Guo Changchun, Yuan Xiaojuan, Yan Fengjun, Xiang Kaihong, Wu Yunxia, Zhang Qiao, Wang Zhonglin, He Limei, Fan Ping, Yang Zhiyuan, Chen Zongkui, Sun Yongjian, Ma Jun
Rice Research Institute, Sichuan Agricultural University, Chengdu, China.
Crop Ecophysiology and Cultivation Key Laboratory of Sichuan Province, Chengdu, China.
Front Plant Sci. 2022 Jun 24;13:921130. doi: 10.3389/fpls.2022.921130. eCollection 2022.
Chalkiness, which is highly affected by nitrogen (N) management during grain filling, is critical in determining rice appearance quality and consumer acceptability. We investigated the effects of N application rates 75 (N), 150 (N), and 225 (N) kg ha on the source-sink carbohydrate accumulation and grain filling characteristics of two hybrid rice cultivars with different chalkiness levels in 2019 and 2020. We further explored the relationship between grain filling and formation of chalkiness in superior and inferior grains. In this study, carbohydrates in the functional leaves and grains of the two varieties, and grain filling parameters, could explain 66.2%, 68.0%, 88.7%, and 91.6% of the total variation of total chalky grain rate and whole chalkiness degree, respectively. They were primarily concentrated in the inferior grains. As the N fertilizer application rate increased, the chalky grain rate and chalkiness degree of both the superior and inferior grains decreased significantly. This interfered with the increase in total chalky grain rate and chalkiness. Moreover, the carbohydrate content in the functional leaves increased significantly in N and N compared with that in N. The transfer of soluble sugar from the leaves to the grains decreased the soluble sugar and increased total starch contents, accelerated the development of grain length and width, increased grain water content, and effectively alleviated the contradiction between source and sink. These changes promoted the carbohydrate partition in superior and inferior grains, improved their average filling rate in the middle and later stages, optimized the uniformity of inferior grain fillings, and finally led to the overall reduction in rice chalkiness.
垩白度在灌浆期受氮素管理影响较大，对稻米外观品质及消费者接受度至关重要。2019年和2020年，我们研究了75（N₁）、150（N₂）和225（N₃）kg·ha氮素施用量对两个垩白度水平不同的杂交水稻品种源库碳水化合物积累及灌浆特性的影响。我们进一步探究了优、劣势粒灌浆与垩白形成之间的关系。本研究中，两个品种功能叶和籽粒中的碳水化合物以及灌浆参数分别可解释总垩白粒率和整精米垩白度总变异的66.2%、68.0%、88.7%和91.6%。它们主要集中在劣势粒中。随着氮肥施用量增加，优、劣势粒的垩白粒率和垩白度均显著降低，这对总垩白粒率和垩白度的增加产生了干扰。此外，与N₁相比，N₂和N₃处理功能叶中的碳水化合物含量显著增加。叶片中可溶性糖向籽粒的转运降低了可溶性糖含量，增加了总淀粉含量，加速了粒长和粒宽的发育，提高了籽粒含水量，有效缓解了源库矛盾。这些变化促进了优、劣势粒中碳水化合物的分配，提高了它们在中后期的平均灌浆速率，优化了劣势粒灌浆的均匀性，最终导致稻米垩白整体降低。
