Achieving both high yield and high nitrogen use efficiency （NUE） simultaneously has become a major challenge with increased global demand for food, depletion of natural resources, and deterioration of environment. A...Achieving both high yield and high nitrogen use efficiency （NUE） simultaneously has become a major challenge with increased global demand for food, depletion of natural resources, and deterioration of environment. As the greatest consumers of N fertilizer in the world, Chinese farmers have overused N, and there has been poor synchrony between crop N demand and N supply because of limited understanding of the N uptake-yield relationship. To address this problem, this study evaluated the total and dynamic N requirement for different yield ranges of two major crops （maize and wheat）, and suggested improvements to N management strategies. Whole-plant N aboveground uptake requirement per grain yield （Nreq） initially deceased with grain yield improvement and then stagnated, and yet most farmers still believed that more fertilizer and higher grain yield were synonymous. When maize yield increased from 〈 7.5 to 〉 12.0 Mg ha-I, Nreq decreased from 19.8 to 17.0 kg Mg-1 grain. For wheat, it decreased from 27.1 kg Mg-1 grain for grain yield 〈 4.5 Mg ha-1 to 22.7 kg Mg-1 grain for yield 〉 9.0 Mg ha-1. Meanwhile, the percentage of dry matter and N accumulation in the middle-late growing season increased significantly with grain yield, which indicated that N fertilization should be concentrated in the middle-late stage to match crop demand while farmers often applied the majority of N fertilizer either before sowing or during early growth stages. We accordingly developed an integrated soil-crop system management strategy that simultaneously increases both grain yield and NUE.展开更多
目的:在加速康复外科(ERAS)理念指导下,观察不同时机穴位贴敷对结直肠癌根治术后胃肠功能恢复及心率变异度(HRV)的影响。方法:选取拟择期行腹腔镜下结直肠癌根治术患者105例,随机分为术前贴敷组(35例,脱落3例)、术后贴敷组(35例,脱落1例...目的:在加速康复外科(ERAS)理念指导下,观察不同时机穴位贴敷对结直肠癌根治术后胃肠功能恢复及心率变异度(HRV)的影响。方法:选取拟择期行腹腔镜下结直肠癌根治术患者105例,随机分为术前贴敷组(35例,脱落3例)、术后贴敷组(35例,脱落1例)和对照组(35例,脱落2例)。对照组患者予健康宣教、补液、多模式镇痛等ERAS相关干预;在对照组基础上,术前贴敷组、术后贴敷组分别从术前3 d、术后6 h开始穴位贴敷干预,穴取足三里、上巨虚、三阴交、内关、下巨虚,每次6 h,每天1次,至术后首次出现排气或排便即停止干预。观察3组患者术后首次排气、排便及进食时间;术后1~3 d视觉模拟量表(VAS)评分;术前、术后1周胃肠道症状分级量表(GSRS)评分总分;术前,术后1、3d心率变异度相关指标[全部窦性心搏RR间期的标准差(SDNN)、低频功率/高频功率(LF/HF)]变化,并记录3组患者干预期间的不良反应。结果:术前贴敷组及术后贴敷组患者术后首次排气时间、首次排便时间均早于对照组(P<0.05),术前贴敷组及术后贴敷组术后1~3dVAS评分及术后1周GSRS评分总分均低于对照组(P<0.05),术前贴敷组术后首次进食时间早于对照组(P<0.05),术后1、3 d SDNN、LF/HF均高于对照组(P<0.05)。术前贴敷组术后首次排气时间、首次排便时间均早于术后贴敷组(P<0.05),术后1~3 d VAS评分均低于术后贴敷组(P<0.05),术后1、3 d SDNN及术后1 d LF/HF均高于术后贴敷组(P<0.05)。3组患者均未出现不良反应。结论:在加速康复外科理念指导下,术前穴位贴敷能有效促进行腹腔镜下结直肠癌根治术患者术后胃肠功能恢复,提高心率变异度及自主神经功能,疗效优于术后穴位贴敷。展开更多
基金supported by the National Basic Research Program(973 Program) of China(No.2015CB150402)the National Maize Production System in China(No.CARS-02-24)+1 种基金the Special Fund for Agroscientific Research in the Public Interest of China (No.201103003)the Innovative Group Grant of the NSFC,China(No.31421092)
文摘Achieving both high yield and high nitrogen use efficiency （NUE） simultaneously has become a major challenge with increased global demand for food, depletion of natural resources, and deterioration of environment. As the greatest consumers of N fertilizer in the world, Chinese farmers have overused N, and there has been poor synchrony between crop N demand and N supply because of limited understanding of the N uptake-yield relationship. To address this problem, this study evaluated the total and dynamic N requirement for different yield ranges of two major crops （maize and wheat）, and suggested improvements to N management strategies. Whole-plant N aboveground uptake requirement per grain yield （Nreq） initially deceased with grain yield improvement and then stagnated, and yet most farmers still believed that more fertilizer and higher grain yield were synonymous. When maize yield increased from 〈 7.5 to 〉 12.0 Mg ha-I, Nreq decreased from 19.8 to 17.0 kg Mg-1 grain. For wheat, it decreased from 27.1 kg Mg-1 grain for grain yield 〈 4.5 Mg ha-1 to 22.7 kg Mg-1 grain for yield 〉 9.0 Mg ha-1. Meanwhile, the percentage of dry matter and N accumulation in the middle-late growing season increased significantly with grain yield, which indicated that N fertilization should be concentrated in the middle-late stage to match crop demand while farmers often applied the majority of N fertilizer either before sowing or during early growth stages. We accordingly developed an integrated soil-crop system management strategy that simultaneously increases both grain yield and NUE.
文摘目的:在加速康复外科(ERAS)理念指导下,观察不同时机穴位贴敷对结直肠癌根治术后胃肠功能恢复及心率变异度(HRV)的影响。方法:选取拟择期行腹腔镜下结直肠癌根治术患者105例,随机分为术前贴敷组(35例,脱落3例)、术后贴敷组(35例,脱落1例)和对照组(35例,脱落2例)。对照组患者予健康宣教、补液、多模式镇痛等ERAS相关干预;在对照组基础上,术前贴敷组、术后贴敷组分别从术前3 d、术后6 h开始穴位贴敷干预,穴取足三里、上巨虚、三阴交、内关、下巨虚,每次6 h,每天1次,至术后首次出现排气或排便即停止干预。观察3组患者术后首次排气、排便及进食时间;术后1~3 d视觉模拟量表(VAS)评分;术前、术后1周胃肠道症状分级量表(GSRS)评分总分;术前,术后1、3d心率变异度相关指标[全部窦性心搏RR间期的标准差(SDNN)、低频功率/高频功率(LF/HF)]变化,并记录3组患者干预期间的不良反应。结果:术前贴敷组及术后贴敷组患者术后首次排气时间、首次排便时间均早于对照组(P<0.05),术前贴敷组及术后贴敷组术后1~3dVAS评分及术后1周GSRS评分总分均低于对照组(P<0.05),术前贴敷组术后首次进食时间早于对照组(P<0.05),术后1、3 d SDNN、LF/HF均高于对照组(P<0.05)。术前贴敷组术后首次排气时间、首次排便时间均早于术后贴敷组(P<0.05),术后1~3 d VAS评分均低于术后贴敷组(P<0.05),术后1、3 d SDNN及术后1 d LF/HF均高于术后贴敷组(P<0.05)。3组患者均未出现不良反应。结论:在加速康复外科理念指导下,术前穴位贴敷能有效促进行腹腔镜下结直肠癌根治术患者术后胃肠功能恢复,提高心率变异度及自主神经功能,疗效优于术后穴位贴敷。
