Increasing leaf photosynthesis per area（A） is of great importance to achieve yield further improvement. The aim of this study was to exploit varietal difference in A and its correlation with specific leaf weight（SL...Increasing leaf photosynthesis per area（A） is of great importance to achieve yield further improvement. The aim of this study was to exploit varietal difference in A and its correlation with specific leaf weight（SLW）. Twelve rice cultivars, including 6 indica and 6 japonica varieties, were pot-grown under two N treatments, low N（LN） and sufficient N（SN）. Leaf photosynthesis and related parameters were measured at tillering stage. Compared with LN treatment, A, stomatal conductance（g_s）, mesophyll conductance（g_m）, leaf N content（N_（area））, and chlorophyll content were significantly improved under SN treatment, while SLW and photosynthetic N use efficiency（PNUE） were generally decreased. Varietal difference in A was positively related to both g_s and g_m, but not related to N_（area）. This resulted in a low PNUE in high N_（area） leaves. Varietal difference in PNUE was generally negatively related to SLW. Response of PNUE to N supply varied among different rice cultivars, and interestingly, the decrease in PNUE under SN was negatively related to the decrease in SLW. With a higher N_（area）, japonica rice cultivars did not show a higher A than indica rice cultivars because of possession of high-SLW leaves. Therefore, varietal difference in A was not related to N_（area）, and SLW can substantially interfere with the correlation between A and N_（area）. These findings may provide useful information for rice breeders to maximize A and PNUE, rather than over reliance on N_（area） as an indicator of photosynthetic performance.展开更多
明确吉林省不同年代玉米品种产量、叶片氮含量与光合特性对不同氮素用量的响应趋势,对东北地区玉米高产品种选育具有重要的实践意义。本研究以20世纪70年代年以来吉林省大面积推广应用的6个代表性品种为研究对象(1970s:吉单101、中单2号...明确吉林省不同年代玉米品种产量、叶片氮含量与光合特性对不同氮素用量的响应趋势,对东北地区玉米高产品种选育具有重要的实践意义。本研究以20世纪70年代年以来吉林省大面积推广应用的6个代表性品种为研究对象(1970s:吉单101、中单2号;1990s:四单19、吉单159;2010s:先玉335和农华101),在大田条件下共设置4个氮素水平(0、125、250和375 kg hm^(–2)),分析了氮素施用量对不同年代玉米品种产量、叶片氮含量及光合特征参数等的影响。结果表明,所有氮水平下玉米籽粒产量均随品种更替而提高,现代品种在较高氮水平下(≥250 kg hm^(–2))产量优势更明显,各处理产量的提高主要是单穗粒数和粒重同时增加的结果。当施氮量不高于250 kg hm^(–2)时,各年代玉米品种穗位叶净光合速率(Pn)均随施氮量增加而提高,现代品种显著高于老品种,当施氮量为375kghm^(–2)时Pn均显著降低,降低幅度表现为老品种高于现代品种。而吐丝至蜡熟期,Pn降低幅度随施氮量增加和品种更替而减小。玉米光补偿点、暗呼吸速率在不同时期均表现为2010s最高、1990s次之、1970s最低,其中2010s品种的光补偿点比1990s、1970s品种平均分别提高9.72%、27.84%,暗呼吸速率平均提高7.82%、32.98%。各年代品种比叶重(specific leafweight,SLW)随施氮量增加而提高,同一施氮量下SLW表现为随品种更替而降低。不同品种叶片单位面积氮含量(Narea)均随施氮量增加而提高,不施氮处理老品种显著降低,施氮处理品种间无显著差异。相关分析表明,Pn与SLW呈显著正相关关系,而Pn与Narea之间关系可用二次曲线方程拟合,Pn随Narea增加出现转折的Narea值为1.57g m–2。不同年代品种的光合氮利用效率(PNUE)均随施氮量增加而降低,而较高氮水平下(≥250 kg hm^(–2))PNUE随品种更替而显著提高。综上,在较高氮水平下现代玉米品种比老品种显著增产主要归因于其Pn和PNUE的提高,而Pn和PNUE的提高又与比叶重(SLM)、叶片N含量(Nmass、Narea)等性状密切相关,推荐在玉米品种选育过程中参考。展开更多
基金supported by the National Natural Science Foundation of China(31301840)the National Excellent Doctoral Dissertation of China(201465)+2 种基金the Program for Changjiang Scholars and Innovative Research Team in University of China(IRT1247)the Natural Science Foundation of Hubei Province,China(2013CFB201)the Fundamental Research Funds for the Central Universities,China(2013PY107)
文摘Increasing leaf photosynthesis per area（A） is of great importance to achieve yield further improvement. The aim of this study was to exploit varietal difference in A and its correlation with specific leaf weight（SLW）. Twelve rice cultivars, including 6 indica and 6 japonica varieties, were pot-grown under two N treatments, low N（LN） and sufficient N（SN）. Leaf photosynthesis and related parameters were measured at tillering stage. Compared with LN treatment, A, stomatal conductance（g_s）, mesophyll conductance（g_m）, leaf N content（N_（area））, and chlorophyll content were significantly improved under SN treatment, while SLW and photosynthetic N use efficiency（PNUE） were generally decreased. Varietal difference in A was positively related to both g_s and g_m, but not related to N_（area）. This resulted in a low PNUE in high N_（area） leaves. Varietal difference in PNUE was generally negatively related to SLW. Response of PNUE to N supply varied among different rice cultivars, and interestingly, the decrease in PNUE under SN was negatively related to the decrease in SLW. With a higher N_（area）, japonica rice cultivars did not show a higher A than indica rice cultivars because of possession of high-SLW leaves. Therefore, varietal difference in A was not related to N_（area）, and SLW can substantially interfere with the correlation between A and N_（area）. These findings may provide useful information for rice breeders to maximize A and PNUE, rather than over reliance on N_（area） as an indicator of photosynthetic performance.
文摘明确吉林省不同年代玉米品种产量、叶片氮含量与光合特性对不同氮素用量的响应趋势,对东北地区玉米高产品种选育具有重要的实践意义。本研究以20世纪70年代年以来吉林省大面积推广应用的6个代表性品种为研究对象(1970s:吉单101、中单2号;1990s:四单19、吉单159;2010s:先玉335和农华101),在大田条件下共设置4个氮素水平(0、125、250和375 kg hm^(–2)),分析了氮素施用量对不同年代玉米品种产量、叶片氮含量及光合特征参数等的影响。结果表明,所有氮水平下玉米籽粒产量均随品种更替而提高,现代品种在较高氮水平下(≥250 kg hm^(–2))产量优势更明显,各处理产量的提高主要是单穗粒数和粒重同时增加的结果。当施氮量不高于250 kg hm^(–2)时,各年代玉米品种穗位叶净光合速率(Pn)均随施氮量增加而提高,现代品种显著高于老品种,当施氮量为375kghm^(–2)时Pn均显著降低,降低幅度表现为老品种高于现代品种。而吐丝至蜡熟期,Pn降低幅度随施氮量增加和品种更替而减小。玉米光补偿点、暗呼吸速率在不同时期均表现为2010s最高、1990s次之、1970s最低,其中2010s品种的光补偿点比1990s、1970s品种平均分别提高9.72%、27.84%,暗呼吸速率平均提高7.82%、32.98%。各年代品种比叶重(specific leafweight,SLW)随施氮量增加而提高,同一施氮量下SLW表现为随品种更替而降低。不同品种叶片单位面积氮含量(Narea)均随施氮量增加而提高,不施氮处理老品种显著降低,施氮处理品种间无显著差异。相关分析表明,Pn与SLW呈显著正相关关系,而Pn与Narea之间关系可用二次曲线方程拟合,Pn随Narea增加出现转折的Narea值为1.57g m–2。不同年代品种的光合氮利用效率(PNUE)均随施氮量增加而降低,而较高氮水平下(≥250 kg hm^(–2))PNUE随品种更替而显著提高。综上,在较高氮水平下现代玉米品种比老品种显著增产主要归因于其Pn和PNUE的提高,而Pn和PNUE的提高又与比叶重(SLM)、叶片N含量(Nmass、Narea)等性状密切相关,推荐在玉米品种选育过程中参考。
