In plant factories,the plant microclimate is affected by the control system,plant physiological activities and aerodynamic characteristics of leaves,which often leads to poor ventilation uniformity,suboptimal environm...In plant factories,the plant microclimate is affected by the control system,plant physiological activities and aerodynamic characteristics of leaves,which often leads to poor ventilation uniformity,suboptimal environmental conditions and inefficient air conditioning.In this study,interlayer cool airflow(ILCA)was used to introduce room air into plants’internal canopy through vent holes in cultivation boards and air layer between cultivation boards and nutrient solution surface(interlayer).By using optimal operating parameters at a room temperature of 28℃,the ILCA system achieved similar cooling effects in the absence of a conventional air conditioning system and achieved an energy saving of 50.8% while bringing about positive microclimate change in the interlayer and nutrient solution.This resulted in significantly reduced root growth by 41.7% without a negative influence on lettuce crop yield.Future development in this precise microclimate control method is predicted to replace the conventional cooling(air conditioning)systems for crop production in plant factories.展开更多
Accurate irrigation and nitrogen application are essential for promoting the growth and yield of cherry tomatoes.In investigating the effects of irrigation and nitrogen on the growth,photosynthesis,and yield of cherry...Accurate irrigation and nitrogen application are essential for promoting the growth and yield of cherry tomatoes.In investigating the effects of irrigation and nitrogen on the growth,photosynthesis,and yield of cherry tomatoes,nine treatments including three levels of both irrigation and nitrogen were conducted over two growing seasons.Transverse stem diameter and horizontal stem diameter had the best performance at the irrigation level of 75%evaporation(E_(p)),although their responses to nitrogen were different for the two years.Plant height increased with the increase of irrigation and nitrogen.Plant dry matter(PDM)was significantly affected by irrigation and nitrogen interaction.The lowest PDM was found in the highest proportion of root dry matter,which occurred under low nitrogen level.The net photosynthetic rate(Pn)and transpiration rate enhanced with the increase of irrigation.Medium nitrogen showed promotion effect on all photosynthetic parameters in both growing seasons.Six of all fourteen indicators showed significant correlations with yield.Especially,single plant fruit number and PDM in 2018 Fall had significant positive direct effects on yield with the path coefficients of 0.648 and 1.159,while the significant direct path coefficients were 0.362 and 0.294 in Fruit dry matter and Pn for 2019 Spring,respectively.Based on the comprehensive evaluation of growth and yield by TOPSIS,the irrigation level of 75%E_(p) combined with medium nitrogen application produced higher yields by promoting the growth and photosynthesis of cherry tomatoes.It provides a strategy for water and nitrogen management of cherry tomatoes in Northwest China.展开更多
Solar greenhouse is extensively used in horticultural production in China.Natural ventilation is one of the key technological means to adjust the inside environment of greenhouse,while the effects of window opening st...Solar greenhouse is extensively used in horticultural production in China.Natural ventilation is one of the key technological means to adjust the inside environment of greenhouse,while the effects of window opening styles on the inside environment are still not well understood.In the present study,the temperature and air flow field of five operation styles,namely back roof central opening style(G1),back roof evenly spaced opening style(G2),top roof full opening style(G3),style of G1+G3,and style of G2+G3 were simulated using the CFD method.The results indicated that:(1)the simulated and measured results exhibited favorable agreement,with relative errors within 5%;(2)In the case of the windows opening area was the same and only single ventilation style was applied,back roof full opening style exhibited the best cooling effect.The inside average temperature of the greenhouse with G1 style decreased by 0.5°C and 1.6°C respectively compared with those of greenhouses with G2 and G3.(3)The cooling effect of the style of G2+G3 was more favorable than that of the style of G1+G3.The style of G2+G3 exhibited better cooling effect than the single ventilation styles,with the lowest temperature(27.5°C)and temperature uniformity coefficient(0.36).展开更多
In the northwestern part of China,rational and efficient management of irrigation and nitrogen significantly affects the intensive production of greenhouse cucumbers(Cucumis sativus L).To evaluate the effects of diffe...In the northwestern part of China,rational and efficient management of irrigation and nitrogen significantly affects the intensive production of greenhouse cucumbers(Cucumis sativus L).To evaluate the effects of different combinations of water use and nitrogen(N)on yield,quality,and profitability of the greenhouse cucumbers that planted in 2018 Spring,nine combined treatments were applied.Results indicated the optimal irrigation and nitrogen demands for yield,quality and other indicators were different.The irrigation amount significantly affected the yield,and the yield gradually increased with increasing in irrigation.Single fruit weight(SFW)was significantly affected by the amount of irrigation,nitrogen and their interactions,and the higher amounts of N and irrigation were beneficial to the increase of SFW.The partial factor productivity of the applied N(PFPN)gradually increased with the nitrogen amount decline.Irrigation water use efficiency(IWUE)was closely related to the amount of irrigation.The higher irrigation amount would lead to the lower IWUE.When the amounts of irrigation and nitrogen were at an intermediate level,the content of vitamin C(VC)reached the maximum.As the amount of nitrogen was increased or irrigation was decreased,the Nitrate content(NC)would increase.Free amino acid(FAA)and NC followed a similar variation.When the amounts of irrigation and nitrogen both were at medium levels,the total soluble sugar concentration(TSSC)reached the highest.The multi-level fuzzy evaluation method was used to evaluate different indicators of cucumber.The weights of indicators in the first and second layer were determined by analytic hierarchy process(AHP)and entropy weight method,respectively.Then the fuzzy algorithm was used to comprehensively evaluate all the treatments.The evaluation results show that T4(irrigation,1957.6 m3/hm2;N,210 kg/hm2)is the best strategy for greenhouse cucumber irrigation and nitrogen management in the northwestern part of China.展开更多
The objectives of the present work are focused on exploration of the reasons for temperature difference in different envelopes,the sensitivity of envelopes of solar greenhouse to thermal disfigurements and optimal sel...The objectives of the present work are focused on exploration of the reasons for temperature difference in different envelopes,the sensitivity of envelopes of solar greenhouse to thermal disfigurements and optimal selection of the thermal insulation quilt.Theoretical analysis and derivation are conducted according to the experimental results of surface temperature,convective heat transfer,and heat flux density in different envelopes which with thermal disfigurements of solar greenhouse using heat transfer theory.The results revealed that the difference of intrinsic thermal conductivity and thickness of the envelopes leads to difference in the thermal flux and thus in the surface temperature of different envelopes.Compared with the front roof and back roof,the wall is more sensitive to thermal disfigurements.According to the influence of thermal disfigurements on solar greenhouse temperature,the allowable thermal disfigurements area fraction of front roof and back roof are given.Based on the analysis of heat transfer theory and test results,the work given the expression of the thickness and thermal conductivity of thermal insulation quilt under different outdoor minimum temperatures for optimal selection of thermal insulation quilt based on comprehensive considering factors of the solar greenhouse structure,crop demand,outdoor minimum temperature,and insulation quilt properties.The results of this work give technical criterion for whether the envelopes with thermal disfigurements needs to be repaired or replaced,and it also provides theoretical and technical support for design the solar greenhouse as well as methodological guidance for the optimal selection of the thermal insulation quilt.展开更多
In order to improve the thermal insulation and storage performance of Chinese solar greenhouses in winter,a novel assembled Chinese solar greenhouse(ACSG)without energy supplement in cold climatic areas was designed t...In order to improve the thermal insulation and storage performance of Chinese solar greenhouses in winter,a novel assembled Chinese solar greenhouse(ACSG)without energy supplement in cold climatic areas was designed to evaluate and compare its thermal performance with that of conventional Chinese solar greenhouse(CSG).The thermal properties of both greenhouses were tested in field on cold winter days in Ningxia,China.The results indicated that the land utilization rate of ACSG was 19.3%higher than that of CSG.On a typical sunny day(the lowest outdoor temperature was−22.0℃)and typical cloudy day(the lowest outdoor temperature was−19.7℃)during the experiment,the minimum indoor temperature of ACSG was respectively 1.7℃and 2.0℃higher than that of CSG.The results for 24 consecutive days(the average outdoor daily minimum air temperature was−19.0℃)showed that the average minimum indoor temperature of ACSG was 1.4℃higher than that of CSG(p<0.05).The modular soil wall attached with colored steel polystyrene boards would be exploited as the north wall of CSG in Yinchuan area.展开更多
Solar greenhouse is a typical greenhouse without any additional heating system,which has developed rapidly in Northern China.However,due to the construction quality,management methods,especially the long-term use and ...Solar greenhouse is a typical greenhouse without any additional heating system,which has developed rapidly in Northern China.However,due to the construction quality,management methods,especially the long-term use and other factors,there are usually different degrees of thermodynamic disfigurements in the envelop enclosure of solar greenhouse.The purpose of this study was to investigate the influences of thermodynamic disfigurement on the temperature distribution and convective heat transfer of solar greenhouse.In this study,the east and west compartments of a typical solar greenhouse which is located in Yangling,China(108°4′E,34°16′N)were tested.The air temperature of each compartment was collected using temperature recorders,and the thermal infrared images of different compartment envelopes were obtained by a thermal infrared imager on a typical cloudy day.Convective heat transfer coefficients and heat flux densities of different compartment envelopes in the solar greenhouse were calculated.The results showed that the temperature difference can be displayed in the thermal infrared images of compartment envelopes,the surface temperature of the front roof was the lowest,followed by the back roof,the wall surface temperature was the highest.The minimum average surface temperature of the front roof in the eastern compartment was only 3.8℃,which was 6.8℃ and 9.2℃ lower than the average surface temperature of the back roof and back wall,respectively.The surface average temperature of thermodynamic disfigurements located at the bottom of the south side in the front roof of the eastern compartment,whose area accounted for 16.5%of the total front roof in the eastern compartment,was only 5.4℃.Compared with non-thermodynamic disfigurement,the average convective heat transfer coefficient and heat flux density of thermodynamic disfigurements in the front roof of the eastern compartment were increased by 20.3%and 110.3%,respectively.The average air temperature in the eastern compartment was 3.5℃ lower than the average air temperature in the western compartment of the solar greenhouse.Construction of brick wall at the bottom of the south side of the front roof in the solar greenhouse helped to increase the inner surface temperature of the front roof,with an average temperature rise of 6.2℃,and reduce the area of thermodynamic disfigurement,which only accounted for 2.6%of the total front roof in the western compartment.The average surface temperature of thermodynamic disfigurements mainly caused by the entry and exit door in the wall of the eastern compartment was only 9.8℃,which was lower 3.2℃ than the average temperature of non-thermodynamic disfigurement of the wall.Thermodynamic disfigurement helped to increase heat loss.The weighted average proportion of thermodynamic disfigurement in the western compartment was 2.1%,while that of thermodynamic disfigurement in the eastern compartment was 10.7%.The thermal insulation performance of the western compartment envelope in the solar greenhouse was better than that of the eastern compartment envelope.展开更多
In order to investigate the application performances of the solar greenhouses with new types of backwall(greenhouse W_(2),and greenhouse W_(3))and the ordinary clay brick backwall greenhouse(greenhouse W_(1)),and prov...In order to investigate the application performances of the solar greenhouses with new types of backwall(greenhouse W_(2),and greenhouse W_(3))and the ordinary clay brick backwall greenhouse(greenhouse W_(1)),and provide a theoretical basis for the construction of solar greenhouse in Yangling Demonstration Zone,Shaanxi,China,two greenhouses with different new types of backwall were designed.The backwall of one of them was built with lightweight aggregate concrete block(greenhouse W_(2))and that of the other one was assembled with a row of sand-filled cement pipes(greenhouse W_(3)).The tested greenhouses were constructed in Yangling Demonstration Zone.Based on the data collected on typical sunny and cloudy days,the indoor temperature,inside wall temperature,and the heat flow of the greenhouses with new types of backwall were compared with those detected in the ordinary clay brick backwall solar greenhouse,and the tested results were numerically simulated.According to the comparison of the physiological indicators of tomatoes planted in the greenhouses and the construction costs,the greenhouse type with the best practicability was found.The results indicated that:The average air temperature in greenhouses W_(1),W_(2),and W_(3)and outside was 15.1℃,15.9℃,17.3℃,and−0.4℃ on the night of a sunny day,and the air temperature in W_(3)was the highest.The average air temperature in greenhouses W_(1),W_(2),and W_(3)and outside were 9.5℃,13.3℃,11.0℃,and−5.5℃ on the night of a cloudy day,the air temperature in W_(2)was the highest.In the depth of 0-330 mm from the interface of the backwalls,the walls were obviously affected by the solar radiation,and the temperature changed greatly.The wall temperature on the sunny days exhibited an ascending order of W_(1),W_(2),W_(3),while on the cloudy days was in the ascending order of W_(1),W_(3),W_(2).The wall of W_(3)absorbed the most heat during the daytime and released the most heat at night on the sunny day,while W_(2)exhibited the second most heat absorption during the daytime,however,it exhibited the highest heat release at night on the cloudy day,which were almost equaled to its heat absorption.Tomatoes in W_(3)grew well and exhibited the highest yield,and this greenhouse had the lowest construction costs.Comprehensively considering the physiological indicators of tomatoes and the corresponding construction costs of greenhouses,W_(3)has the best application performance in Yangling Demonstration Zone.展开更多
基金This work was supported by the National Natural Science Foundation of China(31701969)the Key Projects of Ningxia Key R&D Program Fund,China(2018BBF02012)the Science and Technology Program of Shaanxi Province,China(2017ZDXM-NY-057).
文摘In plant factories,the plant microclimate is affected by the control system,plant physiological activities and aerodynamic characteristics of leaves,which often leads to poor ventilation uniformity,suboptimal environmental conditions and inefficient air conditioning.In this study,interlayer cool airflow(ILCA)was used to introduce room air into plants’internal canopy through vent holes in cultivation boards and air layer between cultivation boards and nutrient solution surface(interlayer).By using optimal operating parameters at a room temperature of 28℃,the ILCA system achieved similar cooling effects in the absence of a conventional air conditioning system and achieved an energy saving of 50.8% while bringing about positive microclimate change in the interlayer and nutrient solution.This resulted in significantly reduced root growth by 41.7% without a negative influence on lettuce crop yield.Future development in this precise microclimate control method is predicted to replace the conventional cooling(air conditioning)systems for crop production in plant factories.
基金the research grants from the Scientific&Technological Innovative Research Team of Shaanxi in China(Grant No.2021TD-34)the Agricultural Science and Technology Innovation Project of Shaanxi in China(Grant No.NYKJ-2021-YL(XN)04)+1 种基金the Xi’an Science and Technology Plan Project of China(Grant No.2021JH-04-0024)the China Agriculture Research System(Grant No.CARS-23-D06).
文摘Accurate irrigation and nitrogen application are essential for promoting the growth and yield of cherry tomatoes.In investigating the effects of irrigation and nitrogen on the growth,photosynthesis,and yield of cherry tomatoes,nine treatments including three levels of both irrigation and nitrogen were conducted over two growing seasons.Transverse stem diameter and horizontal stem diameter had the best performance at the irrigation level of 75%evaporation(E_(p)),although their responses to nitrogen were different for the two years.Plant height increased with the increase of irrigation and nitrogen.Plant dry matter(PDM)was significantly affected by irrigation and nitrogen interaction.The lowest PDM was found in the highest proportion of root dry matter,which occurred under low nitrogen level.The net photosynthetic rate(Pn)and transpiration rate enhanced with the increase of irrigation.Medium nitrogen showed promotion effect on all photosynthetic parameters in both growing seasons.Six of all fourteen indicators showed significant correlations with yield.Especially,single plant fruit number and PDM in 2018 Fall had significant positive direct effects on yield with the path coefficients of 0.648 and 1.159,while the significant direct path coefficients were 0.362 and 0.294 in Fruit dry matter and Pn for 2019 Spring,respectively.Based on the comprehensive evaluation of growth and yield by TOPSIS,the irrigation level of 75%E_(p) combined with medium nitrogen application produced higher yields by promoting the growth and photosynthesis of cherry tomatoes.It provides a strategy for water and nitrogen management of cherry tomatoes in Northwest China.
基金This research was financially supported by National Natural Science Foundation of China(31901420)and Shaanxi Provincial Key Research and Development Program(2019TSLNY01-03).
文摘Solar greenhouse is extensively used in horticultural production in China.Natural ventilation is one of the key technological means to adjust the inside environment of greenhouse,while the effects of window opening styles on the inside environment are still not well understood.In the present study,the temperature and air flow field of five operation styles,namely back roof central opening style(G1),back roof evenly spaced opening style(G2),top roof full opening style(G3),style of G1+G3,and style of G2+G3 were simulated using the CFD method.The results indicated that:(1)the simulated and measured results exhibited favorable agreement,with relative errors within 5%;(2)In the case of the windows opening area was the same and only single ventilation style was applied,back roof full opening style exhibited the best cooling effect.The inside average temperature of the greenhouse with G1 style decreased by 0.5°C and 1.6°C respectively compared with those of greenhouses with G2 and G3.(3)The cooling effect of the style of G2+G3 was more favorable than that of the style of G1+G3.The style of G2+G3 exhibited better cooling effect than the single ventilation styles,with the lowest temperature(27.5°C)and temperature uniformity coefficient(0.36).
基金This work was partially supported by the Key Research and Development Program of Shaanxi Province in China(Grant No.2018TSCXL-NY-05-03)the Xi'an Science and Technology Program in China(Grant No.2017050NC/NY011(2))the Key project for Innovation in Production,Education and Research of Yangling in China(Grant No.2017CXY-07).
文摘In the northwestern part of China,rational and efficient management of irrigation and nitrogen significantly affects the intensive production of greenhouse cucumbers(Cucumis sativus L).To evaluate the effects of different combinations of water use and nitrogen(N)on yield,quality,and profitability of the greenhouse cucumbers that planted in 2018 Spring,nine combined treatments were applied.Results indicated the optimal irrigation and nitrogen demands for yield,quality and other indicators were different.The irrigation amount significantly affected the yield,and the yield gradually increased with increasing in irrigation.Single fruit weight(SFW)was significantly affected by the amount of irrigation,nitrogen and their interactions,and the higher amounts of N and irrigation were beneficial to the increase of SFW.The partial factor productivity of the applied N(PFPN)gradually increased with the nitrogen amount decline.Irrigation water use efficiency(IWUE)was closely related to the amount of irrigation.The higher irrigation amount would lead to the lower IWUE.When the amounts of irrigation and nitrogen were at an intermediate level,the content of vitamin C(VC)reached the maximum.As the amount of nitrogen was increased or irrigation was decreased,the Nitrate content(NC)would increase.Free amino acid(FAA)and NC followed a similar variation.When the amounts of irrigation and nitrogen both were at medium levels,the total soluble sugar concentration(TSSC)reached the highest.The multi-level fuzzy evaluation method was used to evaluate different indicators of cucumber.The weights of indicators in the first and second layer were determined by analytic hierarchy process(AHP)and entropy weight method,respectively.Then the fuzzy algorithm was used to comprehensively evaluate all the treatments.The evaluation results show that T4(irrigation,1957.6 m3/hm2;N,210 kg/hm2)is the best strategy for greenhouse cucumber irrigation and nitrogen management in the northwestern part of China.
基金supported by Shaanxi Provincial Key Research and Development Program(Grant No.2019TSLNY01-03)National Natural Science Foundation of China(31901420)Young Scientist Promotion Project of Jiangsu Science and Technology Association(2020-2-46).
文摘The objectives of the present work are focused on exploration of the reasons for temperature difference in different envelopes,the sensitivity of envelopes of solar greenhouse to thermal disfigurements and optimal selection of the thermal insulation quilt.Theoretical analysis and derivation are conducted according to the experimental results of surface temperature,convective heat transfer,and heat flux density in different envelopes which with thermal disfigurements of solar greenhouse using heat transfer theory.The results revealed that the difference of intrinsic thermal conductivity and thickness of the envelopes leads to difference in the thermal flux and thus in the surface temperature of different envelopes.Compared with the front roof and back roof,the wall is more sensitive to thermal disfigurements.According to the influence of thermal disfigurements on solar greenhouse temperature,the allowable thermal disfigurements area fraction of front roof and back roof are given.Based on the analysis of heat transfer theory and test results,the work given the expression of the thickness and thermal conductivity of thermal insulation quilt under different outdoor minimum temperatures for optimal selection of thermal insulation quilt based on comprehensive considering factors of the solar greenhouse structure,crop demand,outdoor minimum temperature,and insulation quilt properties.The results of this work give technical criterion for whether the envelopes with thermal disfigurements needs to be repaired or replaced,and it also provides theoretical and technical support for design the solar greenhouse as well as methodological guidance for the optimal selection of the thermal insulation quilt.
基金financially supported by the Key R&D Program of Shaanxi Province(Grant No.2019TSLNY01-03,No.2021QFY08-02)the Key R&D Program of Ningxia Autonomous Region(Grant No.2016BZ0901).
文摘In order to improve the thermal insulation and storage performance of Chinese solar greenhouses in winter,a novel assembled Chinese solar greenhouse(ACSG)without energy supplement in cold climatic areas was designed to evaluate and compare its thermal performance with that of conventional Chinese solar greenhouse(CSG).The thermal properties of both greenhouses were tested in field on cold winter days in Ningxia,China.The results indicated that the land utilization rate of ACSG was 19.3%higher than that of CSG.On a typical sunny day(the lowest outdoor temperature was−22.0℃)and typical cloudy day(the lowest outdoor temperature was−19.7℃)during the experiment,the minimum indoor temperature of ACSG was respectively 1.7℃and 2.0℃higher than that of CSG.The results for 24 consecutive days(the average outdoor daily minimum air temperature was−19.0℃)showed that the average minimum indoor temperature of ACSG was 1.4℃higher than that of CSG(p<0.05).The modular soil wall attached with colored steel polystyrene boards would be exploited as the north wall of CSG in Yinchuan area.
基金This research was financially supported by Shaanxi Provincial Key Research and Development Program(Grant No.2019TSLNY01-03)National Natural Science Foundation of China(31901420)Shaanxi Science and Technology Plan Program(2019FP-023).
文摘Solar greenhouse is a typical greenhouse without any additional heating system,which has developed rapidly in Northern China.However,due to the construction quality,management methods,especially the long-term use and other factors,there are usually different degrees of thermodynamic disfigurements in the envelop enclosure of solar greenhouse.The purpose of this study was to investigate the influences of thermodynamic disfigurement on the temperature distribution and convective heat transfer of solar greenhouse.In this study,the east and west compartments of a typical solar greenhouse which is located in Yangling,China(108°4′E,34°16′N)were tested.The air temperature of each compartment was collected using temperature recorders,and the thermal infrared images of different compartment envelopes were obtained by a thermal infrared imager on a typical cloudy day.Convective heat transfer coefficients and heat flux densities of different compartment envelopes in the solar greenhouse were calculated.The results showed that the temperature difference can be displayed in the thermal infrared images of compartment envelopes,the surface temperature of the front roof was the lowest,followed by the back roof,the wall surface temperature was the highest.The minimum average surface temperature of the front roof in the eastern compartment was only 3.8℃,which was 6.8℃ and 9.2℃ lower than the average surface temperature of the back roof and back wall,respectively.The surface average temperature of thermodynamic disfigurements located at the bottom of the south side in the front roof of the eastern compartment,whose area accounted for 16.5%of the total front roof in the eastern compartment,was only 5.4℃.Compared with non-thermodynamic disfigurement,the average convective heat transfer coefficient and heat flux density of thermodynamic disfigurements in the front roof of the eastern compartment were increased by 20.3%and 110.3%,respectively.The average air temperature in the eastern compartment was 3.5℃ lower than the average air temperature in the western compartment of the solar greenhouse.Construction of brick wall at the bottom of the south side of the front roof in the solar greenhouse helped to increase the inner surface temperature of the front roof,with an average temperature rise of 6.2℃,and reduce the area of thermodynamic disfigurement,which only accounted for 2.6%of the total front roof in the western compartment.The average surface temperature of thermodynamic disfigurements mainly caused by the entry and exit door in the wall of the eastern compartment was only 9.8℃,which was lower 3.2℃ than the average temperature of non-thermodynamic disfigurement of the wall.Thermodynamic disfigurement helped to increase heat loss.The weighted average proportion of thermodynamic disfigurement in the western compartment was 2.1%,while that of thermodynamic disfigurement in the eastern compartment was 10.7%.The thermal insulation performance of the western compartment envelope in the solar greenhouse was better than that of the eastern compartment envelope.
基金This research was financially supported by the Shaanxi Provincial Key Research and Development Program(Grant No.2019TSLNY01-03)the National Natural Science Foundation of China(Grant No.31901420)the Young Scientist Promotion Project of Jiangsu Science and Technology Association(Grant No.2020-2-46).
文摘In order to investigate the application performances of the solar greenhouses with new types of backwall(greenhouse W_(2),and greenhouse W_(3))and the ordinary clay brick backwall greenhouse(greenhouse W_(1)),and provide a theoretical basis for the construction of solar greenhouse in Yangling Demonstration Zone,Shaanxi,China,two greenhouses with different new types of backwall were designed.The backwall of one of them was built with lightweight aggregate concrete block(greenhouse W_(2))and that of the other one was assembled with a row of sand-filled cement pipes(greenhouse W_(3)).The tested greenhouses were constructed in Yangling Demonstration Zone.Based on the data collected on typical sunny and cloudy days,the indoor temperature,inside wall temperature,and the heat flow of the greenhouses with new types of backwall were compared with those detected in the ordinary clay brick backwall solar greenhouse,and the tested results were numerically simulated.According to the comparison of the physiological indicators of tomatoes planted in the greenhouses and the construction costs,the greenhouse type with the best practicability was found.The results indicated that:The average air temperature in greenhouses W_(1),W_(2),and W_(3)and outside was 15.1℃,15.9℃,17.3℃,and−0.4℃ on the night of a sunny day,and the air temperature in W_(3)was the highest.The average air temperature in greenhouses W_(1),W_(2),and W_(3)and outside were 9.5℃,13.3℃,11.0℃,and−5.5℃ on the night of a cloudy day,the air temperature in W_(2)was the highest.In the depth of 0-330 mm from the interface of the backwalls,the walls were obviously affected by the solar radiation,and the temperature changed greatly.The wall temperature on the sunny days exhibited an ascending order of W_(1),W_(2),W_(3),while on the cloudy days was in the ascending order of W_(1),W_(3),W_(2).The wall of W_(3)absorbed the most heat during the daytime and released the most heat at night on the sunny day,while W_(2)exhibited the second most heat absorption during the daytime,however,it exhibited the highest heat release at night on the cloudy day,which were almost equaled to its heat absorption.Tomatoes in W_(3)grew well and exhibited the highest yield,and this greenhouse had the lowest construction costs.Comprehensively considering the physiological indicators of tomatoes and the corresponding construction costs of greenhouses,W_(3)has the best application performance in Yangling Demonstration Zone.
