Hu Xiangyu, Liu Yanzhuo, Zhong Xuhua, Hu Rui, Li Meijuan, Peng Bilin, Pan Junfeng, Liang Kaiming, Fu Youqiang, Huang Nongrong
Rice Research Institute of Guangdong Academy of Agricultural Sciences, Guangdong Key Laboratory of New Technology for Rice Breeding, Guangdong Rice Engineering Laboratory, Key Laboratory of Genetics and Breeding of High Quality Rice in Southern China (Co-construction by Ministry and Province), Ministry of Agriculture and Rural Affairs, Guangzhou, 510640, China.
Heliyon. 2024 Jul 18;10(14):e34607. doi: 10.1016/j.heliyon.2024.e34607. eCollection 2024 Jul 30.
Optimized nitrogen (N) management (OPT), with reduced total N input and more N applied during panicle development, has been proved to increase grain yield of rice through panicle enlargement. However, the changes in panicle architecture and source of variation are not well understood. A hybrid rice variety named Tianyou 3618 was subjected to OPT and farmer's fertilizer practice (FFP) in early cropping seasons of 2016 and 2017. With 16.7 % less N input, OPT increased panicle size by 8.6 % and 27.4 %, and grain yield by 13.8 % and 12.3 % for 2016 and 2017, respectively. OPT had greater dry matter accumulation and N uptake from panicle initiation to heading, which bolstered panicle enlargement. The number of surviving florets per branch was quite constant under different N treatments for all primary, secondary, and tertiary branches, implying that panicle size was mainly determined by the number of branches rather than the number of florets per branch. Little change was observed between OPT and FFP in differentiation, degeneration and survival of primary branches and their florets. Surviving secondary and tertiary branches and their florets were significantly more under OPT than those under FFP. The increase in surviving secondary branches under OPT resulted from both enhanced differentiation and reduced degeneration. While the increase in surviving tertiary branches under OPT was merely from enhanced differentiation though their degeneration was also dramatically increased. Among the increased differentiated florets under OPT, 32.4%-36.3 % and 61.6%-67.7 % came from secondary and tertiary branches, respectively. Among the increased surviving florets under OPT, 62.2%-65.2 % and 32.5%-37.8 % came from secondary and tertiary branches, respectively. Both secondary branches and tertiary branches were principal contributors to the increase in panicle size of OPT. To our knowledge, this is the first report on the detailed changes in panicle architecture and their involvement in panicle enlargement and yield gain under OPT.
优化施氮管理（OPT）通过减少总氮投入并在穗发育期间增加施氮量，已被证明可通过增大穗部来提高水稻产量。然而，穗部结构的变化及其变异来源尚不清楚。在2016年和2017年的早稻种植季节，对杂交水稻品种天优3618进行了优化施氮管理和农民常规施肥（FFP）处理。优化施氮管理的氮投入减少了16.7%，2016年和2017年的穗大小分别增加了8.6%和27.4%，籽粒产量分别增加了13.8%和12.3%。从穗分化到抽穗期，优化施氮管理具有更大的干物质积累和氮吸收，这促进了穗的增大。对于所有一级、二级和三级分枝，不同施氮处理下每个分枝的存活小花数相当恒定，这意味着穗大小主要由分枝数而非每个分枝的小花数决定。在一级分枝及其小花的分化、退化和存活方面，优化施氮管理和农民常规施肥之间几乎没有变化。优化施氮管理下存活的二级和三级分枝及其小花显著多于农民常规施肥。优化施氮管理下存活二级分枝的增加是分化增强和退化减少共同作用的结果。虽然优化施氮管理下存活三级分枝的增加仅仅是由于分化增强，尽管其退化也显著增加。在优化施氮管理下增加的分化小花中，分别有32.4% - 36.3%和61.6% - 67.7%来自二级和三级分枝。在优化施氮管理下增加的存活小花中，分别有62.2% - 65.2%和32.5% - 37.8%来自二级和三级分枝。二级分枝和三级分枝都是优化施氮管理下穗大小增加的主要贡献者。据我们所知，这是关于优化施氮管理下穗部结构的详细变化及其对穗增大和产量增加的影响的首次报道。
