Abstract Increasing the planting density (PD) of maize (Zea mays L.) crops is the most efficient method for enhancing maize grain yield, but supra-optimum PD leads to an increase in lodged maize, which alters the maize canopy structure. In this study, N, N-Diethyl-2-hexanoyl oxygen radicals-ethyl amine (2-ethyl chloride) phosphonic acid salt (DHEAP, a single compound), a novel plant growth regulator, was sprayed at the seven-expanded-leaf stage under two different PDs (75,000, and 90,000 plants ha-1) using two maize hybrids, ZD958 (lodging-resistance) and XY335 (lodging-susceptible), to reduce maize lodging rates and improve the maize canopy structure under high PD. After DHEAP treatment, the maize lodging rate of ZD958 and XY335 decreased by 70.87% and 75.22%, respectively, through a change in the morphological structure (i.e., reduced plant and ear heights and increased mean tilt angle) and an improvement in the basal internode quality (i.e., increased diameter, dry weight per unit length, crushing strength, cellulose content, lignin content, and vascular area, and reduced length). In addition, DHEAP treatment significantly reduced gibberellin (GA3) contents in maize basal internodes. Moreover, the increase in the mean tilt angle (MTA) above the maize ear leaf after DHEAP treatment improved the light penetration in the middle leaf strata, which increased the chlorophyll content (SPAD), net photosynthetic rate (Pn), and Rubisco enzyme activities. Finally, DHEAP treatment increased the grain yield of ZD958 and XY335 under 90,000 PD by 22.28% and 43.14%, respectively. Thus, it was concluded that the spraying of DHEAP effectively reduced maize lodging rates and improved the photosynthetic performance of the maize ear leaf, which increased maize grain yield under high PDs.

中文翻译：

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一种新型植物生长调节剂通过减少茎秆倒伏和促进株型紧凑来提高高密度玉米作物的产量

摘要 增加玉米（Zea mays L.）作物的种植密度（PD）是提高玉米产量最有效的方法，但超优PD会导致玉米倒伏增加，从而改变玉米冠层结构。本研究将新型植物生长调节剂N,N-二乙基-2-己酰基氧自由基-乙胺（2-乙基氯）膦酸盐（DHEAP，单一化合物）喷洒在七叶使用两种玉米杂交种 ZD958（抗倒伏）和 XY335（抗倒伏）在两种不同的 PD（75,000 和 90,000 株植物 ha-1）下分期，以降低玉米倒伏率并改善高 PD 下的玉米冠层结构。经过 DHEAP 处理后，ZD958 和 XY335 的玉米倒伏率分别下降了 70.87% 和 75.22%，这是通过改变形态结构（即，降低植株和穗高以及增加平均倾斜角）和提高基础节间质量（即增加直径、每单位长度的干重、抗压强度、纤维素含量、木质素含量和维管面积，以及减少的长度）。此外，DHEAP 处理显着降低了玉米基部节间的赤霉素 (GA3) 含量。此外，DHEAP处理后玉米穗叶上方平均倾斜角（MTA）的增加改善了中间叶层的透光率，从而增加了叶绿素含量（SPAD）、净光合速率（Pn）和Rubisco酶活性. 最后，DHEAP 处理使 ZD958 和 XY335 在 90,000 PD 下的籽粒产量分别提高了 22.28% 和 43.14%。因此，