potential to indicate and influence pollination efficiency and plant reproduction, but relatively few studies have examined this relationship [START_REF] Arceo-Gómez | Plant-pollinator network structural properties differentially affect pollen transfer dynamics and pollination success[END_REF][START_REF] Arroyo-Correa | Individual-based plant-pollinator networks are structured by phenotypic and microsite plant traits[END_REF][START_REF] Lázaro | Linking species-level network metrics to flower traits and plant fitness[END_REF][START_REF] Magrach | Niche complementarity among pollinators increases community-level plant reproductive success[END_REF][START_REF] Theodorou | The structure of flower visitor networks in relation to pollination across an agricultural to urban gradient[END_REF][START_REF] Vanbergen | Grazing alters insect visitation networks and plant mating systems[END_REF]. Moreover, reports are idiosyncratic with neutral [START_REF] Theodorou | The structure of flower visitor networks in relation to pollination across an agricultural to urban gradient[END_REF] or positive [START_REF] Arroyo-Correa | Individual-based plant-pollinator networks are structured by phenotypic and microsite plant traits[END_REF][START_REF] Lázaro | Linking species-level network metrics to flower traits and plant fitness[END_REF] effects of network structure on seed production.

Plant-pollinator interactions are filtered by the combination of organism traits and environmental conditions at different levels of ecological organization [START_REF] Arroyo-Correa | Individual-based plant-pollinator networks are structured by phenotypic and microsite plant traits[END_REF][START_REF] Lázaro | Co-flowering neighbors influence the diversity and identity of pollinator groups visiting plant species[END_REF].

Cost-benefit dynamics governing mutualistic plant-insect relationships [START_REF] Bronstein | Conditional outcomes in mutualistic interactions[END_REF] mean that reproductive outcomes are often unbalanced among plant species and individuals [START_REF] Mesgaran | How to be a good neighbour: Facilitation and competition between two co-flowering species[END_REF]. Furthermore, the occurrence of distinct assemblages of species interactions at different ecological scales (organism to community) may have complementary or opposing effects on plant pollination and reproduction [START_REF] Hegland | Floral neighbourhood effects on pollination success in red clover are scale-dependent[END_REF]cf. specialization-Brosi, 2016). For instance, plant species that are scarce within a species-rich assemblage may experience dilution of pollinator visits, reduced pollen transfer, and seed production [START_REF] Evans | Florally rich habitats reduce insect pollination and the reproductive success of isolated plants[END_REF].

Conversely, large intraspecific or interspecific floral displays can increase plant-mating opportunities through the overall attraction of floral visitors [START_REF] Akter | Effects of small-scale clustering of flowers on pollinator foraging behaviour and flower visitation rate[END_REF][START_REF] Hegland | Floral neighbourhood effects on pollination success in red clover are scale-dependent[END_REF]. However, a large floral display in an individual plant may increase the risk of geitonogamous pollen transfer (self-pollination), which can increase risks of inbreeding and in self-incompatible species reduce seed production [START_REF] Akter | Effects of small-scale clustering of flowers on pollinator foraging behaviour and flower visitation rate[END_REF][START_REF] Eckert | Plant mating systems in a changing world[END_REF][START_REF] Karron | Effects of floral display size on male and female reproductive success in Mimulus ringens[END_REF].

Apart from spatial effects, flowering phenology (i.e., the timing and duration of flowering period) is a species trait that influences plant reproduction. Inter-and intraspecific phenological variation filters the precise assemblage of interacting species that a plant individual is exposed to during the temporal succession of plants and pollinators, both in the immediate local assemblage and the wider community across the landscape [START_REF] Arroyo-Correa | Individual-based plant-pollinator networks are structured by phenotypic and microsite plant traits[END_REF][START_REF] Caradonna | Temporal flexibility in the structure of plant-pollinator interaction networks[END_REF][START_REF] Gallagher | Pollinator visitation rate and effectiveness vary with flowering phenology[END_REF][START_REF] Rafferty | Pollinator effectiveness varies with experimental shifts in flowering time[END_REF]. The degree of overlap in the timing and duration of flowering periods, within and between species, therefore modulates the level of insect-mediated conspecific pollen transfer and the balance of interspecific interactions (competition, interference, or facilitation) at different ecological scales affecting pollination services and plant seed set [START_REF] Kovács-Hostyánszki | Contrasting effects of massflowering crops on bee pollination of hedge plants at different spatial and temporal scales[END_REF].

Pollinators and pollination services face anthropogenic threats with conventional intensive agricultural management the foremost worldwide [START_REF] Dicks | A global-scale expert assessment of drivers and risks associated with pollinator decline[END_REF][START_REF] Potts | Safeguarding pollinators and their values to human well-being[END_REF]. Ecological intensification of agriculture is one alternative management model to reduce the negative impacts of agriculture and respond to global change while maintaining food production [START_REF] Vanbergen | Transformation of agricultural landscapes in the Anthropocene: Nature's contributions to people, agriculture and food security[END_REF].

Ecologically intensive practices include the use and rotation of diverse crops and existing or restored agroecological infrastructures (e.g., semi-natural habitats, sown wildflower, or grass strips) to harness ecosystem services, like pollination, in support of agriculture [START_REF] Kovács-Hostyánszki | Ecological intensification to mitigate impacts of conventional intensive land use on pollinators and pollination[END_REF]. Ecological intensification thus creates a heterogeneous and dynamic community in space and time, which is expected to modify pollinator interactions and wild plant reproductive success.

We aimed to understand how individual seed set in two wild plant species (Cyanus segetum Hill, and Centaurea jacea L.; Asteraceae) in herbaceous agroecological infrastructure was affected by spatiotemporal heterogeneity in floral resources and plant-pollinator interactions across multiple ecological scales (individual-local assemblage-interaction network of agroecological infrastructure in the farm landscape). Because of the prolonged and variable flowering periods of each species [START_REF] Monticelli | Agroecological farming, flowering phenology and the pollinator-herbivore-parasitoid nexus regulate non-crop plant reproduction[END_REF], we used an individualcentered and phenologically explicit approach to match precisely the flowering period of different plant individuals (transplanted into sown wildflower or grass-legume strips) to the concomitant level of spatiotemporal heterogeneity in plant-pollinator interactions (at different ecological scales) and abiotic conditions. A priori this assumed that the intraspecific variation in flowering phenologies would modulate the level of seed set due to variable pollinator-mediated competition or facilitation encountered by the plants in these spatio-temporally distinct assemblages. We predicted that:

1. Individual seed set of focal plant species would be positively related to abiotic conditions (nitrogen, precipitation, and temperature) affecting the plant's physiological state and potential to invest in reproduction. [START_REF] Bellanger | Pseudo-selfcompatibility in Centaurea cyanus L. Flora: Morphology, Distribution[END_REF][START_REF] Hicks | Food for pollinators: Quantifying the nectar and pollen resources of urban flower meadows[END_REF][START_REF] Ouvrard | Flower-strip Agrienvironment schemes provide diverse and valuable summer flower resources for pollinating insects[END_REF][START_REF] Steffan-Dewenter | Pollination, seed set and seed predation on a landscape scale[END_REF]. Their prolonged flowering periods [START_REF] Monticelli | Agroecological farming, flowering phenology and the pollinator-herbivore-parasitoid nexus regulate non-crop plant reproduction[END_REF] present intraspecific phenological variations that dictate individual plant exposure to plant-pollinator interactions.

| Experimental design

The experiment was conducted (May-September 2019) on the INRAE CA-SYS experimental farm (Burgundy, France, 47°19′06.7″N 5°04′17.6″E). Established in 2018, this farm-scale agroecological system experiment (125 ha) is testing zero-pesticide agroecological farming systems, including spatio-temporal crop diversity and ecological infrastructures [START_REF] Vanbergen | Transformation of agricultural landscapes in the Anthropocene: Nature's contributions to people, agriculture and food security[END_REF]. This included sowing 6.8 ha (22.67 km × 3 m) of grass-legume (seven species) strips and 2.69 ha (8.96 km × 3 m) of wildflower (37 species) strips with mixtures designed to promote pollination and biocontrol ecosystem services (Table S1).

| Abiotic environment-influencing plant physiological capacity to invest in seed production

At the farm scale, we calculated the mean temperature (°C) and the mean precipitation (mm) for each individual's flowering period until harvested using daily records from an automated meteorological station at the experimental farm (Equations S1). At the individual plant scale, we used the foliar N content (%) of each plant individual as an indicator of its physiological state and a proxy for the biochemical resources available for investment in reproduction [START_REF] Wang | Development of a critical nitrogen dilution curve of Siberian wildrye for seed production[END_REF].

One leaf sample per individual (~5 g) was collected before the flowering period of each species (C. segetum-mid-May; C. jacea-early July). After oven drying (40°C) and milling (diameter ≤80 μm), the N content in 4-6 mg of foliar tissues (%) was quantified using a Thermo Scientific FLASH 2000 Organic Elemental Analyzer™.

| Reproductive development and seed set of focal plant individuals

We counted the open and wilted composite flowers, floral buds, and fruits produced by each focal plant individual at monthly intervals. Combined with insect visitation data, these measurements allowed us to estimate the flowering period of each individual plant (precision to the week). At the end of the flowering period (i.e., C. segetum-mid-July; C. jacea-early-September), all surviving focal plants were harvested. We counted the total number of seeds produced per individual (hereafter "seed set") and the total number of floral heads (fruits with or without seeds) as a measure of the size of the total individual floral display.

| Local flowering plant assemblage

| Plant-pollinator interactions from individual to local assemblage scales

We quantified plant-pollinator interactions to each focal plant species (plot-Table S2) and in the local floral assemblage (transect-Tables S2 andS3 We calculated linkage density Lq-the mean number of links per species weighted by the mean frequency of interactions [START_REF] Dormann | Indices, graphs and null models: Analyzing bipartite ecological networks[END_REF]. This indicates the wider diversity and density of plantpollinator interactions in the agroecological infrastructure across the farm and hence the potential activity and species redundancy in the pollination service to the focal plants. The potential level of conspecific pollen transfer in the network was described using two network metrics: plant species specialization in pollinator interactions (d′-Blüthgen et al., 2006) and total weighted mutual dependence between the focal plant species and its pollinators (MD; Equation 2-following [START_REF] Bascompte | Asymmetric coevolutionary networks facilitate biodiversity maintenance[END_REF] The dependence of the plant species (c) on pollinator p and reciprocally (p on c) were multiplied and the products were summed across all pollinator species to give the total mutual dependence of each focal plant species. The interactions were weighted according to the total observation frequency of pollinator species to exclude pollinator species only observed once [START_REF] Blüthgen | What do interaction network metrics tell us about specialization and biological traits?[END_REF]. This index varies between 0 (weak mutual dependence) and 1 (strong mutual dependence = pairwise mutualism or perfect nestedness), with higher values expected to reflect increased efficiency of focal plant pollen transfer [START_REF] Vázquez | Species abundance and asymmetric interaction strength in ecological networks[END_REF].

| Statistical analyses

We used one generalized linear mixed model per species (GLM, "lme4") to explain the intraspecific variations in seed set between surviving focal individuals of C. segetum (n = 144) and C. jacea (n = 105) fitting a negative binomial distribution to control for overdispersion. We fitted "plot" as a random effect to account for the spatial dispersion of the replicates and unmeasured microsite conditions (singularity meant we dropped this random effect in the (2) of the interaction network of agroecological infrastructure, we fitted the network linkage density (Lq), focal plant specialization (d′), and the total weighted MD between the focal plant species and its pollinators.

MD c = N ∑ p=1 n interactions p,c -1 total n interactions c -1 * n interactions p,
All predictors were calculated to correspond to the individual flowering period of the 249 focal plants that produced a fruit (≥1).

This ensured high precision in the estimation of the abiotic context and assemblages of plant-pollinator interactions the individual was exposed to at the level of the individual plant, local assemblage, and the interaction network of agroecological infrastructure across the farm (Table S4). S2 andS3). Including non-focal conspecifics in the plant assemblages (transects), the number of potential pollinators observed foraging on C. segetum and C. jacea were, respectively, 356 insects from 26 species and 88 insects from 24 species (Table S2).

| Abiotic variables influencing focal plant seed set

Only mean temperature over the flowering period related negatively and positively to seed set in C. segetum and C. jacea, respectively (Tables 1 and2). Neither precipitation nor foliar N content were selected in the best models.

| Plant-pollinator interactions influencing seed set at focal plant and local assemblage scales

The seed set of C. segetum and C. jacea was positively related to the relative attractiveness of each individual focal plant for foraging pollinators (Tables 1 and2; Figure 1a,d) and the floral density in the local plant assemblage (Tables 1 and2; Figure 1b,d). Moreover, for C.

jacea, this relationship between seed set and the relative individual attractiveness was accentuated by increasing floral density (Table 2;

Figure 1d). C. jacea seed set also responded positively to the density of potential conspecific pollen donors in the local assemblage (Table 2; Figure 1e), but C. segetum was unaffected.

Although for both focal plant species, the species richness of potential pollinators active in the local floral assemblage was among the main fixed effects predicting seed set, its effect was relatively weak compared to other parameters (Tables 1 and2; Figure 1c,f).

An albeit weak statistical interaction (floral richness × potential pollinator richness) indicated that the response of C. segetum seed set

to the species richness of potential pollinators foraging in the local assemblage was negative when situated in florally poor local assemblages, but positive in most species-rich floral assemblages (Table 1;

Figure 1c).

| Properties of plant-pollinator network structure in agroecological infrastructure affecting seed set

As a main effect, network linkage density positively affected seed set in both focal species (Tables 1 and2; Figures 2a-c and3a).

Network linkage density also influenced C. segetum reproduction by modifying the effect on individual seed set of the density and species richness of the local floral assemblage or richness of potential pollinators foraging locally (Table 1; Figure 2a-c).

C. segetum seed set was negatively related to greater floral richness in the local assemblage when network linkage density was higher and only responded positively to local floral richness under lowest values of network linkage density (Table 1; Figure 2a). The strength of the positive relationship between local floral density and C. segetum seed set increased as the network linkage density increased (Table 1; Figure 2b). In the more densely linked networks, the local species richness of potential pollinators had a positive relation to C. segetum seed set, with only a negative relationship at the lowest level of linkage density (Table 1; Figure 2c).

C. jacea specialization in pollinator interactions (d′) had a negative impact on its individual seed set as a main fixed effect (Table 2), but C. segetum was unaffected. As a main fixed effect, the effect of total weighted MD between C. segetum and its pollinators had a positive influence on seed set (Table 1; Figure 2d). For C. jacea, there was a strong interaction (d′ × MD) showing a positive effect on seed set as both specialization and mutual dependence increased, but a negative effect on seed set under low values of d′ (Table 2; Figure 3b).

Overall, the final best model including environmental temperature and variation in floral assemblages and plant-pollinator interactions across ecological scales explained (R 2 ) a high level of the phenologically explicit variation in individual seed production of C. segetum and C. jacea (Tables 1 and2). Note: The GLMM (negative binomial) was derived from AIC-based multi-model selection, and predictors were present in >50% of the 22 best models (ΔAIC <2). Total variance explained (R 2 ) by marginal (fixed effects) and conditional (fixed + random) predictors, and the plot random effect (σ 2 ) are cited. Predictors were log-transformed where required to account for non-linear relationships with the log of seed number.

| DISCUSS ION

Model fit: R 2 marginal = 0.65; R 2 conditional = 0.93; random σ 2 = 0.95.

TA B L E 2

Final GLM of C. jacea seed set in response to abiotic (N, H 2 O, and °C) and biotic (plant-pollinator interactions and floral assemblage) predictors matched to the flowering period of focal plant individuals at the scale of the individual plant, local assemblage, and the plant-pollinator network of the agroecological infrastructure across the farm. Note: The GLM (negative binomial) was derived from AIC-based multi-model selection and predictors were present in >60% of the 15 best models (ΔAIC <2). The random effect was dropped due to model singularity and to avoid overfitting; therefore, the total variance explained (R 2 ) is due solely to the fixed effects. Predictors were log-transformed (n + 0.0001) where required to account for non-linear relationships with the log of seed number.

Model fit: R 2 = 0.79. [START_REF] Arroyo-Correa | Individual-based plant-pollinator networks are structured by phenotypic and microsite plant traits[END_REF][START_REF] Hegland | Floral neighbourhood effects on pollination success in red clover are scale-dependent[END_REF][START_REF] Kovács-Hostyánszki | Contrasting effects of massflowering crops on bee pollination of hedge plants at different spatial and temporal scales[END_REF].

Nitrogen and water availability were predicted to affect the plant's capacity to invest in reproduction [START_REF] Akter | Water stress and nitrogen supply affect floral traits and pollination of the white mustard, Sinapis alba (Brassicaceae)[END_REF][START_REF] Guilioni | High temperature and water deficit may reduce seed number in field pea purely by decreasing plant growth rate[END_REF], but they were unimportant in this case, perhaps because the farm-scale (125 ha) environmental gradients in abiotic resources were insufficiently strong to affect seed production. Although the environmental temperature at the farm scale was selected in the final model for both species, it was generally a less important determinant of seed production than floral assemblages or plant-pollinator interactions.

The size of the individual floral display is an important determinant of insect visitation rate, pollination, and seed set [START_REF] Akter | Effects of small-scale clustering of flowers on pollinator foraging behaviour and flower visitation rate[END_REF][START_REF] Karron | Effects of floral display size on male and female reproductive success in Mimulus ringens[END_REF]. As predicted, seed set for both focal species was related positively to the individual plant's relative attractiveness, an index integrating the plant's capacity to invest in a large floral display, the attraction via the floral display of conspecific neighbors, and the corresponding pollinator visitation rate [START_REF] Akter | Effects of small-scale clustering of flowers on pollinator foraging behaviour and flower visitation rate[END_REF]. Individual C. jacea with larger floral displays also had greater success at attracting and concentrating visitation with subsequent benefits for seed set when situated within assemblages with greater interspecific floral densities. Along with the direct relationship between focal plant seed set and floral density in the local assemblage, this suggests the overall attraction of pollinators to a dense floral community [START_REF] Hegland | Floral neighbourhood effects on pollination success in red clover are scale-dependent[END_REF] whose plastic foraging behaviors then facilitated the transfer of pollen among focal plants [START_REF] Jha | Resource diversity and landscape-level homogeneity drive native bee foraging[END_REF][START_REF] Petanidou | Long-term observation of a pollination network: Fluctuation in species and interactions, relative invariance of network structure and implications for estimates of specialization[END_REF].

A greater density of potential conspecific pollen donors in the local assemblage enhanced individual seed set of C. jacea but not C.

segetum. This difference is possibly due to the relative population size of the two focal species (Table S4). Although both focal species were part of the sown wildflower seed mix, C. jacea only flowers after a year of vegetative growth, whereas C. segetum is annual [START_REF] Nitschke | Time course of plant diversity effects on Centaurea jacea establishment and the role of competition and herbivory[END_REF][START_REF] Tison | Flora gallica. Flore de France (Biotope Ed)[END_REF]. Consequently, the availability of potential pollen donors was more limiting for C. jacea with only few naturally occurring individuals on the farm providing a source of outcross pollen in addition to the transplanted focal individuals, whereas in the sown mixtures there were readily available pollen donors for C. segetum [START_REF] Eckert | Plant mating systems in a changing world[END_REF]. higher, niche partitioning may have reduced such competitive interactions [START_REF] Brosi | Single pollinator species losses reduce floral fidelity and plant reproductive function[END_REF], thereby improving floral constancy and facilitating conspecific pollen transfer and C. segetum seed set [START_REF] Morales | Interspecific pollen transfer: Magnitude, prevalence and consequences for plant fitness[END_REF]. If correct, this interpretation shows how the balance of interspecific competition (plant and pollinator; [START_REF] Arceo-Gómez | Coflowering community context influences female fitness and alters the adaptive value of flower longevity in Mimulus guttatus[END_REF][START_REF] Fontaine | Generalist foraging of pollinators: Diet expansion at high density[END_REF][START_REF] Hegland | Floral neighbourhood effects on pollination success in red clover are scale-dependent[END_REF] and foraging plasticity of pollinators via niche partitioning in local assemblages [START_REF] Jha | Resource diversity and landscape-level homogeneity drive native bee foraging[END_REF][START_REF] Valdovinos | Adaptive foraging allows the maintenance of biodiversity of pollination networks[END_REF] Linkage density provides a metric of the overall species richness and frequency of interactions in the network [START_REF] Dormann | Indices, graphs and null models: Analyzing bipartite ecological networks[END_REF].

Greater network linkage density had a strong positive influence on individual C. segetum seed set (but less strongly for C. jacea).

Furthermore, the species richness of potential pollinators and floral density in the local assemblage most benefited C. segetum seed set when linkage density was higher, showing how spatio-temporal heterogeneity across ecological scales influenced plant reproduction [START_REF] Hegland | Floral neighbourhood effects on pollination success in red clover are scale-dependent[END_REF][START_REF] Kovács-Hostyánszki | Contrasting effects of massflowering crops on bee pollination of hedge plants at different spatial and temporal scales[END_REF]. Together, these results suggest that the reproduction of these focal species (particularly C. segetum) visited mostly by generalist pollinators (Table S2) benefited from being embedded within a wider species-rich network with high flower visitation rates. This might be due to adaptive foraging [START_REF] Valdovinos | Adaptive foraging allows the maintenance of biodiversity of pollination networks[END_REF], trait matching [START_REF] Garibaldi | Trait matching of flower visitors and crops predicts fruit set better than trait diversity[END_REF], and/or species complementarity or redundancy [START_REF] Blüthgen | Functional complementarity and specialisation: The role of biodiversity in plant-pollinator interactions[END_REF][START_REF] Venjakob | Plant diversity increases spatio-temporal niche complementarity in plant-pollinator interactions[END_REF][START_REF] Woodcock | Meta-analysis reveals that pollinator functional diversity and abundance enhance crop pollination and yield[END_REF] in the pollination service, which may have diluted plant competition for pollinators.

In contrast, local floral richness had a positive influence on C. segetum seed set only under low values of linkage density. This effect became negative as observed network linkage density increased. This implies that at low levels of linkage density (and potential complementarity or redundancy) the higher levels of floral species richness in the local assemblage concentrate pollinator activity [START_REF] Ghazoul | Floral diversity and the facilitation of pollination[END_REF][START_REF] Jha | Resource diversity and landscape-level homogeneity drive native bee foraging[END_REF][START_REF] Potts | Enhancing pollinator biodiversity in intensive grasslands[END_REF], spilling over to benefit C. segetum pollination and reproduction.

However, an increase in linkage density at the farm scale may have enhanced interspecific pollinator-mediated plant competition at the local scale, hindering efficient conspecific pollen transfer (Arceo-Gómez & Ashman, 2014; [START_REF] Morales | Interspecific pollen transfer: Magnitude, prevalence and consequences for plant fitness[END_REF].

We also predicted that seed set would be modulated by the level of focal plant specialization on pollinators (d′) or MD in the farm-scale network of agroecological infrastructure through gains in conspecific pollen transfer between spatially separated plants [START_REF] Bascompte | Asymmetric coevolutionary networks facilitate biodiversity maintenance[END_REF][START_REF] Valdovinos | Adaptive foraging allows the maintenance of biodiversity of pollination networks[END_REF][START_REF] Vázquez | Species abundance and asymmetric interaction strength in ecological networks[END_REF]. A greater level of MD between the focal species and their pollinators, indicating higher constancy of pollinator interactions on the focal plants compared to other plant species, contributed to increase seed set [START_REF] Morales | Interspecific pollen transfer: Magnitude, prevalence and consequences for plant fitness[END_REF][START_REF] Vázquez | Species abundance and asymmetric interaction strength in ecological networks[END_REF]. For C. jacea, the positive effect of MD was augmented when specialization on pollinators (d′) was high. Pollinator networks are typically nested, meaning there is a high reliance of specialist plants on generalist pollinators foraging on many floral species [START_REF] Bascompte | Plant-animal mutualistic networks: The architecture of biodiversity[END_REF], potentially diluting conspecific pollen transfer [START_REF] Arceo-Gómez | Plant-pollinator network structural properties differentially affect pollen transfer dynamics and pollination success[END_REF][START_REF] Lázaro | Linking species-level network metrics to flower traits and plant fitness[END_REF].

Under adaptive foraging, those generalist pollinators may minimize competition by concentrating on their specialist plant partners [START_REF] Valdovinos | Adaptive foraging allows the maintenance of biodiversity of pollination networks[END_REF]. Concomitantly high levels of MD and d′ may reflect a level of adaptive foraging that overcame the negative influence of nestedness on conspecific pollen transfer. Whereas when C. jacea specialization was low, there was an inverse relationship between MD and seed set which may be consistent with interspecific pollinator interferences resulting from high pollinator activity on C. jacea [START_REF] Greenleaf | Wild bees enhance honey bees' pollination of hybrid sunflower[END_REF].

Our analysis reveals the complex species-specific patterns in wild plant visitation and seed set driven by the distribution of floral resources and pollinator foraging movements in a heterogeneous farmed landscape [START_REF] Jha | Resource diversity and landscape-level homogeneity drive native bee foraging[END_REF][START_REF] Kovács-Hostyánszki | Contrasting effects of massflowering crops on bee pollination of hedge plants at different spatial and temporal scales[END_REF]. Overall, C. jacea seed set was supported by the attraction of pollinators to individual floral displays, by interspecific floral densities in the neighboring assemblage, and pollinator constancy of visits to conspecifics in the network of agroecological infrastructure across the farm [START_REF] Hegland | Floral neighbourhood effects on pollination success in red clover are scale-dependent[END_REF][START_REF] Morales | Interspecific pollen transfer: Magnitude, prevalence and consequences for plant fitness[END_REF]. C. segetum individual seed set benefited from a more complex combination of intra-and interspecific biodiversity and interactions operating at individual plant, local assemblage, and wider network levels [START_REF] Arroyo-Correa | Individual-based plant-pollinator networks are structured by phenotypic and microsite plant traits[END_REF][START_REF] Hegland | Floral neighbourhood effects on pollination success in red clover are scale-dependent[END_REF]. These differences reflected the seasonal turnover in floral resources distributed across the agroecological infrastructure and the dynamics and co-occurrence of pollination facilitation and competition operating within and between ecological scales [START_REF] Brosi | Pollinator specialization: From the individual to the community[END_REF][START_REF] Hegland | Floral neighbourhood effects on pollination success in red clover are scale-dependent[END_REF][START_REF] Kovács-Hostyánszki | Contrasting effects of massflowering crops on bee pollination of hedge plants at different spatial and temporal scales[END_REF][START_REF] Mesgaran | How to be a good neighbour: Facilitation and competition between two co-flowering species[END_REF].

A caveat to our study is that we only detect correlative patterns in pollinator and plant biodiversity and interactions, which we interpret according to known ecological processes (e.g., competition vs facilitation). Although we predicted and controlled for the effect of intra-and interspecific phenology on plant-pollinator interactions, the two plant species differ in other traits (e.g., life cycle; [START_REF] Tison | Flora gallica. Flore de France (Biotope Ed)[END_REF] that may also affect their interaction with pollinators. Additional field experiments that manipulate these processes (e.g., competition and temporal turnover) or assemblage structure (e.g., diversity, trait, or functional group structure) are needed to verify the precise mechanisms that produced the observed patterns at different ecological scales [START_REF] Magrach | Niche complementarity among pollinators increases community-level plant reproductive success[END_REF].

Our results highlight how the balance of intra-and interspecific plant-pollinator interactions may respond to spatio-temporal heterogeneity arising from individual phenology and agroecological management, in ways that affect wild plant species reproduction. How these biotic interactions are affecting the longer-term population persistence and genetic health of these wild flowering plant species remains unknown, however, but has implications for the performance of agroecological farm management in terms of weed management and provision of biodiversity and ecosystem services.

  des relations de compétition et de facilitation entre plantes pour la pollinisation et la disponibilité des ressources abiotiques affectent le succès reproducteur des espèces et des individus de plantes. La succession temporelle et l'hétérogénéité spatiale des ressources florales modifient les interactions plantes-pollinisateurs à différentes échelles écologiques (individu végétal, assemblage plantes-pollinisateurs local, réseau d'interactions des infrastructures écologiques à travers la ferme). Les variations intraspécifiques de phénologie de floraison peuvent moduler le succès reproducteur individuel en déterminant le niveau d'hétérogénéité spatio-temporelle de densité de donneurs de pollen, des interactions plantes-pollinisateurs et des ressources florales auxquelles un individu de plante est exposé. Nous avons mené une expérimentation pour tester comment la production de graines des plantes sauvages est affectée par les interactions plantes-pollinisateurs à différentes échelles écologiques, ces interactions étant modulées par la phénologie florale et l'hétérogénéité spatio-temporelle des ressources florales (découlant des infrastructures agroécologiques). Nous avons transplanté 144 individus de deux espèces végétales entomophiles (Cyanus segetum et Centaurea jacea) dans des infrastructures agroécologiques (10 bandes fleuries et six bandes enherbées semées) d'un domaine agroécologique expérimental (125 ha). Ces espèces à phénologie de floraison contrastée présentent toutes deux une longue période de floraison avec des variations intraspécifiques qui déterminent l'exposition des individus aux interactions plantes-pollinisateurs et aux conditions météorologiques. Nous avons appliqué une approche phénologiquement explicite centrée sur l'individu végétal, de manière à relier précisément la période de floraison de chaque individu aux niveaux correspondants d'hétérogénéité spatiotemporelle des interactions plantes-pollinisateurs, des densités de donneurs de pollen potentiels, des ressources florales (aux échelles de l'individu végétal, de l'assemblage local et du réseau d'interactions des infrastructures écologiques à travers la ferme) et des conditions abiotiques (température, précipitations, azote). L'attractivité individuelle (offre florale et taux de visite par les pollinisateurs) ainsi que la densité florale (toutes espèces) dans l'assemblage interspécifique local ont affecté positivement la production individuelle de graines des deux espèces végétales. Celle de C. jacea augmentait aussi directement avec la densité d'individus conspécifiques fleuris dans l'assemblage local. La densité de couplage du réseau a

  affecté positivement la production individuelle de graines des deux espèces et a influencé celle de C. segetum en modifiant l'effet de l'assemblage local (richesse et densité florales, richesse spécifique de pollinisateurs potentiels) sur le nombre de graines par individu. Le succès reproducteur individuel de C. segetum augmentait aussi avec le niveau de dépendance mutuelle entre l'espèce et ses pollinisateurs dans le réseau. Chez C. jacea, la production de graines individuelle était maximisée quand à la fois le niveau de spécialisation de C. jacea sur ses pollinisateurs dans le réseau et sa dépendance mutuelle à ses pollinisateurs étaient élevés. Les conditions abiotiques n'ont eu qu'un impact limité voire inexistant sur le succès reproducteur. Nos résultats montrent comment l'équilibre des interactions plantes-pollinisateurs entre espèces et individus, peut répondre à l'hétérogénéité spatio-temporelle liée à la gestion agroécologique de différentes façons qui affectent la reproduction des plantes sauvages. Les relations entre les interactions plantes-pollinisateurs et la production individuelle de graines des plantes focales se déclinent entre et au sein de différentes échelles écologiques, de l'individu à la communauté, impliquant une co-occurrence d'interactions facilitatrices et compétitrices entre espèces et individus de plantes via les pollinisateurs.

2.

  At the individual-plant scale, higher seed production would be related to greater relative individual attractiveness to pollinators, defined as the combination of a larger relative individual floral display compared to the floral display of other conspecifics of the plot, and a greater associated pollinator visitation rate. 3. Seed set would be increased by greater conspecific pollen donor densities and by higher species richness of potential pollinators attracted by larger heterospecific blooms of flowers (species richness and densities) in the local assemblage surrounding the plot of focal conspecific individuals. 4. Greater linkage density (Lq) and specialization (d′) or mutual dependence (MD) of focal plants on their pollinators in the interaction network at the scale of agroecological infrastructure (sown wildflower and grass/legume strips) across the farm would increase seed set by providing connectivity of conspecific pollen transfer between spatially separated plants. 5. Seed set will be modulated by the interplay of plant-pollinator relationships occurring within and between ecological scales due to the mobility of insects transferring pollen. 2 | MATERIAL AND ME THODS 2.1 | Focal plant species Cyanus segetum Hill, 1762, and Centaurea jacea L., 1753 [Asteraceae], were chosen as phylogenetically related herbaceous species with contrasting flowering phenology and with populations on the study 20457758, 2023, 1, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ece3.9707 by Cochrane France, Wiley Online Library on [04/01/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License site. C. segetum is an annual segetal species with individuals flowering from May to July. C. jacea is a common perennial of grassy environments flowering in late summer (July-October in Burgundy, France; Tison & de Foucault, 2014). Both species require insect pollinators (C. jacea-self-incompatible; C. segetum-pseudo-selfcompatible) and provide high-quality pollen and nectar resources for flower-visiting insects

  In mid-March 2019, we transplanted 144 individuals per species, split into 16 plots of nine individuals per species (three triplets, 100 cm apart), located either in 10 wildflower strips or in six grass strips (together referred to as "agroecological infrastructure" hereafter), with plots at least 150 m apart (Figure S1). C. segetum focal individuals originated from ARBIOTECH (http://www.arbio tech.com) and were germinated in controlled conditions (22 ± 3°C; 16 h light: 8 h dark) prior to transplantation. We collected 48 large C. jacea rosettes (second-year individuals ready to flower) from each of three local populations (CA-SYS platform: 47°19′06.7″N 5°04′17.6″E; Dijon: 47°19′06.7″N 5°04′17.6″E; and Champdôtre: 47°10′42.5″N 5°17′02.0″E) and transplanted three individuals from each population into the experimental plots.

  Centered on each focal plant plot, we established a transect (100 m × 2 m, n = 16 transects) to assess the local flowering plant assemblage and plant-pollinator interactions (see below). At monthly intervals, a team of two botanists surveyed the assemblages in six systematically placed quadrats (0.5 × 2 m) per transect to identify all entomophilous (Eudicotyledon) plant species present and the total number of floral units per species (a single or composite flower, spike, or umbel). From these data, we calculated corresponding to the flowering period of each individual focal plant: the mean floral richness (Equation S2), mean floral density (m -2 ; Equation S3), and the mean density (m -2 ) of potential conspecific pollen donors (C. segetum or C. jacea) in the local assemblage. Furthermore, to ensure representativity of the assemblages and interactions considered, these means were temporally weighted by the overlap between the individual plant's flowering period and the time period (number of days) covered by each botanical survey (Equations S2-S3).

  ) matched to focal individual flowering phenology (C. segetum: May-July; C. jacea: July-September, with only a brief phenological overlap in mid-July). Bimonthly standardized sampling sessions were done per focal plant plot (15 min observing flowering ≤9 C. segetum or ≤9 C. jacea individuals) and per local floral community (15 min transect observing insects visiting all flowering species) with insect visitors actively feeding or having contact with floral stamen/anthers directly captured to avoid resampling individuals. Hymenoptera and Syrphidae were subsequently identified 20457758, 2023, 1, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ece3.9707 by Cochrane France, Wiley Online Library on [04/01/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License as species using standard keys (References S1), while other Diptera and a few Lepidoptera individuals were assigned to a Recognizable Taxonomic Unit (RTU = morphospecies approach following Oliver & Beattie, 1993). Standard pollinator sampling protocols (09:30-17:30, in dry and warm weather ≥14°C and with minimal wind: Beaufort scale <4/5) were applied with each sampling round involving two teams of two people who, after an initial harmonization session, followed the identical protocol (insect capture and monitoring focal plant development) in parallel on different plots/transects. The order the plots/transects were sampled was randomized on each occasion (1-3 days for all plots/transects) to avoid introducing a systematic bias. We quantified the relative attractiveness (RIA, n insect visits/individual/15 min) of each individual focal plant for foraging pollinators in terms of the visitation rate per 15 min weighted by the size of the individual floral display relative to the total plot-level floral display of each focal plant species (Equation 1). where i = the focal individual considered; s = a single pollinator survey conducted on the plot of conspecific focals including individual i during the flowering period of individual i; N = the total number of pollinator surveys conducted during the flowering period of individual i. We also calculated the local species richness of potential pollinators of C. segetum or C. jacea during each individual's flowering period. We defined potential pollinators as insects observed visiting focal or non-focal C. segetum or C. jacea, respectively, in the surveyed agroecological infrastructure (TableS2). For each focal plant individual, only those insect species captured foraging (on any plant species) in the local assemblage surrounding the individual during its flowering period were included in the species list of potential pollinators.2.7 | Structure of plant-pollinator networks of agroecological infrastructure across the farmTo create phenologically explicit quantitative (weighted) bipartite networks matching the flowering period of each focal plant individual, we summed the data of plant-pollinator interactions across the assemblages in the farm (16 transects) and the focal plots of C. segetum and C. jacea (16 plots) collected during each individual's flowering period.

  . While d′ describes the diversity of focal plant interactions, MD accounts for pollinator constancy in terms of the relative amount of pollinator interactions on the focal plants compared to other plant species in the network. where c = the focal plant species considered (C. segetum or C. jacea here); p = a pollinator species having visited the focal plant species (C. segetum or C. jacea); N = the total number of pollinator species having visited the focal plant species (C. segetum or C. jacea).

C

  . jacea model to avoid overfitting). Predictors of seed set reflecting the influence of the abiotic environment on each individual plant's growth and reproductive capacity were the foliar N content (%), mean temperature (°C), and mean precipitation (mm). Spatio-temporal heterogeneity in plant-pollinator interactions and floral assemblages at different ecological scales (focal plant individual; local assemblage; and interaction network of agroecological infrastructure across the farm) were fitted as fixed effects and two-way interactions between and within scales. These fixed effects predicted to affect seed set were the relative attractiveness of the focal plant (n visits/individual/15 min) at the individual plant scale and, at the local assemblage scale, the floral species richness, floral density (m -2 ), density of potential conspecific pollen donors (m -2 ), and local species richness of potential pollinators. At the scale (1) RIA i = ∑ N s=1 n visits on focal conspecific flowers of the plot s * n flowers i,s n tot conspecific focal flowers in the plot s ∕N

From

  each full model, we used an AIC-based multi-model selection procedure (ΔAIC <2; package MuMIn), avoiding the input of highly correlated variables (>70% Pearson coefficient), to identify the best subset of seed set predictors for each species according to their relative sum of weights (ω i ) contained in the top-ranked models. For C. jacea, to obtain model convergence, we had to compute several selection steps dropping certain predictors in turn from full models (foliar N content, density of potential conspecific pollen donors, individual attractiveness × floral richness or floral density, and floral density or floral richness × species richness of potential pollinators). Then, we ran a final selection process on the most complete full model containing parameters previously retained in the successive selection steps, and retained the best average model and subset of predictors.Predictors were scaled (z-transformation) and log-transformed where necessary to improve model fit. Model assumptions (normality and homoscedasticity of residuals) were checked (package DHARMa), as was collinearity among model predictors (package performance). We used the "effects" and "ggplot2" packages to calculate and visualize the marginal effects (fitted lines) of the predictors in both models. All statistical procedures were performed with R Studio (version 4.2.0).3 | RE SULTSC. segetum and C. jacea individuals that reached the flowering stage produced a mean (± SE) of 250.1 ± 29.4 seeds and 980.8 ± 188.5 seeds, respectively. In total, 1034 insects (Hymenoptera = 840 individuals, Diptera = 188, and Lepidoptera = 6) from 90 species were captured foraging on flowers of focal plant species (C. segetum: 197 individual insects; C. jacea: 86 individual insects) and the wider floral assemblages (751 individual insects; for species abundances and identities, see Tables

  Our individual-based, phenologically explicit approach and models accounted for the intraspecific variation in flowering phenology that can affect pollination processes by filtering the precise combination of spatio-temporal heterogeneity of floral resources and plant-pollinator interactions to which the individual plant was exposed (Arroyo-Correa et al., 2021; CaraDonna & Waser, 2020; Rafferty & Ives, 2012). As predicted, focal plant reproduction TA B L E 1 Final GLMM of C. segetum seed set in response to abiotic (N, H 2 O, and °C) and biotic (plant-pollinator interactions and floral assemblage) predictors matched to the flowering period of focal plant individuals at the scale of the individual plant, local assemblage, and the plant-pollinator network of the agroecological infrastructure across the farm.

  was affected by the combination of pollinator interactions and floral resource heterogeneity operating at the scale of the plant individual, the local assemblage, and the plant-pollinator network of agroecological infrastructure across the farm landscape (Arroyo

  The interplay between pollinator and floral species richness in the local assemblage further affected C. segetum reproduction, although relatively weakly, compared to other predictors. C. segetum seed set tended to decrease or increase with increasing local species richness of potential pollinators when assemblage floral richness was low or high, respectively. A potential explanation is that in species-poor floral assemblages, although plant competition for F I G U R E 1 Seed yield of focal C. segetum (a-c) and C. jacea (d-f) individuals in relation to: (a) relative individual attractiveness; (b) assemblage floral density; (c) assemblage floral richness × species richness of potential pollinators; (d) relative individual attractiveness × assemblage floral density; (e) local density of potential pollen donors; and (f) species richness of potential pollinators. Fitted lines (± CI) are partial residuals accounting for other fixed and random (C. segetum) effects from GLMMs. To visualize the interactive effect on seed set, values of local floral density and richness were fixed to the mean of the data included in each of the four data quarters, using the three quartiles as threshold values. The scatter plots show the distribution of the raw data. One point (C. jacea seed set = 15,769) was removed from graphs d, e, and f for better visualization (but not from the calculation of marginal effects). pollinators was reduced (Arceo-Gómez & Ashman, 2014), there was greater interspecific competition and interference among pollinator species enhancing their movement (Fontaine et al., 2008; Greenleaf & Kremen, 2006) in ways that disrupted conspecific pollen transfer and lowered seed set. Alternatively, where species richness of the floral assemblage and foraging pollinators were both F I G U R E 2 Seed yield of focal C. segetum individuals in relation to: Network linkage density interacting with (a) assemblage floral richness, (b) assemblage floral density, and (c) species richness of potential pollinators; and (d) the mutual dependence between C. segetum and its pollinators. Fitted lines (± CI) are partial residuals from GLMMs accounting for other fixed and random effects. The scatter plots show the distribution of the raw data. One point was deleted from graph d (seed set = 2009) for better visualization (but not from the calculation of marginal effects).F I G U R E 3 Seed yield of focal C. jacea individuals in relation to (a) network linkage density and (b) d′ specialization × mutual dependence between C. jacea and its pollinators. Fitted lines (± CI) are partial residuals from GLMs accounting for other fixed effects. The scatter plots show the distribution of the raw data. One point was deleted from graph A (seed set = 15,769) for better visualization (but not from the calculation of marginal effects).

  can influence plant species reproductive outcomes. The structure of plant-pollinator networks in agroecological infrastructure across the farm also influenced the reproduction of the individual focal plants during their respective flowering periods.

  c -1 total n interactions p -1 20457758, 2023, 1, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ece3.9707 by Cochrane France, Wiley Online Library on [04/01/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License

	LABONTÉ et al.	| 7 of 14

  20457758, 2023, 1, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ece3.9707 by Cochrane France, Wiley Online Library on [04/01/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License

  20457758, 2023, 1, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ece3.9707 by Cochrane France, Wiley Online Library on [04/01/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License

  20457758, 2023, 1, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ece3.9707 by Cochrane France, Wiley Online Library on [04/01/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License

	LABONTÉ et al.	| 11 of 14

  20457758, 2023, 1, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ece3.9707 by Cochrane France, Wiley Online Library on [04/01/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License

20457758, 2023, 1, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ece3.9707 by Cochrane France, Wiley Online Library on [04/01/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License

Funding information

ANER Bourgogne-Franche-Comté (ESREA Project), Grant/Award Number: C2325-1552-1565; European Commission (H2020 Safeguard), Grant/Award Number: GA 101003476; French Ministry for Education and Research (Ecole Doctorale Environnement-Santé, Université de Bourgogne), Grant/Award Number: MESR 2019-18; Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (SPE -SCOURGE Project), Grant/Award Number: INRAE-SPE-IB2019 and facilitation among co-flowering plants and abiotic resource availability can modify plant species and individual reproduction.

DATA AVA I L A B I L I T Y S TAT E M E N T

Data are available via the Dryad Digital Repository: doi: 10.5061/ dryad.bvq83bkdk. O RCI D Audrey Labonté https://orcid.org/0000-0001-5092-1471 Lucie S. Monticelli https://orcid.org/0000-0002-0745-3905 Stéphane Cordeau https://orcid.org/0000-0003-1069-8388

CO N FLI C T O F I NTE R E S T

The authors declare no conflict of interest.

S U PP O RTI N G I N FO R M ATI O N

Additional supporting information can be found online in the Supporting Information section at the end of this article.


domain: spi chim phys

text:
Mathilde Courel

Barbara Rega

Souad Fehaili

Pierre Giampaoli

Catherine Bonazzi

Instrumentation of a semi-industrial oven to monitor non-enzymatic browning kinetics during baking

Instrumentation of a semi-industrial oven to monitor nonenzymatic browning kinetics during baking M. Courel, M. Courel, B. Rega, S. Fehaili, P. Giampaoli and C. Bonazzi UMR1145 Ingénierie Procédés Aliments, AgroParisTech, INRA, F-91300 Massy (mathilde.courel@agroparistech.fr)

This work deals with the design and characterization of a reactor enabling to generate reliable and realistic kinetic data on non enzymatic browning reactions occurring during the transformation of bakery products. A semi-industrial baking oven was thus developed with the objective of controlling heat transfers and delivering synchronous information on the physical and chemical transformations of the product during baking. Sponge cake was used as a model of solid matrix and 5-hydroxymethylfurfural (HMF) was selected as a specific chemical indicator of both Maillard and caramelization reactions.

T (°C)ventilation

h conv (W.m -2 .K -1 )  rad / total (

Conclusion

  Maillard and caramelization reactions could be monitored synchronously in the cake matrix and emitted vapors during a complete baking operation under fully controlled thermal conditions. This oven should be of precious help for further kinetic modeling of complex thermal reactions occurring in solid food matrix baked under real process conditions. This work was carried out with the financial support of the French National Research Agency, project ANR-06-PNRA-023 REACTIAL.


Zhiyan Chen

Haozhe Li

Keyan Sheng

Xiaohan Dong

Jushigang Yuan

Shuai Hao

Minghao Li

Rongxian Bai

Yves Queneau

Alexander Sidorenko

Jiang Huang
email: jhuang@hust.edu.cn

Yanlong Gu

Zhiyan Chen -Key

Dipolar Modification in Heterogeneous Catalysts under Electron Beam Irradiation for the Conversion of Biomass-derived Platform Molecules

Keywords: biomass-derived platform molecules, electron beam irradiation, irradiation, dipolar catalyst, biomass

Herein, an efficient and practical approach for dipolar modification of commercially available solid catalysts is reported. The solid catalysts HMS (hexagonal mesoporous silica)-DMSO decorated with organic dipolar layers are designed and synthesized by radiation technology under simple and accessible conditions. The dipolar catalysts can serve as platforms to introduce various active sites, benefiting from the flexibility and diversity of the dipolar layer, which in turn allow them to achieve catalytic performance in relatively friendly systems. Specifically, the upgraded dipolar catalyst HMS-DMSO-SO3H exhibits good performance in converting the oxidized lignin model compound of α-hydroxyacetophenone to 1,3dioxolane derivatives and dehydrating isomaltulose to glycosyloxymethyl-furfural (GMF).

With the world energy crisis and total global energy consumption increasing dramatically, it is essential to develop methods for the efficient use of renewable resources. [START_REF] Shen | Catalytic self-transfer hydrogenolysis of lignin with endogenous hydrogen: road to the carbon-neutral future[END_REF][START_REF] Ates | Structures, and Advanced Applications of Nanocomposites from Biorenewable Resources[END_REF][START_REF] De | Hydrodeoxygenation processes: Advances on catalytic transformations of biomass-derived platform chemicals into hydrocarbon fuels[END_REF] Biomass, as an attractive carbon-based source, has been widely used to produce value-added fine chemicals and fuels. [START_REF] Xu | Recent catalytic routes for the preparation and the upgrading of biomass derived furfural and 5-hydroxymethylfurfural[END_REF][START_REF] Gu | Bio-based solvents: an emerging generation of fluids for the design of eco-efficient processes in catalysis and organic chemistry[END_REF][START_REF] Shuai | Formaldehyde stabilization facilitates lignin monomer production during biomass depolymerization[END_REF][START_REF] Xia | Direct hydrodeoxygenation of raw woody biomass into liquid alkanes[END_REF][START_REF] Zhao | Metal chlorides in ionic liquid solvents convert sugars to 5hydroxymethylfurfural[END_REF] The catalytic activation/cleavage of ubiquitous C-C/C-O bonds in biomass is crucial through various methods, including oxygen removal processes and increasing the molecular weight via C-C coupling reactions. [START_REF] Espro | Sustainable production of pharmaceutical, nutraceutical and bioactive compounds from biomass and waste[END_REF][START_REF] Corma | Chemical Routes for the Transformation of Biomass into Chemicals[END_REF][START_REF] Thiyagarajan | A Facile Solid-Phase Route to Renewable Aromatic Chemicals from Biobased Furanics[END_REF] Efficient regulation of the state of reaction intermediates derived from C-C/C-O bond activation/cleavage to maximize the selectivity and yield of bio-based products is a key challenge. In this context, a valid strategy for this goal in heterogeneous catalysis is to enrich the dipolarity of the solid catalyst surface, allowing the reactants to participate in specific non-covalent interactions to stabilize or destabilize the reaction intermediates, thereby enabling the transformations to proceed smoothly. [START_REF] Gao | Replacement strategies for non-green dipolar aprotic solvents[END_REF][START_REF] Zhang | Heterogeneously Catalyzed Hydrothermal Processing of C5-C6 Sugars[END_REF][START_REF] Mellmer | Solvent Effects in Acid-Catalyzed Biomass Conversion Reactions[END_REF][START_REF] Nikolakis | Fructose-Water-Dimethylsulfoxide Interactions by Vibrational Spectroscopy and Molecular Dynamics Simulations[END_REF][START_REF] Mellmer | Effects of chloride ions in acidcatalyzed biomass dehydration reactions in polar aprotic solvents[END_REF][START_REF] Bui | Domino Reaction Catalyzed by Zeolites with Brønsted and Lewis Acid Sites for the Production of γ-Valerolactone from Furfural[END_REF][START_REF] Marković | Polysulfones: Catalysts for Alkene Isomerization[END_REF] However, there is still a lack of universal methods to prepare dipolar catalysts.

Despite these encountered challenges, with great efforts and contributions from many pioneers, various dipolar catalysts have been designed and synthesized successfully for the conversion of biomass. [START_REF] Gao | Replacement strategies for non-green dipolar aprotic solvents[END_REF][START_REF] Schwartz | Engineering Catalyst Microenvironments for Metal-Catalyzed Hydrogenation of Biolog-ically Derived Platform Chemicals[END_REF] For example, the organic-inorganic nanocomposite catalysts with dipolar microenvironments were prepared, which exhibited excellent catalytic performance for the selective conversion of fructose to HMF in a mixed solvent of water and tetrahydrofuran. [START_REF] Alamillo | A Tailored Microenvironment for Catalytic Biomass Conversion in Inorganic-Organic Nanoreactors[END_REF] Xiao and co-workers developed the heterogeneous catalyst with strong dipolar moieties through constructing microenvironment to tune the performance of active sites. [START_REF] Sun | Creating solvation environments in heterogeneous catalysts for efficient biomass conversion[END_REF] The catalysts exhibit high yields of fructose to 5-hydroxymethylfurfural in THF. Parallelly, a dipolar and flexible linear polymer polyvinylpyrrolidone (PVP) was incorporated into the pores of the acidic COF material to facilitate the fructose dehydration reaction. [START_REF] Sun | Reaction Environment Modification in Covalent Organic Frameworks for Catalytic Performance Enhancement[END_REF] Recently, the HCP materials with a dipolar moiety have been developed as alternatives to DMF in the conversion of NaN3 to benzylic azides and triazoles. [START_REF] Gao | Dipolar HCP materials as alternatives to DMF solvent for azide-based synthesis[END_REF] Although these strategies have been developed, complex designs, long synthesis periods and lack of clean processes lead to high costs of catalyst synthesis, which are the important factors that limiting their application in industry. [START_REF] Hübner | Why Does Industry Not Use Immobilized Transition Metal Complexes as Catalysts?[END_REF] From a catalyst design perspective, it is generally recommended to optimize the already existing catalyst for a specific process, which mainly depends on the needs of the user, rather than to develop an entirely new catalyst material. [START_REF] Arun | Green diesel synthesis by hydrodeoxygenation of bio-based feedstocks: Strategies for catalyst design and development[END_REF] Obviously, the development of general and eco-efficient methods for dipolar modification of readily available catalysts or supports is one of the important issues that chemists need to address urgently at present.

Currently, electron beam irradiation (EBI) technology has been used as a green replacement method for traditional chemical processing, especially surface modification processes. [START_REF] Kim | The state of the art in the electron beam manufacturing processes[END_REF][START_REF] Zhang | Electron Beam Irradiation as a General Approach for the Rapid Synthesis of Covalent Organic Frameworks under Ambient Conditions[END_REF][START_REF] Chen | Electron Beam Irradiation-Induced Formation of Defect-Rich Zeolites under Ambient Condition within Minutes[END_REF][START_REF] Xie | Radiationinduced surface modification of silanized silica with n-alkylimidazolium ionic liquids and their applications for the removal of ReO4 -as an analogue for TcO4[END_REF][START_REF] Sheng | Increasing the surface hydrophobicity of silicone rubber by electron beam irradiation in the presence of a glycerol layer[END_REF] The EBI process is a flow of energetic electrons generated by an accelerator that directly injects energy to the materials, and then initiates a series of chemical reactions through free radicals to improve product quality by changing its chemical and physical properties. Compared with other conventional methods, the EBI technology is an efficient method of chemical modification because no catalysts or additives are required to initiate the reaction, and the chemical reaction can be easily adjusted by varying the radiation conditions under simple operation, thus enabling large-scale production. The EBI technology thus offers a great opportunity for the production of dipolar catalysts that are not easily accessible by chemical methods.

Out of all these considerations, in this work, without changing the specific preparation process of the original catalysts, an efficient and versatile method is reported for dipolar modification of commercially available solid catalysts by EBI technology. The high-density dipolar moieties were anchored on the surface of catalyst via rapid thiol-ene reaction, which endows the catalyst with polar properties. Notably, the upgrade catalyst exhibits outstanding performance in the conversion of lignin model compound to valuable 1,3-dioxolane derivatives and the dehydration of isomaltulose to glycosyloxymethyl-furfural (GMF). The successful implementation of this protocol not only brings innovation to the catalysts synthesis industry, but also significantly relieves the dependence on unfriendly polar aprotic solvents in the conversion process of biomassderived platform molecules. In order to confirm the structures of the grafted moieties, the prepared catalysts including HMS-DMSO and HMS-DMSO-SO3H were characterized by various spectroscopic methods. The FTIR spectroscopy showed that the profiles of fresh and irradiated silica-based catalysts were quite similar, as shown in Figure 1a, indicating that the chemical structure of catalysts was not significantly changed through electron beam irradiation. The silica-based HMS-SH catalysts showed weak characteristic peak appearing at about 2527 cm -1 , which was assigned to the vibration of the HS group. [START_REF] Sun | Postsynthetically Modified Covalent Organic Frameworks for Efficient and Effective Mercury Removal[END_REF][START_REF] Rostamizadeh | Au anchored to (α-Fe2O3)-MCM-41-HS as a novel magnetic nanocatalyst for watermedium and solvent-free alkyne hydration[END_REF] Meanwhile, the bands at 2985 cm -1 and 2934 cm -1 corresponded to the symmetric stretching vibrations and asymmetric stretching vibrations of the -CH2 group. [START_REF] Li | Mercury nano-trap for effective and efficient removal of mercury(II) from aqueous solution[END_REF] The disappearance of the S-H stretching band, while the peaks of catalysts with DMSO moieties, including HMS-DMSO and HMS-DMSO-SO3H, were significantly enhanced at these locations, indicating that the grafting of sulfolane onto the surface of silica-base was successful. Despite the fact that the broad area at 1250-1000 cm -1 may include many characteristic peaks, the emerging peaks at 1188 cm -1 and 1132 cm -1 in HMS-DMSO-SO3H were related to stretching vibration of the S=O bonds of aromatic sulfonic acid. [START_REF] Chen | Conversion of fructose into 5-hydroxymethylfurfural catalyzed by recyclable sulfonic acid-functionalized metal-organic frameworks[END_REF][START_REF] Phang | Superprotonic Conductivity of a UiO-66 Framework Functionalized with Sulfonic Acid Groups by Facile Postsynthetic Oxidation[END_REF] These results implied that the grafting of double bond-containing species onto the silica-based surface via electron beam irradiation was successful. Besides, the characterization with [START_REF] Zhang | Heterogeneously Catalyzed Hydrothermal Processing of C5-C6 Sugars[END_REF] C MAS NMR spectra also suggested dipolar moieties and acid sites were successfully introduced, as demonstrated in Figure 1b. It was clearly observed that the chemical shifts of three catalysts varied with the grafted species. Compared with the starting material of HMS-SH, the carbon peaks in HMS-DMSO around 55.8, 51.9, 39.8 and 33.9 ppm were ascribed to sulfolane species. After treatment of acidification, the emerging peaks at 149.0, 147.1, 140.4, 126.7 ppm in HMS-DMSO-SO3H were related to the aromatic sulfonic acid. [START_REF] Zhan | The carbon material functionalized with NH2 + and SO3H groups catalyzed esterification with high activity and selectivity[END_REF][START_REF] Yang | Sulfuric Acid-Functionalized Mesoporous Benzene-Silica with a Molecular-Scale Periodicity in the Walls[END_REF] In addition, with the increase of the strong electron-withdraw groups, the resonance-absorption peaks move to lower field, resulting in larger chemical shifts of HMS-DMSO-SO3H.

As representative samples, X-ray photoelectron spectroscopy (XPS) of HMS-DMSO-SO3H was shown in Figure 1, while the detailed characterization results of other samples are provided in the ESI (Figures S6-S7). As expected, all the essential elements were observed (Figure S8), and the conspicuous signal of C 1s appeared at 284.79 eV was assigned to the C-C bond (Figure 1d). [START_REF] Lang | Novel fluorination of polystyrene sulfonic acid resin by CF3SO3H for high stability and strong acidity[END_REF] The two peaks were located at 285.80 and 286.45 eV, which were assigned to the C-S and C-O bands, respectively. [START_REF] Kang | Cost-Effective, High-Performance Porous-Organic-Polymer Conductors Functionalized with Sulfonic Acid Groups by Direct Postsynthetic Substitution[END_REF] The O 1s clearly evidenced the presence of three chemical environments for the oxygen atoms (Figure 1e). The predominant peak at 532.71 eV was characteristic of the HMS backbone, while the peak at 533.68 corresponds to the C-O groups. [START_REF] González | Microwave-assisted synthesis of sulfonic acid-functionalized microporous materials for the catalytic etherification of glycerol with isobutene[END_REF] Notably, in the O 1s XPS spectra of HMS-DMSO-SO3H, the existence of S-O band was evidenced by the peak appearing at 531.80 eV. Indeed, the S-O bands were also found in the O 1s XPS spectrum of HMS-DMSO, and the content of surface elements increased significantly after sulfonation. Correspondingly, it was clearly showed that in the S 2p region (Figure 1f), the characteristic peaks at 168.12 eV and the peaks area ratio were about 2:1, which can be attributed to the S-O bond. [START_REF] Liu | Design and Synthesis of Mesoporous Polymer-Based Solid Acid Catalysts with Excellent Hydrophobicity and Extraordinary Catalytic Activity[END_REF][START_REF] Fu | Lithium Nitrate Regulated Sulfone Electrolytes for Lithium Metal Batteries[END_REF] The pattern of the S 2p region showed peaks located at around 163.47 eV, which is attributed to the presence of C-S groups on the surface of HMS-DMSO-SO3H (Tables S2-S3). These results indicated that the grafting of dipolar moieties and -SO3H groups onto the surface was successful. The morphologies of the obtained catalysts were investigated by emission scanning electron microscopy (FE-SEM), and the changes of the three catalysts were shown in Figure 2. With the increase of monomer G1, a large number of particles are generated on the surface of the smooth massive solid (Figure 2a), forming unique spatial structures (Figure 2b). After treatment of sulfonic modification, the structures were more compact (Figure 2c), which was consistent with the above description. The energydispersive spectroscopy (EDX) analysis indicated that all the expected elements were present and uniformly distributed in the HMS-DMSO-SO3H (Figure 2d-2f) catalyst as well as HMS-DMSO (Figure S9). Furthermore, the effect of electron beam energy on the catalyst preparation process is evaluated by means of the Monte Carlo code FLUKA. Electron beam energy is one of the most vital parameters in the process of electron irradiation, which affects the absorbed dose distribution in catalysts and determines the quality of the product. [START_REF] Apiwattanakul | Electron beam dynamic study and Monte Carlo simulation of accelerator-based irradiation system for natural rubber vulcanization[END_REF][START_REF] Chen | Metal-Organic Framework@Metal Oxide Heterostructures Induced by Electron-Beam Radiation[END_REF] The results show that the EBI technology is amenable for the role of surface modification due to its strong penetrating ability and uniform distribution (Figures S12-S15). In addition, the prepared materials including HMS-SH, HMS-DMSO and HMS-DMSO-SO3H were also submitted to elemental analysis to confirm the amount of grafted DMSO or -SO3H fragment on silica-based composite. Compared with the raw material of HMS-SH, the sulfur content of HMS-DMSO increased significantly after treating HMS-SH with 3-sulfolene, indicating the occurrence of grafting. By attributing the increase in sulfur content to the anchoring of monomer G1 onto HMS-SH, the amount of grafted DMSO moieties was approximately 1.1 mmol/g. Indeed, HMS-SH exhibits a better ability to graft monomer G1 due to its high loading of thiol groups (2.21 mmol/g). [START_REF] Lai | Silica-supported metal acetylacetonate catalysts with a robust and flexible linker constructed by using 2-butoxy-3,4-dihydropyrans as dual anchoring reagents and ligand donors[END_REF] To facilitate the subsequent introduction of active sites to maximize the catalytic ability, an excess amount of aromatic sulfonic acid was used. The concentration of the grafted -SO3H fragment on the HMS-DMSO is approximately 0.88 mmol/g (Table S1).

The N2 sorption isotherms were collected and the N2 isotherms corresponded to type-IV isotherm, which was typical for mesoporous materials (Figures S10). Analysis of pore-size distribution evaluated shows that pore-sizes were predominantly distributed at 4.0 nm. The Brunauer-Emmett-Teller (BET) surface areas of all the obtained materials were also calculated. The SBET of the dipolar catalysts decreased from 1351 m 2 g -1 of HMS-SH to 979 m 2 g -1 of HMS-DMSO, mainly contributed by the increase of G1 content. After treatment of sulfonation, the catalysts still exhibited high surface areas (768 m 2 g -1 ) and no significant change in surface area was observed. The thermal stability of the obtained catalysts was inspected by thermogravimetric analysis (TGA) (Figure S11). Although the organic components in HMS-DMSO or HMS-DMSO-SO3H were significantly higher than that in HMS-SH, it was observed from the TGA curves that all the catalysts were quite stable below 240 o C. When the temperature was elevated to around 270 o C, the weight loss was clearly observed in HMS-DMSO-SO3H. The TGA results implied that the obtained catalysts have an excellent thermostability, it is feasible to use them in harsh conditions. The fluorescence emission spectra were also analyzed, as shown in Figure 1c. To the best of our knowledge, Nile red was a sensitive probe, which was considered the best choice to determine the local polarity of some media in a variety of heterogeneous systems because the photophysical properties of Nile red vary with the polarity of the solvent. [START_REF] Yang | Macro-/micro-environment-sensitive chemosensing and biological imaging[END_REF][START_REF] Yang | A Nile Red/BODIPY-based bimodal probe sensi-tive to changes in the micropolarity and microviscosity of the endoplasmic reticulum[END_REF][START_REF] Swain | Nile red fluorescence for quantitative monitoring of micropolarity and microviscosity of pluronic F127 in aqueous media[END_REF] Upon photo-excitation at 400 nm, the fluorescence intensity of Nile red adsorbed in HMS-DMSO and HMS-DMSO-SO3H almost disappeared with the increase content of sulfone group, while the obvious peak at 649 nm was maintained after treatment with HMS-SH (see ESI for details). Significant decrease or even disappearance in intensity has been attributed to a formation of the twisted intramolecular charge transfer (TICT) state. [START_REF] Jee | Excited state dynamics of Nile Red in polymers[END_REF] The results demonstrated that the polarity of HMS-DMSO and HMS-DMSO-SO3H significantly enhanced by decoration of polar moieties.

To verify the applicability of dipolar catalysts as reaction medium, lignin model compound [START_REF] Chen | Synthesis of indoles and carbazoles from a lignin model compound αhydroxyacetophenone[END_REF] (1a) and formaldehyde (2a) were employed as reaction substrates to synthesize 1,3-dioxolane derivative 3a, which is useful intermediates in the synthesis of pharmaceuticals and fine chemicals. [START_REF] Tarr | Lanthanum Tricyanide-Catalyzed Acyl Silane-Ketone Benzoin Additions and Kinetic Resolution of Resultant α-Silyloxyketones[END_REF][START_REF] Lei | Visible-light-enabled aerobic synthesis of benzoin bis-ethers from alkynes and alcohols[END_REF][START_REF] Yoshikawa | Direct Catalytic Asymmetric Aldol Reaction: Synthesis of Either syn-or anti-α,β-Dihydroxy Ketones[END_REF] In the presence of HMS-DMSO-SO3H, various solvents were screened (Table 1, entries 1-4). EtOH and 2methyltetrahydrofuran (2-Me-THF) were not suitable for this reaction (entries 1 and 2). Although 1a didn't completely converted (entry 3), the result indicated that the dipolar catalyst is promising for achieving a good result. A moderate yield of 3a was obtained in cyclopentyl methyl ether (CPME, entry 3). When the reaction was performed in isopropyl acetate ( i PrOAc), 3a was obtained in 95% of yield (entry 4). Under the identical conditions, the reactions over p-toluenesulfonic, Amberlyst-15 and HMS-SO3H gave only moderate yields (entries 5-7). HMS-DMSO has no acidic site, but contains G1 fragment in the solid surface, has no catalytic acitivity for the synthesis of 3a (entry 8). When HMS-DMSO was used along with TsOH, 3a can be isolated with 56% yield (entry 9). To evaluate the effect of acid content, the catalysts with different ratios were prepared and the results were described in Table S4. Furthermore, the reference catalyst PSS-DMSO-SO3H [START_REF] Sun | Creating solvation environments in heterogeneous catalysts for efficient biomass conversion[END_REF] with dipolar moieties also exhibits good catalytic performance, affording the desired product in 62% yield (entry 10). These results demonstrate that the presence of dipolar components is indeed effective in enhancing the activity of the catalyst. The reactions over the analogous dipolar catalysts that were prepared through the conventional chemical grafting with free radical initiators proceeded sluggishly (entries 11 and 12). These results implied that the use of EBI is a key for ensuring the dipolar catalyst to have a good catalytic performance. It should be noted that the catalyst is also recyclable (Figure S23) and still maintains good catalytic activity after 5 cycles. Finally, a possible mechanism is illustrated, as depicted in Figure S16-S21.

Table 1. Condition optimization of the reaction lignin model compound and 2a.

Various substituents patterns and diverse functional groups in the aryl ring were used as viable substrates to react with 2a (Scheme 2). A series of compounds bearing electron-donating groups (3b, 3g, 3h) can also be successfully converted to the desired products with excellent yields.

Di-substituted electron-rich hydroxyacetophenones (3c, 3i) can react smoothly with 2a, affording the desired products in good yields. Various electron-withdraw groups, varying from halogen to cyano group (3k-3n), were also able to efficiently offer the corresponding products with the yields ranging from 83% to 59%.

Lignin model compounds contained large steric hindrance groups (3d-3e, 3j) was also welltolerated in this reaction. Notably, the substituent bearing phenyl group reacted smoothly in the presence of HMS-DMSO-SO3H, and the desired product 3f was obtained in 74%, which has been reported by using HCl as a catalyst in HOAc at 110 o C for 24 h. [START_REF] Vainer | ChemInform Abstract: Study of Products of the Condensation of Benzoin with Formaldehyde in an Acetic Acid Medium[END_REF] Interestingly, the heteroaromatic substrates could also be easily delivered uneventfully into the target product in moderate to good yields (3o-3q). These results indicated that the dipolar solid acids prepared with the aid of EBI were indeed efficient catalysts for the transformations of lignin model compounds to 1,3dioxolane derivatives.

Scheme 2. The substrate scope of lignin model compounds to 1,3-dioxolane derivatives.

The conversion of isomaltulose to glucosyloxymethylfurfural (GMF) was also evaluated. GMF is an interesting analog of 5-hydroxymethylfurfural (HMF) with a glucosyl moiety that has several applications and is highly sensitive to the dipolar environment. [START_REF] Tan | Glucosyloxymethylfurfural (GMF): a creative renewable scaffold towards bioinspired architectures[END_REF][START_REF] Lichtenthaler | Sugar-derived building blocks. Part 26. Hydrophilic pyrroles, pyridazines and diazepinones from -fructose and isomaltulose[END_REF][START_REF] Ontiveros | Design and Properties of a Novel Family of Nonionic Biobased Furanic Hydroxyester and Amide Surfactants[END_REF] As shown in Table 2, the reaction proceeded smoothly in valerolactone (GVL), but hardly proceeded in THF and CPME (entries 1-3). Gratifyingly, when HMS-DMSO-SO3H was used as the catalyst, the conversion of isomaltulose proceed smoothly in i PrOAc, providing the desired product 5a in 63% yield (entry 4). Given that 5a can be effectively separated in a low boiling solvent, the results are acceptable (see the NMR spectra of the product in ESI), despite the fact that the yields obtained are not as good as those already reported for the method performed in DMSO. When TsOH and Amberlyst-15 were used as catalysts, the yield obtained is inferior to the former catalysts of HMS-DMSO-SO3H (entries 5 and 6). In addition, HMS-DMSO and HMS-SO3H proved to be unsuitable for this reaction (entries 7 and 8). When TsOH was introduced into the reaction system of HMS-DMSO, only 17% of the desired product was obtained (entry 9). Besides, when the grafting rate of sulfolene was decreased, the yield of the product also decreased significantly (entry 12). Furthermore, the desired product can be obtained in 25%, when the reference catalyst PSS-DMSO-SO3H was used (entry 10). These observations imply the cooperative effect between the dipolar moieties and the acid groups are important factors in promoting chemical reactions (the mechanism see Figure S22 for details). The catalyst of HMS-DMSO-SO3H prepared by free radical initiators did not display the expected catalytic performance (entry 11). These results further demonstrate that the dipolar catalysts modified by EBI techniques are indeed necessary to enhance the catalytic capacity in the process of transformation, especially the transformation of biomass-derived platform molecules.

Table 2. Catalytic reaction in the dehydration of isomaltulose to GMF.

summary, the EBI technology provides an efficient and general method for dipolarization based on existing catalysts. Compared with traditional chemical methods, it has the advantages of simple steps, high efficiency, no initiator and easy engineering production. The use of the dipolar catalysts, not only enables successfully conversion of the biomass platform molecules, but also facilitated the separation of products in low boiling point solvent. Considering the economy and high efficiency of this method, this work opens up an avenue for the design, synthesis, and application of catalysts.

Scheme 1 .a

 1 Scheme 1. Schematic illustration of the preparation process of dipolar silica-based catalysts by electron beam

Figure 1 .

 1 Figure 1. a) The FT-IR spectra of HMS-SH, HMS-DMSO, and HMS-DMSO-HSO3H; b) solid-state 13 C NMR spectra of different dipolar catalysts; c) fluorescence emission spectra of Nile red adsorbed in three catalysts; XPS spectra of HMS-DMSO-SO3H, including magnifications of the C 1s (d), O 1s (e), S 2p region (f), the data of HMS-SH and HMS-DMSO are shown in figure S6-S7.

Figure 2 .

 2 Figure 2. FSEM image characterizations of different dipolar catalysts, a) HMS-SH; b) HMS-DMSO; c) HMS-DMSO-SO3H; d-f) elemental mapping of HMS-DMSO-SO3H for C (d), O (e) and S (f), the data of HMS-SH and HMS-DMSO are shown in figure S8.

ACKNOWLEDGMENT

We gratefully acknowledge the financial support from National Key Research and Development Project (2022YFE0124100), Ordos Key Research and Development Project (2022EEDSKJZDZX003), the National Natural Science Foundation of China (22072049, 21902054 and 21872060) and the HUST Academic Frontier Youth Team (2019QYTD06) for the financial support. Financial support from CNRS and MESRI and the China Scholarship Council for a scholarship to Lianjie Wang who prepared GMF samples in the Lyon team is also acknowledged.

Funding Sources

National Key Research and Development Project (2022YFE0124100), Ordos Key Research and Development Project (2022EEDSKJZDZX003), the National Natural Science Foundation of China (22072049, 21902054 and 21872060) and the HUST Academic Frontier Youth Team (2019QYTD06) are the key funding sources for the financial support. Financial support is also partially from CNRS and MESRI for financial support and to the China Scholarship Council for a scholarship to Lianjie Wang who prepared GMF samples in the Lyon team.

AUTHOR INFORMATION

Notes

The authors declare no competing financial interest.

ASSOCIATED CONTENT

The Supporting Information is available free of charge via the Internet at http://pubs.acs.org. The synthetic procedures, optimization data, chemical computations, experimental procedures, and characterization data (PDF)


domain: spi phys

text:
Mathilde Courel

Manuel Dornier

Marcel Gilbert

Max Rios

Reynes

Combination of microfiltration and osmotic evaporation to prepare high quality passionfruit juice concentrates

Concentration methods :

❏ OE Model E06 (Cogia, France), 10.3 m 2 0.2 µm PP fibres, 41 w/w % CaCl 2 brine, 4.3 kg.h -1 evaporation rate ❏ VD of juice, Corning unit 3 kg.h -1 condensation rate under 3.10 3 Pa. Fractionation of condensate, Büchi unit 15 % rate of recovery for 25 l.h -1 of fruit juice.

Materials and methods

Context and objective

Osmotic evaporation (OE) is a membrane technique allowing concentration of aqueous solutions at ambient temperature and pressure. The water is extracted in gas phase by circulating the dilute solution on one side of a hydrophobic porous polymer and a hypertonic salt solution on the other side (Fig. 1). In this work, crossflow microfiltration (MF) and OE are combined to concentrate passionfruit juice and compared to conventional vacuum distillation (VD) on the basis of physical-chemical characteristics as well as flavour loss in the reconstituted juice.

Conclusion

OE as well as VD allowed to achieve high concentration degrees of 40 to 50°Brix with total retention of the sugars and acids in the passiofruit juice concentrates. Although OE appears more gentle, the aroma loss remains non negligible and sensory analysis would help evaluating the perceived impact on final organoleptic quality. The high quality of the products obtained by cut-back shows the benefit of combining MF and OE: the performance of OE is improved because of lower viscosity of the clarified juice and the aroma retention is increased by mixing back the pulp to the concentrate.

Results

The OE applied to pulpy or clarified juices allows to maintain the composition of the juice and to achieve concentration degrees of 45 to 50 % total soluble solid (TSS), comparable with a conventional VD process (Table I).

Among the 25 volatile compounds identified by GC-MS in the initial juice, 7 were selected on the basis of reproducibility (Fig. 2) and used to compare the flavour loss of 4 concentration methods. VD leads to severe losses and reincorporating the fractionated distillate into the concentrate (VD-RA) hardly improves the flavour loss in this study. OE generates significantly lower losses but the best results are obtained for the cut-back method (MF-OE) (Table II). (1) nr: non reproducible, (2) tr: trace, too small to quatify

M❏

  Design and production: Cirad-dist, fax: 33(0)4 67 61 55 13 enzymation with 400 mg.kg -1 Rapidase Liq + (Gist Brocades) ❏ Imeca crossflow MF device, 1.3 m 2 0.2 µm Membralox® IP19-40 (SCT France)

Table I :

 I Comparison of the physical-chemical characteristics of the initial passionfruit juice (IJ) with the concentrates obtained by : osmotic evaporation (OE) or vacuum distillation (VD) of pulpy juice, OE of clarified juice (OE) mixed with microfiltration retentate (MF-OE).

Table II :

 II Flavour loss measured as initial vs final concentration (C i /C f ) in passionfruit juice reconstituted from the concentrates obtained by : osmotic evaporation of pulpy juice (OE), OE of clarified juice mixed with microfiltration retentate (MF-OE), vacuum distillation of pulpy juice (VD) with aroma recovery (VD-AR).

	Aroma compound		Aroma loss factor (Ci/Cf)
		OE	MF-OE	VD	VD-AR
	Ethyl acetate	3.0	1.6	11.4	10.8
	Ethyl butanoate	4.8	2.1	23.4	nr (1)
	Hexyl butanoate	nr	1.9	tr (2)	nr
	Ethyl hexanoate	5.6	~ 1	tr	tr
	β-myrcene	6.1	~ 1	25.2	22.3
	Limonene	~ 1	~ 1	13.8	10.6
	Trans-ocimene	nr	~ 1	17.3	19.1