玉米果穗不同部位籽粒激素含量及其与胚乳发育和籽粒灌浆的关系

以玉米品种登海11为材料, 分别进行大田和温室试验, 观察灌浆期果穗不同部位籽粒玉米素(Z)+玉米素核苷(ZR)、吲哚-3-乙酸(IAA)、脱落酸(ABA)和赤霉素(GA₃)含量变化及其与胚乳发育和籽粒灌浆的关系。结果显示, 籽粒最大胚乳细胞数目、最大胚乳细胞增殖速率及平均速率、最大灌浆速率、平均灌浆速率和百粒重表现为果穗下部籽粒>中部籽粒>上部籽粒。在胚乳细胞活跃增殖期或活跃灌浆期, 籽粒Z+ZR、IAA和ABA含量以果穗下部籽粒最高, 中部籽粒其次, 上部籽粒最低。GA₃含量则为果穗上部籽粒>中部籽粒>下部籽粒。两个试验的结果趋势一致。胚乳细胞增殖速率和籽粒灌浆速率与籽粒Z+ZR、IAA和ABA含量呈极显著正相关, 与籽粒GA₃含量呈显著负相关。说明玉米果穗上部籽粒轻主要是由于这些籽粒的胚乳细胞增殖速率小, 导致其胚乳细胞数少, 这与其灌浆期较低的Z+ZR、IAA和ABA含量及较高的GA₃含量有密切关系。

Hormone Contents in Kernels at Different Positions on an Ear and Their Relationship with Endosperm Development and Kernel Filling in Maize

Kernels at the upper position of a maize ear usually show poorer filling and lower weight in contrast to those at the basal position. The mechanism has not been understood. The experiments were conducted using a maize cultivar Denghai 11, grown in both field and greenhouse conditions, to determine number of endosperm cells, kernel filling rate, and contents of zeatin (Z) + zeatin riboside (ZR), indole-3-acetic acid (IAA), abscisic acid (ABA), and gibberellin-3 (GA₃) in the kernels at different positions on an ear from silking to maturity. The results indicated that the maximum number of endosperm cells, maximum division rate of endosperm cells,mean endosperm cell division rate,maximumkernel filling rate, mean kernel filling rate and 100-kernel weight for kernels showed an order of basal position > middle position> upper position. During the active endosperm development and the active kernel filling period, contents of Z+ZR, IAA and ABA in kernels were the greatest at the basal position, the mediate at the middle position, and the least at the upper position on an ear. The two experiments exhibited similar results. The endosperm cell division rate and kernel filling rate were very significantly and positively correlated with contents of Z+ZR, IAA, and ABA in kernels, whereas significantly and negatively correlated with content of GA₃. The results suggested that a lower kernel weight at the upper position on a maize ear is mainly due to a smaller division rate of endosperm cells, leading to less number of endosperm cells, which is closely associated with lower contents of Z+ZR, IAA, and ABA, as well as higher content of GA₃ in the kernels during kernel filling.