To assess the impacts of clouds during the grain‐filling period on the leaf senescence and yield of wheat (Triticum aestivum L.), we conducted a 4‐year plot shading experiment in a well‐drained Andosol in northern Japan. Plants were shaded after the beginning of anthesis in mid‐June, which corresponds to a naturally cloudy period in the study region. The effect of shading depended on its synchronization with soil drying, which affected leaf senescence. Grain yield was determined by solar radiation at the beginning of the grain‐filling period, except in 2015, which was a dry year. Later anthesis in 2016 and 2017 significantly reduced the number and weight of individual grains in the shading treatments. Moreover, “Kitahonami”, with late anthesis, showed a significantly slower increase in the individual‐grain weight during the grain‐filling process after shading than “Yumechikara”. When the duration between anthesis and shading was short, shading significantly reduced the number and weight of grains, and later anthesis makes it more likely that regional reduced light levels are encountered, resulting in fewer grains; the sensitivity of individual‐grain weight to shading synchronized with an increase in grain protein contents. Our results suggest that in wet years, later anthesis makes it easier to encounter regional reduced light and fewer grains; in addition, insufficient light limits photosynthesis under shade and decreases yield.

中文翻译：

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潮湿气候下冬小麦（Triticum aestivum L.）对花后遮光的籽粒灌浆响应

评估灌浆期云对小麦叶片衰老和产量的影响（普通小麦）L.），我们在日本北部排水良好的Andosol中进行了为期4年的地块遮蔽实验。6月中旬开始开花后，将植物遮荫，这对应于研究区域的自然多云时期。遮荫的效果取决于它与土壤干燥的同步性，这会影响叶片的衰老。谷物产量是在灌浆期开始时通过太阳辐射确定的，除了2015年是干旱的一年。2016年和2017年后期的花药显着减少了遮光处理中单个谷物的数量和重量。此外，花期较晚的“ Kitahonami”与“ Yumechikara”相比，遮光后的籽粒充实过程中单粒重的增加明显减慢。当花期和阴影之间的持续时间较短时，阴影显着减少了谷物的数量和重量，随后的开花期使得更有可能遇到区域降低的光照水平，从而导致谷物减少；单粒重对阴影的敏感性与谷物蛋白质含量的增加同步。我们的结果表明，在潮湿的年份，以后的花期使其更容易遇到局部光照减少和谷物减少的现象。此外，光照不足会限制荫凉下的光合作用并降低产量。以后的花期使遇到区域减少的光照和较少的谷物变得更容易。此外，光照不足会限制荫凉下的光合作用并降低产量。以后的花期使遇到区域减少的光照和较少的谷物变得更容易。此外，光照不足会限制荫凉下的光合作用并降低产量。