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首页> 外文期刊>European Journal of Agronomy >Carbon assimilation, leaf area dynamics, and grain yield in contemporary earlier- and later-senescing maize hybrids
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Carbon assimilation, leaf area dynamics, and grain yield in contemporary earlier- and later-senescing maize hybrids

机译：当代早熟和晚熟玉米杂交种的碳同化，叶面积动态和籽粒产量

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Maize breeding during the past 50 years has been associated with a delay of leaf senescence, but it is not clear whether this trait is likewise associated with higher grain yield in modern hybrids. Post-silking growth, leaf area dynamics, photosynthetic parameters and yield were compared in modern maize hybrids differing in canopy senescence rate. In the first two experiments, four hybrids were grown in the field at Balcarce, Argentina (37 degrees 45' S, 58 degrees 18 W). In spite of differences in chlorophyll retention and photosynthesis of the ear leaf, post-silking growth and grain yield were very similar in all four hybrids while kernel N concentration was lower in the later-senescing hybrids. In a third experiment, a later-senescing (NK870) and an earlier-senescing (DK682) hybrid were grown to analyze the potential photosynthetic contribution of delayed leaf senescence. Leaf area and chlorophyll content were larger in NK870, especially at the lower canopy level (0.75 m above the ground). However, hybrids did not differ for canopy light interception. Because photosynthetic photon flux density below 1 m above the ground was less than 10% of incident radiation and photosynthesis quantum yield did not change during senescence, the potential photosynthetic output of lower leaves below 1 m was very low. Lower leaves of NK870 had N concentrations higher than those needed to sustain photosynthesis at the light conditions below 1 m. Therefore, we show that delayed senescence does not necessarily improve post-silking C accumulation because; (i) canopy light interception is not reduced by senescence except at very late stages of grain filling; (ii) contrasting hybrids show more pronounced senescence differences at canopy levels receiving less than 10% of incident radiation; (iii) delayed senescing hybrids present lower kernel N concentrations while extra N is retained in leaves exposed to a light limiting micro-environment. Delayed senescence at lower canopy levels may be unproductive, at least under non-stressing conditions
机译：在过去的50年中，玉米育种与叶片衰老的延迟有关，但是尚不清楚这种性状是否与现代杂交种的更高谷物产量有关。比较了不同的冠层衰老率的现代玉米杂交种的生后生长，叶面积动态，光合参数和产量。在前两个实验中，四个杂种在阿根廷Balcarce的田间生长（37度45'S，58度18 W）。尽管耳叶的叶绿素保留和光合作用存在差异，但在所有四个杂交种中，粉化后的生长和籽粒产量都非常相似，而在后感杂交的杂交种中，籽粒氮含量较低。在第三个实验中，种植了先衰老（NK870）和先衰老（DK682）杂种来分析延迟叶片衰老的潜在光合作用。 NK870的叶面积和叶绿素含量较高，尤其是在较低的冠层水平（离地面0.75 m）。但是，混合动力车对于顶篷的拦截没有区别。由于离地面1 m以下的光合光子通量密度不到入射辐射的10％，并且光合作用的量子产率在衰老过程中没有变化，因此低于1 m的下部叶片的潜在光合输出非常低。 NK870的下部叶片的氮浓度高于在低于1 m的光照条件下维持光合作用所需的氮浓度。因此，我们表明，延迟衰老并不一定会改善生丝后的C积累，因为： （i）除非在籽粒灌装的非常后期，否则衰老不会减少冠层的光截获; （ii）形成对比的杂种在冠层水平下接收不到入射辐射的10％时显示出更明显的衰老差异; （iii）延迟衰老的杂种表现出较低的籽粒氮浓度，而多余的氮保留在暴露于光限制微环境的叶片中。至少在非胁迫条件下，较低冠层水平的延迟衰老可能无济于事

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