In the regions where crops were mostly produced by smallholder farmers, the analysis of yield gap is difficult due to diverse cultivars, crop managements and yield levels. In order to find an effective method that can...In the regions where crops were mostly produced by smallholder farmers, the analysis of yield gap is difficult due to diverse cultivars, crop managements and yield levels. In order to find an effective method that can reasonably verify the yield gap and the limiting cultivation factors in narrowing yield gaps in areas that are dominanted by smallholder farmers, we worked out a method consisting five progressive procedures as follows: questionnaire investigation of farmer cultivation regime, identification of yield levels and yield gaps, generalization of key cultivation measurements, reconstruction of representative maize populations, and process-based analysis of yield gap. A case study was carried out in Jiangsu Province, China, in which maize is mostly produced by smallholder farmers. A questionnaire investigation of 1 023 smallholder farmers was carried out firstly, then the frequency distribution of maize yield was simulated by an normal distribution function, and then the covering range and average value of the basic yield, farmer yield and high-yield farmer yield levels were calculated out from the equation. Hereby, the yield gaps 1, 2 and 3 were calculated along with the record highest yield from literature and experts, which were 2 564, 2 346 and 2 073 kg ha^(–1), respectively. Moreover, with the covering range of each yield level, the suveyed farmers belonging to each yield level were grouped together and then their major cultivation measures were traced and generalized. With the generalized cultivation measures, representative maize populations of the four yield levels were reconstructed, and thereby clarifing lots of characters of the populations or single plant of each population with processbased analysis of the reconstructed populations. In this case, the main factors causing the yield gap were plant density, fertilizer application rate, logging caused by hurricane, and damages caused by pests. The case study primarily indicated that this five-step method is feasible and effective in yield gap study, especially in smallholder farmers dominant regions.展开更多
Cotton growth and development are determined and influenced by cultivars, meteorological conditions, and management practices. The objective of this study was to quantify the optimum of temperature-light meteorologica...Cotton growth and development are determined and influenced by cultivars, meteorological conditions, and management practices. The objective of this study was to quantify the optimum of temperature-light meteorological factors for seedcotton biomass per boll with respect to boll positions. Field experiments were conducted using two cultivars of Kemian 1 and Sumian 15 with three planting dates of 25 April （mean daily temperature （MDT） was 28.0 and 25.4°C in 2010 and 2011, respectively）, 25 May （MDT was 22.5 and 21.2°C in 2010 and 2011, respectively）, and 10 Jun （MDT was 18.7 and 17.9°C in 2010 and 2011, respectively）, and under three shading levels （crop relative light rates （CRLR） were 100, 80, and 60％） during 2010 and 2011 cotton boll development period （from anthesis to boll open stages）. The main meteorological factors （temperature and light） affected seedcotton biomass per boll differently among different boll positions and cultivars. Mean daily radiation （MDR） affected seedcotton biomass per boll at all boll positions, except fruiting branch 2 （FB2） fruting node 1 （FN1）. However, its influence was less than temperature factors, especially growing degree-days （GDD）. Optimum mean daily maximum temperature （MDTmax） for seedcotton biomass per boll at FB11FN3 was 29.9-32.4°C, and the optimum MDR at aforementioned position was 15.8-17.5 MJ m-2. Definitely, these results can contribute to future cultural practices such as rational cultivars choice and distribution, simplifying field managements and mechanization to acquire more efficient and economical cotton management.展开更多
Crop performance is determined by the combined effects of the genotype of the crop and the environmental conditions of the production system. This study was undertaken to develop a dynamic model for simulating environ...Crop performance is determined by the combined effects of the genotype of the crop and the environmental conditions of the production system. This study was undertaken to develop a dynamic model for simulating environmental （temperature and solar radiation） and N supply effects on fiber fineness, maturity and micronaire. Three different experiments involving genotypes, sowing dates, and N fertilization rates were conducted to support model development and model evaluation. The growth and development duration of fiber fineness, maturity, and micronaire were scaled by using physiological development time of secondary wall synthesis （PDT SWSP ）, which was determined based on the constant ratio of SWSP/ BMP. PTP （product of relative thermal effectiveness （RTE） and photosynthetically active radiation （PAR）, MJ m-2） and subtending leaf N content per unit area （N A , g m-2） and critical subtending leaf N content per unit area （CN A , g m-2） of cotton boll were calculated or simulated to evaluate effects of temperature and radiation, and N supply. Besides, the interactions among temperature, radiation and N supply were also explained by piecewise function. The overall performance of the model was calibrated and validated with independent data sets from three field experiments with two sowing dates, three or five flowering dates and three or four N fertilization rates for three subsequent years （2005, 2007, and 2009） at three ecological locations. The average RMSE and RE for fiber fineness, maturity, and micronaire predictions were 372 m g-1 and 5.0%, 0.11 m g-1 and 11.4%, 0.3 m g-1 and 12.3%, respectively, indicating a good fit between the simulated and observed data. It appears that the model can give a reliable prediction for fiber fineness, maturity and micronaire formation under various growing conditions.展开更多
The upper earshoots with higher superiority usually have higher yield potential and higher efficiency.To determine the key period for the asynchronous differentiation of superior and inferior earshoots and how hormone...The upper earshoots with higher superiority usually have higher yield potential and higher efficiency.To determine the key period for the asynchronous differentiation of superior and inferior earshoots and how hormones are involved in this process,a two-year experiment was designed using two maize hybrids:Suyu 41(S41,single-ear hybrid)and AN 101(A101,double-ear hybrid).The results showed that the lag of lower earshoot differentiation was not only caused by the delay of the differentiation starting time but also related to extension of the duration in spikelet differentiation(stageⅡ)and sexual organ formation stage(stageⅣ).From 12 days before silking(DBS),the contents of indole-3-acetic acid(IAA),zeatin riboside(ZR)+zeatin(ZT),and gibberellic acid(GA_(3))in both upper and lower earshoots of the two hybrids increased dramatically and then decreased quickly.ABA slightly increased in the two hybrids and then decreased slowly in S41,while it was maintained at a high level in A101.At 8 DBS,i.e.,the transition period from floret differentiation to sexual organ formation stage,not only the growth of upper-to-lower earshoot difference(ULED),but also the values for ULED of IAA,ZR+ZT and GA_(3)were all significantly higher in S41 than in A101.Furthermore,the upper-to-lower hormone ratios IAA_(U)/AA_(L)and(ZR+ZT)_(U)/(ZR+ZT)_(L)were also much higher in the single-ear hybrid than in the double-ear hybrid,while the GA_(3U)/GA_(3L)and ABA_(U)/ABA_(L)had no significant differences.In addition,the time course of ULED_(hormone)/ULED_(earshoot growth rate)also suggested that the hormones work in different ways in earshoot superiority/inferiority formation.The delayed differentiation of lower ear shoots was conclusively related to the later initiation of differentiation and the longer durations of specific differentiation stages.Compared with the regulating roles of IAA and ZR+ZT in the key period(8 DBS)of superiority/inferiority differentiation,GA_(3) seems to be affected earlier,while ABA contributes little to this process.展开更多
A two-year field experiment was conducted to illustrate the effects of sowing date on cottonseed properties at different fruiting-branch positions（FBPs）.Two cotton cultivars（Kemian 1 and Sumian 15）were sowed on 25...A two-year field experiment was conducted to illustrate the effects of sowing date on cottonseed properties at different fruiting-branch positions（FBPs）.Two cotton cultivars（Kemian 1 and Sumian 15）were sowed on 25 April,25 May,and10 June in 2010 and 2011,respectively.The boll maturation period increased with the delaying of sowing date.Normal sowing treatment（25 April）had higher seed weight,embryo weight,embryo oil content and protein content than late sowing treatments（25 May and 10 June）.The flowering date,seed weight,embryo weight,embryo oil and protein contents,and the dynamic changes of embryo oil and protein contents were altered by different FBPs.A significant interaction of sowing date×FBP was observed on embryo weight,embryo oil content,embryo protein content and the dynamic changes of embryo oil and protein contents,but was not observed on seed weight.Seed weight,embryo weight,embryo oil and protein content had significant positive correlations with the mean daily temperature（MDT）,mean daily maximum temperature（MDTmax）,mean daily minimum temperature（MDTmin）,and mean daily solar radiation（MDSR）,indicating that temperature and light resources were the main reasons for different sowing dates affecting the cottonseed properties at different FBPs.Moreover,the difference in MDT was the main difference in climatic factors among different sowing dates.展开更多
基金funded by the National Key Research and Development Program of China(2016YFD0300109)。
文摘In the regions where crops were mostly produced by smallholder farmers, the analysis of yield gap is difficult due to diverse cultivars, crop managements and yield levels. In order to find an effective method that can reasonably verify the yield gap and the limiting cultivation factors in narrowing yield gaps in areas that are dominanted by smallholder farmers, we worked out a method consisting five progressive procedures as follows: questionnaire investigation of farmer cultivation regime, identification of yield levels and yield gaps, generalization of key cultivation measurements, reconstruction of representative maize populations, and process-based analysis of yield gap. A case study was carried out in Jiangsu Province, China, in which maize is mostly produced by smallholder farmers. A questionnaire investigation of 1 023 smallholder farmers was carried out firstly, then the frequency distribution of maize yield was simulated by an normal distribution function, and then the covering range and average value of the basic yield, farmer yield and high-yield farmer yield levels were calculated out from the equation. Hereby, the yield gaps 1, 2 and 3 were calculated along with the record highest yield from literature and experts, which were 2 564, 2 346 and 2 073 kg ha^(–1), respectively. Moreover, with the covering range of each yield level, the suveyed farmers belonging to each yield level were grouped together and then their major cultivation measures were traced and generalized. With the generalized cultivation measures, representative maize populations of the four yield levels were reconstructed, and thereby clarifing lots of characters of the populations or single plant of each population with processbased analysis of the reconstructed populations. In this case, the main factors causing the yield gap were plant density, fertilizer application rate, logging caused by hurricane, and damages caused by pests. The case study primarily indicated that this five-step method is feasible and effective in yield gap study, especially in smallholder farmers dominant regions.
基金supported by the National Natural Science Foundation of China (31471444,31401327)the Special Fund for Agro-scientific Research in the Public Interest of China (Impact of Climate Change on Agriculture Production,201203096)the Jiangsu Overseas Research and Training Program for University Prominent Young and Middle-aged Teachers and President,China (2016)
文摘Cotton growth and development are determined and influenced by cultivars, meteorological conditions, and management practices. The objective of this study was to quantify the optimum of temperature-light meteorological factors for seedcotton biomass per boll with respect to boll positions. Field experiments were conducted using two cultivars of Kemian 1 and Sumian 15 with three planting dates of 25 April （mean daily temperature （MDT） was 28.0 and 25.4°C in 2010 and 2011, respectively）, 25 May （MDT was 22.5 and 21.2°C in 2010 and 2011, respectively）, and 10 Jun （MDT was 18.7 and 17.9°C in 2010 and 2011, respectively）, and under three shading levels （crop relative light rates （CRLR） were 100, 80, and 60％） during 2010 and 2011 cotton boll development period （from anthesis to boll open stages）. The main meteorological factors （temperature and light） affected seedcotton biomass per boll differently among different boll positions and cultivars. Mean daily radiation （MDR） affected seedcotton biomass per boll at all boll positions, except fruiting branch 2 （FB2） fruting node 1 （FN1）. However, its influence was less than temperature factors, especially growing degree-days （GDD）. Optimum mean daily maximum temperature （MDTmax） for seedcotton biomass per boll at FB11FN3 was 29.9-32.4°C, and the optimum MDR at aforementioned position was 15.8-17.5 MJ m-2. Definitely, these results can contribute to future cultural practices such as rational cultivars choice and distribution, simplifying field managements and mechanization to acquire more efficient and economical cotton management.
基金funded by the National Natural Science Foundation of China (30771277 and 30771279)
文摘Crop performance is determined by the combined effects of the genotype of the crop and the environmental conditions of the production system. This study was undertaken to develop a dynamic model for simulating environmental （temperature and solar radiation） and N supply effects on fiber fineness, maturity and micronaire. Three different experiments involving genotypes, sowing dates, and N fertilization rates were conducted to support model development and model evaluation. The growth and development duration of fiber fineness, maturity, and micronaire were scaled by using physiological development time of secondary wall synthesis （PDT SWSP ）, which was determined based on the constant ratio of SWSP/ BMP. PTP （product of relative thermal effectiveness （RTE） and photosynthetically active radiation （PAR）, MJ m-2） and subtending leaf N content per unit area （N A , g m-2） and critical subtending leaf N content per unit area （CN A , g m-2） of cotton boll were calculated or simulated to evaluate effects of temperature and radiation, and N supply. Besides, the interactions among temperature, radiation and N supply were also explained by piecewise function. The overall performance of the model was calibrated and validated with independent data sets from three field experiments with two sowing dates, three or five flowering dates and three or four N fertilization rates for three subsequent years （2005, 2007, and 2009） at three ecological locations. The average RMSE and RE for fiber fineness, maturity, and micronaire predictions were 372 m g-1 and 5.0%, 0.11 m g-1 and 11.4%, 0.3 m g-1 and 12.3%, respectively, indicating a good fit between the simulated and observed data. It appears that the model can give a reliable prediction for fiber fineness, maturity and micronaire formation under various growing conditions.
基金the National Key Research and Development Program of China(2016YFD0300109)。
文摘The upper earshoots with higher superiority usually have higher yield potential and higher efficiency.To determine the key period for the asynchronous differentiation of superior and inferior earshoots and how hormones are involved in this process,a two-year experiment was designed using two maize hybrids:Suyu 41(S41,single-ear hybrid)and AN 101(A101,double-ear hybrid).The results showed that the lag of lower earshoot differentiation was not only caused by the delay of the differentiation starting time but also related to extension of the duration in spikelet differentiation(stageⅡ)and sexual organ formation stage(stageⅣ).From 12 days before silking(DBS),the contents of indole-3-acetic acid(IAA),zeatin riboside(ZR)+zeatin(ZT),and gibberellic acid(GA_(3))in both upper and lower earshoots of the two hybrids increased dramatically and then decreased quickly.ABA slightly increased in the two hybrids and then decreased slowly in S41,while it was maintained at a high level in A101.At 8 DBS,i.e.,the transition period from floret differentiation to sexual organ formation stage,not only the growth of upper-to-lower earshoot difference(ULED),but also the values for ULED of IAA,ZR+ZT and GA_(3)were all significantly higher in S41 than in A101.Furthermore,the upper-to-lower hormone ratios IAA_(U)/AA_(L)and(ZR+ZT)_(U)/(ZR+ZT)_(L)were also much higher in the single-ear hybrid than in the double-ear hybrid,while the GA_(3U)/GA_(3L)and ABA_(U)/ABA_(L)had no significant differences.In addition,the time course of ULED_(hormone)/ULED_(earshoot growth rate)also suggested that the hormones work in different ways in earshoot superiority/inferiority formation.The delayed differentiation of lower ear shoots was conclusively related to the later initiation of differentiation and the longer durations of specific differentiation stages.Compared with the regulating roles of IAA and ZR+ZT in the key period(8 DBS)of superiority/inferiority differentiation,GA_(3) seems to be affected earlier,while ABA contributes little to this process.
基金funded by the National Natural Science Foundation of China (31571606)the Special Fund for Agro-scientific Research in the Public Interest, China (201303002)+1 种基金the Jiangsu Collaborative Innovation Center for Modern Crop Production, China (JCICMCP)the China Agriculture Research System (CARS-18-20)
文摘A two-year field experiment was conducted to illustrate the effects of sowing date on cottonseed properties at different fruiting-branch positions（FBPs）.Two cotton cultivars（Kemian 1 and Sumian 15）were sowed on 25 April,25 May,and10 June in 2010 and 2011,respectively.The boll maturation period increased with the delaying of sowing date.Normal sowing treatment（25 April）had higher seed weight,embryo weight,embryo oil content and protein content than late sowing treatments（25 May and 10 June）.The flowering date,seed weight,embryo weight,embryo oil and protein contents,and the dynamic changes of embryo oil and protein contents were altered by different FBPs.A significant interaction of sowing date×FBP was observed on embryo weight,embryo oil content,embryo protein content and the dynamic changes of embryo oil and protein contents,but was not observed on seed weight.Seed weight,embryo weight,embryo oil and protein content had significant positive correlations with the mean daily temperature（MDT）,mean daily maximum temperature（MDTmax）,mean daily minimum temperature（MDTmin）,and mean daily solar radiation（MDSR）,indicating that temperature and light resources were the main reasons for different sowing dates affecting the cottonseed properties at different FBPs.Moreover,the difference in MDT was the main difference in climatic factors among different sowing dates.
