A special kind of rice field exists in China that is flooded year-round. These rice fields have substantially large CH4 emissions during the rice-growing season and emit CH4 continuously in the non-rice growing season...A special kind of rice field exists in China that is flooded year-round. These rice fields have substantially large CH4 emissions during the rice-growing season and emit CH4 continuously in the non-rice growing season. CH4 emission factors were used to estimate the CH4 emissions from year-round flooded rice fields during the rice-growing season in China. The CH4 emissions for the year-round flooded rice fields in China for the rice growing season over a total area of 2.66 Mha were estimated to be 2.44 Tg CH…展开更多
Maximizing profit is usually the objective of optimal control of greenhouse cultivation.However,due to the problem of“the curse of dimensionality”,the global optimization of greenhouse climate is usually difficult w...Maximizing profit is usually the objective of optimal control of greenhouse cultivation.However,due to the problem of“the curse of dimensionality”,the global optimization of greenhouse climate is usually difficult when faced with a complex dynamic model and a long cultivation period.Compared with leafy vegetables with a much simpler dynamic model and a much shorter cultivation period,the year-round tomato model usually has many more states to describe its dynamics better.To solve the year-round climate control of greenhouse tomato cultivation,a rule-based model predictive control(MPC)algorithm is raised.The innovation of this paper lies in that the setpoints of the proposed MPC algorithms are determined by the external weather and the month-averaged predictions of the tomato price.With the greenhouse climate–tomato growth dynamic model and the economic performance index,different MPC algorithms are compared with the traditional on/off control algorithm and the open field cultivation.Quantified results of yield,cost,and profit are obtained with the weather data and market data collected in Beijing.Findings of this paper showed that the year-round greenhouse tomato cultivation in Beijing is hardly profitable with the tomato price sold as an open field product(XFD price).With the tomato price sold as a high-tech greenhouse product(JD price),the higher yield guarantees a higher profit.Moreover,the simple emphasis on energy minimization cannot even guarantee a higher yield than that in the open field.A synthetical consideration of yield and cost is a prerequisite for a high profit.展开更多
Greenhouse vegetable production in Canadian Prairies is important for creating a sustainable regional food economy,especially in northern communities.This study included the estimation of heating demand for year-round...Greenhouse vegetable production in Canadian Prairies is important for creating a sustainable regional food economy,especially in northern communities.This study included the estimation of heating demand for year-round production and evaluation of the economic feasibility of greenhouse vegetable production(tomato,cucumber,and pepper)in a conceptually designed greenhouse(0.6 ha)located in remote northern communities in Saskatchewan,Canada.The heating simulation was based on a greenhouse heating simulation model(GREENHEAT)developed by the authors recently.The simulation results showed that the annual heating requirement for the production of tomato,cucumber,and pepper are 1486 MJ m^2,1657 MJ m^2,and 1754 MJ m^2,respectively.The economic analysis indicates the net return(NR)from the production of tomato,cucumber,and pepper,are C$69.2/m^2(in Canadian dollar,CAD),C$41.5/m^2,and C$43.8/m^2,respectively,based on the market price C$3.5/kg,C$2.7/kg,and C$8.0/kg,and yields of 55.0 kg m^-2,65.0 kg m^-2,and 23.0 kg m^-2.The net present value(NPV)for the tomato,cucumber,and pepper production are C$1.9 M,C$1.2 M,and C$1.1 M,respectively,and the benefit-cost ratio(BCR)are 1.38,1.21,and 1.21.The economic feasibility analysis indicates the year-round production of vegetables in a greenhouse at remote northern Saskatchewan would be economically profitable.展开更多
Jujube Witches’ Broom (JWB), caused by phytoplasma, is the most serious and destructive disease of Chinese Jujube. The distribution and year_round concentration variation of JWB phytoplasma were studied under fluores...Jujube Witches’ Broom (JWB), caused by phytoplasma, is the most serious and destructive disease of Chinese Jujube. The distribution and year_round concentration variation of JWB phytoplasma were studied under fluorescence microscope using DAPI. The results showed that phytoplasma might exist in the sieve tubes of all organs, phytoplasma contents varied with organs, sides of organs and growing seasons, phytoplasma usually existed in the roots of the same direction with diseased branches. The uneven_distribution could be observed much often in lightly diseased trees than in seriously diseased one. In roots, the content of phytoplasma was highest in May, relatively low in June, July and August, and lowest in December to March. In branches, the content of phytoplasma increased gradually with the rising of the temperature after bud sprouting in April and May, then increased dramatically and reached peak in July and August, thereafter decreased in autumn. From December to February, there was still a large amount of phytoplasma in diseased branches. The content of phytoplasma in branches kept higher than in roots throughout a year.展开更多
文摘A special kind of rice field exists in China that is flooded year-round. These rice fields have substantially large CH4 emissions during the rice-growing season and emit CH4 continuously in the non-rice growing season. CH4 emission factors were used to estimate the CH4 emissions from year-round flooded rice fields during the rice-growing season in China. The CH4 emissions for the year-round flooded rice fields in China for the rice growing season over a total area of 2.66 Mha were estimated to be 2.44 Tg CH…
基金supported by Key Technology Research and Development Program of Shandong(2022CXGC020708)National Natural Science Foundation of China(32371998 and U20A2020)+2 种基金National Modern Agricultural Technology System Construction Project(CARS-23-D02)Beijing Innovation Consortium of Agriculture Research System(BAIC01-2023)the 2115 Talent Development Program of China Agricultural University.
文摘Maximizing profit is usually the objective of optimal control of greenhouse cultivation.However,due to the problem of“the curse of dimensionality”,the global optimization of greenhouse climate is usually difficult when faced with a complex dynamic model and a long cultivation period.Compared with leafy vegetables with a much simpler dynamic model and a much shorter cultivation period,the year-round tomato model usually has many more states to describe its dynamics better.To solve the year-round climate control of greenhouse tomato cultivation,a rule-based model predictive control(MPC)algorithm is raised.The innovation of this paper lies in that the setpoints of the proposed MPC algorithms are determined by the external weather and the month-averaged predictions of the tomato price.With the greenhouse climate–tomato growth dynamic model and the economic performance index,different MPC algorithms are compared with the traditional on/off control algorithm and the open field cultivation.Quantified results of yield,cost,and profit are obtained with the weather data and market data collected in Beijing.Findings of this paper showed that the year-round greenhouse tomato cultivation in Beijing is hardly profitable with the tomato price sold as an open field product(XFD price).With the tomato price sold as a high-tech greenhouse product(JD price),the higher yield guarantees a higher profit.Moreover,the simple emphasis on energy minimization cannot even guarantee a higher yield than that in the open field.A synthetical consideration of yield and cost is a prerequisite for a high profit.
文摘Greenhouse vegetable production in Canadian Prairies is important for creating a sustainable regional food economy,especially in northern communities.This study included the estimation of heating demand for year-round production and evaluation of the economic feasibility of greenhouse vegetable production(tomato,cucumber,and pepper)in a conceptually designed greenhouse(0.6 ha)located in remote northern communities in Saskatchewan,Canada.The heating simulation was based on a greenhouse heating simulation model(GREENHEAT)developed by the authors recently.The simulation results showed that the annual heating requirement for the production of tomato,cucumber,and pepper are 1486 MJ m^2,1657 MJ m^2,and 1754 MJ m^2,respectively.The economic analysis indicates the net return(NR)from the production of tomato,cucumber,and pepper,are C$69.2/m^2(in Canadian dollar,CAD),C$41.5/m^2,and C$43.8/m^2,respectively,based on the market price C$3.5/kg,C$2.7/kg,and C$8.0/kg,and yields of 55.0 kg m^-2,65.0 kg m^-2,and 23.0 kg m^-2.The net present value(NPV)for the tomato,cucumber,and pepper production are C$1.9 M,C$1.2 M,and C$1.1 M,respectively,and the benefit-cost ratio(BCR)are 1.38,1.21,and 1.21.The economic feasibility analysis indicates the year-round production of vegetables in a greenhouse at remote northern Saskatchewan would be economically profitable.
文摘Jujube Witches’ Broom (JWB), caused by phytoplasma, is the most serious and destructive disease of Chinese Jujube. The distribution and year_round concentration variation of JWB phytoplasma were studied under fluorescence microscope using DAPI. The results showed that phytoplasma might exist in the sieve tubes of all organs, phytoplasma contents varied with organs, sides of organs and growing seasons, phytoplasma usually existed in the roots of the same direction with diseased branches. The uneven_distribution could be observed much often in lightly diseased trees than in seriously diseased one. In roots, the content of phytoplasma was highest in May, relatively low in June, July and August, and lowest in December to March. In branches, the content of phytoplasma increased gradually with the rising of the temperature after bud sprouting in April and May, then increased dramatically and reached peak in July and August, thereafter decreased in autumn. From December to February, there was still a large amount of phytoplasma in diseased branches. The content of phytoplasma in branches kept higher than in roots throughout a year.
