Greenhouse canopy transpiration not only has effects on greenhouse air temperature and humidity, but also is important for determining the set-point of fertigation. In this study, Penman-Monteith equation was used to ...Greenhouse canopy transpiration not only has effects on greenhouse air temperature and humidity, but also is important for determining the set-point of fertigation. In this study, Penman-Monteith equation was used to calculate the greenhouse cucumber canopy transpiration under summer climate condition.The effects of greenhouse environmental factors on canopy transpiration were analyzed based on the measurements of greenhouse microclimate factors and canopy transpiration. The results showed that Penman-Monteith equation was reliable and robust in estimating greenhouse cucumber canopy transpiration under summer climate condition. Greenhouse cucumber canopy transpiration rate increased linearly with the increase of net radiation and water vapor pressure deficit (VPD) above the canopy. But the maximum value of the canopy transpiration rate occurred at the same time as that of VPD whereas about two hours later than that of net radiation. Based on the results, it was concluded that in addition to radiation, air humidity should also be considered when determine the set-point of fertigation.展开更多
This paper mainly studies the disease of cucumber downy mildew, powdery mildew and anthracnose leaf image processing and recognition technologies. Application of median filtering method of filtering noise, leaf spot d...This paper mainly studies the disease of cucumber downy mildew, powdery mildew and anthracnose leaf image processing and recognition technologies. Application of median filtering method of filtering noise, leaf spot disease of cucumber leaf color range segmentation part extract color feature parameters of the lesion site, characteristic parameters of the shape;extraction texture parameters by using gray level co-occurrence matrix. Based on the shortest distance methods to identify diseases of images. The experimental result showed that the current method on disease recognition accuracy rates more than 96%.展开更多
Different pumpkin rootstocks were used to study the effects of different rootstocks on the growth and fruit quality of greenhouse cucumber in early spring. The results showed that the grafted cucumber could signifi ca...Different pumpkin rootstocks were used to study the effects of different rootstocks on the growth and fruit quality of greenhouse cucumber in early spring. The results showed that the grafted cucumber could signifi cantly improve the production, and different rootstock had a certain effect on the survival rate and fruit quality. Jinhuanghou and Fengyijiajiewang as rootstock had the highest survival rate, which were 79.0% and 70.7%, respectively. As rootstocks of greenhouse cucumber, Jinhuanghou, Lvzhoujuxing, Fengyi, Huofenghuang, and Dawei No.17 were better than others according to taste, and Heizinangua, Jinhuanghou, Fengyi, Huofenghuang, and Dawei No.17 were better according to output.展开更多
Water scarcity is the most significant barrier to agricultural development in arid and semi-arid regions.Deficit irrigation is an effective solution for managing agricultural water in these regions.The use of additive...Water scarcity is the most significant barrier to agricultural development in arid and semi-arid regions.Deficit irrigation is an effective solution for managing agricultural water in these regions.The use of additives such as vermicompost(VC)to improve soil characteristics and increase yield is a popular practice.Despite this,there is still a lack of understanding of the interaction between irrigation water and VC on various crops.This study aimed to investigate the interaction effect of irrigation water and VC on greenhouse cucumber yield,yield components,quality,and irrigation water use efficiency(IWUE).The trials were done in a split-plot design in three replicates in a semi-arid region of southeastern Iran in 2018 and 2019.Three levels of VC in the experiments,i.e.,10(V_(1)),15(V_(2)),and 20 t/hm^(2)(V_(3)),and three levels of irrigation water,i.e.,50%(I_(1)),75%(I_(2)),and 100%(I_(3))of crop water requirement were used.The results showed that the amount of irrigation water,VC,and their interaction significantly affected cucumber yield,yield components,quality,and IWUE in both years.Reducing the amount of irrigation water and VC application rates reduced the weight,diameter,length,and cucumber yield.The maximum yield(175 t/hm^(2))was recorded in full irrigation using 20 t/hm^(2)of VC,while the minimum yield(98 t/hm^(2))was found in I_(1)V_(1)treatment.The maximum and minimum values of IWUE were recorded for I_(1)V_(3)and I_(3)V_(1)treatments as 36.07 and 19.93 kg/(m^(3)•hm^(2)),respectively.Moreover,reducing irrigation amount decreased chlorophyll a and b,but increased vitamin C.However,the maximum carbohydrate and protein contents were obtained in mild water-stressed conditions(I_(2)).Although adding VC positively influenced the value of quality traits,no significant difference was observed between V_(2)and V_(3)treatments.Based on the results,adding VC under full irrigation conditions leads to enhanced yield and IWUE.However,in the case of applying deficit irrigation,adding VC up to a certain level(15 t/hm^(2))increases yield and IWUE,after which the yield begins to decline.Because of the salinity of VC,using a suitable amount of it is a key point to maximize IWUE and yield when applying a deficit irrigation regime.展开更多
The fruit yield of cucumber are associated with high input of nitrogen,which poses a risk of pollution to the environment.The EU-Rotate_N model has been used widely for its high performance in the simulation of vegeta...The fruit yield of cucumber are associated with high input of nitrogen,which poses a risk of pollution to the environment.The EU-Rotate_N model has been used widely for its high performance in the simulation of vegetable growth,water and nitrogen dynamics.However,whether the underground water level affects the performance of the EU-Rotate_N model is unclear.In this study,we modified the groundwater level algorithms to the original model and named the modified model'the HG EU-Rotate_N model'.Experiments over two years on greenhouse cucumber with four different nitrogen(N)treatments(N1-N4)were conducted in Jiangsu Province,China,which has a high groundwater level(area_(HG)).Both original and modified models were used to simulate cucumber growth,water movement and N fate.For the soil water content,the measured values were significantly larger than the simulated values of the original model(value_(O))and closer to those of the HG model(value_(HG));for the soil available nitrogen concentration(SNC),the measured values were significantly higher and lower than value_(O) in 0−10 cm and 10−30 cm soil layers,respectively,and were also closer to those of the values_(HG).The higher SNC in the 0-10 cm soil layer indicated that a high groundwater level might increase the upwards movement of water and nitrogen in the 0-30 cm soil layer.The root mean square error,Nash Sutcliffe Efficiency and difference values show that the HG model was more applicable for areaHG than the original model.In this study,the nitrogen dosage of the N3 treatment was sufficient to meet the requirements of cucumber growth,indicating that the fertilization recommendation according to nitrogen nutrient balance was applicable in this area.展开更多
China removed fertilizer manufacturing subsidies from 2015 to 2018 to bolster market-oriented reforms and foster environmentally sustainable practices.However,the impact of this policy reform on food security and the ...China removed fertilizer manufacturing subsidies from 2015 to 2018 to bolster market-oriented reforms and foster environmentally sustainable practices.However,the impact of this policy reform on food security and the environment remains inadequately evaluated.Moreover,although green and low-carbon technologies offer environmental advantages,their widespread adoption is hindered by prohibitively high costs.This study analyzes the impact of removing fertilizer manufacturing subsidies and explores the potential feasibility of redirecting fertilizer manufacturing subsidies to invest in the diffusion of these technologies.Utilizing the China Agricultural University Agri-food Systems model,we analyzed the potential for achieving mutually beneficial outcomes regarding food security and environmental sustainability.The findings indicate that removing fertilizer manufacturing subsidies has reduced greenhouse gas(GHG)emissions from agricultural activities by 3.88 million metric tons,with minimal impact on food production.Redirecting fertilizer manufacturing subsidies to invest in green and low-carbon technologies,including slow and controlled-release fertilizer,organic-inorganic compound fertilizers,and machine deep placement of fertilizer,emerges as a strategy to concurrently curtail GHG emissions,ensure food security,and secure robust economic returns.Finally,we propose a comprehensive set of government interventions,including subsidies,field guidance,and improved extension systems,to promote the widespread adoption of these technologies.展开更多
High-temperature stress threatens the growth and yield of crops. Basic helix-loop-helix(bHLH) transcription factors(TFs) have been shown to play important roles in regulating high-temperature resistance in plants. How...High-temperature stress threatens the growth and yield of crops. Basic helix-loop-helix(bHLH) transcription factors(TFs) have been shown to play important roles in regulating high-temperature resistance in plants. However, the bHLH TFs responsible for high-temperature tolerance in cucumbers have not been identified. We used transcriptome profiling to screen the high temperature-responsive candidate bHLH TFs in cucumber. Here, we found that the expression of 75 CsbHLH genes was altered under high-temperature stress. The expression of the CsSPT gene was induced by high temperatures in TT(Thermotolerant) cucumber plants. However, the Csspt mutant plants obtained by the CRISPR-Cas9 system showed severe thermosensitive symptoms, including wilted leaves with brown margins and reduced root density and cell activity.The Csspt mutant plants also exhibited elevated H_(2)O_(2) levels and down-regulated photosystem-related genes under normal conditions.Furthermore, there were high relative electrolytic leakage(REC), malondialdehyde(MDA), glutathione(GSH), and superoxide radical(O_(2)^(·-)) levels in the Csspt mutant plants, with decreased Proline content after the high-temperature treatment. Transcriptome analysis showed that the photosystem and chloroplast activities in Csspt mutant plants were extremely disrupted by the high-temperature stress compared with wildtype(WT) plants. Moreover, the plant hormone signal transduction, as well as MAPK and calcium signaling pathways were activated in Csspt mutant plants under high-temperature stress. The HSF and HSP family genes shared the same upregulated expression patterns in Csspt and WT plants under high-temperature conditions. However, most bHLH, NAC, and bZIP family genes were significantly down-regulated by heat in Csspt mutant plants. Thus, these results demonstrated that CsSPT regulated the high-temperature response by recruiting photosynthesis components, signaling pathway molecules, and transcription factors. Our results provide important insights into the heat response mechanism of CsSPT in cucumber and its potential as a target for breeding heat-resistant crops.展开更多
Leaf color mutants in higher plants are considered to be ideal materials for studying the chlorophyll biosynthesis,photosynthesis mechanism and chloroplast development.Herein,we identified a spontaneous mutant,yc412,i...Leaf color mutants in higher plants are considered to be ideal materials for studying the chlorophyll biosynthesis,photosynthesis mechanism and chloroplast development.Herein,we identified a spontaneous mutant,yc412,in cultivated cucumber that exhibited yellow cotyledons.The yellow-lethal mutant was diagnosed with an abnormal chloroplast ultrastructure,and reduced photosynthetic capacity and pigment content.Through bulked segregant analysis-based whole-genome sequencing and fine genetic mapping,we narrowed the yellow cotyledons (yc) locus to a 96.8 kb interval on chromosome 3.By resequencing and molecular cloning,we showed that Csyc is a potential candidate gene,which encodes a yellow stripe-like (YSL) transporter.The T to C mutation in the promoter region of Csyc caused the yellow cotyledon phenotype in yc412.Compared to YZU027A (WT),the expression of Csyc was significantly downregulated in the cotyledons of yc412.Silencing of Csyc in cucumber via virus-induced gene silencing resulted in chlorotic leaves,mainly by suppressing the chlorophyll content.Furthermore,a comparative transcriptome analysis revealed that chloroplast-related genes and chlorophyll biosynthesis genes were significantly downregulated in yc412 cotyledons.Our results provide new insights into the molecular function of the YSL transporter in plant chloroplast development and chlorophyll synthesis.展开更多
This study was conducted to provide a preliminary assessment of the sea cucumber fishery in Aurora, Philippines. This was conducted from February to June 2013. All sea cucumber gatherers and traders, obtained through ...This study was conducted to provide a preliminary assessment of the sea cucumber fishery in Aurora, Philippines. This was conducted from February to June 2013. All sea cucumber gatherers and traders, obtained through snowball sampling, in each identified sea cucumber fishery area in six coastal municipalities (Baler, Dipaculao, Dinalungan, Casiguran, Dilasag and Dingalan) were interviewed using a structured interview schedule and focused group discussions (FGD). Results revealed that gathering sea cucumbers were accomplished by handpicking, skin diving or compressor diving. A total of 15 commercial species were regularly gathered. Out of this, three species are of very high economic value (≥Php 4000/kg) (Holothuria nobilis, Holothuria scabra, and Actinopyga lecanora). The average number of kilograms harvested per hour per trip ranges from 0.21 (Holothuria fuscopunctata) to 2.71 (Holothuria scabra), while the average size of commonly gathered sea cucumber varies among species with Holothuria lecanora showed an average length (29.26 cm) greater than recorded 24 cm. Processing mainly involves washing, slicing, boiling, drying and packing. Processed sea cucumbers or trepan were sold to middlemen or direct buyers who usually offered higher prices (36.36% up to 69.20%) than the former. Problems encountered by sea cucumber gatherers and traders include a decline in total catch, a shift in area of collection from intertidal zones to deeper waters, an increase in the number of hours spent in finding and gathering sea cucumbers, the use of compressors in gathering, the decline of larger species and gathering of smaller sizes in huge amount, the absence of conservation program for sea cucumber, and the lenient implementation of government policies with regards to coastal resources management.展开更多
The production environment of greenhouse cultivation is relatively closed,the multiple cropping index is high,the management of fertilizationwatering and pesticideapplication isblindtosomeextent,andthe phenomenonofcon...The production environment of greenhouse cultivation is relatively closed,the multiple cropping index is high,the management of fertilizationwatering and pesticideapplication isblindtosomeextent,andthe phenomenonofcontinuous cropping isalsocommonSoilquali-ty affects the sustainable development of greenhouse cultivation.Earthworm is a ubiquitous invertebrate organism in soil,an important part of soil system,a link between terrestrial organisms and soil organisms,an important link in the small cycle of soil material organisms,and plays an important role in maintaining the structure and function of soil ecosystem.Different ecotypes of earthworms are closely related to their habi-tats(soil layers)and food resource preferences,and then affect their ecological functions.The principle of earthworm regulating soil function is essentially the close connection and interaction between earthworm and soil microorganism.Using different ecotypes of earthworms and bio-logical agents to carry out combined remediation of greenhouse cultivation soil is a technical model to realize sustainable development of green-house cultivation.展开更多
Microplastics can influence global climate change by regulating the emissions of greenhouse gases from different ecosystems. The effects of microplastics in terrestrial ecosystems are still not well studied particular...Microplastics can influence global climate change by regulating the emissions of greenhouse gases from different ecosystems. The effects of microplastics in terrestrial ecosystems are still not well studied particularly greenhouse gases emissions. Thus, we conducted a laboratory experiment over a period of 90 days with two types of microplastics (differing in their chemical structure), high density polyethylene (HDPE) and low density polyethylene (LDPE), which were applied to the soil at a rate of 0% to 0.1% (w/w). The overarching aim was to investigate the effects of microplastic type, microplastic concentration and days of exposure on greenhouse gases emissions. We also used original and artificially weathered microplastics (the same HDPE and LDPE) to make a comparison of greenhouse gases emissions between the original microplastics treated soils and the soils treated with weathered microplastics. Our findings showed that HDPE and LDPE microplastics significantly increased the emissions of greenhouse gases from the soil than that of the control soils. Emissions were increased with the increases in the level of microplastic in the soil. The weathered microplastic emitted greater quantity of greenhouse gases compared to that of the original microplastics. In contrast to a low initial emission quantity, the emissions were gradually increased at the termination of the experiment. Our experiment on the emissions of greenhouse gases from the soil vis-à-vis microplastic additions indicated that the microplastic increased the emissions of greenhouse gases in terrestrial ecosystems, and pervasive microplastic impacts may have consequences for the global climate change. Greenhouse gases emissions from the soil not only depend on the type and concentration of the microplastic, but also on the days of exposure to the microplastic.展开更多
The present paper first investigates the collapse behavior of a conventional pipe-framed greenhouse under snow loading based on a 3-D finite element analysis,in which both geometrical and material non-linearities are ...The present paper first investigates the collapse behavior of a conventional pipe-framed greenhouse under snow loading based on a 3-D finite element analysis,in which both geometrical and material non-linearities are considered.Three snow load distribution patterns related to the wind-driven snow particle movement are used in the analysis.It is found that snow load distribution affects the deformation and collapse behavior of the pipe-framed greenhouse significantly.The results obtained in this study are consistent with the actual damage observed.Next,discussion is made of the effects of reinforcements by adding members to the basic frame on the strength of the whole structure,in which seven kinds of reinforcement methods are examined.A buckling analysis is also carried out.The results indicate that the most effective reinforcement method depends on the snow load distribution pattern.展开更多
This research was conducted to investigate the effects of three heating systems on cucumber yield,and cost and gas volume consumed in greenhouses located in Varamin region,Tehran province,Iran.Conventional heating sys...This research was conducted to investigate the effects of three heating systems on cucumber yield,and cost and gas volume consumed in greenhouses located in Varamin region,Tehran province,Iran.Conventional heating systems used in the greenhouses are:central heating system(including boiler+hot water pipes),gas heater system(including double-walled tank+blower)and traditional furnace system(including ignition chamber+torch+pipes carrying a mixture of hot air and flammable gases).The study was carried out for two consecutive cucumber cultivation periods from January to June.Average values of crop yield,volume and cost of gas consumed were determined separately for each heating system.Results of the study indicated that the central heating system with the highest crop yield(295 t/ha),and the lowest volume(100,000 m^(3)/ha)and cost(840 USD/ha)of gas consumed was the best and most suitable heating system for greenhouses producing cucumbers in Varamin region and other regions with the same and similar climate as well as regions with active greenhouses in the cold season.展开更多
This research was conducted to study the effect of different heating systems in cucumber production greenhouses in Varamin region,Tehran province,Iran on crop yield,volume and cost of gas consumed.Three types of conve...This research was conducted to study the effect of different heating systems in cucumber production greenhouses in Varamin region,Tehran province,Iran on crop yield,volume and cost of gas consumed.Three types of conventional heating systems,namely the central heating system(including boiler+hot water pipes),gas heater system(including double-walled tank+blower)and traditional furnace system(including ignition chamber+torch+pipes carrying a mixture of hot air and flammable gases)were studied during two consecutive periods of greenhouse cucumber cultivation in the cold season(from January to June),and average values of crop yield,volume and cost of gas consumed were determined separately.Results of the study indicated that the central heating system with the highest crop yield(295 tha^-1),and the lowest volume(100,000 m3ha^-1)and cost(210,000,000 Rialsha^-1)of gas consumed was the best and most suitable heating system for greenhouses producing cucumbers in Varamin region and other regions with the same and similar climate as well as regions with active greenhouses in the cold season.展开更多
In this study,machine vision technology was used to capture images of greenhouse cucumber canopy,and image segmentation was implemented under various natural lighting conditions.The images were enhanced by multi-scale...In this study,machine vision technology was used to capture images of greenhouse cucumber canopy,and image segmentation was implemented under various natural lighting conditions.The images were enhanced by multi-scale retinex with color restore(MSRCR),and the MSRCR images were segmented by four algorithms:normalized difference index(NDI),excess green(ExG),modified excess green(MExG),and modified excess green minus excess red(MExG-ExR).The results indicated that compared with the original images,under various lighting conditions,the average evaluation indexes of brightness,information entropy,average gradient and mean gray value of the MSRCR images were increased by 38.71%,8.04%,4.54%,and 37.81%,respectively,and only the contrast degree decreased by 12.13%.The MExG-ExR segmentation algorithm was used to segment the MSRCR images(fifty images under various lighting conditions in the test and it performed best among the four segmentation algorithms,average overlap ratios and recognition rates of were 99.28%and 98.91%,respectively,while 38.39%and 37.95%respectively for original image.These results indicated that the MExG-ExR segmentation algorithm applied to a MSRCR canopy image produced the most stable results among the four algorithms.By using the MSRCR image enhancement algorithm,the interference of lighting on greenhouse cucumber canopy images was reduced and the foundation for achieving accurate segmentation of a canopy region was laid,which is of great significance for greenhouse cucumber phenotypic parameter measurements.展开更多
The objective of this study was to investigate the effects of different water and fertilizer applications on biomass,yield and fruit physical quality of greenhouse cucumber under drip irrigation.The experiment was con...The objective of this study was to investigate the effects of different water and fertilizer applications on biomass,yield and fruit physical quality of greenhouse cucumber under drip irrigation.The experiment was conducted at Water Conservancy Research Institute,Shenbei District,Shenyang,Northern China during February-July,2016.Nine treatments were used in randomized block design consisted of three levels of water field capacity(FC)and urea-potash(N-K)fertilizer combinations:W1(65%of FC),W_(2)(75%of FC),W3(85%of FC)and N_(1)-K_(1)(285-305 kg/hm^(2)),N2-K2(420-435 kg/hm^(2)),N_(3)-K_(3)(530-565 kg/hm^(2)).Local farmers’conventional application of water(100%)and fertilizer(NPK)was considered as check(CK)for comparison.Data obtained was analyzed(ANOVA)to check the significant effect of treatments.The results revealed that,treatment W_(3)N_(2)K_(1) obtained highest cucumber yield of 129.99 t/hm^(2),while W_(1)N_(1)K_(1) recorded the lowest yield(113.29 t/hm^(2)),in which total amount of seasonal water applied ranges from 85.3 mm to 172.36 mm.The highest yield was obtained 0.5%greater than the CK yield(129.35 t/hm^(2)).The water and fertilizer application was significantly(p<0.001)influenced on cucumber yield.Moreover,the influence of water application was significantly(0.01<p<0.05)on both green and dry biomass accumulation except green leaf weight and fruit physical quality.It was also revealed that,the highest green biomass accumulation(572.4 g/plant)and fruit diameter(27.92 mm)with treatment W_(3)N_(2)K_(1) have significant influence on improved yield.In conclusion,the improved cucumber yield indicated 15%deficit water tolerance,in which average seasonal yield response factor(Ky)was calculated as 0.22.Therefore,the treatment W_(3)N_(2)K_(1) could successfully be used to minimize water and fertilizer application for improving greenhouse cucumber yield.展开更多
The solar greenhouse without heating system has been widely used for vegetable production in Northeast China since the 1980s. The experiment was conducted in the solar greenhouse to study the relationship between evap...The solar greenhouse without heating system has been widely used for vegetable production in Northeast China since the 1980s. The experiment was conducted in the solar greenhouse to study the relationship between evapotranspiration (ET) of cucumber and climatic factors. Reference evapotranspiration (ET0) and pan evaporation (Ep) were applied to determine cucumber evapotranspiration by regression methods. Results showed that the ET of cucumber increased with the increasing of solar radiation, air temperature and vapor pressure. The solar radiation was the most important factor that influences ET among environmental parameters. The determination coefficient (R2) was 0.865 between ET and Ep, higher than that between ET and ET0 (application of a constant vegetation coefficient, R2 = 0.46). The pan coefficient (kp, determined from the ratio of ET to Ep) and the crop coefficients (kc, determined from the ratio of ET to ET0) showed considerable variability and no obvious systematic pattern could be described throughout the study period. Ep was linearly related to ET and 20 cm pan can be well used to determine the water requirement of cucumber under subsurface drip irrigation in this type of solar greenhouse.展开更多
To obtain the mechanical properties of greenhouse cucumber cane,tensile and shear properties of the greenhouse cucumber cane were studied by using computer-controlled electronic universal testing machine and homemade ...To obtain the mechanical properties of greenhouse cucumber cane,tensile and shear properties of the greenhouse cucumber cane were studied by using computer-controlled electronic universal testing machine and homemade cutting test bench,respectively.Firstly,the root,middle and head of cucumber cane were subjected for tensile tests.The tensile stress-strain curves showed that the root of cumber cane presented the characteristics of plastic material,while the middle and head showed the characteristics of brittle material.The average tensile strength of root,middle and head of fresh cucumber cane were 7.35 MPa,6.30 MPa and 4.68 MPa,respectively.The average elastic modulus of root of fresh cucumber cane was 280.58 MPa,which was much greater than the middle and head with average elastic modulus of 198.81 MPa and 137.22 MPa,respectively.A pendulum impact cutting test-rig and a cutting force measurement system composed of a cantilever weigh sensor,a high frequency DAQ card and motion control card were developed.The cutting mechanical property experiments of different parts of greenhouse cucumber cane were carried out,and the continuous curves of cutting force were measured.The single factor test for cross-sectional area,cutting speed,cutting tool type and manner were analyzed.The results indicated that the peak cutting force increased approximately linearly with the increasing of cutting sectional area,but decreased gradually with the increasing of cutting speed.In the same conditions,the cutting force could be reduced by using straight blade cutting tool and ramp cutting way.Through the multifactor interaction impact test of the cutting way,the blade type and the cutting speed,it was found that the corresponding F-value of the three factors were 21.316,49.141 and 0.222,which suggests that the blade type is the most significant factor for the cutting force.展开更多
The influence of light and temperature conditions inside solar greenhouse of winter-spring and autumn-winter crop in northern China on uptake and distribution of nitrogen, phosphorus and potassium of cucumber was stud...The influence of light and temperature conditions inside solar greenhouse of winter-spring and autumn-winter crop in northern China on uptake and distribution of nitrogen, phosphorus and potassium of cucumber was studied. The results showed that plant root development and uptake and distribution of N, P and K benefited more from inside light and temperature changes in winter-spring crop. Root volume and root activity increased more rapidly in winter-spring than in autumn-winter. Uptake of total N, P2O5 and K2O increased with plant development in winter-spring, and declined in autumn-winter crop. Distribution of total N,P2O5 and K2O at different part of cucumber at fruit bearing stage was significantly influenced by inside light and temperature of solar greenhouse. Total N, P2O5 and K2O were mainly distributed to leaves and stems at early stage, and increasingly to fruits after fruit bearing.展开更多
The photosynthetic characteristics and ultrastructure of chloroplast of cucumber in solar-greenhouse were studied. The result showed that the photosynthetic rate (Pn), photosyntheticability (A350), carboxylation effic...The photosynthetic characteristics and ultrastructure of chloroplast of cucumber in solar-greenhouse were studied. The result showed that the photosynthetic rate (Pn), photosyntheticability (A350), carboxylation efficiency, light saturation point and light compensation pointall declined remarkably under low light density, indicating that the photosynthetic characteristicsof cucumber were closely related to light environment. Under low light density, the minimalfluorescence (Fo), alterable fluorescence (Fv), photochemical efficiency of PSⅡ(Fv/Fm), steadyfluorescence in light (Fs), maximal fluorescence (Fm) and actual efficiency of PSⅡ(φPSⅡ)etcincreased, indicating that the photochemical activity and efficiency for solar energy transformationenhanced, thus the light proportion used to electron transport also increased. The chlorophylla, b, a/b and carotenoid of shading leaves decreased. However, the depressed extent of Chl a andChl a/b were obviously larger than that of Chl b. The number of chloroplast and starch grainin cucumber leaves descended, but that of grana and lamella increased as a shaded result. Thesize of chloroplast and starch grain of shading leaves minished.展开更多
基金the National Natural Science Foundation of China(60073028) the National“863”High-Tech Program(2001AA-247023)
文摘Greenhouse canopy transpiration not only has effects on greenhouse air temperature and humidity, but also is important for determining the set-point of fertigation. In this study, Penman-Monteith equation was used to calculate the greenhouse cucumber canopy transpiration under summer climate condition.The effects of greenhouse environmental factors on canopy transpiration were analyzed based on the measurements of greenhouse microclimate factors and canopy transpiration. The results showed that Penman-Monteith equation was reliable and robust in estimating greenhouse cucumber canopy transpiration under summer climate condition. Greenhouse cucumber canopy transpiration rate increased linearly with the increase of net radiation and water vapor pressure deficit (VPD) above the canopy. But the maximum value of the canopy transpiration rate occurred at the same time as that of VPD whereas about two hours later than that of net radiation. Based on the results, it was concluded that in addition to radiation, air humidity should also be considered when determine the set-point of fertigation.
文摘This paper mainly studies the disease of cucumber downy mildew, powdery mildew and anthracnose leaf image processing and recognition technologies. Application of median filtering method of filtering noise, leaf spot disease of cucumber leaf color range segmentation part extract color feature parameters of the lesion site, characteristic parameters of the shape;extraction texture parameters by using gray level co-occurrence matrix. Based on the shortest distance methods to identify diseases of images. The experimental result showed that the current method on disease recognition accuracy rates more than 96%.
基金Supported by Science and Technology Innovation Fund of Undergraduation of Northeast Agricultural University (20070206)
文摘Different pumpkin rootstocks were used to study the effects of different rootstocks on the growth and fruit quality of greenhouse cucumber in early spring. The results showed that the grafted cucumber could signifi cantly improve the production, and different rootstock had a certain effect on the survival rate and fruit quality. Jinhuanghou and Fengyijiajiewang as rootstock had the highest survival rate, which were 79.0% and 70.7%, respectively. As rootstocks of greenhouse cucumber, Jinhuanghou, Lvzhoujuxing, Fengyi, Huofenghuang, and Dawei No.17 were better than others according to taste, and Heizinangua, Jinhuanghou, Fengyi, Huofenghuang, and Dawei No.17 were better according to output.
文摘Water scarcity is the most significant barrier to agricultural development in arid and semi-arid regions.Deficit irrigation is an effective solution for managing agricultural water in these regions.The use of additives such as vermicompost(VC)to improve soil characteristics and increase yield is a popular practice.Despite this,there is still a lack of understanding of the interaction between irrigation water and VC on various crops.This study aimed to investigate the interaction effect of irrigation water and VC on greenhouse cucumber yield,yield components,quality,and irrigation water use efficiency(IWUE).The trials were done in a split-plot design in three replicates in a semi-arid region of southeastern Iran in 2018 and 2019.Three levels of VC in the experiments,i.e.,10(V_(1)),15(V_(2)),and 20 t/hm^(2)(V_(3)),and three levels of irrigation water,i.e.,50%(I_(1)),75%(I_(2)),and 100%(I_(3))of crop water requirement were used.The results showed that the amount of irrigation water,VC,and their interaction significantly affected cucumber yield,yield components,quality,and IWUE in both years.Reducing the amount of irrigation water and VC application rates reduced the weight,diameter,length,and cucumber yield.The maximum yield(175 t/hm^(2))was recorded in full irrigation using 20 t/hm^(2)of VC,while the minimum yield(98 t/hm^(2))was found in I_(1)V_(1)treatment.The maximum and minimum values of IWUE were recorded for I_(1)V_(3)and I_(3)V_(1)treatments as 36.07 and 19.93 kg/(m^(3)•hm^(2)),respectively.Moreover,reducing irrigation amount decreased chlorophyll a and b,but increased vitamin C.However,the maximum carbohydrate and protein contents were obtained in mild water-stressed conditions(I_(2)).Although adding VC positively influenced the value of quality traits,no significant difference was observed between V_(2)and V_(3)treatments.Based on the results,adding VC under full irrigation conditions leads to enhanced yield and IWUE.However,in the case of applying deficit irrigation,adding VC up to a certain level(15 t/hm^(2))increases yield and IWUE,after which the yield begins to decline.Because of the salinity of VC,using a suitable amount of it is a key point to maximize IWUE and yield when applying a deficit irrigation regime.
基金supported by the Special Funds for Scientific and Technological Innovation of Jiangsu province,China (BE2022425)Project of Jiangsu Province Science and Technology (BE2017380)+1 种基金the National Key Research and Development Program (2018YFD1000800)the National Natural Science Foundation of China (32072579,31672160 and 30871721).
文摘The fruit yield of cucumber are associated with high input of nitrogen,which poses a risk of pollution to the environment.The EU-Rotate_N model has been used widely for its high performance in the simulation of vegetable growth,water and nitrogen dynamics.However,whether the underground water level affects the performance of the EU-Rotate_N model is unclear.In this study,we modified the groundwater level algorithms to the original model and named the modified model'the HG EU-Rotate_N model'.Experiments over two years on greenhouse cucumber with four different nitrogen(N)treatments(N1-N4)were conducted in Jiangsu Province,China,which has a high groundwater level(area_(HG)).Both original and modified models were used to simulate cucumber growth,water movement and N fate.For the soil water content,the measured values were significantly larger than the simulated values of the original model(value_(O))and closer to those of the HG model(value_(HG));for the soil available nitrogen concentration(SNC),the measured values were significantly higher and lower than value_(O) in 0−10 cm and 10−30 cm soil layers,respectively,and were also closer to those of the values_(HG).The higher SNC in the 0-10 cm soil layer indicated that a high groundwater level might increase the upwards movement of water and nitrogen in the 0-30 cm soil layer.The root mean square error,Nash Sutcliffe Efficiency and difference values show that the HG model was more applicable for areaHG than the original model.In this study,the nitrogen dosage of the N3 treatment was sufficient to meet the requirements of cucumber growth,indicating that the fertilization recommendation according to nitrogen nutrient balance was applicable in this area.
基金The authors acknowledge the financial support received from the National Natural Science Foundation of China(72061147002).
文摘China removed fertilizer manufacturing subsidies from 2015 to 2018 to bolster market-oriented reforms and foster environmentally sustainable practices.However,the impact of this policy reform on food security and the environment remains inadequately evaluated.Moreover,although green and low-carbon technologies offer environmental advantages,their widespread adoption is hindered by prohibitively high costs.This study analyzes the impact of removing fertilizer manufacturing subsidies and explores the potential feasibility of redirecting fertilizer manufacturing subsidies to invest in the diffusion of these technologies.Utilizing the China Agricultural University Agri-food Systems model,we analyzed the potential for achieving mutually beneficial outcomes regarding food security and environmental sustainability.The findings indicate that removing fertilizer manufacturing subsidies has reduced greenhouse gas(GHG)emissions from agricultural activities by 3.88 million metric tons,with minimal impact on food production.Redirecting fertilizer manufacturing subsidies to invest in green and low-carbon technologies,including slow and controlled-release fertilizer,organic-inorganic compound fertilizers,and machine deep placement of fertilizer,emerges as a strategy to concurrently curtail GHG emissions,ensure food security,and secure robust economic returns.Finally,we propose a comprehensive set of government interventions,including subsidies,field guidance,and improved extension systems,to promote the widespread adoption of these technologies.
基金supported by grants from the Key Project of Guangzhou (Grant No.202103000085)National Natural Science Foundation of China (Grant No.31902014)+1 种基金Guangzhou Science and Technology Project (Grant No.202102020502)Fruit and Vegetable Industry System Innovation Team Project of Guangdong (Grant No.2021KJ110)。
文摘High-temperature stress threatens the growth and yield of crops. Basic helix-loop-helix(bHLH) transcription factors(TFs) have been shown to play important roles in regulating high-temperature resistance in plants. However, the bHLH TFs responsible for high-temperature tolerance in cucumbers have not been identified. We used transcriptome profiling to screen the high temperature-responsive candidate bHLH TFs in cucumber. Here, we found that the expression of 75 CsbHLH genes was altered under high-temperature stress. The expression of the CsSPT gene was induced by high temperatures in TT(Thermotolerant) cucumber plants. However, the Csspt mutant plants obtained by the CRISPR-Cas9 system showed severe thermosensitive symptoms, including wilted leaves with brown margins and reduced root density and cell activity.The Csspt mutant plants also exhibited elevated H_(2)O_(2) levels and down-regulated photosystem-related genes under normal conditions.Furthermore, there were high relative electrolytic leakage(REC), malondialdehyde(MDA), glutathione(GSH), and superoxide radical(O_(2)^(·-)) levels in the Csspt mutant plants, with decreased Proline content after the high-temperature treatment. Transcriptome analysis showed that the photosystem and chloroplast activities in Csspt mutant plants were extremely disrupted by the high-temperature stress compared with wildtype(WT) plants. Moreover, the plant hormone signal transduction, as well as MAPK and calcium signaling pathways were activated in Csspt mutant plants under high-temperature stress. The HSF and HSP family genes shared the same upregulated expression patterns in Csspt and WT plants under high-temperature conditions. However, most bHLH, NAC, and bZIP family genes were significantly down-regulated by heat in Csspt mutant plants. Thus, these results demonstrated that CsSPT regulated the high-temperature response by recruiting photosynthesis components, signaling pathway molecules, and transcription factors. Our results provide important insights into the heat response mechanism of CsSPT in cucumber and its potential as a target for breeding heat-resistant crops.
基金supported by the the“JBGS”Project of Seed Industry Revitalization in Jiangsu Province,China(JBGS[2021]018)the Jiangsu Agricultural Innovation of New Cultivars,China(PZCZ201720)the Open Project Program of Jiangsu Key Laboratory for Horticultural Crop Genetic Improvement,China(K2020030)。
文摘Leaf color mutants in higher plants are considered to be ideal materials for studying the chlorophyll biosynthesis,photosynthesis mechanism and chloroplast development.Herein,we identified a spontaneous mutant,yc412,in cultivated cucumber that exhibited yellow cotyledons.The yellow-lethal mutant was diagnosed with an abnormal chloroplast ultrastructure,and reduced photosynthetic capacity and pigment content.Through bulked segregant analysis-based whole-genome sequencing and fine genetic mapping,we narrowed the yellow cotyledons (yc) locus to a 96.8 kb interval on chromosome 3.By resequencing and molecular cloning,we showed that Csyc is a potential candidate gene,which encodes a yellow stripe-like (YSL) transporter.The T to C mutation in the promoter region of Csyc caused the yellow cotyledon phenotype in yc412.Compared to YZU027A (WT),the expression of Csyc was significantly downregulated in the cotyledons of yc412.Silencing of Csyc in cucumber via virus-induced gene silencing resulted in chlorotic leaves,mainly by suppressing the chlorophyll content.Furthermore,a comparative transcriptome analysis revealed that chloroplast-related genes and chlorophyll biosynthesis genes were significantly downregulated in yc412 cotyledons.Our results provide new insights into the molecular function of the YSL transporter in plant chloroplast development and chlorophyll synthesis.
文摘This study was conducted to provide a preliminary assessment of the sea cucumber fishery in Aurora, Philippines. This was conducted from February to June 2013. All sea cucumber gatherers and traders, obtained through snowball sampling, in each identified sea cucumber fishery area in six coastal municipalities (Baler, Dipaculao, Dinalungan, Casiguran, Dilasag and Dingalan) were interviewed using a structured interview schedule and focused group discussions (FGD). Results revealed that gathering sea cucumbers were accomplished by handpicking, skin diving or compressor diving. A total of 15 commercial species were regularly gathered. Out of this, three species are of very high economic value (≥Php 4000/kg) (Holothuria nobilis, Holothuria scabra, and Actinopyga lecanora). The average number of kilograms harvested per hour per trip ranges from 0.21 (Holothuria fuscopunctata) to 2.71 (Holothuria scabra), while the average size of commonly gathered sea cucumber varies among species with Holothuria lecanora showed an average length (29.26 cm) greater than recorded 24 cm. Processing mainly involves washing, slicing, boiling, drying and packing. Processed sea cucumbers or trepan were sold to middlemen or direct buyers who usually offered higher prices (36.36% up to 69.20%) than the former. Problems encountered by sea cucumber gatherers and traders include a decline in total catch, a shift in area of collection from intertidal zones to deeper waters, an increase in the number of hours spent in finding and gathering sea cucumbers, the use of compressors in gathering, the decline of larger species and gathering of smaller sizes in huge amount, the absence of conservation program for sea cucumber, and the lenient implementation of government policies with regards to coastal resources management.
基金Supported by Key Scientific Research Project in Colleges and Universities of Henan Province(22B180011)Project of Henan Provincial Department of Science and Technology(232102320262)+1 种基金Education and Teaching Reform Research Project of Pingdingshan University(2021-JY55)Key Demonstration Course of Pingdingshan University in 2022——Comprehensive Experiment of Environmental Biology.
文摘The production environment of greenhouse cultivation is relatively closed,the multiple cropping index is high,the management of fertilizationwatering and pesticideapplication isblindtosomeextent,andthe phenomenonofcontinuous cropping isalsocommonSoilquali-ty affects the sustainable development of greenhouse cultivation.Earthworm is a ubiquitous invertebrate organism in soil,an important part of soil system,a link between terrestrial organisms and soil organisms,an important link in the small cycle of soil material organisms,and plays an important role in maintaining the structure and function of soil ecosystem.Different ecotypes of earthworms are closely related to their habi-tats(soil layers)and food resource preferences,and then affect their ecological functions.The principle of earthworm regulating soil function is essentially the close connection and interaction between earthworm and soil microorganism.Using different ecotypes of earthworms and bio-logical agents to carry out combined remediation of greenhouse cultivation soil is a technical model to realize sustainable development of green-house cultivation.
文摘Microplastics can influence global climate change by regulating the emissions of greenhouse gases from different ecosystems. The effects of microplastics in terrestrial ecosystems are still not well studied particularly greenhouse gases emissions. Thus, we conducted a laboratory experiment over a period of 90 days with two types of microplastics (differing in their chemical structure), high density polyethylene (HDPE) and low density polyethylene (LDPE), which were applied to the soil at a rate of 0% to 0.1% (w/w). The overarching aim was to investigate the effects of microplastic type, microplastic concentration and days of exposure on greenhouse gases emissions. We also used original and artificially weathered microplastics (the same HDPE and LDPE) to make a comparison of greenhouse gases emissions between the original microplastics treated soils and the soils treated with weathered microplastics. Our findings showed that HDPE and LDPE microplastics significantly increased the emissions of greenhouse gases from the soil than that of the control soils. Emissions were increased with the increases in the level of microplastic in the soil. The weathered microplastic emitted greater quantity of greenhouse gases compared to that of the original microplastics. In contrast to a low initial emission quantity, the emissions were gradually increased at the termination of the experiment. Our experiment on the emissions of greenhouse gases from the soil vis-à-vis microplastic additions indicated that the microplastic increased the emissions of greenhouse gases in terrestrial ecosystems, and pervasive microplastic impacts may have consequences for the global climate change. Greenhouse gases emissions from the soil not only depend on the type and concentration of the microplastic, but also on the days of exposure to the microplastic.
基金financially supported by the Steel Structure Research and Education Promotion Project of the Japan Iron and Steel Federation in FY2016.
文摘The present paper first investigates the collapse behavior of a conventional pipe-framed greenhouse under snow loading based on a 3-D finite element analysis,in which both geometrical and material non-linearities are considered.Three snow load distribution patterns related to the wind-driven snow particle movement are used in the analysis.It is found that snow load distribution affects the deformation and collapse behavior of the pipe-framed greenhouse significantly.The results obtained in this study are consistent with the actual damage observed.Next,discussion is made of the effects of reinforcements by adding members to the basic frame on the strength of the whole structure,in which seven kinds of reinforcement methods are examined.A buckling analysis is also carried out.The results indicate that the most effective reinforcement method depends on the snow load distribution pattern.
基金the Agricultural Research,Education and Extension Organization(AREEO)。
文摘This research was conducted to investigate the effects of three heating systems on cucumber yield,and cost and gas volume consumed in greenhouses located in Varamin region,Tehran province,Iran.Conventional heating systems used in the greenhouses are:central heating system(including boiler+hot water pipes),gas heater system(including double-walled tank+blower)and traditional furnace system(including ignition chamber+torch+pipes carrying a mixture of hot air and flammable gases).The study was carried out for two consecutive cucumber cultivation periods from January to June.Average values of crop yield,volume and cost of gas consumed were determined separately for each heating system.Results of the study indicated that the central heating system with the highest crop yield(295 t/ha),and the lowest volume(100,000 m^(3)/ha)and cost(840 USD/ha)of gas consumed was the best and most suitable heating system for greenhouses producing cucumbers in Varamin region and other regions with the same and similar climate as well as regions with active greenhouses in the cold season.
基金The supports provided by the Agricultural Research,Education and Extension Organization,Iran in research project number 2-41-14-031-960719 are gratefully acknowledged.
文摘This research was conducted to study the effect of different heating systems in cucumber production greenhouses in Varamin region,Tehran province,Iran on crop yield,volume and cost of gas consumed.Three types of conventional heating systems,namely the central heating system(including boiler+hot water pipes),gas heater system(including double-walled tank+blower)and traditional furnace system(including ignition chamber+torch+pipes carrying a mixture of hot air and flammable gases)were studied during two consecutive periods of greenhouse cucumber cultivation in the cold season(from January to June),and average values of crop yield,volume and cost of gas consumed were determined separately.Results of the study indicated that the central heating system with the highest crop yield(295 tha^-1),and the lowest volume(100,000 m3ha^-1)and cost(210,000,000 Rialsha^-1)of gas consumed was the best and most suitable heating system for greenhouses producing cucumbers in Varamin region and other regions with the same and similar climate as well as regions with active greenhouses in the cold season.
基金National Natural Science Foundation of China(Project No:61273227)Youth Foundation of Jiangsu Province(Project No:BK20150686).
文摘In this study,machine vision technology was used to capture images of greenhouse cucumber canopy,and image segmentation was implemented under various natural lighting conditions.The images were enhanced by multi-scale retinex with color restore(MSRCR),and the MSRCR images were segmented by four algorithms:normalized difference index(NDI),excess green(ExG),modified excess green(MExG),and modified excess green minus excess red(MExG-ExR).The results indicated that compared with the original images,under various lighting conditions,the average evaluation indexes of brightness,information entropy,average gradient and mean gray value of the MSRCR images were increased by 38.71%,8.04%,4.54%,and 37.81%,respectively,and only the contrast degree decreased by 12.13%.The MExG-ExR segmentation algorithm was used to segment the MSRCR images(fifty images under various lighting conditions in the test and it performed best among the four segmentation algorithms,average overlap ratios and recognition rates of were 99.28%and 98.91%,respectively,while 38.39%and 37.95%respectively for original image.These results indicated that the MExG-ExR segmentation algorithm applied to a MSRCR canopy image produced the most stable results among the four algorithms.By using the MSRCR image enhancement algorithm,the interference of lighting on greenhouse cucumber canopy images was reduced and the foundation for achieving accurate segmentation of a canopy region was laid,which is of great significance for greenhouse cucumber phenotypic parameter measurements.
文摘The objective of this study was to investigate the effects of different water and fertilizer applications on biomass,yield and fruit physical quality of greenhouse cucumber under drip irrigation.The experiment was conducted at Water Conservancy Research Institute,Shenbei District,Shenyang,Northern China during February-July,2016.Nine treatments were used in randomized block design consisted of three levels of water field capacity(FC)and urea-potash(N-K)fertilizer combinations:W1(65%of FC),W_(2)(75%of FC),W3(85%of FC)and N_(1)-K_(1)(285-305 kg/hm^(2)),N2-K2(420-435 kg/hm^(2)),N_(3)-K_(3)(530-565 kg/hm^(2)).Local farmers’conventional application of water(100%)and fertilizer(NPK)was considered as check(CK)for comparison.Data obtained was analyzed(ANOVA)to check the significant effect of treatments.The results revealed that,treatment W_(3)N_(2)K_(1) obtained highest cucumber yield of 129.99 t/hm^(2),while W_(1)N_(1)K_(1) recorded the lowest yield(113.29 t/hm^(2)),in which total amount of seasonal water applied ranges from 85.3 mm to 172.36 mm.The highest yield was obtained 0.5%greater than the CK yield(129.35 t/hm^(2)).The water and fertilizer application was significantly(p<0.001)influenced on cucumber yield.Moreover,the influence of water application was significantly(0.01<p<0.05)on both green and dry biomass accumulation except green leaf weight and fruit physical quality.It was also revealed that,the highest green biomass accumulation(572.4 g/plant)and fruit diameter(27.92 mm)with treatment W_(3)N_(2)K_(1) have significant influence on improved yield.In conclusion,the improved cucumber yield indicated 15%deficit water tolerance,in which average seasonal yield response factor(Ky)was calculated as 0.22.Therefore,the treatment W_(3)N_(2)K_(1) could successfully be used to minimize water and fertilizer application for improving greenhouse cucumber yield.
基金supported by the Young Scientist Innovation Science of Shandong Agricultural University, China (23653)
文摘The solar greenhouse without heating system has been widely used for vegetable production in Northeast China since the 1980s. The experiment was conducted in the solar greenhouse to study the relationship between evapotranspiration (ET) of cucumber and climatic factors. Reference evapotranspiration (ET0) and pan evaporation (Ep) were applied to determine cucumber evapotranspiration by regression methods. Results showed that the ET of cucumber increased with the increasing of solar radiation, air temperature and vapor pressure. The solar radiation was the most important factor that influences ET among environmental parameters. The determination coefficient (R2) was 0.865 between ET and Ep, higher than that between ET and ET0 (application of a constant vegetation coefficient, R2 = 0.46). The pan coefficient (kp, determined from the ratio of ET to Ep) and the crop coefficients (kc, determined from the ratio of ET to ET0) showed considerable variability and no obvious systematic pattern could be described throughout the study period. Ep was linearly related to ET and 20 cm pan can be well used to determine the water requirement of cucumber under subsurface drip irrigation in this type of solar greenhouse.
基金the National Key Technologies R&D Program of China(No.2014BAD08B04)the National Natural Science Fund of China(No.51175230,No.51475212)+1 种基金Independent Innovation of Agricultural Science and Technology Project in Jiangsu Province(cx(10)224)Research and Innovation Project for College Graduates of Jiangsu Province of China(CXLX12_0625).
文摘To obtain the mechanical properties of greenhouse cucumber cane,tensile and shear properties of the greenhouse cucumber cane were studied by using computer-controlled electronic universal testing machine and homemade cutting test bench,respectively.Firstly,the root,middle and head of cucumber cane were subjected for tensile tests.The tensile stress-strain curves showed that the root of cumber cane presented the characteristics of plastic material,while the middle and head showed the characteristics of brittle material.The average tensile strength of root,middle and head of fresh cucumber cane were 7.35 MPa,6.30 MPa and 4.68 MPa,respectively.The average elastic modulus of root of fresh cucumber cane was 280.58 MPa,which was much greater than the middle and head with average elastic modulus of 198.81 MPa and 137.22 MPa,respectively.A pendulum impact cutting test-rig and a cutting force measurement system composed of a cantilever weigh sensor,a high frequency DAQ card and motion control card were developed.The cutting mechanical property experiments of different parts of greenhouse cucumber cane were carried out,and the continuous curves of cutting force were measured.The single factor test for cross-sectional area,cutting speed,cutting tool type and manner were analyzed.The results indicated that the peak cutting force increased approximately linearly with the increasing of cutting sectional area,but decreased gradually with the increasing of cutting speed.In the same conditions,the cutting force could be reduced by using straight blade cutting tool and ramp cutting way.Through the multifactor interaction impact test of the cutting way,the blade type and the cutting speed,it was found that the corresponding F-value of the three factors were 21.316,49.141 and 0.222,which suggests that the blade type is the most significant factor for the cutting force.
基金the National Natural Science Foundation of China (39830230) Beijing Natural Science Foundation (6011002).
文摘The influence of light and temperature conditions inside solar greenhouse of winter-spring and autumn-winter crop in northern China on uptake and distribution of nitrogen, phosphorus and potassium of cucumber was studied. The results showed that plant root development and uptake and distribution of N, P and K benefited more from inside light and temperature changes in winter-spring crop. Root volume and root activity increased more rapidly in winter-spring than in autumn-winter. Uptake of total N, P2O5 and K2O increased with plant development in winter-spring, and declined in autumn-winter crop. Distribution of total N,P2O5 and K2O at different part of cucumber at fruit bearing stage was significantly influenced by inside light and temperature of solar greenhouse. Total N, P2O5 and K2O were mainly distributed to leaves and stems at early stage, and increasingly to fruits after fruit bearing.
文摘The photosynthetic characteristics and ultrastructure of chloroplast of cucumber in solar-greenhouse were studied. The result showed that the photosynthetic rate (Pn), photosyntheticability (A350), carboxylation efficiency, light saturation point and light compensation pointall declined remarkably under low light density, indicating that the photosynthetic characteristicsof cucumber were closely related to light environment. Under low light density, the minimalfluorescence (Fo), alterable fluorescence (Fv), photochemical efficiency of PSⅡ(Fv/Fm), steadyfluorescence in light (Fs), maximal fluorescence (Fm) and actual efficiency of PSⅡ(φPSⅡ)etcincreased, indicating that the photochemical activity and efficiency for solar energy transformationenhanced, thus the light proportion used to electron transport also increased. The chlorophylla, b, a/b and carotenoid of shading leaves decreased. However, the depressed extent of Chl a andChl a/b were obviously larger than that of Chl b. The number of chloroplast and starch grainin cucumber leaves descended, but that of grana and lamella increased as a shaded result. Thesize of chloroplast and starch grain of shading leaves minished.
