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作者	单位
李刘龙，库旭灿，李赟，王小燕	(长江大学农学院/主要粮食作物产业化湖北省协同创新中心,湖北荆州 434025)

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中文摘要:

为了探究连阴雨天气弱光逆境导致小麦减产的机理，于2017-2018年度对长江中下游流域适宜推广的48个小麦品种开展了灌浆期全程遮光试验（遮去自然光强的45%），初步筛选出两个弱光敏感品种（扶麦1228和生选6号）和两个弱光钝感品种（襄麦55和扬麦158），2018-2019年以此4个品种和江汉平原主推品种郑麦9023为供试材料，研究了开花期至成熟期遮光对小麦干物质积累与分配、植株氮素转运及籽粒产量的影响。结果表明：（1）花后遮光后小麦籽粒产量显著降低，两年度5个品种平均减产49.1%～61.1%，千粒重平均下降34.4%～42.5%，遮光对穗数和穗粒数的影响两年度均未达0.05显著水平。（2）花后遮光抑制了小麦干物质的积累，显著减少各营养器官干物质积累量，使成熟期干物质积累总量较CK平均下降23.4%，降低籽粒灌浆速率。花后遮光增大了营养器官花前同化物的转运量及其对籽粒产量的贡献率，而减少了花后光合同化物量及其贡献率，降低收获指数。（3）花后遮光后营养器官中氮素向籽粒的再分配受抑，较多的氮素滞留在营养器官中，茎鞘氮素积累量平均增加了88.0%，穗轴与颖壳次之，叶片增加了32.8%。遮光导致各营养器官花前贮存氮素向籽粒的转运量和转运效率均显著下降，使籽粒氮素积累对花后吸收氮素的依赖加大。总之，花后遮光会导致小麦显著减产，其主要原因是粒重大幅度下降；遮光加大了籽粒干物质积累对花前碳水化合物再分配的依赖，以及籽粒氮素积累对花后氮素吸收的依赖。襄麦55和扬麦158遮光条件下籽粒产量下降幅度较小，是稻麦周年高产适宜推广品种。

英文摘要:

In order to explore the mechanism of wheat yield reduction caused by low light stress in continuous rainy days,48 wheat varieties suitable for promotion in the middle and lower reaches of the Yangtze River were tested in the whole process of shading(45% natural light was shaded) during the filling period in 2017-2018,and two low light sensitive varieties(Fumai 1228 and Shengxuan 6) and two low light insensitive varieties(Xiangmai 55 and Yangmai 158) were preliminarily screened out. From 2018 to 2019,the effects of shading on dry matter accumulation and distribution,plant nitrogen transport and grain yield of wheat from anthesis to maturity were studied with the above four materials and Zhengmai 9023,the major wheat variety in Jianghan plain as research materials. The results showed that:Post-anthesis shading significantly reduced the grain yield of wheat,with an average decrease of 49.1% to 61.1% in 2017-2019. The average decrease of 1 000-grain weight was 34.4%-42.5%,and the effect of shading on the number of spikes per hectare and the number of grains per panicle was not significant in two years. Shading after anthesis inhibited the accumulation of dry matter in wheat,significantly reduced the accumulation of dry matter in various vegetative organs,decreased the total accumulation of dry matter in mature period by 23.4% on average compared with those of CK,and reduced the grain filling rate. Shading after anthesis increased the transport capacity of assimilates before anthesis and their contribution rate to grain yield,but decreased the amount of assimilates after anthesis and their contribution rate and harvest index. The redistribution of nitrogen from vegetative organs to grains was inhibited after shading after anthesis,and the accumulation of nitrogen in stem and sheath increased by 88.0% on average,followed by rachis and spikelet,and leaf increased by 32.8%. Shading led to a significant decrease in the amount and efficiency of nitrogen transport from pre-anthesis storage to grain,which increased the dependence of nitrogen accumulation on nitrogen absorption after anthesis. In a word,shading after anthesis will lead to a significant reduction in wheat yield,which is mainly due to a significant decrease in grain size; shading increases the dependence of dry matter accumulation on carbohydrate redistribution before anthesis,and the dependence of nitrogen accumulation on nitrogen absorption after anthesis. Xiangmai 55 and Yangmai 158 were suitable for rice and wheat rotation for high-yield production.

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