冬小麦不同穗位籽粒淀粉粒差异及其与粒重的相关性

为研究小麦不同穗位籽粒淀粉粒差异及其与粒重相关性, 以露天池栽冬小麦济麦20, 测定不同小穗位成熟颖果胚乳细胞大小、淀粉粒的数目、体积和表面积分布及胚乳发育过程中淀粉体数量变化。结果表明, 小麦胚乳淀粉粒发育具有显著的粒位、穗位效应, 相同小穗位, 强势粒淀粉体起始时间比弱势粒早4~5 d。相同粒位, 中部小穗籽粒淀粉体最先发育, 上部小穗次之, 下部小穗最晚。淀粉体数量在中部小穗籽粒最多, 随着灌浆进程, 下部小穗逐渐赶上并超过上部小穗。成熟籽粒淀粉粒数目分布总趋势为B_L型>B_S型>A型; B_S型淀粉粒表现强势粒>弱势粒, 且随小穗位的升高而呈增加趋势; B_L型则相反。淀粉粒的数目分布导致其体积与表面积分布表现出相同的变化趋势。粒重与大、小淀粉体数目相关系数随灌浆进程逐渐增大, 且前者大于后者; 成熟期分别达到0.88^**和0.78^**。粒重增加与大、小淀粉粒数目增长的相关系数分别高于0.96^**和0.93^**, 前者在穗位间差异不显著, 后者表现为下部小穗>上部小穗>中部小穗。小麦胚乳淀粉粒形成及粒度分布既具有强弱势籽粒间的粒位效应, 也具有显著的小穗位效应; 弱势籽粒仍有通过增加淀粉粒数量以减小其与强势籽粒间粒重差异的调控空间。

Differences of Starch Granules in Grains from Different Spikelet Positions and Their Correlation with Grain Weight in Winter Wheat

The purpose of this study was to reveal the differences in development and size-distribution of starch granules in endosperm of wheat grains in different grain positions and spikelet positions. The endosperm cell size, and the number, volume and surface area distribution of starch granules in mature caryopsis, as well as the changes of starch granule number during endosperm development, were studied using wheat cultivar Jimai 20 grown in the field. The results showed that the development of starch granule was closely related with grain position and spikelet position. In the same spikelet position, starch grains formed 4–5 d earlier in superior grains (the first and the second grains) than in inferior grains (the third and the fourth grains).At the same grain position, starch granules developed first in the grains of the middle spikelets, and then in grains of upper and lower spikelets. The amount of starch granules was the highest in the middle spikelet grains all the time. The lower spikelet grains had the least starch granules at the beginning of grain filling, however, the number of starch granules increased gradually and surpassed that of the upper spikelet grains as caryopsis matured. Correlation coefficients between grain weight and starch granule amount became more significant with grain filling, which reached 0.88 ** (large starch granule) and 0.78 ** (small starch granule) at mature stage. Correlation coefficients between grain weight and large starch granule amount were higher than 0.96 ** , and had no difference among different spikelet positions. Correlation coefficients between grain weight and small starch granule amount were higher than 0.93 ** , and had a trend of upper>lower>middle in different spikelet positions. The trend of size distribution was BL-type>BS-type>A-type. There were more BS-type granules in superior grains than in inferior grains. The number of BS-type granules increased with the spikelet position rising, whereas the number of BL-type granules showed a reverse trend. The size distribution of starch granules had similar changes to volume and surface area. The formation and size distribution of starch granules were affectedsignificantly by grain position and spikelet position, and inferior grains had the potential of increasing grain weight through increasing the quantity of starch granules.