Grain Filling Mechanisms in Spring Wheat : IV. Effects of shadings on number and size of spikes, grains, endosperm cells and starch granules in wheat

[摘要] Changes in the number and size of spikes, grains, endosperm cells and starch granules was examined in relation to the limited assimilates caused by shading treatments. Spring wheat canopy (Triticum aestivum L. cv. Haruyutaka) was covered with a 95% shading cloth so as to cause failure in the assimilation at the initial, early and late grain filling phases; initial shading, from two days before anthesis until seven days after anthesis; early shading, from seven days until 14 days after anthesis; and late shading, from 14 days until 21 days after anthesis. The grain yield decreased (11% as compared to no shading) due to a decrease in the number of grains (17%), especially decreasing (62%) at the third floret position in the initial shading, while a decrease of one grain weight at all floret positions resulted in 20% and 16% decreases in the grain yield in early and late shadings, respectively. The reduction of grain weight was not due to a decrease in the number of endosperm cells, but to a decrease in the size of large starch granules. Differences in the effects of shading on changes in sink characters could be explained in terms of the physiological process of grain formation.

[学科分类] 农业科学（综合）

[关键词] Endosperm cell;子実収量と収量構成要素;Floret position in spikelet;遮光処理;Grain filling phase;小穂内の小花位置;Grain yield and yield component;シンク形成;Shading;デンプン粒;Sink formation;登熟相;Spring wheat;胚乳細胞;Starch granule;春播コムギ