Ren Hong, Jiang Ying, Zhao Ming, Qi Hua, Li Congfeng
Institute of Crop Science, Chinese Academy of Agricultural Sciences/Key Laboratory of Crop Physiology and Ecology, Ministry of Agriculture and Rural Affairs, Beijing, China.
College of Agronomy, Shenyang Agricultural University, Shenyang, China.
Front Plant Sci. 2021 Jan 8;11:602739. doi: 10.3389/fpls.2020.602739. eCollection 2020.
Nitrogen (N) fertilizer application greatly enhances grain yield by improving dry matter accumulation and grain filling in spring maize. However, how N application rates regulate the vascular bundle structure, matter transport and grain filling of spring maize under a high planting density has been poorly understood thus far. In this study, we analyzed the relationship between grain filling, vascular bundle structure and matter transport efficiency (MTE) of spring maize in the field. Zhongdan909 (ZD909) was used as the experimental material in a 2-year field experiment from 2015 to 2016, and it was grown under different N levels (0, 150, and 300 kg N ha) applied to the grain-filling stage of plots with planting densities of 67,500 plants ha (ND) and 90,000 plants ha (HD). Nitrogen application significantly optimized the structure of the big and small vascular bundles. In particular, there was an increase in the total number of small vascular bundles in the peduncle and cob of the ear system, i.e., increases of 51.8% and 25.7%, respectively, and the proportions of small vascular bundles to the total number of vascular bundles in the peduncle and cob were significantly increased. The root bleeding sap and MTE of maize were significantly increased by N application under both ND and HD, as indicated by the significant increase in the rate of C-photosynthate allocation to grain and amount of postsilking dry matter at maturity. Moreover, N application greatly improved the mean grain-filling rate ( ) under ND and HD by 30.0% and 36.1%, respectively, and the grain-filling rate increased, leading to a distinct improvement in the grain sink at the grain-filling stage. We concluded that nitrogen application significantly optimized the vascular bundle structure of the ear system, increased the MTE and improved photosynthate distribution to the grain, ultimately enhancing the filling rate and grain yield.
氮肥施用通过改善春玉米的干物质积累和籽粒灌浆，极大地提高了籽粒产量。然而，迄今为止，在高种植密度下施氮量如何调控春玉米的维管束结构、物质转运和籽粒灌浆仍知之甚少。在本研究中，我们分析了田间春玉米籽粒灌浆、维管束结构与物质转运效率（MTE）之间的关系。以中单909（ZD909）为试验材料，于2015年至2016年进行了为期2年的田间试验，在种植密度为67500株/公顷（ND）和90000株/公顷（HD）的小区的籽粒灌浆期施加不同氮水平（0、150和300 kg N/公顷）。施氮显著优化了大小维管束的结构。特别是，穗部系统的穗轴和果穗中小维管束的总数增加，即分别增加了51.8%和25.7%，并且穗轴和果穗中小维管束占维管束总数的比例显著增加。在ND和HD条件下，施氮均显著提高了玉米的伤流液和MTE，表现为C-光合产物向籽粒分配的速率和成熟时吐丝后干物质的量显著增加。此外，施氮分别使ND和HD条件下的平均籽粒灌浆速率（ ）显著提高了30.0%和36.1%，籽粒灌浆速率增加，导致籽粒灌浆期的籽粒库明显改善。我们得出结论，施氮显著优化了穗部系统的维管束结构，提高了MTE，并改善了光合产物向籽粒的分配，最终提高了灌浆速率和籽粒产量。
