This experiment examined the fluctuations in nitrogen gas supersaturation throughout the day in three karst springs (upper, side, and lower) at McNenny State Fish Hatchery, rural Spearfish, Lawrence County, South Dako...This experiment examined the fluctuations in nitrogen gas supersaturation throughout the day in three karst springs (upper, side, and lower) at McNenny State Fish Hatchery, rural Spearfish, Lawrence County, South Dakota, USA. Total gas pressures, oxygen percent saturation, and nitrogen percent saturation were recorded six times/day on eight days over a 26-day period in each of the three springs. Total gas pressure did not vary significantly throughout the day in any of the springs. However, percent oxygen and nitrogen saturation were significantly different throughout the day in all three springs. The highest mean (SE) nitrogen supersaturation value of 118.5 (1.1)% was observed in the lower spring at 07:00. The lowest mean nitrogen supersaturation values were 114.5 (1.1)% at 13:00 in the upper spring, and 114.2 (0.2)% and 113.1 (0.7)% at 15:00 in the side and lower spring, respectively. At 118% nitrogen supersaturation, gas bubble disease is likely to occur in fish, resulting in potentially high levels of mortality if untreated spring water was used for fish production. The results of this study indicate the importance of recording nitrogen gas levels at sunrise or early in the morning, when nitrogen is highest and oxygen is lowest, to obtain accurate and reproducible data.展开更多
为优化不同降水年型下春小麦高产稳产和高效利用水氮资源的管理决策方案,利用2009-2012年内蒙古自治区额尔古纳市上库力农场试验站与拉布大林农场试验站春小麦(内麦19)的试验观测资料,确定APSIM-wheat模型中小麦生长发育关键参数;基于...为优化不同降水年型下春小麦高产稳产和高效利用水氮资源的管理决策方案,利用2009-2012年内蒙古自治区额尔古纳市上库力农场试验站与拉布大林农场试验站春小麦(内麦19)的试验观测资料,确定APSIM-wheat模型中小麦生长发育关键参数;基于校准后的APSIM-wheat模型模拟分析1967-2017年雨养条件下春小麦生长发育过程,并依据降水量划分了3种降水年型(干旱、平水和湿润年型),根据土壤水分亏缺指数(soil water deficit on photosynthesis,SWD_(ef))确定最优水分管理时期;设计8个灌溉量梯度(15、30、45、60、90、120、150和180 mm)和13个施N量梯度(30、45、60、75、90、105、120、150、180、210、240、270和300 kg·hm^(-2))情景模式,结合水氮管理决策的遴选关键指标[水分利用效率(water use efficiency,WUE)、氮肥利用效率(nitrogen use efficiency,NUE)和产量],探究不同气候年型下最优春小麦水氮管理模式。结果表明:(1)校准后的APSIM-wheat模型春小麦发育期模块(出苗期、抽穗期和成熟期)模拟值与观测值的均方根误差(root mean square error,RMSE)在1.17~3.64 d范围内,归一化均方根误差(normalized root mean square error,NRMSE)在0.82%~1.90%范围内;产量模块模拟值与观测值的RMSE为371.50 kg·hm^(-2),NRMSE为8.54%,说明APSIM-wheat模型可以较好地反映不同降水年型下小麦的动态生长发育过程。(2)雨养条件下春小麦分蘖期—拔节期、拔节期—抽穗期和抽穗期—开花期的SWD_(ef)较低,且在生育期内仅灌溉一次的前提下,拔节期灌溉可以减轻干旱胁迫并显著提高产量。(3)干旱、平水和湿润年型春小麦拔节期最优水氮管理模式分别为灌溉量60 mm和施氮量105 kg·hm^(-2)、灌溉量60 mm和施氮量120 kg·hm^(-2)、灌溉量30 mm和施氮量150 kg·hm^(-2),其产量分别为4810.96±551.43、5378.06±768.86和6421.33±454.09 kg·hm^(-2)。展开更多
Spring maize is one of the most popular crops planted in northeastem China. The cropping systems involving spring maize have been maintaining high production through intensive management practices. However, the high r...Spring maize is one of the most popular crops planted in northeastem China. The cropping systems involving spring maize have been maintaining high production through intensive management practices. However, the high rates of nitrogen （N） fertilizers application could have introduced a great amount of nitrous oxide （N2O） into the atmosphere. It is crucial for sustaining the maize production systems to reduce N2O emissions meanwhile maintaining the optimum yields by adopting alternative farming management practices. The goal of this study was to evaluate effects of alternative fertilization and crop residue management practices on N2O emission as well as crop yield for a typical maize field in northeastern China. Field experiments were conducted during the 2010-2011 maize growing seasons （from early May to late September） in Liaoning Province, northeastern China. N2O fluxes were measured at the field plots with six different treatments including no N fertilizer use （CK）, farmers＇ conventional N fertilizer application rate （FP）, reduced N fertilizer rate （OPT）, reduced N fertilizer rate combined with crop straw amendment （OPTS）, slow-release N fertilizer （CRF）, and reduced N fertilizer rate combined with nitrification inhibitor （OPT＋DCD）. The static chamber method combined with gas chromatography technique was employed to conduct the measurements of N2O fluxes. The field data showed that N2O emissions varied across the treatments. During the maize growing season in 2010, the total N2O emissions under the treatments of CK, FP, OPT, OPTS, and CRF were 0.63, 1.11, 1.03, 1.26, and 0.98 kg N ha-1, respectively. The seasonal cumulative N2O emissions were 0.54, 1.07, 0.96, 1.12, and 0.84 kg N ha1, respectively, under CK, FP, OPT, OPTS, and OPT＋DCD in 2011. In comparison with FP, CRF or OPT＋DCD reduced the N2O emissions by 12 or 21%, respectively, while the crop yields remained unchanged. The results indicate that the reduction of N-fertilizer application rate in combination with the slow-release fertilizer type or nitrification inhibitor could effectively mitigate N2O emissions from the tested field. The incorporation of crop residue didn＇t show positive effect on mitigating N2O emissions from the tested cropping system. The field study can provide useful information for the on-going debate on alternative N fertilization strategies and crop straw management in China. However, further studies would be needed to explore the long-term impacts of the alternative management practices on a wide range of environmental services.展开更多
Gliadin, the major storage protein in endosperm, affects grain quality in spring wheat by its content and composition. Eighteen cultivars differing in HMW-GS were used in the study to approach the accumulation pattern...Gliadin, the major storage protein in endosperm, affects grain quality in spring wheat by its content and composition. Eighteen cultivars differing in HMW-GS were used in the study to approach the accumulation pattern of gliadin fractions α, β, γ, ω and regulation of three kinds of nitrogen source. The results showed that the content of gliadin in grains increased gradually along with the process of grain-filling, but the accumulation intensity and final content differed evidently among cultivars with different HMW-GS composition. Of all the subunit types used here, cultivars with subunits 7＋9 and 2＋12 had smaller accumulation intensity and lower final content. During grain-filling, 4 gliadin fractions had the same increase trend, but differed in accumulation course. The dynamic trends of gliadin accumulation were similar in different nitrogen treatments whose effects on initial amount, accumulation intensity and final level of accumulation varied with cultivars. Of three nitrogen fertilizer types, the amide-form nitrogen source was better to the formation and accumulation of gliadin as well as its four fractions.展开更多
文摘This experiment examined the fluctuations in nitrogen gas supersaturation throughout the day in three karst springs (upper, side, and lower) at McNenny State Fish Hatchery, rural Spearfish, Lawrence County, South Dakota, USA. Total gas pressures, oxygen percent saturation, and nitrogen percent saturation were recorded six times/day on eight days over a 26-day period in each of the three springs. Total gas pressure did not vary significantly throughout the day in any of the springs. However, percent oxygen and nitrogen saturation were significantly different throughout the day in all three springs. The highest mean (SE) nitrogen supersaturation value of 118.5 (1.1)% was observed in the lower spring at 07:00. The lowest mean nitrogen supersaturation values were 114.5 (1.1)% at 13:00 in the upper spring, and 114.2 (0.2)% and 113.1 (0.7)% at 15:00 in the side and lower spring, respectively. At 118% nitrogen supersaturation, gas bubble disease is likely to occur in fish, resulting in potentially high levels of mortality if untreated spring water was used for fish production. The results of this study indicate the importance of recording nitrogen gas levels at sunrise or early in the morning, when nitrogen is highest and oxygen is lowest, to obtain accurate and reproducible data.
文摘为优化不同降水年型下春小麦高产稳产和高效利用水氮资源的管理决策方案,利用2009-2012年内蒙古自治区额尔古纳市上库力农场试验站与拉布大林农场试验站春小麦(内麦19)的试验观测资料,确定APSIM-wheat模型中小麦生长发育关键参数;基于校准后的APSIM-wheat模型模拟分析1967-2017年雨养条件下春小麦生长发育过程,并依据降水量划分了3种降水年型(干旱、平水和湿润年型),根据土壤水分亏缺指数(soil water deficit on photosynthesis,SWD_(ef))确定最优水分管理时期;设计8个灌溉量梯度(15、30、45、60、90、120、150和180 mm)和13个施N量梯度(30、45、60、75、90、105、120、150、180、210、240、270和300 kg·hm^(-2))情景模式,结合水氮管理决策的遴选关键指标[水分利用效率(water use efficiency,WUE)、氮肥利用效率(nitrogen use efficiency,NUE)和产量],探究不同气候年型下最优春小麦水氮管理模式。结果表明:(1)校准后的APSIM-wheat模型春小麦发育期模块(出苗期、抽穗期和成熟期)模拟值与观测值的均方根误差(root mean square error,RMSE)在1.17~3.64 d范围内,归一化均方根误差(normalized root mean square error,NRMSE)在0.82%~1.90%范围内;产量模块模拟值与观测值的RMSE为371.50 kg·hm^(-2),NRMSE为8.54%,说明APSIM-wheat模型可以较好地反映不同降水年型下小麦的动态生长发育过程。(2)雨养条件下春小麦分蘖期—拔节期、拔节期—抽穗期和抽穗期—开花期的SWD_(ef)较低,且在生育期内仅灌溉一次的前提下,拔节期灌溉可以减轻干旱胁迫并显著提高产量。(3)干旱、平水和湿润年型春小麦拔节期最优水氮管理模式分别为灌溉量60 mm和施氮量105 kg·hm^(-2)、灌溉量60 mm和施氮量120 kg·hm^(-2)、灌溉量30 mm和施氮量150 kg·hm^(-2),其产量分别为4810.96±551.43、5378.06±768.86和6421.33±454.09 kg·hm^(-2)。
基金the National Natural Science Foundation of China(31270486)the Special Fund for Agriculture Scientific Non-Profit Research of China(201103039)+1 种基金the National Basic Research Program of China(2012CB417104)the National Nonprofit Institute Research Grant of Chinese Academy of Agricultural Sciences(IARRP-2014-402-15)
文摘Spring maize is one of the most popular crops planted in northeastem China. The cropping systems involving spring maize have been maintaining high production through intensive management practices. However, the high rates of nitrogen （N） fertilizers application could have introduced a great amount of nitrous oxide （N2O） into the atmosphere. It is crucial for sustaining the maize production systems to reduce N2O emissions meanwhile maintaining the optimum yields by adopting alternative farming management practices. The goal of this study was to evaluate effects of alternative fertilization and crop residue management practices on N2O emission as well as crop yield for a typical maize field in northeastern China. Field experiments were conducted during the 2010-2011 maize growing seasons （from early May to late September） in Liaoning Province, northeastern China. N2O fluxes were measured at the field plots with six different treatments including no N fertilizer use （CK）, farmers＇ conventional N fertilizer application rate （FP）, reduced N fertilizer rate （OPT）, reduced N fertilizer rate combined with crop straw amendment （OPTS）, slow-release N fertilizer （CRF）, and reduced N fertilizer rate combined with nitrification inhibitor （OPT＋DCD）. The static chamber method combined with gas chromatography technique was employed to conduct the measurements of N2O fluxes. The field data showed that N2O emissions varied across the treatments. During the maize growing season in 2010, the total N2O emissions under the treatments of CK, FP, OPT, OPTS, and CRF were 0.63, 1.11, 1.03, 1.26, and 0.98 kg N ha-1, respectively. The seasonal cumulative N2O emissions were 0.54, 1.07, 0.96, 1.12, and 0.84 kg N ha1, respectively, under CK, FP, OPT, OPTS, and OPT＋DCD in 2011. In comparison with FP, CRF or OPT＋DCD reduced the N2O emissions by 12 or 21%, respectively, while the crop yields remained unchanged. The results indicate that the reduction of N-fertilizer application rate in combination with the slow-release fertilizer type or nitrification inhibitor could effectively mitigate N2O emissions from the tested field. The incorporation of crop residue didn＇t show positive effect on mitigating N2O emissions from the tested cropping system. The field study can provide useful information for the on-going debate on alternative N fertilization strategies and crop straw management in China. However, further studies would be needed to explore the long-term impacts of the alternative management practices on a wide range of environmental services.
文摘Gliadin, the major storage protein in endosperm, affects grain quality in spring wheat by its content and composition. Eighteen cultivars differing in HMW-GS were used in the study to approach the accumulation pattern of gliadin fractions α, β, γ, ω and regulation of three kinds of nitrogen source. The results showed that the content of gliadin in grains increased gradually along with the process of grain-filling, but the accumulation intensity and final content differed evidently among cultivars with different HMW-GS composition. Of all the subunit types used here, cultivars with subunits 7＋9 and 2＋12 had smaller accumulation intensity and lower final content. During grain-filling, 4 gliadin fractions had the same increase trend, but differed in accumulation course. The dynamic trends of gliadin accumulation were similar in different nitrogen treatments whose effects on initial amount, accumulation intensity and final level of accumulation varied with cultivars. Of three nitrogen fertilizer types, the amide-form nitrogen source was better to the formation and accumulation of gliadin as well as its four fractions.
