为了探讨露地西兰花的NPK合理施用量,提出科学的施肥配比。在宁夏引黄灌区通过田间试验研究了不同NPK供应水平对露地西兰花产量和地上部NPK吸收累积的影响,并评价了其肥料效率。结果表明:施用N、P肥对西兰花有显著增产作用,而施K处理间...为了探讨露地西兰花的NPK合理施用量,提出科学的施肥配比。在宁夏引黄灌区通过田间试验研究了不同NPK供应水平对露地西兰花产量和地上部NPK吸收累积的影响,并评价了其肥料效率。结果表明:施用N、P肥对西兰花有显著增产作用,而施K处理间无显著差异。相对于N0和P0处理,增施N、P肥可分别提高23.6%～36.2%和7.6%～11.5%的经济产量。适当增施NPK肥能显著提高西兰花的地上部NPK养分累积。西兰花的肥料利用率、农学效率和偏生产力都随施肥量增加而降低。每施用1 kg N、1 kg P_2O_5、1 kg K2O分别可生产50.9～184.7、89.3～369.1、53.9～220.2 kg西兰花经济产量,其随施肥量增加呈显著降低趋势。西兰花经济产量与施N量(R2=0.886)、施P量(R2=0.906)和施K量(R2=0.794)都呈二次曲线关系。综合考虑蔬菜产量、养分累积和肥料效率,建议宁夏引黄灌区露地西兰花的施肥量分别为N 189.8～200.0 kg/hm^2、P_2O_579.8～86.8 kg/hm^2和K2O 80.2～112.5 kg/hm^2,其施肥配比为1:0.42～0.43:0.42～0.56。展开更多
Background:Lack of an observable vertical impact peak in fore/mid-foot running has been suggested as a means of reducing lower extremity impact forces,although it is unclear if impact characteristics exist in other ax...Background:Lack of an observable vertical impact peak in fore/mid-foot running has been suggested as a means of reducing lower extremity impact forces,although it is unclear if impact characteristics exist in other axes.The purpose of the investigation was to compare three-dimensional(3 D)impact kinetics among foot-strike conditions in over-ground running using instantaneous loading rate–time profiles.Methods:Impact characteristics were assessed by identifying peak loading rates in each direction(medial–lateral(ML),anterior–posterior(AP),vertical,and 3 D resultant)following foot-strike instructions(fore-foot,mid-foot,subtle heel,and obvious heel strike).Kinematic and kinetic data were analyzed among 9 male participants in each foot-strike condition.Results:Loading rate peaks were observed in each direction and foot-strike condition,differing in magnitude by direction(3 D resultant and vertical>AP>ML,p≤0.031)and foot-strike:ML(fore-foot and mid-foot strike>obvious heel strike,p≤0.032),AP(fore-foot and mid-foot strikes>subtle-heel and obvious heel strikes,p≤0.023).In each direction,the first loading rate peak occurred later during heel strike running relative to fore-foot(p≤0.019),with vertical and 3 D resultant impact durations exceeding shear(ML and AP,p≤0.007)in each condition.Conclusion:Loading rate–time assessment identified contrasting impact characteristics in each direction and the 3 D resultant following foot-strike manipulations,with potential implications for lower extremity structures in running.展开更多
文摘为了探讨露地西兰花的NPK合理施用量,提出科学的施肥配比。在宁夏引黄灌区通过田间试验研究了不同NPK供应水平对露地西兰花产量和地上部NPK吸收累积的影响,并评价了其肥料效率。结果表明:施用N、P肥对西兰花有显著增产作用,而施K处理间无显著差异。相对于N0和P0处理,增施N、P肥可分别提高23.6%～36.2%和7.6%～11.5%的经济产量。适当增施NPK肥能显著提高西兰花的地上部NPK养分累积。西兰花的肥料利用率、农学效率和偏生产力都随施肥量增加而降低。每施用1 kg N、1 kg P_2O_5、1 kg K2O分别可生产50.9～184.7、89.3～369.1、53.9～220.2 kg西兰花经济产量,其随施肥量增加呈显著降低趋势。西兰花经济产量与施N量(R2=0.886)、施P量(R2=0.906)和施K量(R2=0.794)都呈二次曲线关系。综合考虑蔬菜产量、养分累积和肥料效率,建议宁夏引黄灌区露地西兰花的施肥量分别为N 189.8～200.0 kg/hm^2、P_2O_579.8～86.8 kg/hm^2和K2O 80.2～112.5 kg/hm^2,其施肥配比为1:0.42～0.43:0.42～0.56。
基金funded by the Institutional Development Award Network of Biomedical Research Excellence through the National Institute of General Medical Sciences(820 GM103440-11)
文摘Background:Lack of an observable vertical impact peak in fore/mid-foot running has been suggested as a means of reducing lower extremity impact forces,although it is unclear if impact characteristics exist in other axes.The purpose of the investigation was to compare three-dimensional(3 D)impact kinetics among foot-strike conditions in over-ground running using instantaneous loading rate–time profiles.Methods:Impact characteristics were assessed by identifying peak loading rates in each direction(medial–lateral(ML),anterior–posterior(AP),vertical,and 3 D resultant)following foot-strike instructions(fore-foot,mid-foot,subtle heel,and obvious heel strike).Kinematic and kinetic data were analyzed among 9 male participants in each foot-strike condition.Results:Loading rate peaks were observed in each direction and foot-strike condition,differing in magnitude by direction(3 D resultant and vertical>AP>ML,p≤0.031)and foot-strike:ML(fore-foot and mid-foot strike>obvious heel strike,p≤0.032),AP(fore-foot and mid-foot strikes>subtle-heel and obvious heel strikes,p≤0.023).In each direction,the first loading rate peak occurred later during heel strike running relative to fore-foot(p≤0.019),with vertical and 3 D resultant impact durations exceeding shear(ML and AP,p≤0.007)in each condition.Conclusion:Loading rate–time assessment identified contrasting impact characteristics in each direction and the 3 D resultant following foot-strike manipulations,with potential implications for lower extremity structures in running.
