Ecological factors affect maize growth and development, and induce stalk lodging. Studying the effects of ecological factors on the stalk lodging within dense planting maize is essential to develop field management strategies. To investigate the response of stalk lodging resistance to density and ecological site. To identify the key ecological factors affecting lodging. This study conducted field experiments in 2019–2020 at 6 sites in Southwest China, with 6 densities (3.0, 4.5, 6.0, 7.5, 9.0 and 10.5 × 10 plants hm) to determine the variation in lodging rate and stalk lodging resistance traits. The dense planting reduced stalk lodging resistance and varied among ecological sites. Plant morphology exhibited relatively high stability, with coefficients of variation (CV) of 0.01143–0.1097. Bending strength and dry matter constituents of basal internodes were more sensitive (CV: 0.1425–0.4446) compared to other traits, while the density effect was more significant. The extreme weather and stalk lodging resistance index jointly determined lodging, with lodging lowest at high stalk lodging resistance index (≥1.367) and low frequency of extreme weather events (＜14.40 %). Among the internode traits, the dry matter constituents contributed more than 55.0 % to mechanical strength. In addition, internode diameter was important for bending strength, while skin group was for rind penetration strength. Altitude or net solar radiation explained 28.70 % or 21.10 % of the mechanical strength, being the most important ecological factor. Maize stalk lodging resistance decreased with dense planting and also influenced by ecological factors, but the response of different stalk lodging resistance traits to density and ecological site. The higher altitude and net solar radiation favored higher internode mechanical strength, resulting in greater stalk lodging resistance. The lower frequency of extreme weather events and higher stalk lodging resistance index resulted in a lower lodging rate. The selection of maize hybrids with high internode plumpness, cellulose and lignin content in the basal internodes and less affected by density and ecological sites, can enhance stalk lodging resistance and its stability. The appropriate planting density should match the ecological conditions of the site.

中文翻译：

---

生态因素调节密植玉米中的茎倒伏


生态因素影响玉米生长发育，诱发玉米秆倒伏。研究生态因素对密植玉米秸秆倒伏的影响对于制定田间管理策略至关重要。探讨秸秆抗倒伏能力对密度和生态位点的响应。确定影响倒伏的关键生态因素。本研究于2019-2020年在西南地区6个站点以3.0、4.5、6.0、7.5、9.0和10.5×10株·hm 6种密度进行田间试验，测定倒伏率和茎秆抗倒伏性状的变化。密植降低了茎秆的抗倒伏能力，且不同生态位点的抗倒伏能力存在差异。植物形态表现出较高的稳定性，变异系数（CV）为0.01143-0.1097。与其他性状相比，基部节间的抗弯强度和干物质成分更敏感（CV：0.1425-0.4446），而密度效应更显着。极端天气与茎秆抗倒伏指数共同决定倒伏，茎秆抗倒伏指数高（≥1.367）、极端天气事件发生频率低（＜14.40%）时倒伏最低。节间性状中，干物质成分对机械强度的贡献率超过55.0%。此外，节间直径对于弯曲强度很重要，而皮组对于果皮穿透强度很重要。海拔高度或净太阳辐射解释了机械强度的 28.70% 或 21.10%，是最重要的生态因素。玉米秸秆抗倒伏性随密植而降低，也受生态因素的影响，但不同秸秆抗倒伏性状对密度和生态位点的响应。 较高的海拔和净太阳辐射有利于较高的节间机械强度，从而导致较高的茎秆抗倒伏能力。极端天气事件发生频率较低，茎秆抗倒伏指数较高，导致倒伏率较低。选择节间丰满度高、基部节间纤维素和木质素含量高、受密度和生态位点影响较小的玉米杂交种，可以增强秸秆的抗倒伏能力及其稳定性。适宜的种植密度应与场地的生态条件相匹配。