Xin Zhang
email: zhangx@nercita.org.cn

Xiaojun Qiao
email: qiaoxj@nercita.org.cn

Wengang Zheng
email: zhengwg@nercita.org.cn

Cheng Wang
email: wangc@nercita.org.cn

Yunhe Zhang
email: zhangyh@nercita.org.cn

The Design of Portable Equipment for Greenhouse's Environment Information Acquirement base on Voice Service

Keywords: greenhouse, environment parameters, voice service, portable equipment

For settling the problem of acquiring environment parameters quickly and responding in time in greenhouse which has low ability of autocontrolling environment. This paper designed a voice service system which was used in greenhouse for environment information collecting. This equipment can acquire and analyze the parameters of temperature, humidity, illumination, dew point temperature, soil temperature, soil humidity. And it offered alarm and environment controlling suggestion by voice. This equipment achieved data acquiring, storage, displaying and voice service by MCU msp430 and voice chip PM50S100. Expert knowledge which had simple decision logic was embedded in this system . This equipment offered simple voice service based on the collecting data in greenhouse. And it had advantages of convenience operation, low power consumption through the test in greenhouse.

Introduction

The main symbol of agriculture modernization's level is the facilities agriculture's development which uses protected agriculture as the main representative. Facilities agriculture in China has made rapid development in recent years. And it plays an important role to improve farmer's incomes and quality of life. But at present, simple structure greenhouses such as solar greenhouse & plastic greenhouse which are widely used in China. Most of these greenhouses have backward technology, low levels of machinery and automation. The current advanced information technology is not used in these greenhouse deeply . Facilities production remains in experience management, unscientific & non-standard management. All these situations are seriously affected the yield and efficiency. Most of information collection instruments in greenhouse environment are expensive, un-flexible and single parameter collection. But equipments with more parameters acquisition function has large size, high power consumption and bring the inconvenience in installation and maintenance. All these equipments also need personal view and recording by operators. When many equipments are used in large-scale greenhouses, it is needed for additional staff and long time observation which may cause nervous fatigue and error record [START_REF] Jing | Development of voice warning system for the environmental information in greenhouse[END_REF]. The voice communication technology combines with the environment information collection equipment is a new direction of greenhouse environment collection & controlling in intelligence and information. The technology which mentioned upon is used in many fields. Agricultural consulting and calling business has matured in Europe and United States [START_REF] Qi | The design and realization on voice service system orienting cow[END_REF]. One of U.S. research institution designed a soil moisture meter with wireless voice service which could dial to user's cell phone to send alarm information when the data exceeded the setting [START_REF] Li | The design of voice alarm system[END_REF]. Agricultural calling center base on mid-ware which designed by Beijing Institute of machinery had made expert system in networks, remote consultation and calling center to come true. And built a model which could bring out 24 hour pest diagnosis, advisory services. Beijing Academy of Agriculture and Forestry had similar system [START_REF] Zhang | The construction of agriculture calling center base on middle ware. The dynamic of telecom decision[END_REF] [START_REF] Song | The past, now and future of calling center[END_REF].Bo Jing, Xiaojun Qiao proposed and developed the voice warning system for the environmental information in greenhouse [START_REF] Jing | Development of voice warning system for the environmental information in greenhouse[END_REF].Caili designed a voice-alarm system for greenhouse base on DDE and FCS technique [START_REF] Cai | Design of the voice-alarm system for greenhouse base on DDE and FCS technique[END_REF]. The applications above focused on passive network calling and initiative alarm. But there are lack of deep study in the expert knowledge and smart voice technology which integrated with portable greenhouse environment information acquisition device. It is urgent need to design low price and practical product which rely on the voice service technology.

This paper has designed a portable equipment for greenhouse's environment information acquirement base on voice service. This equipment is cost-effective, easy to use, multi-parameters measurement and can use voice to guide the different cultural level farmers to manage greenhouse production according to different crop growth stages' demands. Promote the use of this product can effectively increase the level of greenhouse production and management, and give full play to the potential of greenhouse production.

Design ideas overview

As figure 1 showed greenhouse site needs to measure the common environment parameters accurately by external ways. Temperature & humidity, soil temperature, light etc. are the key parameters in greenhouse management. Solar radiation shield is used for measuring temperature & humidity avoiding solar radiation and bad weather. The portable equipment obtains and stores data from sensors according to the setting time interval. And data were showed in the liquid crystal displayer at the same time. Simple logic expert knowledge table was integrated in the device. So it could guide farmer by voice. Many communication methods were used in this system. RS485 /Internet/Wireless achieved the greenhouses monitoring by network. When used USB to communication with the PC, this equipment as a portable device to measure the data from greenhouse by moving. This paper focus on the design of sensor, data gathering equipment and PC software. The hardware design used ultra-low power MCU MSP430F149 which had 60KB flash, 2KB RAM, two 16bit timers, eight channels 12bit A/D converter, USART/SPI port and so on [START_REF] Sheng | The elements of 16bit ultra-low power MCU MSP430[END_REF]. 128*64 dots matrix LCD was used for displaying the sensor data and setting menu. Real time clock chip DS1302 provided clock and date for system. Flash data storage memory chip AT45DB081 provided 1Mbytes space for store the data of environment [START_REF] Atmel | The datasheet of 8Megabit 2.7-volt Only Serial DataFlash[END_REF]. 4*5 touch panel was used for system setting. Embedded real audible voice module (PM50S100) was used for voice service. Charge chip LTC4055 charged for the inside 2A lion battery . NCP500 provided 3.3V voltage for the system. Ti's chip TPS2044 was used for managing the power of sensors. Zigbee module ,GPRS module, Internet module, usb and RS485 could used in this equipment. User can choose the suitable communication ways for application. Some kinds of crop production's expert knowledge were embedded in the ROM chip FM24CL64. Temperature and humidity sensor SHT11 was used in this system. This sensor integrated sensor element plus signal processing on a tiny foot print and provide a fully calibrated digital output. The applied CMOSens® technology guarantees excellent reliability and long term stability. Both sensors are seamlessly coupled to a 14bit analog to digital converter and a serial interface circuit. DS18B20 encapsulated in stainless steel was used for measuring the soil temperature. Programmable light to frequency converter chip TSL230B was used for measuring the light.

Voice processing circuit

This design used smart voice chip PM50S100 which was produced by ATVOC company. Compared with the ISD's voice chip , PM50 had better tone quality and lower price. This chip was made up of voice MCU and Flash RAM. 100 seconds playback function was enough for this equipment. Actual circuit is showed in Figure3. MSP430F149 sent instruction to PM50 for controlling the voice file by series port.

Voice signal could through the op amp LM386 for output or PWM mode was used for driving 8 ohm 0.5W speaker directly [START_REF]Atvoc:The datasheet of PM50 series smart voice chip[END_REF].  IF Tn> Tmax then voice file "baby cry sound", " It's too hot, open the windshield quickly" .  IF Tn< Tmin then voice file "baby cry sound", " It's too cold, close the windshield quickly" . Tn is the temperature now, Tmax is the setting maximun temperature ,Tmin is the setting minium temperature.

Integrated design of expert knowledge

This design choosed the representative crops which often grow in greenhouse . These crops were also classified into six kinds, and coded in binary. (See the Table 1) The 64Kbit FRAM FM24CL64 used for storing the expert knowledge [START_REF] Qiao | High performance planting technology of greenhouse's vegetables and flowers[END_REF]. User can choose different crops and growth stages from the expert knowledge. The data in the expert knowledge table was also changed by user's experience and actual environment. FAT store structure was used for storing the expert knowledge. Expert knowledge divided the crops into eggplant, melon and fruit, leafy, beans, fruit trees, flowers. The RAM address 0x0000-0x001F was used as the first index of partition which was showed in Table 2. The equipment get the actual crop's store address through index address in Table2. Actual crop's store information was store in the second index of partition(partition's address is 0x0020-0x01FF). Table 3 showed part of actual crop's store information. The stages in Table 3 means that the number of stages. promote germination period, germination period, seeding period, transplant period, after transplant period, one week before planting, planting to seeding stage, growth stage, flowering fruit setting period, expanding fruit stage, harvest storage period were used in expert knowledge [START_REF] Qiao | High performance planting technology of greenhouse's vegetables and flowers[END_REF]. Table 4 showed that the actual data in promote germination period. All the tables showed that the physical address was memory's address, and the number is the content stored in this address. The expert knowledge table which mentioned above was managed by two levels address index method. This method made the expert knowledge's embedded application conveniently because it searched data easily and saved the memory space.

Low power embedded software design

As a portable equipment whose sensors' data gathered , LCD displayer, background light, voice output had large power consumption. All these devices were not suited working for a long time. Work mode should been managed by software and hardware. The sensors' power must be closed when they did not used. LCD displayer was in doze mode when there were no data refreshed or keypad acted. The part of voice output's working mode was divided into real time, compare, alarm, close mode. All these modes were used in equipment could lower the power consumption.

The structure of low power software was showed in Figure 4. The program came into low power mode after it started and initialize the system. The flags were changed in the interrupt service routine. Subroutines were called by flags' judgment in main routine. This software coding mode base on interrupt-wake up could lower more power consumption [START_REF]Application Report of MSP430 Software Coding Techniques[END_REF].

PC software design

Base on the design of the underlying hardware and software. The information's analysis & management software was designed on PC platform. This PC software could get the environment information which gathered by the hardware. Many kinds of communication ways were used in the software. The data collected could be showed by figures and tables. Search and statistical analysis service were also provided in the PC software. Software design based on the operation system Windows XP Professional. Programming language was Visual C++ 6.0. The software design followed the below outline.  Good compatibility. Software was designed by module method. Other module could not affected when one of module was changed.  Fine interface. Toolbar and pull-down menu were used in the software. User did not study the usage of the software. It is easy to operating the software by click some icons.  Simple operation. Each operation function was distributed by user's operate habit. The sensors used in this equipment were tested and calibrated by National Standards Research Center which belong to National Bureau of Quality and Technical Supervision. The sensors' performance parameters were showed in Table 5. Took temperature and humidity testing as example. Calibration and test followed the test rules of JJG368-2000, Copper-copper nickel thermocouple was used for calibrating the temperature. Constant temperature and humidity box MFT-434A provide stable temperature and humidity environment. Precision equipment M4/1111H was used for testing dew point temperature . Calibrate the humidity followed the rules of JJF1076-2001. The humidity generator M4/1311DR provided stable environment. Dew point temperature calibration followed the rule of JJG499-87 [12]. Calibration result was showed in Table 6. Table 6 showed the sensors were suitable for greenhouse measurement.

Function test

The equipment was tested in greenhouse for a long time. The M.T.B.F. is over one year. It's stability and adaptability could meet the greenhouse's production acquirement . Test picture and real time data were showed in Figure 6

The 3 Fig. 1 . 3 . The design of underlying hardware and software 3 . 1

 31331 Fig.1. Structure of portable equipment for greenhouse's environment information acquirement base on voice service

Fig. 2 .

 2 Fig.2. Structure of hardware

Fig. 3 .

 3 Fig. 3. Voice processing circuit Voice files were recorded by professional recording equipment. Software Cool editor edited the voice files and divided file into sections which were programmed to

The 7 Fig. 4 .

 74 Fig.4. The structure of low power software

Fig. 5 . 5 . 1

 551 Fig. 5. Part of interface of PC software

Fig. 6 .

 6 Fig. 6. Test and real time data pictures

Table 1

 1 Actual crops' kings and codes

	Crop kinks	Code	Crops
	Eggplant	0001	Tomato, Pepper
	Melon and fruit	0010	Muskmelon, Cucumber
	Leafy	0011	Fennel, ,Celery
	Fruit trees	0101	Grape, Pear
	Flowers	0110	China rose, Chrysanthemum

Table 2 .

 2 The first index of partition (0x0000-0x001F)

	Physical Address	0x0000	0x0001	0x0002	0x0003
	Note	eggplant	kinds	Address. H	Address. L
	Number	0x01	0x02	0x00	0x20

Table 3 .

 3 The second index of partition (0x0020-0x00FF)

	Physical Address 0x0020 0x0021	0x0022	0x0023
	Note	tomato	stages	Address. H	Address. L
	Number	0x01	0x04	0x02	0x00

Table 4 .

 4 Part of parameter table of expert knowledge

	Physical Address	0x0280	0x0281	0x0282	0x0283	0x0284	0x0285	0x0286	0x0287	0x0288
	Note	germination Tdmax.L Tdmax.H	Tdmin.L	Tdmin.H Tnmax.L Tnmax.H Tnmin.L Tnmin.H
	Number	0x01	16	25	16	15	16	25	15	16
	Physical Address	0x0289	0x028A	0x028B	0x028C	0x028D	0x028E	0x028F	0x0290	0x0291
	Note	Hdmax	Hdmin	Hnmax	Hnmin	Lmin	Lmax	STdmax.L STdax.H STdmin.L
	Number	60	80	60	80	2	30	16	36	10
	Physical Address	0x0292	0x0293	0x0294	0x0295	0x0296	0x0297	0x0298	__	__
	Note	STdmin.H STnmax.L STnmax.H STnmin.L STnmin.H	SHmin	SHmax	---	---
	Number	16	16	26	10	16	obligate	obligate	----	----

*T: temperature, H: humidity, L: light, ST: soil temperature, SH: soil humidity, d: daylight, n: night

Table 5 .

 5 Sensors' performance parameters

	Sensors	Resolution Accuracy	Range
	Temperature 0.1℃	±0.1℃	-40℃~80℃
	Humidity	0.1%RH	±2%RH	0~100%RH
	Soil Temp.	0.1℃	±0.2℃	-40℃~80℃
	Dew point	0.1℃	±1℃	-40℃~80℃
	Light	0.1 Lux	±5%	0~200000Lux

Table 6 .

 6 The data of calibration and testThe Design of Portable Equipment for Greenhouse's Environment Information Acquirement base on Voice Service 9

	Num.	Temperature(℃) Standard Measure Amend Standard Measure Humidity(%RH) Amend	Standard	Dew point(℃) Measure Amend
	1	-10.5	-10.5	0.0	10.4	11.0	-0.6	-11.7	-10.8	-0.9

Xin Zhang1,2 , Xiaojun Qiao1,Wengang Zheng2, , Cheng Wang2 , Yunhe Zhang2

Xin Zhang1,2 , Xiaojun Qiao1,Wengang Zheng2, , Cheng Wang2 , Yunhe Zhang2

Xin Zhang1,2 , Xiaojun Qiao1,Wengang Zheng2, , Cheng Wang2 , Yunhe Zhang2

Xin Zhang1,2 , Xiaojun Qiao1,Wengang Zheng2, , Cheng Wang2 , Yunhe Zhang2


Dan Jin
email: jindan76@163.com

Jingying Tan
email: jingyingtan@163.com

Qing Wang

Study on Refrigeratory Compressor with Frequency Conversion and Its Economical Efficiency

Keywords:

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

Introduction

It is essential that the quality of fruits and vegetables is sustained by pre-cooling and cold storage. Compressor in cold storage is the most energy-consuming unit in the refrigeration system, which consumes 30% of the input power of the electric machinery [1] . The property of the compressor is the most important in the whole refrigeration system. Now more researchers focus on frequency conversion applied on compressor, and propose better advice [2]~ [5] .Those compressor are mainly applied on air conditioning, some on electric refrigerator. There are few literatures about cold storage with frequency conversion. Now the main mode for temperature control is on-off full-frequency in precooling and cold storage. The control precision of temperature and humidity by full-frequency is less than that by frequency conversion, even more energy is wasted [START_REF] Jingying | Experiment on the Control of Temperature and Humidity and Thermal Response for Pre-cooling Cold Storage[END_REF]. In the paper, energy-saving by frequency conversion on compressor is discussed in pre-cooling and cold storage and its prospect is analyzed in detail.

Energy-regulating and Energy-consuming

The choice of compressor is based on the refrigerating output. The environmental temperature of the refrigeration system is between the extreme high one in summer and the extreme low one in winter. It fluctuates more than that of the air conditioning system. It is shown by literature [START_REF] Meffect | Energy Efficiency of Transport Refrigeration Units[END_REF] that cold container works in its partial condition during most time. There is a great difference between actual application and ISO criteria for cold container. The common cold storage is even so. So it is necessary to regulate energy in order to match the refrigerating output with thermal loading and make the compressor serve the more conditions. There are several regulation means for compressor to control the energy-consuming, such as On/off, inspiration throttle, cylinder off-bear, hot gas by-pass and frequency conversion. Refrigeration compressor in cold storage mostly depends on On/off to control the energy-consuming. When temperature in cold storage is higher than that of the upper limit set, compressor starts to decrease the temperature. While temperature in cold storage is lower than that of the low limit set, compressor stops. Therefore, temperature in the cold storage fluctuates between the low limit set and the up limit set. On/off is suitable for the thermal loading fluctuating little. In fact, thermal loading of cold storage varies much due of the season. In addition, the load of the portable cold storage and the cold container is influenced by the climate in different place. The compressor works in varying condition, enables and closes down frequently. This results in energy-consuming and leads to reduction of service life of the compressor at the same time. So On/off has much limitation. With the development of frequency conversion, it is widely used in air conditioning compressor, which provides much information to apply it on refrigeration compressor in cold storage. The features [START_REF] Zhu | Energy Regulating by Frequency Conversion on Air Conditioning Equipment[END_REF][7] of stepless regulation, simple construction, high accuracy control and high efficiency of frequency conversion make frequency conversion have a good prospect in application on cold storage.

Theoretical Analysis of Energy-saving of Compressor with Frequency Conversion

Given a certain condition, refrigerating output is ratio to mass flux of refrigerant. The basic theory of frequency conversion is based on rotating speed of compressor to obtain different mass flux of refrigerant and to gain refrigerating output expected.

Energy-consuming is obtained by theoretical analysis as follows:

2 1 1 2 1 2 1 4 1 H H Q Q N Q H H η η ε η η - = = = - K (1) 2 1 1 2 1 4 1 H H K H H η η - = - (2) v Q Cn q λ = (3)
where K-effective power consumption per refrigerating output C-structural coefficient of compressor Q-refrigerating output q v -refrigerating output per volume λ-transfer coefficient ε-EER n-number of speeds H 1~4 -enthalpy η 1 -mechanical efficiency η 2 -adiabatic efficiency It is concluded from the equation ( 1)-( 3) that power consumption is related to both K of effective power consumption per refrigerating output and Q of effective power consumption per refrigerating output. When the thermal loading decreases, rotating speed of compressor is reduced by transducer. It can be seen from Fig. 1. This leads to the reduction of mass flux. So the condensing temperature of refrigerant increases, the evaporating temperature of it decreases, the value of (H2-H1)/(H1-H4) decreases, and the refrigerating output decreases. On the other hand, it is showed in Fig. 2 that reduction of rotating speed will lead to the reduction of friction work and increase of adiabatic efficiency. It decreases K. The power consumption is greatly reduced by decreasing rotating speed of compressor at partial loading. The power consumption versus mass flux of refrigerant is nearly linear [START_REF] Scalabrin | Experimental Thermo-dynamic Analysis of a Variable Speed Open Reciprocating Refrigeration Compressor[END_REF] [START_REF] Benamer | Test Bench for Comparative Measurement of Energy Efficiency of Variable Speed Open Reciprocating Refrigeration Compressor[END_REF]. Conclusions can be drawn from Fig. 3 that EER is 40%~90% of high rate of rotating speed. The effect of energy-saving is very obvious.

Q/Q max W/W max
Fig. 3. Relations between the rates of refrigerating output, power consumption and rotate speed

Analysis of Energy-saving of Frequency Conversion and its Economical Efficiency

The portable cold storage is examined in the fruits and vegetables place of origin. There are two compressors in a cold storage. The power of one compressor is 2.2kw, air exhaust of it is 9.38m3/h, and rotating speed of it is 2950rpm.

Thermal Loading of the Portable Cold Storage

1 Thermal loading from cold storage wall The surrounding T1 is 40℃, the extreme high temperature, temperature T2 is 0 in cold storage, and the thermal conductivity λ of the cold storage wall with 100mm is 0.032W/(m•K) ,the heat transfer area A is 46m 2 , and the inner volume V of the cold storage is 15.625m3 The thermal loading q1 is 563w, which is obtained according to Fourier equation as follows: q1=λ×A×(T1-T2)/ δ=0.032×44×40/0.1=563(w)

The thermal loading q2 caused by gas exchanger for fresh air in cold storage is 50w.

2 Thermal loading of fruits and vegetables It is presumed that specific heat of grapes is 3.6kJ/kg• and density ℃ is 300kg/m 3 . It is supposed that the body temperature decreases from 30 of T3 to 0 of T4 within 8 hours and the capacity coefficient of the cold storage is 0.4, which demonstrates the ratio of volume of grapes to volume of cold storage. Thermal loading q3 of fruits and vegetables is 7031w, which is calculated as follows: q3=C×ρ×0.4×V×(T3-4)/t=3600×300×0.4×15.625(30-0)/(8×3600)= 7031w

(5)

3 Thermal loading caused by respiration of grapes At 30 , the coefficient q40 ℃ of respiration heat is 420kJ/(T•h) The overall thermal loading q4 caused by respiration of grapes is 218.75w, which is calculated as follows: q4=ρ×0.4×V×q40= 300×0.4×15.625×420/3600=218.75(w) [START_REF] Jingying | Experiment on the Control of Temperature and Humidity and Thermal Response for Pre-cooling Cold Storage[END_REF] 4 Total thermal loading q5 calculates as follows:

q=q1+q2+q3+q4+q5=563+50+7031+218.75=7862.75w (7)
The total thermal loading is taken to be 8000w. The power of compressor is 4.4kw if EER is 2

Energy Calculation and Economics Analysis

The weight of grapes being pre-cooled in a cold storage, W W=300×15.625×0.4=1875(kg)

If the weight of grapes is 20000kg, the total amount of electricity will be saved by H t .

Ht =94376.8×20000/1875/1000=1006.686(kw.h)

The profit of ¥503.3 will be obtained in a month considered the common electricity price of ¥0.5/(kw.h). A common transducer is ¥2000-3000.

So rate of return on investment is higher to apply frequency conversion for compressor in cold storage.

Conclusions

The energy regulation on the refrigeratory compressor by frequency conversion is better than that by fullfrequency. On/off is suitable for the thermal loading fluctuating little. It is favorable for compressors by frequency conversion to work in varying condition, which can enable and close down frequently. The most economical way for energy-saving are demonstrated by an example. Rate of return on investment is higher to apply frequency conversion for compressor in cold storage.

High efficiency and energy-saving, environmental protection, stepless regulating, and little noises will be the future features of the refrigeration compressor in cold storage. Compared with other means for energy regulation, frequency conversion application has a new broad prospect because of its features.

Fig. 1 .Fig. 2 .

 12 Fig. 1. Relations between mass flux and rotating speed

Table 1 .

 1 Regulating means and its energy-consuming

	regulating means		Feature	Power-consuming rate at 60% load
				(%)
	On/off	simple structure, low price, low accuracy control,	63%
		commonly used in compact units with partly thermal
		loading, and much energy-consuming at enablement.
	cylinder off-bear	Step regulation, used in units with several cylinders	-----
		and low efficiency at partly thermal loading
	inspiration throttle	stepless regulation, simple structure, regulation range	70%
		limited, and low efficiency
	hot gas by-pass	stepless regulation, complicated constructure, and low	100%
		efficiency
	frequency	stepless regulation,	simple constructure, high	60%
	conversion	accuracy control, high efficiency, and high cost

Table 2 .

 2

		thermal loading and energy-consuming
	thermal loading(%)	energy-consuming of compressor(w.h)	energy-saving rate(%)
		Frequency conversion	ON/OFF
	20	300	522	43
	30	496	687	28
	50	886	1016	13
	70	1277	1345	5
	80	1472	1509	2
	100	1863	2200	0
	According to Tab.2, power-consuming in a month between frequency conversion and ON-OF is compared after
	initial stages of pre-cooling at the total thermal loading 20%.
	The amount of electricity is saved by 94376.8 w•h of H s ,
	H s =2×(522-300)×30×24×2200/1863=94376.8(w.h)

Acknowledgements:

The authors are grateful for the sponsorship of National Natural Science Foundation of China(50874045) and Liaoning Province Education Office (2008T158) for the research.


Haiou Wang
email: wanghaiou@ustb.edu.cn

Guangrong Zhong

Fangting Pan
email: fangting@ustb.edu.cn

{wang Haiou

Zhong Guangrong

Pan Shi Guoqing

Toxicity of Cu, Pb, and Zn on seed germination and young seedlings of wheat (Triticum aestivum L.)

Keywords: Heavy metals, Seed, Germination parameters, Seedling

Seeds and young seedlings of wheat (Triticum aestivum L.) under exposure to Copper (Cu), lead (Pb) and Zinc (Zn) were studied by employing a hydroponic experiment. Addition of Cu or Pb or Zn to the solution inhibited seed germination, plumule and radicle elongation. The toxic of metals to seed germination parameters can be arranged in the rank order of inhibition as follows: Cu > Pb >> Zn. This study showed the contents of chlorophyll and soluble protein in young seedlings of wheat were decreased after 4 d of all heavy metal treatments. Among the tested metals, the toxic of metal to young seedlings was found similar to seeds. All heavy metal concentrations in seedlings increase with their increase in the medium and the duration of treatments. On the other hand, the results demonstrated that the excess accumulation of Cu in leaf and roots could reduce accumulations of zinc (Zn); the excess accumulation of Pb decreased the levels of Cu or Zn in leaf and roots; the excess accumulation of Zn had no influence on Cu accumulations in leaf and roots.

Introduction

Toxic heavy metals have no function to organism and can be highly toxic when their concentrations are exceeded threshold value. Other heavy metals at low doses are essential micronutrients for plants, but in higher doses they may cause metabolic disorders and growth inhibition for most of the plants species [START_REF] Fargašová | Toxicity comparison of some possible toxic metals (Cd, Cu, Pb, Se, Zn) on young seedlings of Sinapis alba L[END_REF][START_REF] He | Effects of Cadmium Stress on Seed Germination, Seedling Growth and Seed Amylase Activities in Rice (Oryza sativa)[END_REF]. Researchers have observed that some plants species are endemic to metalliferous soils and can tolerate greater than usual amounts of heavy metals [START_REF] Yoon | Accumulation of Pb, Cu, and Zn in native plants growing on a contaminated Florida site[END_REF]. Several studies have been conducted in order to evaluate the effects of different heavy metal concentrations on live plants [START_REF] Bose | Heavy metal accumulation in wheat plant grown in soil amended with industrial sludge[END_REF][START_REF] Gholamabbas | Transport of Cd, Cu, Pb and Zn in a calcareous soil under wheat and safflower cultivation-A column study[END_REF]. Most of these studies have been conducted using seedlings or adult plants. In a few studies, the seeds have been exposed to the metals [START_REF] He | Effects of Cadmium Stress on Seed Germination, Seedling Growth and Seed Amylase Activities in Rice (Oryza sativa)[END_REF]. All data shows heavy metals delay the normal growth periods of plants.

Seed germination is a process of crucial importance and as such it must be tightly regulated. In the plant's life cycle, seed is a stage that is well protected against various stresses. However, soon after imbibitions and subsequent vegetative developmental processes, they become stress sensitive in general. Therefore, seeds are equipped with sensing mechanisms that allow it to obtain the information required to assure that germination will only occur when environmental factors are favorable to complete developmental processed. The effects of metals in seed germination had been investigated. Li et al. [START_REF] Li | Effects of heavy metals on seed germination and early seedling growth of Arabidopsis thaliana[END_REF] reported toxic heavy metals could significantly inhibit Arabidopsis thaliana seed germination, plumule and radicle growth.

The accumulation of metals, the content of total soluble protein, and chlorophyll in wheat seedlings were further examined in order to disclose the toxicity mechanisms of metals in plants. Thereafter, it could be helpful to improve the plant growth security in polluted soil.

2

Materials and methods

Plant materials and heavy metal treatments

The heavy metals used in this study (Cu, Pb and Zn) were in the form of nitrates.

Seven concentrations (between 0 and 250 mM) of each metal were used in this study.

The selected concentrations of Cu, Pb and Zn were 0.5 1, 10, 50, 100 and 250 mM, respectively. For each treatment, the pH was adjusted to 6.5. Wheat seeds were purchased from a local seed market. The seeds were sterilized in 10% Nahypochlorite solution for 20 min to prevent fungal growth, washed with distilled water for several changes. A second hydroid culture experiment was performed to determine whether the supply of Cu, Pb and Zn would inhibit seedling growth (e.g. Chlorophyll and soluble protein content) or whether descend mineral nutrient metal uptake. Ten-day-old wheat seedlings were exposed to Cu, Pb and Zn (1 and 50 mM, respectively) and studied during 4 d.

Determination of germination parameters

Seed germination and shoot/root elongation test on filter paper was carried out in glass Petri dishes (90 × 15 mm) with three layers of filter paper on the bottom. Each dish contained 9 mL of metal solution or 9 mL of distilled water (control), and 100 seeds, covered by lid. Petri dishes containing seeds were incubated for 8 d in a dark chamber at 28 ºC ± 1 ºC. Number of geminated seeds was counted 3 d after the treatments. Radicle and plumule lengths were recorded at 4 d, 6d and 8d. Each treatment was in triplicate.

Determination of metal contents

The uniform wheat seedlings at 4 d after the treatments were immerged in ice Tris-Mes solution for 15 min, rinsed with demonized water thoroughly, and then plant material was dried at 70 °C for 2 d, weighed and then milled. Samples were digested in a 3 : 1 mixture of HNO 3 : HClO 4 . The digests were used to determine cations, by ICP-OES. All measurements were repeated in triplicate.

Determination of Chlorophyll and protein

Total chlorophylls were extracted with 80% acetone and estimated according to Arnon [START_REF] Arnon | Copper enzymes in isolated chloroplasts: polyphenoloxidase in Beta vulgaris[END_REF]. Total soluble protein content was determined by the method of Bradford [START_REF] Bradford | A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding[END_REF] using BSA as a standard.

Results and Discussion

3.1

Effects of heavy metals on wheat seed germination The germination percentages of wheat seeds exposed to different concentrations of metals were given in Table 1. The seed germination rate over control decreased significantly with increasing metal concentration. The toxic of metals to seed germination parameters can be arranged in the rank order of inhibition as follows: Cu > Pb >> Zn. Germination inhibitory rate of Cu increased by 4.9%, 6.3%, 26.7%, 64.8%, 100% and 100% at 0.5, 1, 10, 50, 100 and 250 mM, respectively; the increase was 0.6%, 0.7%, 1.9%, 8.7%, 17.7% and 47.9% at 0.5, 1, 10, 50, 100 and 250 mM, respectively, for Zn; and the increase 5.3%, 9.7%, 13.9%, 53.7, 81.3% and 100% at 0.5, 1, 10, 50, 100 and 250 mM, respectively, for Pb. The seed germination rate was found no affected by Cu and Pb at lower concentrations of 0.5 and 1 mM, while significantly affected by Cu and Pb at higher concentration of metal ranging from 10 to 250 mM. Wheat seed was able to germinate at all Zn concentration evaluated, even at a concentration 250 mM in this study. Jadia and Fulekar [START_REF] Jadia | Phytoremediation: The Application Of Vermicompost To Remove Zinc, Cadmium, Copper, Nickel And Lead By Sunflower Plant[END_REF] obtained similar results in a study using Cd, Cu, Ni, Pb and Zn on sunflower seeds. Salvatore et al. [START_REF] Di Salvatore | Assessment of heavy metals phytotoxicity using seed germination and root elongation tests: A comparison of two growth substrates[END_REF] also reported low metal concentrations were observed to have no effect on seed germination while the inhibiting effect of heavy metals on seed germination was tested at high concentrations, such as to reduce the germination percentage.

2 Effects of heavy metals on seedling growth

In the present experiment, the toxicological effects of metals (Cu, Pb, Zn) on the wheat seedling root and shoot growth were observed. The inhibitory effects of metals on the radicle and plumule lengths of young seedlings were evaluated (Table 2 and3). Based on these values, metals can be arranged in a rank order of inhibition as follows: Cu > Pb >> Zn. The metal toxic rank of plumule elongation is similar with the result of radicle elongation; the only difference is the three metal concentrations which caused significant inhibition for plumule growth was much higher than that for radicle growth. That can be explained that metal accumulation in roots of wheat seedling was more than those of in leaves under the same metal treatment. Fargašová [START_REF] Fargašová | Toxicity comparison of some possible toxic metals (Cd, Cu, Pb, Se, Zn) on young seedlings of Sinapis alba L[END_REF] reported mustard seedlings (Sinapis alba L.) exhibited some symptoms of metal toxicity (e.g. reduced growth, chlorosis). The toxicity effect of the trace elements on the mustard seedling growth was, in descending order of damage, Cu > Se > Cd > Zn >> Pb. Cu is introduced as very toxic metals to many plants [START_REF] Tanyolac | Changes in photochemical and antioxidant enzyme activities in maize (Zea mays L.) leaves exposed to excess copper[END_REF] and this statement was fully confirmed during our experiments with wheat seedlings. A good agreement for the Cu inhibitory effect was found for the root and shoot elongation of wheat seedlings as compared with those reported by Fargašová [START_REF] Fargašová | Toxicity comparison of some possible toxic metals (Cd, Cu, Pb, Se, Zn) on young seedlings of Sinapis alba L[END_REF] for mustard seedlings. However, the difference was in the position of Zn, which was for mustard introduced as more toxic than Pb. Zinc indicated the lowest inhibitory effect on the root and shoot elongation of wheat in our tests corresponds with the values introduced by Mahmood et al. [START_REF] Mahmood | Germination and seedling growth of corn (Zea mays l.) under varying levels of copper and zinc[END_REF]. Even, Zn at 0.5 mM concentration promoted the root growth over the control root size by approximately 22.9% at the 4 d th of treatment. The similar effect also was reported by Jadia and Fulekar [START_REF] Jadia | Phytoremediation: The Application Of Vermicompost To Remove Zinc, Cadmium, Copper, Nickel And Lead By Sunflower Plant[END_REF].

Cu, Pb and Zn in wheat plants

In general, all heavy metal concentrations in seedlings increase with their increase in the medium and the duration of treatments (Table 4). The heavy metals, Cu, Pb and Zn were taken up by shoot and root both; and all metal concentrations were found to be higher in roots. The heavy metals were untaken by the wheat plants in the following order: Zn > Cu > Pb. Jadia and Fulekar [START_REF] Jadia | Phytoremediation: The Application Of Vermicompost To Remove Zinc, Cadmium, Copper, Nickel And Lead By Sunflower Plant[END_REF] demonstrated the heavy metals were accumulated by the sunflower plants in the following order: Zn > Cu > Cd > Ni > Pb and this rank order corresponds with the results obtained for wheat in here presented study. On the other hand, the results demonstrated that the excess accumulation of Cu in leaf and roots could reduce the level of zinc (Zn); the excess accumulation of Pb decreased the level of Cu or Zn in leaf and roots; the excess accumulation of Zn had no influence on Cu accumulations in leaf and roots.

Normal and phytotoxic concentrations of Pb, Zn and Cu were reported by Levy et al. [START_REF] Zengin | Effects of some heavy metals on content of chlorophyll, proline and some antioxidant chemicals in bean (phaseolus vulgaris l.) Seedlings[END_REF], which were 0.5 -10 and 30 -300mg kg -1 for Pb, 3 -30 and 20 -100mg kg -1 for Cu, and 10 -150 and > 100 mg kg -1 for Zn. In the present study, Cu and Pb were observed that they could interfere with the absorption process of Zn or Cu as nutrient element when heavy metal concentration in wheat seedling is higher than the normal or phytotoxic levels.

Heavy metals can bind strongly to oxygen, nitrogen and sulphur atoms. Because of these feature, heavy metals can inactivate enzymes by binding to cysteine residues and block the essential biological function of enzyme. Heavy metal can also displace the essential metal ions in bimolecular. Many enzymes contain metals in positions important for their activity. Therefore, the displacement of one metal by another will normally also lead to inhibition or loss of enzyme activities [START_REF] Shakya | Impact of heavy metals (copper, zinc, and lead) on the chlorophyll content of some mosses[END_REF]. Goyer [START_REF] Broadley | Zinc in plants[END_REF] introduced lead may interact metabolically with nutritionally essential metals and replace zinc on heme enzymes.

The displacement mechanism of toxicity is best explained by classification of the metal ions according to their binding preference, i.e. oxygen-seekong class A metals, nitrogen-or sulfur-seeking class B metals, and the bordenline metals show more or less the same preference of bonding to O-, S-or N-containing ligands [START_REF] Kim | Investigation of heavy metal accumulation in Polygonum thunbergii for phytoextraction[END_REF]. The class B (Cu and Pb) metals readily displace either borderline (Zn) or class A (Mg or Ca) metals from essential binding sites through much more tenacious bonding mechanisms. Borderline metals become toxicants when they displace Class A metals from essential binding sites in biomolecular, bonding to these sites more strongly. Besides, they are the most effective binders to SH group and nitrogen containing groups at the catalytically active centers in the enzymes. The data of metal concentrations are means ± s. e. from three experiments.

3.4

Effects of metals on total soluble protein and chlorophyll (a+b) content of wheat

The alteration of total soluble protein level in leaves of wheat seedlings was presented in Table 5. Total soluble protein levels and the inhibition rate in leaves decreased significantly with increasing concentrations and treatment time of metals in solution. The toxicity effect of metal on total soluble protein was arranged in a rank order of inhibition as follow: Cu> Pb >Zn. There was a negative correlation between metal concentration and total soluble protein content in leaves of wheat seedlings.

The data of the chlorophyll content of the wheat seedlings exposed to differing concentrations of metals were also shown in Table 5. Heavy metals accumulation in plants can result in a decrease of the chlorophyll concentration in the leaves/stems [START_REF] Levy | Evaluating the phytotoxicity of Pb-Zn tailings to big bluesteam (Andropogon gerardii vitman) and switchgrass (Panicum virgatum L.)[END_REF]. In the present study, chlorophyll (a+b) content declined progressively with increasing concentrations of heavy metals. Cu accumulation showed a significant inhibitory effect on chlorophyll (a+b). An insignificant decrease in chlorophyll content in wheat seedlings was observed after Zn and Pb accumulation, especially Zn. The statement was supported by Shakya et al. report [START_REF] Schützendübel | Plant responses to abiotic stresses: heavy metal-induced oxidative stress and protection by mycorrhization[END_REF]. Zinc has long been considered to be one of the least toxic metals in the environment [START_REF] Goyer | Toxic and essential metal interactions[END_REF]. Compared with level of metal application, the toxicity of metals is distinguished from different applied concentrations. The most toxic metal among three metals is Cu at 1 mM dose. Pb is the most toxic metal at 50 mM, although, Pb accumulation in leaves is obviously lower than others metals accumulation after 4 d treatment. High concentrations of Cu are known to activate oxidative damage and alter cell-membrane properties by lipid peroxidation, thereby demonstrating the inhibitory effect on the enzymes involved in chlorophyll production. Lead can be toxic to photosynthetic activity, chlorophyll synthesis and antioxidant enzymes [START_REF] Prasad | Heavy Metal Stress in Plants: From Biomolecules to Ecosystems[END_REF].

conclusion

In the present study, addition of Cu or Pb or Zn inhibited seed germination, plumule and radicle elongation. The toxic of metals to seed germination parameters can be arranged in the rank order of inhibition as follows: Cu > Pb >> Zn. All heavy metal concentrations in seedlings increase with their increase in the medium and the duration of treatments. The toxic of metals to young seedlings was found similar to seeds. And heavy metal treatments could reduce the contents of chlorophyll and soluble protein in young seedlings of wheat. On the other hand, the results demonstrated that the excess accumulation of Cu in leaf and roots could reduce accumulations of zinc (Zn); the excess accumulation of Pb decreased the levels of Cu or Zn in leaf and roots; the excess accumulation of Zn had no influence on Cu accumulations in leaf and roots. Acknowledgments. The Project was supported by Fundamental Research Funds for the Central Universities(06108003)and CNPC Innovation Fund (2009D-5006-04-02).

Table 1 .

 1 Seed

		germination rate (%) compared to the control at different heavy metal
	concentration.
	Metal	Cu	Pb	Zn
	dose	Germination	Inhibitory rate	Germination	Inhibitory rate	Germination	Inhibitory rate
	(mM)	rate (%)	(%)	rate (%)	(%)	rate (%)	(%)
	0	100.0 ± 5.6	0	100.0 ± 5.6	0	100.0 ± 5.6	0
	0.5	95.1 ± 2.6	4.9	94.7 ± 1.5	5.3	99.3 ± 0.6	0.6
	1.0	93.7 ± 1.2	6.3	90.3 ± 2.4	9.7	99.3 ± 0.6	0.7
	10.0 73.3 ± 7.6	26.7	86.1 ± 1.2	13.9	98.1 ± 1.7	1.9
	50.0 35.2 ± 5.1	64.8	46.3 ± 1.0	53.7	91.3 ± 1.5	8.7
	100.0	n.d.	100	18.7 ± 6	81.3	82.3 ± 2.5	17.7
	250.0	n.d.	100	n.d.	100.	52.1 ± 1.9	47.9
	The data of seed germination rate are means s.e. from three experiments.

Table 2 .

 2 Effect of metals on radicle elongation of wheat on filter Paper.

	Metal		4 d		6 d		8 d
	Dose	Radicle	Inhibitory	Radicle	Inhibitory	Radicle	Inhibitory
	(mM)	length (cm)	rate (%)	length (cm)	rate (%)	length (cm)	rate (%)
	Cu 0	3.7±0.9	0.0	7.6 ± 0.5	0.0	9.7 ± 0.3	0.0
	0.5 1.7 ± 0.5	54.1	1.8 ± 0.2	76.3	2.2 ± 0.1	77.3
	1.0 0.8 ± 0.1	78.4	1.2 ± 0.2	84.2	1.4 ± 0.3	85.6
	10.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	50.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	100.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	250.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	Pb 0	3.7	0.0	7.6 ± 0.5	0.0	9.7 ± 0.3	0.0
	0.5 3.4 ± 0.2	8.1	6.4 ± 0.2	15.8	7.9 ± 0.5	18.6
	1.0 2.5 ± 0.1	32.4	5.9 ± 0.7	22.4	6.0 ± 0.3	38.1
	10.0 0.2 ± 0.0	94.6	0.1 ± 0.0	98.7	0.2 ± 0.1	97.9
	50.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	100.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	250.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	Zn 0	3.7 ± 0.2	0.0	7.6 ± 0.5	0.0	9.7 ± 0.3	0.0
	0.5 4.5 ± 0.1	-21.6	5.0 ± 0.2	34.2	6.2 ± 0.4	36.1
	1.0 3.6 ± 0.1	2.7	4.8 ± 0.4	36.8	6.1 ± 0.7	37.1
	10.0 0.6 ± 0.0	83.8	0.7 ± 0.5	90.8	0.8 ± 0.2	91.8
	50.0 0.3 ± 0.0	91.9	0.3 ± 0.1	96.1	0.3 ± 0.1	96.9
	100.0 0.2 ± 0.0	94.6	0.2 ± 0.0	97.4	0.2 ± 0.0	97.9
	250.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	The data of radicle elongation are means ± s. e. from three experiments.

Table 3 .

 3 Effect of metals on plumule elongation of wheat on filter Paper.

	Metal		4 d		6 d		8 d
	Dose	Plumule	Inhibitory	Plumule	Inhibitory	Plumule	Inhibitory
	(mM)	length (cm)	rate (%)	length (cm)	rate (%)	length (cm)	rate (%)
	Cu 0	3.2±0.5	0.0	6.5±1.3	0.0	10.1±1.8	0.0
	0.5	2.9±0.5	9.4	3.2±1.0	50.8	6.8±0.8	32.7
	1.0	1.3±0.2	59.4	3.2±0.8	50.8	5.7±0.7	43.6
	10.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	50.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	100.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	250.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	Pb 0	3.2±0.5	0.0	6.5±1.3	0.0	10.1±1.8	0.0
	0.5	2.9±0.4	9.4	4.5±0.7	30.8	8.6±1.3	14.9
	1.0	2.7±0.5	15.6	4.2±0.8	35.4	8.2±1.8	18.8
	10.0	0.6±0.1	81.3	2.3±0.7	64.6	4.0±1.0	60.4
	50.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	100.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	250.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	Zn 0	3.2±0.5	0.0	6.5±1.3	0.0	10.1±1.8	0.0
	0.5	2.9±0.5	9.4	3.5±1.7	46.2	7.6±1.2	24.8
	1.0	2.1±0.3	34.4	2.7±0.8	58.5	6.7±1.0	33.7
	10.0	1.4±0.3	56.3	2.1±0.4	67.7	2.9±1.0	71.3
	50.0	0.7±0.1	78.1	1.1±0.2	83.1	1.7±0.5	83.2
	100.0	0.2±0.1	93.8	0.3±0.1	95.4	0.4±0.1	96.0
	250.0	n.d.	100.0	n.d.	100.0	n.d.	100.0
	The data of plumule elongation are means ± s. e. from three experiments.

Table 4 .

 4 Effect of metals on the accumulation of metals in leaves and in roots.

	Heavy metal accumulation (mg gDW -1 )


Jingying Tan
email: jingyingtan@163.com

Dan Jin
email: jindan76@163.com

Qing Wang

Experimental Study on the Quality of Dutch Cucumber in Storage

Keywords:

The quality of Dutch cucumbers in storage was investigated by four kinds of storage technique, especially such as weight loss, soluble solid content, firmness and their appearance. The results indicates that the quality of the Dutch cucumbers stored after pre-cooling is very near that of those stored after preheating, while they are higher than that of those primarily stored. And the quality of those stored in room-temperature. The quality of Dutch cucumbers with preservative film excels that of those without it by the same technique. Therefore it is a good way to precool or preheat the cucumbers and latter to pack them with preservative film before their storage to sustain the fresh quality of Dutch cucumbers.

Introduction

Cucumber (Cucumis sativus L) is a chilling sensitive commodity. It is very welcomed for its delicious brilliance and high nutrition. But it goes bad in a short time after harvest. Some key qualities of cucumbers such as weight, soluble solid content, firmness and their appearance decreases soon. It is very concerned to keep cucumbers fresh after harvest all the along. Jennifer R. DeEll , etc [START_REF] Jennifer | Water temperature for hydrocooling field cucumbers in relation to chilling injury during storage[END_REF] studied water temperature for hydrocooling field cucumbers in relation to chilling injury during storage. Abdul Hakim, Albert C. Purvis, and Ben G. Mullinix [START_REF] Abdul | Differences in chilling sensitivity of cucumber varieties depends on storage temperature and the physiological dysfunction evaluated[END_REF]pointed out differences in chilling sensitivity of cucumber varieties depends on storage temperature and the physiological dysfunction evaluated. Rob E. Schouten, L.M.M. Tijskens, Olaf van Kooten [START_REF] Schouten | Predicting keeping quality of cucumber fruit based on a physiological mechanism[END_REF]Predicted keeping quality of cucumber fruit based on a physiological mechanism. Pan Yonggui [START_REF] Pan | Effect of Intermittent Warming on Membrance-Lipid Peroxidation System of Cucumber Fruit[END_REF][START_REF] Pan | Study on effects of Intermittent Warming on chilling harm[END_REF] etc studied effects of Intermittent Warming on cucumber storage. Hou Jian-she etc [START_REF] Hou | Effects of prestorage treatment on chilling endurance and free radical biology[END_REF] investigated effects of prestorage treatment on chilling endurance and free radical biology. The objective of this study was to find a new economic technique to sustain the freshest possible quality of cucumbers in longest possible shelf life. Weight loss, soluble solid content, firmness and appearance of cucumbers were used to assess the effects of storage.

Materials and Methods

Materials

Freshly harvested field cucumbers were obtained from Tianjin farming demonstration center during May12, 2005. All of them were carried to the preservative cold-storage at once after harvest. Marketable cucumbers of similar size, color and color but without mechanical damage and insect pest were selected for the experiments.

Quality Measurement, Instruments and Storage Techniques

Results and Discussions

Effects of Different Techniques on Weight Loss of Dutch Cucumbers

Weight loss of cucumbers is affected by many factors. On the one hand, it is related to physical construction of Dutch cucumbers themselves, such as specific surface areas, surface histology, cell retention ability and cell gap length. Specific surface areas indicate areas per gramme cucumber. Surface histology means the natural duct and cuticle layer. The natural duct is made up of gas porosity and cortical pore which is open in the surface of cucumbers. Water diffusion in cucumber was affected by cuticle layer. Cell retention ability is expressed by the content of soluble substance and hydrophilia colloid in the cell. Cell gap affects the drag force of water diffusion. On the other hand, weight loss was also affected by external factors, such as temperature, relative humidity, air speed, light and air pressure. Weight loss per time and per surface areas is calculated as equation [START_REF] Jennifer | Water temperature for hydrocooling field cucumbers in relation to chilling injury during storage[END_REF].

dm k dt = - (1)
Given a constant temperature, equation ( 2) is obtained

0 m m kt = - (2)
Where m is the mass at time t, m 0 is the initial value of m.

Therefore, weight loss ratio is obtained as follows:

.

m . 0 0 m m pt m m - = = ( 3
)
where p is constant.

Relations between weight loss ratio of cucumber and storage time is described in Fig. 1. After 16 days of cucumbers storage, it is concluded that the four close values among 1.4-1.9 of weight loss ratio of cucumber with preservative film in the 4 different groups show powerful ability of preservative film to control weight loss ratio. Preservative film not only provides a high humidity condition to prevent the water evaporation from the surface of cucumbers but also decreases the metabolism of them. Without Preservative film, weight loss ratio of group a was the biggest, amounting to 11.81%, where cucumbers looked wilt. The one of b group took second place, the value of which is 7.11%. The one of c group and the one of d group are very nice, respectively 4.71% and 4.02%, and the cucumbers in these two groups looked fresh.

Effects of Different Techniques on Soluble Solid Content of Dutch Cucumbers

There is different for soluble solid content in different position, for example, the higher soluble solid content for cucumber head, the lower for behind-of-center and almost zero soluble solid content for cucumber tail and it is difficult to measure the soluble solid content. The soluble solid content value is given by the mean value of soluble solid content in 6-7 points for different position. Soluble solid content of cucumber is 4.5-4.8% in experiment beginning. It is shown from Fig. 2 and Fig. 3 that soluble solid content of cucumber decreases significantly with the storage time increasing for all experiment data, i.e., the property of storage cucumber is worse obvious than that of experiment beginning. Comparing the different experiment groups, it can be observed that the soluble solid content of cucumber by precooling and preheating treating groups is higher than that of the direct cool storage and room-temperature group. The property of the first two groups is better than that of other two groups. On the whole, the soluble solid content of cucumber in the preservative film is higher than that of the corresponding contrast group. It is shown that the better storage result is obtained by using the preservative bag. Cucumber firmness is different for different position. Generally, it is soft for cucumber head and hard for cucumber tail. So 7~8 points in different position are chosen for measuring and the mean value is considered as the cucumber firmness. The changes of cucumber firmness with time for different treating groups are shown in Fig. 4. As observed in Fig. 5, the cucumber firmness for experiment groups decreases with time, i.e., the property of storage cucumber is worse than that of experiment beginning. But on the whole, the storage results for three cold-storage groups are better than that of room temperature groups. The effect of preservative bag package for cucumber firmness is not significant and the former result is a little better than that of the latter. The difference is between 0.6 and 1.1.

Effects of Different Techniques on Firmness of Dutch Cucumbers

Effects of Different Techniques on Appearance of Dutch Cucumbers

The observed results for appearance of cucumber are shown in Table 2. The appearance for room temperature storage except the preservative film decreases quickly, the appearance with the preservative film by precooling is equivalent to that of preheating treatment. The appearance by precooling and preheating is best for all treating condition and that of direct cool storage is in the middle. Experiment finishing, the photos of cucumbers in all groups are shown in Fig. 6~9. Group a: They are shown in Fig. 6. Group a2 lies in nearest above /up and group a1 right /down.

Fig. 6. Appearance and cross section in group a

There is an amount of froth in the cucumber surface of group a1 and the surface has become yellow too. There is only the froth in the surface of group a2. Comparing the section, it can be seen that the inside of group a1 has become white and group a2 green.

Group b They are shown in Fig. 7. Group b1 lies in right /up and group b 2 nearest above /down. From the surface, the storage quality for cool storage group is better than that of the room temperature group but the chilling injury is obvious. The cucumber tail has withered and cucumber inside has be empty. It can be seen from the group 1. So the cucumber quality of group 2 is better than that of group 1.

Group c They are shown in Fig. 8. Group c1 lies in right /up and Group c 2 / nearest above down. The surface symptom for precooling groups and preheating groups is almost the same. There is the chilling injury (due to no aseptic treatment before storage). Comparing the second group and the first group, the storage quality for the second group is better than that of the first group.

Group d: They are shown in Fig. 9. Group d1 lies in nearest above /up and Group d 2 right /down. From the surface, the storage quality for preheating group is better than that of the room temperature group. There is chilling injury appearance for the two preheating groups(due to no aseptic treatment before storage). Comparing the two groups, the chilling injury for group 1 is more obvious and the cucumber tail of group 1 has withered. But the cucumber tail of group 2 is good.

As a result, it is observed that different states are gained for different groups cucumbers by 16 days storage. So the property for different pretreatment methods and storage forms is directly shown from the phenomena.

Conclusions

From the experiment results, it is concluded that it is important for Dutch cucumbers storage to adopt low temperature and high humidity. The low temperature reduces the cucumber metabolism and the high humidity keeps the moisture content of cucumber so as to keep the cucumber refresh. It is an important means to maintain the fruit and vegetable quality by pretreatment. The suitable precooling and preheating treating can improve the storage quality of cucumber. The better quality can be gained by using the preservative film based on the pretreatment, especially its controlling the cucumber dehydration preferably and preventing soluble solid content from decreasing so as to keep the cucumber fresh and essential saccharinity. But preservative film has little effect on firmness of the cucumbers during storage.

Fig. 1 .

 1 Fig. 1. Relations between weight loss ratio and storage timeAccording to Fig.1, the fitting value of p in equation (3) was obtained as Tab.1

Fig. 2 .Fig. 3

 23 Fig. 2. Soluble solid content of cucumber with time except the preservative film

Fig. 4

 4 Fig. 4 storage cucumber firmness with time except the package film

Fig. 5

 5 Fig. 5 storage cucumber firmness with time by the package film

Fig. 7 .

 7 Fig. 7. Appearance and cross section in Group b

Fig. 8 .

 8 Fig. 8. Appearance and cross section in group c

Fig. 9 .

 9 Fig. 9. Appearance and cross section in group d

2.2.1. Quality Measurement and Instruments

	Group d
	Cucumbers were stored in 4℃,95%RH after being preheated to 4 and sustaining ℃
	for 24 hours.
	Each group is classified to two kinds as follows:
	Group *1 means cucumbers stored without preservative film and Group *2 means
	cucumbers stored with preservative film, where symbol * stands for a, b, c, or d.
	1) Loss weight in storage
	It was measured by JA5003H ,1/1000 scale made in Shanghai precise instrument
	plant, China.
	2) soluble solid content in Dutch cucumber
	It was measured with WYT saccharimeter made in Chengdu optical plant, China.
	3) Dutch cucumber firmness
	It was measured by GY-1 hardmeter made in Mudanjiang mechine research institute,
	China.
	4)Dutch cucumber appearance
	Dutch cucumber appearance was assessed by eye-measurement.
	2.2.2. Storage Techniques
	Experimental cucumbers were randomly sorted to 4 groups, as follows:
	Group a
	Cucumbers were directly stored in 25℃,70%RH.
	Group b
	Cucumbers were directly stored in 4℃,95%RH.
	Group c
	Cucumbers were stored in 4℃,95%RH after being precooled to 4 . ℃

Table 1 .

 1 the fitting values of p

	Groups	a1	a2	b1	b2	c1	c2	d1	d2
	p	0.70764 0.09674 0.47007 0.09957 0.30706 0.09957	0.257	0.0902
	s.e	±0.0120 ±0.00179 ±0.01083 ±0.00212 ±0.00524 ±0.00194 ±0.00557 ±0.00261
	R 2	0.99295 0.99174	0.984	0.98767 0.99164 0.99315 0.98561 0.97551

Table 2 .

 2 Appearance contrast for different experiment group cucumbers

	Time(d) Group a1		Group a2		Group b1		Group b2
	0	Fresh cucumber	Fresh cucumber	Fresh			Fresh cucumber
							cucumber
	2	Froth appearance	The same with that	The same with	The same with
		in surface		of	the	nearest	that	of	the	that of the nearest
				above		nearest above	above
	4	Froth and macula,	The same with that	The same with	The same with
		appearance	in	of	the	nearest	that	of	the	that of the nearest
		surface, coarseness	above		nearest above	above
	6	Froth appearance	Little		froth	The same with	The same with
		in 80% surface	appearance	in	that	of	the	that of the nearest
				surface		nearest above	above
	8	Froth and macula,	The same with that	The same with	The same with
		white in cucumber	of	the	nearest	that	of	the	that of the nearest
				above		nearest above	above
	10	serious	froth	Fresh green in	The same with	Little	chilling
		appearance in 90%	cucumber, sweet	that	of	the	injury appearance
		surface, white in				nearest above
		cucumber, no sweet
	12	serious	froth	Froth appearance	Half	chilling	chilling	injury
		appearance in all	in almost surface,	injury,		more	appearance, little
		surface, complete	green in cucumber	serious			thickness	in
		white in cucumber,							surface
	14	Little	yellow
		appearance in

froth position, soft The same with that of the nearest above Serious chilling injury, surface thicker chilling injury in 40% surface, more serious surface thickness 16 Yellow appearance in froth position, very soft The same with that of the nearest above chilling injury in 75% surface, surface thickness more serious chilling injury

				above		nearest above	above
	8	The same with that	The same with that	The same with	The same with
		of the nearest above	of	the	nearest	that	of	the	that of the nearest
				above		nearest above	above
	10	The same with that	The same with that	chilling injury	The same with
		of the nearest above	of	the	nearest	appearance	that of the nearest
				above				above
	12	chilling	injury	White	thickness	chilling injury	White	thickness
		appearance, surface	liquid appearance	appearance,	liquid appearance
		thickness					surface
							thickness
	14	chilling injury in
		50%	surface,
	Time(d) Group c1		Groupc2		Group d1	Group d2
	0	Fresh cucumber	Fresh cucumber	Fresh		Fresh cucumber
							cucumber
	2	The same with that	The same with that	The same with	The same with
		of the nearest above	of	the	nearest	that	of	the	that of the nearest
				above		nearest above	above
	4	The same with that	The same with that	The same with	chilling	injury
		of the nearest above	of	the	nearest	that	of	the	appearance
				above		nearest above
	6	The same with that	The same with that	The same with	The same with
		of the nearest above	of	the	nearest	that	of	the	that of the nearest

surface thickness Little chilling injury 50% little chilling injury, surface thickness Little chilling injury 16 more serious chilling injury The same with that of the nearest above The same with that of the nearest above The same with that of the nearest above

Acknowledgements. The authors are grateful for the sponsorship of National Natural Science Foundation of China(50874045) and Liaoning Province Education Office (2008T158) for the research.


Dazhou Zhu

Baoping Ji

Zhaoshen Qing

Cheng Wang

Manuela Zude

The Detection of Quality Deterioration of Apple Juice by Near Infrared and Fluorescence Spectroscopy

Keywords: near infrared spectroscopy, fluorescence spectroscopy, EEM, N-PLS, apple juice

Processing and storage of apple juice often triggers quality deterioration regarding nutritional valuable compounds and unfavourable color changes resulting from browning. Fluorescence and near-infrared (NIR) spectroscopy were applied to detect such quality loss in apple juice. Juice samples were produced from Malus x domestica 'Pinova', stored at 20 ℃ for 4 days or heated at 80 ℃ for 10 min and stored at the same conditions. The quality of apple juice was measured by standard parameters such as soluble solids content, pH, CIE L*, a*, and b* values. Juice fluorescence spectra were recorded with fluorescence excitation at 250, 266, 355, and 408 nm and emission at 280-899 nm resulting in an excitation-emission-matrix (EEM) of 1240×4 for each sample. The NIR transmittance spectra were recorded in the wavelength range 900-1350 nm. The often used color b*-value for monitoring browning was correlated with the EEM variation and a reasonable calibration was built by means of n-way partial least squares (N-PLS) regression. The correlation coefficients were >0.9 in all treatments. NIR spectra were sensitive for predicting soluble solids content, but had poor capability to measure the color deterioration. Results indicated that the combination of NIR spectra and fluorescence EEM can be used to monitor the quality deterioration of apple juice.

Introduction

Apple juice is very popular due to its beneficial health effect and pleasant flavor. However, quality deterioration temporarily appears during the processing and storage. Enzymatic browning of damaged tissues of fruits during postharvest handling and processing is one of the main causes for quality loss of fresh fruit produce [START_REF] Mathew | Food browning as a polyphenol reaction[END_REF]. Enzymatic browning in fruit juice starts after the mechanical breakage of the apple cell integrity during the juice extraction procedure [START_REF] Castaldo | Presence of residual pectin methylesterase activity in thermally stabilized industrial fruit preparations[END_REF]. It is influenced by the substrate, which are phenolic compounds, polyphenoloxidases and influencing factors (ascorbic acid and peroxidases). The reaction is characterized by an initial enzymatic oxidation of phenols into slightly colored quinones and following polymerization. Nonenzymatic browning occurs mainly in thermal processing, which involves caramelization, ascorbic acid degradation and Maillard reaction [START_REF] Ibarz | Kinetic models of non-enzymatic browning in apple puree[END_REF].

Since quality is supremely important for apple juice, deterioration has to be controlled during processing and storage. Therefore, the fast and real-time detection of the extent of quality changes would provide a valuable tool. Conventionally, the quality of apple juice was measured by enzymatic and chromatographic methods [START_REF] Lee | Quality changes and nonenzymatic browning intermediates in grapefruit juice during storage[END_REF], which are time-consuming and laborious. The browning degree has been formerly measured by colorimetry and the result expressed as CIE L*a*b* color system. However, all these methods have some disadvantages such as the tristimulus data is often influenced by physical changes [START_REF] Nicolas | Enzymatic browning reactions in apple and apple products[END_REF].

As a fast, non-destructive and environmentally safe analyzing method, near infrared (NIR) spectroscopy was applied for measuring the quality of fresh juice with respect to sugar and water content [START_REF] Singh | Evaluation of inline sensors for prediction of soluble and total solids/moisture in continuous processing of fruit juices[END_REF][START_REF] Chang | Development of a universal algorithm for use of. NIR in estimation of soluble solids in fruit juices[END_REF]. Fluorescence spectroscopy was introduced to measure, e.g., bitterness in beer [START_REF] Christensen | Rapid determination of bitterness in beer using fluorescence spectroscopy and chemometrics[END_REF] or other parameters related to the content of auto fluorescent compounds. In the present study, NIR and fluorescence spectroscopy were applied to detect the quality deterioration of apple juice during processing and storage. The quantitative relation between variation in the NIR spectra, fluorescence spectra and the quality parameters of apple juice such as soluble solids content, pH, and color were investigated.

Materials and Methods

Preparation and Processing of Apple Juice

Malus x domestica 'Pinova' apples with differences in color and size for capturing a wide range of pigments and soluble solids contents were picked from an orchard in Germany and preserved at 4 ℃. The juice was extracted with a home juice extractor (Bifinett, Kompernass GmbH, Bochum, Germany). Two or three apples with similar color were consider as one sample and extracted. Totally, 30 samples were prepared. The core was eliminated, while the skin was reserved. The juice was centrifuged for 10 min with a speed of 3600 rpm and room temperature (16 ℃) (Sigma 4K 15, SIGMA Laborzentrifugen GmbH, Germany). Subsequently the juice was filtered and each sample was separated into two portions. One portion was measured immediately (marked as 'Fresh') and stored at 20 ℃ for 4 days (marked as 'stored'). The other portion was heated in a water bath (Victor Rector, Krankenhaus-Laborbedarf GmbH, Germany) at 80 ℃ for 10 min. The juice was cooled rapidly with an ice-water bath, and stored at 20 ℃. On the forth day, the spectra and reference values were measured (marked as 'heated-stored'). Resulting, three juice states were obtained.

Spectroscopic Readings

NIR spectra were measured using a UV-VIS-NIR scanning spectrophotometer (Lambda 950, PerkinElmer, USA). Because higher wavelength regions had significant noise and the lower wavelength regions were almost flat, only the wavelength range of 900-1350 nm was collected. Spectral resolution was 1 nm. Distilled water was used as zero reference.

Fluorescence emission spectra were measured using a fluorescence spectrophotometer (LS55, PerkinElmer, USA) in front-face geometry at four excitation wavelengths (250 nm, 266 nm, 355 nm, and 408 nm). The corresponding emission spectra ranged from 280-899 nm, 296-899 nm, 385-899 nm, and 438-899 nm, respectively. Spectral resolution was 0.5 nm. Therefore, an EEM with the size of 1240×4 (emission×excitation) was obtained for each sample. Appropriate cut-off filters were used to prevent the influence of direct reflectance from the excitation light. Each sample was measured twice and the average spectra were considered as the output.

Measurement of Laboratory Reference Values

Soluble solids content (SSC) was measured with a digital refractometer (PR-1, Atago Co., Ltd, Japan). The pH was measured with a pH-meter (pH340i, WTW, Germany). Color measurement was made using a colorimeter (CM-2600d, Konica Minolta Sensing, Inc. Japan) based on the CIE L*a*b color system. SCI mode was selected because it considered the influence of specular component. The colorimeter was calibrated with dark and white references. A glass cell containing the apple juice was placed against the head of the colorimeter and the three color parameters, namely L*, a*, b*, were recorded. Each sample was measured three times and the average values were calculated. The color degradation (∆L*, ∆a*, ∆b*) were calculated as the difference between the processed juice and fresh juice. Also, the total color change was calculated as follows:

* 2 * 2 * 2 0.5 (( ) ( ) ( ) ) E L a b ∆ = ∆ + ∆ + ∆ (1)

Data Processing

Partial least squares (PLS) regression was used to construct the calibration model between NIR spectra and reference values. Here, the optimal number of factors were selected by leave-one-out cross validation. For each model, the reference value was arranged with an ascending order, and then every third sample was selected as calibration set, and the remaining part provided the prediction set. The correlation coefficient and standard error for the prediction set were used to measure the model quality. The n-way partial least squares (N-PLS) analysis [START_REF] Bro | Multiway calibration[END_REF] was applied to build regression models between the fluorescence excitation-emission matrices (EEM) and laboratory reference values. Mean centering was used as data preprocessing for all spectra.

Software

PLS_Toolbox 3.0 (Eigenvector Research, Inc. Manson, WA, USA) was used for PLS calculation and N-PLS were constructed with the N-way toolbox [START_REF] Andersson | The N-way Toolbox for MATLAB[END_REF]. All calibrations were carried out in the environment of MATLAB (2006a, The Math Works Inc., USA). The three dimensional EEM of the fresh juice (Fig. 1a) mainly represents the fluorescent polyphenols (such as hydroxycinnamic acid derivates) and chlorophyll. However, chlorophyll is mostly located in the skin and although apple juice was extracted from both skin and flesh, the chlorophyll content was low. Using the spectrophotometric analysis after acetone/diethyl ether extraction [START_REF] Holden | Chlorophylls[END_REF], the chlorophyll concentration was below the detection limit. The emission spectra with excitation wavelength of 250 nm and 266 nm have show peaks with maximum at 350 nm and 630 nm. The two peaks are possibly related to polyphenols. The excitation wavelength of 355 nm yields a peak with maximum at 450 nm and a relatively smaller peak at 715 nm. The 450 nm peak is related to polyphenols, while the 715 nm peak is possibly related to chlorophyll residues [START_REF] Lai | Analysis of the main secondary metabolites produced in tomato (Lycopersicon esculentum, Mill.) epicarp tissue during fruit ripening using fluorescence techniques[END_REF]. The excitation wavelength of 408 nm yields one broad peak at 500 nm, which is possibly related to 5hydroxymethylfurfural (HMF) [START_REF] Cohen | Rapid method to monitor quality of apple juice during thermal processing[END_REF]. The present study focused on the correlation between fluorescence spectra and the quality of apple juice by means of laboratory reference data SSC and colour, while the investigation of specific fluorophores in apple juice will be studied in further experiments. The NIR spectra of original fresh juice (Fig. 1b) appear with broad absorption peaks as reported earlier [START_REF] Laure | Detection and quantification of apple adulteration in strawberry and raspberry purées using visible and near infrared spectroscopy[END_REF]. One spectrum that is obviously different from others was considered as outlier according to the criterion of general Mahalanobis distance [START_REF] Burns | Handbook of Near-Infrared Analysis[END_REF]. Resulting, this sample was deleted and the remained 29 samples were used for NIR analysis. In the fluorescence readings, no outlier appeared (n=30).

Results and Discussion

Characteristics of Laboratory Reference Values

The quality of juice was characterized by means of five reference parameters: SSC, pH, CIE L*, a*, and b*. Changes during heating and storage are presented in figure 2. The SSC was almost stable in all juice variants, suggesting that caramelization did not occur to a high extend due to relatively low temperature impact. In addition, heating at 80℃ for 10 minutes inactivated polyphenol oxidase [START_REF] Krapfenbauer | Effect of thermal treatment on the quality of cloudy apple juice[END_REF]. Therefore, the color change observed in stored juice was mainly due to enzymatic browning. While in heated and stored juice, Maillard reaction or ascorbic acid degradation might provide the main reason for quality loss. The pH value decreased slightly during storage. The L* hardly changed during storage, but increased after heating and storage. The color parameters a* and b* had similar changes: both values decreased after heating or storage. This indicated that SSC, pH and L* were not applicable as indicators for quality deterioration due to browning, while a* or b* can be used for this purpose.

Calibration Models

In order to see the potential ability to describe the quality of browning juice by fluorescence and NIR spectra, N-PLS was used to construct the multi-way calibration model with fluorescence EEM, and PLS was applied to construct model with NIR spectra. The quality of juice during the browning process was measured by SSC, pH, L*, a*, b*, ∆L*, ∆a*, ∆b*, ∆E (Table 1). The absolute NIR spectra and fluorescence EEM were used to build calibration models for SSC, pH, L*, a* and b*, while the different spectra were used to build calibration models for ∆L*, ∆a*, ∆b*, and ∆E. For detection of SSC, NIR showed high correlation and low measuring uncertainty, which was consistent with previous research for measuring fresh juice published by many working groups. In contrast, the correlation coefficient of models based on fluorescence EEM was low. This is consistent with the result of Seiden et al. (1996), who reported a correlation coefficient of 0.804 for 'Elstar' apple juice predicted by fluorescence spectra. Both fluorescence EEM and NIR spectra had low correlation with pH as no direct information can be expected in the spectral data. For L*, NIR had better results than fluorescence EEM. Both data sets had poor correlation for a* and ∆a*. The models based on fluorescence EEM had high correlation for both b* and ∆b* prediction. Among the three parameters of colorimetric method, [START_REF] Krapfenbauer | Effect of thermal treatment on the quality of cloudy apple juice[END_REF] reported that b* values changed to a greater extent in comparison to a* and L* values for cloudy apple juice. Resulting, b* is considered as being more important than other two for describing the browning extent of apple juice. Fluorescence EEM has shown a high correlation with colorimetric method and can be applied to predict the b*. Therefore, fluorescence EEM can be used to detect the quality change of apple juice during browning, encouraging further studies on developing a standardized method. On the other hand, NIR spectra, although high correlation was obtained for prediction of lightness parameter L* and ∆L*, showed no information for the browning color a* and b*.

Conclusions

During heating and storage of apple juice, the quality and color changed due to enzymatic browning and non-enzymatic browning. NIR spectra can be used to detect SSC and L* and ∆L*, while fluorescence spectra were feasible for predicting b* and ∆b*. Both spectral readings had poor ability for measuring pH and a*. The results indicated that the combination of NIR spectra and fluorescence EEM provided a fast and non-invasive method for detecting quality deterioration of apple juice during storage and heating.

  it a ti o n [n m ] Emission [nm] Intensity [a.u.]

Fig. 1 .

 1 Fig. 1. (a) The mean excitation-emission matrix (EEM) for fresh juice; (b) The NIR transmission spectra of the 30 original fresh juice samples. Absorption was calculated by log (I/I0) from transmittance readings

FreshFig. 2 .

 2 Fig. 2. Box-whisker plots of laboratory reference values

Table 1 .

 1 The correlation coefficients for N-PLS model of fluorescence EEM and PLS model of NIR spectra

			SSC	pH	L*	a*	b*
	Fresh juice	EEM 0.7079 0.5006 0.6963 0.4816 0.9087 NIR 0.9827 0.5237 0.8000 0.7902 0.7069
	Stored juice	EEM 0.6576 0.1906 0.6976 0.5998 0.9052 NIR 0.8976 0.4024 0.9010 0.7693 0.6127
	Heated-stored juice	EEM 0.8172 0.944 NIR 0.9528 0.6092 0.9511 0.2876 0.7921 0.8892 0.7876 0.9280
			∆L*	∆a*	∆b*	∆E
	Difference between fresh and stored	EEM 0.6754 0.6499 0.9610 0.7446
	juice	NIR	0.9258 0.3465 0.7338 0.8741
	Difference between fresh and heated-	EEM 0.7833 0.3612 0.8769 0.4912
	stored juice	NIR	0.8787 0.3148 0.9501 0.7132


Lihua Zheng

Dongmei Zhao
email: zhaodongm@vip.163.com

Nan Zhou

Xiaobing Qiu

Li Xu1

Shicong Wang

Zhong Qiao

The Development of Remote Labor Training System for Rural Small Towns Based on MVC Model

Keywords: Remote rural labor training system, MVC, JSP, B/S, UML

In view of the characteristics of the rural labor force in China, a remote training system for small towns is developed based on B/S architecture and MVC model by using object-oriented and JSP technology on the Java J2EE platform. The system is designed to be used by administrator, training enterprise and individuals. The administrator can manage the website, permission assignment and maintain database. Training enterprise can use the system as their working operation platform. They can release their business information, manage their training materials and maintain their own data in the database. A registered individual user can access the information within his respective authorities, take study online, take part in the test online, question online, etc. By means of UML, the system is analyzed and both the database and class structure are built. By using Filter, Struts and Hibernate technologies, the system is developed with the characteristics of crossing-platform, better expansibility and maintainability.

Introduction

With China economic and cultural development, 3-issues concerning Chinese agriculture, rural areas and farmers are increasingly becoming the critical factors which restrict the development of overall national strength. It is the key to solve the issue of farmers by reasonable transferring the rural surplus labors to urban. An investigation showed that china mobile population had reached 21.1 billion in 2009, the average age at about 27.3 and 78.7% of them come from rural and they mainly engaged in low wages or dangerous industries [START_REF]China mobile population more than 20 Billion, most engage in low wages or dangerous industries[END_REF]. This condition made serious challenge to national strategic planning, social management and public services, and in the meantime, it is becoming a social instability problem. Hence it is the essence way to address the problem of migrant workers' employment by increasing their professional skills, enhancing their operational qualities and improving their knowledge structure and quality. Y. J. He et al [START_REF] He | Discussion on Agricultural Information and Building of the well-off society in an All-round Way in Countryside[END_REF], W. C. Qin [START_REF] Qin | The study and reflection of rural labor force transfer in Suining county[END_REF], W. L. Wang et al [START_REF] Wang | The Forming Reasons of China County Remained Labor and Its Transferring Fashion[END_REF], Z. H. Tian [START_REF] Tian | The Thought and Countermeasures of Rural Labor Force Transferring -The Reflection of Todaro Model[END_REF] and W. Huang [START_REF] Huang | Analyzing And Thinking About Employment Difficulty of Shanghai Farmers Leaving Land[END_REF] analyzed the forming reasons and status quo of china rural labor resources quality, and brought forward many constructive views. Since the rural labor force in China has a number of large, strong mobility and relatively unenlightened knowledge structure, D. R. Zhong et al [START_REF] Zhong | Strengthen The Training of Farmers and Stimulate The Construction of Small Towns[END_REF], Z. H. Han et al [START_REF] Han | The Development of Vocational Education During The Construction of Small Towns[END_REF], D. X. Fu [START_REF] Fu | The Research of Rural Labor Employment Capacity Training System Building[END_REF], X. Liu et al [START_REF] Liu | Sun: The Training System and Safeguard Mechanism of The Transformation of Rural Labor Force[END_REF], Z. H. Han et al [START_REF] Han | Discussion on Interaction Between Small Town Construction and Vocational Education Development[END_REF], S. Y. Wang et al [START_REF] Wang | The Government Participating in The Vocational Education Development of Small Town[END_REF], A. H. Xi et al [START_REF] Xi | Study on Vocational Education Mode of Wide Places in The Road[END_REF] and J. X. Guan [START_REF] Guan | Taking a Road of Development Through Orderly & Stable Training Transferring[END_REF] have taken great effort to do large-scale research and in-depth investigation. Then they drew the same conclusion that it is the only right way to solve the problem of farmers by taking a road of orderly and stable training transfer.

However, it is impossible to organize the farmers to learn together because they are scattering in various places and various fields. C. H. Pan et al [START_REF] Pan | Research on Rural Distance Education And Training System Based on Network[END_REF], Y. C. Wu et al [START_REF] Wu | Design of Agricultural Science Training System Based on MVC Model[END_REF], Y. Chen et al [START_REF] Chen | By Countryside Science And Technology Information Strut System Constructing[END_REF], H. W. Luo et al [START_REF] Luo | Research And Application of The Model of Long-Distance Training of Agriculture sci-tech Based on Internet[END_REF], X. J. Huang et al [START_REF] Huang | The Explore of Remote Educational Standardization in Guangdong[END_REF] made out a solution for the vocational education status quo, that is, remote training by means of internet platform.

With the spread of the computer and internet, it is becoming possible to delivery tele-educational materials through internet. A practical remote training platform for both training organizations and rural surplus labors should be very much helpful and widely needed. It can help the training organizations mapping out their training plan according to the labor force supply and market demand, and changing timely. And on the other hand, it can help the rural surplus labors finding a right and convenient way to learn knowledge and skills and lead them to apply a suitable urban job. And on a long view, it might help the government to adjust the industry positioning, to transfer rural surplus labor force reasonably and orderly, to maintain social stability and healthy development, so as to solve the facing three rural issues finally.

System Design

In response to the knowledge level and features of the rural surplus labor force, the remote labor training system was designed as B/S structure, and developed on J2EE platform by using object-oriented technology based on MVC model. The software developing environment included IE6.0, Tomcat 6, JDK 1.4.2, SQL Server 2000, Eclipse Galileo with struts 2 and hibernate.

System Function Analysis

The system was designed as multi-user system, which included system administrator, enterprise user, personal user and its son-class of register personal user. Fig. 1 shows the use case diagram of the system. For administrator, the completed background management function was provided by the system. It comprised user management, item bank management, materials management, common training information management, common data maintenance, etc.

For enterprise user, a multi-user platform was built by the system. The registered training company could achieve its training business management by means of this platform, which consisted of training and interview information releasing, new trainees enrolling, training materials delivering and its maintaining, item bank maintaining and online training. For registered individual user, a plenty of powerful and convenient functions were provided by the system. If the individual user chose a training institution to register as its trainee, the services of that company would become available to him. Trainees could choose a suitable training project for his professional study. Then he could inquiry the relevant information, download training materials, join in the online training, question and get answers online, take online test, submit the examination paper and retrieve the answer sheet and check the test point and item analysis. On addition, trainees could collect the favorite information to their bench which provided by the system, advertise his job application form, etc.

And an ordinary user was allowed to browse the common information of the site.

System Module Design

According to the function analysis of the system, ten modules as well as their submodules contained by the system were drawn out. The whole module structure of the system is shown as Fig. 2. They were user management, material management, item bank management, favorite folder management, online answer management, training news management, interview information management, training trends management, training information management and message board management. Each module included its sub modules, such as, the module of material management comprised material upload, material download, material query, material delete, material scan evaluate and material online play.

Various sub modules were developed tally with high cohesion and would be called by the relevant invoker with their corresponding rights. For the above example module, the sub-modules of material upload and material delete were assigned for the administrator and registered enterprise user. Thereinto the administrator could upload and delete the common materials, and the registered enterprise user could upload and delete his own training materials; The sub-module of material download was assigned for the registered individual user, who could download the common materials from administrator as well as the materials from the belonged training institution; The sub-module of material query was designed for all of users but with different query conditions respectively, i.e. the administrator could retrieve the materials uploaded by himself and any other enterprise users, the registered enterprise user could only access the materials uploaded by itself, and the registered individual user could only query the common materials or the materials from the training company which he belonged to; The sub modules of the material scan evaluate and material online play were assigned for the registered individual user who could release his comments about the materials; And at the mean time, the materials such as *.doc, *.xls, *.ppt, *.swf, *.avi, *.wmv, *.mpg, etc. could be played or opened online.

System Database Design

To a B/S web application system, designing and building a correct and proper database is the key to success. Bolstered by the powerful functions of MS SQL Server2000, a relational database which meets the third normal form for the remote labor training system is designed and established based on object-oriented data analyzing.

2.3.1

Logical Design of the Database By investigating the entities and the relationship between them elaborately, the E-R diagram of the system was obtained. And it is shown in Fig. 3.

2.3.2

Physical Design of The Database According to the logical design of the database, fifteen base tables are established in terms of the third normal form. Table 1 shows the main information of all the tables.

System Class Design

According to the E-R diagram and data analysis, seventeen entity classes were built. Fig. 4 shows the classes and their relationship. By using Struts framework, fourteen action classes were established to acquire the data from forms and transmit them to the business logic layer. And then the JavaBeans were called to fulfill the main performances or to forward HTTP requests to JSPs. In addition, seventeen DAO classes inherited from Hibernate SessionFactory were built to implement the persistent layer; Two classes implementing Filter interface were used to filtrate character set encoding and login request; Three Servlet classes were used to control online questioning and answering; Several other classes were built to implement the common functions or to assist to implement some function.

TbAnswer

System Implementation

By using Tomcat as the J2EE application server, adopting Struts, Hibernate and Filter as the developing technologies, the data logic layer and business logic layer were established, in which the entity beans were used to implement the system data tier, and action beans were used to implement logical tier. The architecture diagram is shown as Fig. 5. With the step of new socialist countryside building, Chinese government is improving rural communication infrastructure construction gradually. Therefore, remote vocational education is becoming realistic. A suitable and practical teletraining system for small cities and towns can provide convenient service for those rural surplus labors and help them to solve their facing employment problem.

Based on the object-oriented methodology, by means of java developing platform, by using Struts, Filter and Hibernate technologies, the remote labor training system for small rural towns was built with a good man-machine interface, rich applications and easy to operate. It is highly cohesive, loosely coupled, highly credible, easy to maintain and extend.

The system's commissioning showed that it could meet the needs of rural labor remote training service. It is time-saving, low cost, efficient and practical. And it will be helpful for the government to transfer rural surplus labor force to urban cities in an orderly management, so as to untie the facing three rural issues finally.

Fig. 1 .

 1 Fig. 1. Use case diagram of the remote labor training system for rural small town.

Fig. 2 .

 2 Fig. 2. The module structure diagram of the remote labor training system for rural small town

Fig. 3 .

 3 Fig. 3. The E-R diagram of the remote labor training system for rural small town

1 Fig. 4 .

 14 Fig. 4. The class diagram of the remote labor training system for rural small town

Fig. 5 .

 5 Fig. 5. The architecture based on Hibernate and struts The remote labor training system mainly consisted of ten modules. Among them, the subscriber management module included user registration, user login/query/delete and user information edition. Question bank management module consisted of add/delete/edit/query question. Training examination management module included random test paper auto-formation, online testing and automatic scoring. Materials management module included upload training materials, query/edit/delete training materials, download general materials, video online play and materials evaluation message. Online Q&A module was tailor-made for rural training participants, and it consisted of online question, online answer and online exchange. A hundred and seventy five web pages were made in the system. Fig. 6 is the homepage of the registered individual user.

Fig. 6 .

 6 Fig. 6. The homepage of the registered individual user

Table 1 .

 1 The information of the base tables

	table	Primary key	Foreign key	Field number
	tb_user	ID/username	Usertype	12
	tb_usertype	ID		2
	tb_docs	ID	username/usertype	8
	tb_test	ID	username/usertype	17
	tb_comment	ID	Username/usertype/Book_ID	7
	tb_books	Book_ID	Username/usertype	8
	tb_favorite	ID	Username/usertype	6
	tb_news	ID	Username/usertype	6
	tb_leaveword	ID	Username/usertype	6
	tb_traininginfo	ID	Username/usertype	9
	tb_exampaper	ID	Username/usertype	16
	tb_seeker	ID	Username/usertype	10
	tb_video	ID	Username/usertype	7
	tb_job	ID	Username/usertype	10

Acknowledgments

. This research was financially supported by the National High Technology Research and Development Program of China (2006BAJ07B02).