The field experiments were carried out to investigate the dynamics and models of N, P and K absorption for the cotton plants with a lint of 3 000 kg ha-1 in Xinjiang. The main results were as follows: The contents of ...The field experiments were carried out to investigate the dynamics and models of N, P and K absorption for the cotton plants with a lint of 3 000 kg ha-1 in Xinjiang. The main results were as follows: The contents of N, P2O5, K2O in cotton leaves, stems, squares and bolls decreased obviously with the time over the whole growth duration and the falling extent was greater in high-yield cotton than in CK. Contents of N in leaves, squares and bolls, in particular in the leaves of fruit-bearing shoot was higher in high-yield cotton than in CK. Contents of P2O5 in squares and bolls and that of K2O in stems were higher in high-yield cotton than in CK during the whole growing period. The accumulations of N, P2O5 and K2O in the cotton plants could be described with a logistic curve equation. There was the fastest nutrient uptake at about 90 d for N, 92 d for P2O5 and 85 d for K2O after emergence, respectively. Total nutrient accumulation of N, P2O5 and K2O was 385.8, 244. 7 and 340.3 kg ha-1, respectively. Approximately 12. 5 kg N, 8. 0 kg P2O5 and 11.1 kg K2O were needed for producing 100 kg lint with the leaves and stems under the super high yield condition of 3 000 kg ha-1 in Xinjiang.展开更多
To understand the high strain rate deformation mechanism and determine the grain size,strain rate and porosity dependent yield strength of nanocrystalline materials,a new mechanical model based on the deformation mech...To understand the high strain rate deformation mechanism and determine the grain size,strain rate and porosity dependent yield strength of nanocrystalline materials,a new mechanical model based on the deformation mechanism of nanocrystalline materials under high strain rate loading was developed.As a first step of the research,the yield behavior of the nanocrystalline materials under high strain rate loading was mainly concerned in the model and uniform deformation was assumed for simplification.Nanocrystalline materials were treated as composites consisting of grain interior phase and grain boundary phase,and grain interior and grain boundary deformation mechanisms under high strain rate loading were analyzed,then Voigt model was applied to coupling grain boundary constitutive relation with mechanical model for grain interior phase to describe the overall yield mechanical behavior of nanocrystalline materials.The predictions by the developed model on the yield strength of nanocrysatlline materials at high strain rates show good agreements with various experimental data.Further discussion was presented for calculation results and relative experimental observations.展开更多
The integrated planting and breeding of paddy fields is a kind of eco-planting and breeding mode which makes rice and aquatic animals benefit from each other,greatly reducing the harm of rice pests and diseases,using ...The integrated planting and breeding of paddy fields is a kind of eco-planting and breeding mode which makes rice and aquatic animals benefit from each other,greatly reducing the harm of rice pests and diseases,using less or even no fertilizers or pesticides,greatly reducing the agricultural non-point source pollution,thus achieving the " multiple use of water,multiple harvests in one field,grain and fishing winwin,ecological and high efficient use. " In this paper,the high yield and efficient cultivation techniques of rice under the rice-fish intergrowth model in Chengdu was introduced from the aspects of selecting good paddy fields for fishing,using appropriate rice varieties,soaking disinfection,timely sowing and nurturing strong seedlings,reasonable close planting,reasonable fertilization,scientific water management,scientific pest control and rice harvests.展开更多
【目的】开展气候变化对冬小麦生长发育和产量影响研究,为未来气候变化下小麦可持续生产提供依据。【方法】利用2017—2020年度控制气室中不同温度和[CO_(2)]处理下的良星99(晚熟品种)和中科2011(早熟品种)冬小麦生长发育、土壤及气象数...【目的】开展气候变化对冬小麦生长发育和产量影响研究,为未来气候变化下小麦可持续生产提供依据。【方法】利用2017—2020年度控制气室中不同温度和[CO_(2)]处理下的良星99(晚熟品种)和中科2011(早熟品种)冬小麦生长发育、土壤及气象数据,对APSIM(agricultural production systems simulator)模型进行校验,然后,以1986—2005年为基准年份,利用校验好的APSIM模型对未来不同气候条件下(RCP 4.5和RCP 8.5)的冬小麦产量、产量构成和生育期进行模拟,分析气候变化和极端高温对不同熟性冬小麦品种生产潜力的影响。【结果】APSIM模型能较好地模拟不同温度和[CO_(2)]处理下2个品种冬小麦的生育期、产量和生物量,模拟值与实测值的R2均高于0.614,nRMSE均低于10.6%,叶面积指数(LAI)的模拟效果相对较差。从长期模拟结果来看,不同气候条件下,2个品种小麦的播种-拔节天数均较基准年份缩短,且早熟品种小麦播种-拔节缩短的天数小于晚熟品种,2个品种拔节-成熟天数均无明显变化。相较基准年份,未来RCP条件下,2个品种小麦的实际产量和潜在产量均增加,且2100s时段RCP 8.5条件下的产量和潜在产量最高,早熟品种的产量和潜在产量相较晚熟品种增产更明显。与基准年份相比,未来RCP条件下,生育前期2个品种小麦的LAI均升高,但早熟品种LAI变化更明显,生育后期晚熟品种的LAI明显降低,而早熟品种的LAI无明显差异;未来RCP条件下,2个品种的地上部生物量均增加,早熟品种生物量增长更明显。不同RCP条件下,极端高温对2个品种冬小麦产量和千粒重均有一定的负面影响,且开花期极端高温对千粒重的影响最大。与正常年份相比,极端高温年份晚熟品种2100s时段RCP 8.5条件下的千粒重和产量明显降低,籽粒数也略有降低。与正常年份相比,未来RCP条件下,极端高温均明显降低了早熟品种的千粒重,但籽粒数略有升高,因此,极端高温年份早熟品种产量降低不明显。【结论】冬小麦早熟品种更能适应未来气候变化,而选育适宜的小麦品种是应对未来气候变化的有效措施之一。展开更多
The paper expounded the basic concept and principles of ecosystem management,and analyzed the state and trend of industrial plantation ecosystem management in other countries.Based on the analysis of typical case stud...The paper expounded the basic concept and principles of ecosystem management,and analyzed the state and trend of industrial plantation ecosystem management in other countries.Based on the analysis of typical case studies,the eco-economic benefits were evaluated for the management models of fast-growing and high-yield plantations.展开更多
基金supported by the National Key Technologies R&D Program in 10th Five-year Plan of China(2001BA507A)the National Natural Sicence Foundation of China(39760040).
文摘The field experiments were carried out to investigate the dynamics and models of N, P and K absorption for the cotton plants with a lint of 3 000 kg ha-1 in Xinjiang. The main results were as follows: The contents of N, P2O5, K2O in cotton leaves, stems, squares and bolls decreased obviously with the time over the whole growth duration and the falling extent was greater in high-yield cotton than in CK. Contents of N in leaves, squares and bolls, in particular in the leaves of fruit-bearing shoot was higher in high-yield cotton than in CK. Contents of P2O5 in squares and bolls and that of K2O in stems were higher in high-yield cotton than in CK during the whole growing period. The accumulations of N, P2O5 and K2O in the cotton plants could be described with a logistic curve equation. There was the fastest nutrient uptake at about 90 d for N, 92 d for P2O5 and 85 d for K2O after emergence, respectively. Total nutrient accumulation of N, P2O5 and K2O was 385.8, 244. 7 and 340.3 kg ha-1, respectively. Approximately 12. 5 kg N, 8. 0 kg P2O5 and 11.1 kg K2O were needed for producing 100 kg lint with the leaves and stems under the super high yield condition of 3 000 kg ha-1 in Xinjiang.
基金Project(10502025) supported by the National Natural Science Foundation of ChinaProject(101005) supported by Fok Ying Tong Education FoundationProject(BK2007528) supported by the Natural Science Foundation of Jiangsu Province,China
文摘To understand the high strain rate deformation mechanism and determine the grain size,strain rate and porosity dependent yield strength of nanocrystalline materials,a new mechanical model based on the deformation mechanism of nanocrystalline materials under high strain rate loading was developed.As a first step of the research,the yield behavior of the nanocrystalline materials under high strain rate loading was mainly concerned in the model and uniform deformation was assumed for simplification.Nanocrystalline materials were treated as composites consisting of grain interior phase and grain boundary phase,and grain interior and grain boundary deformation mechanisms under high strain rate loading were analyzed,then Voigt model was applied to coupling grain boundary constitutive relation with mechanical model for grain interior phase to describe the overall yield mechanical behavior of nanocrystalline materials.The predictions by the developed model on the yield strength of nanocrysatlline materials at high strain rates show good agreements with various experimental data.Further discussion was presented for calculation results and relative experimental observations.
文摘The integrated planting and breeding of paddy fields is a kind of eco-planting and breeding mode which makes rice and aquatic animals benefit from each other,greatly reducing the harm of rice pests and diseases,using less or even no fertilizers or pesticides,greatly reducing the agricultural non-point source pollution,thus achieving the " multiple use of water,multiple harvests in one field,grain and fishing winwin,ecological and high efficient use. " In this paper,the high yield and efficient cultivation techniques of rice under the rice-fish intergrowth model in Chengdu was introduced from the aspects of selecting good paddy fields for fishing,using appropriate rice varieties,soaking disinfection,timely sowing and nurturing strong seedlings,reasonable close planting,reasonable fertilization,scientific water management,scientific pest control and rice harvests.
文摘【目的】开展气候变化对冬小麦生长发育和产量影响研究,为未来气候变化下小麦可持续生产提供依据。【方法】利用2017—2020年度控制气室中不同温度和[CO_(2)]处理下的良星99(晚熟品种)和中科2011(早熟品种)冬小麦生长发育、土壤及气象数据,对APSIM(agricultural production systems simulator)模型进行校验,然后,以1986—2005年为基准年份,利用校验好的APSIM模型对未来不同气候条件下(RCP 4.5和RCP 8.5)的冬小麦产量、产量构成和生育期进行模拟,分析气候变化和极端高温对不同熟性冬小麦品种生产潜力的影响。【结果】APSIM模型能较好地模拟不同温度和[CO_(2)]处理下2个品种冬小麦的生育期、产量和生物量,模拟值与实测值的R2均高于0.614,nRMSE均低于10.6%,叶面积指数(LAI)的模拟效果相对较差。从长期模拟结果来看,不同气候条件下,2个品种小麦的播种-拔节天数均较基准年份缩短,且早熟品种小麦播种-拔节缩短的天数小于晚熟品种,2个品种拔节-成熟天数均无明显变化。相较基准年份,未来RCP条件下,2个品种小麦的实际产量和潜在产量均增加,且2100s时段RCP 8.5条件下的产量和潜在产量最高,早熟品种的产量和潜在产量相较晚熟品种增产更明显。与基准年份相比,未来RCP条件下,生育前期2个品种小麦的LAI均升高,但早熟品种LAI变化更明显,生育后期晚熟品种的LAI明显降低,而早熟品种的LAI无明显差异;未来RCP条件下,2个品种的地上部生物量均增加,早熟品种生物量增长更明显。不同RCP条件下,极端高温对2个品种冬小麦产量和千粒重均有一定的负面影响,且开花期极端高温对千粒重的影响最大。与正常年份相比,极端高温年份晚熟品种2100s时段RCP 8.5条件下的千粒重和产量明显降低,籽粒数也略有降低。与正常年份相比,未来RCP条件下,极端高温均明显降低了早熟品种的千粒重,但籽粒数略有升高,因此,极端高温年份早熟品种产量降低不明显。【结论】冬小麦早熟品种更能适应未来气候变化,而选育适宜的小麦品种是应对未来气候变化的有效措施之一。
基金supported by the project of "Research on Comprehensive Management Techniques for Fast-growing and High-yield Plantation Ecosystem" in "Eleventh Five-year" Plan for National Science and Technology Support (2006BAD24B1003)
文摘The paper expounded the basic concept and principles of ecosystem management,and analyzed the state and trend of industrial plantation ecosystem management in other countries.Based on the analysis of typical case studies,the eco-economic benefits were evaluated for the management models of fast-growing and high-yield plantations.
