关键词: 根倒伏, 茎倒伏, 产量灾损, 夏玉米

Abstract: 【Objective】The objective of this study was to analyze the effects of lodging on dry matter, yield components and final yield of summer maize, and further to evaluate the yield losses due to different types of lodging at different growing stages. 【Method】The field experiments were conducted during two growing seasons of summer maize with the variety of Xundan 20 from 2011 to 2012 at Zhengzhou Agro-meteorological Experiment Station. The lodging was implemented by kicking down the maize plants artificially at two growing stage, the big flare stage (B) and the grain filling stage (F). And at each stage, the lodging included four types, light lodging of roots (R1, in which the angle between the lodged stem and ground was between 30 and 60 degree), serious lodging of roots (R2, in which the angle between the lodged stem and ground was lower than 30 degree), lower node lodging of stem (SL, in which the bend position was below the third node) and upper node lodging of stem (SH, in which the bend position was above the third node). LAI, dry matter, yield and yield components were measured during experiments, and the relative reduction percentage was calculated which indicating the damage degree.【Result】The results showed that LAI was significantly decreased by lodging. The relative reduction percentage was larger in two treatments of stem lodging at the filling stage, with the value of 38.9% (FSL) and 50.7% (FSH), respectively. The accumulation of aboveground dry matter was significantly reduced after lodging (P＜0.05) in all treatment except FR1, and the reduction percentages were larger in two treatments of stem lodging at the filling stage, with the value of 34.9% (FSL) and 46.8% (FSH), respectively. Lodging also affected the partition of dry matter among leaves, stems and corncobs, with the increased partition to leaves and stems but the decreased partition to corncobs. In two treatments of stem lodging at the filling stage, the weight of leaves and stems was 9.2% (FSL) and 3.7% (FSH) higher than CK, but the weight of corncobs was 9.9% and 7.0% lower than CK. In addition, lodging made the corncobs shorter and thinner, and with longer barren ear tips. The length of corncobs in treatments with lodging at the filling stage was 3 to 4 cm shorter compared to CK. Except for the FSL treatment in 2012, the rate of barren ear tips in treatments with lodging at the filling stage were statistically and significantly higher than CK, but it was not significant with treatment with lodging at the big flare stage. And the rate of barren ear tips was the highest in FSH treatment in 2011, with the percentage of 27.4%. Lodging caused the decrease of both grains per ear and 100-grain weight. Due to the differences of experimental conditions between two years, results were slightly different. In 2011, grains per ear were significantly less than CK in all treatments, but in 2012, they were only significant in the treatments with stem lodging at filling stage. The effects of lodging on 100-grain weight were more significant in treatments with lodging at filling stage. Lodging also significantly decreased the final grain yield. According to the analysis of yield components, the yield reduction by lodging was due to the decreases in both grains per ear and 100-grain weight. And the correlation coefficients of the two components with grain yield were 0.729 and 0.842 (P＜0.01), respectively. Except for BR1, the final yields in all treatments were significantly lower than CK. For the lodging at the big flare stage, the yield loss was 13.9%, 27.9% and 27.1% in the treatments of BR2, BSL and BSH, respectively. For the lodging at the grain filling stage, the yield loss was 29.0%, 38.4%, 45.0% and 48.3%, respectively.【Conclusion】Comprehensively, compared between growing stages with the same lodging type, lodging at grain filling stage had more negative effects than that at big flare stage. While compared between lodging types at the same stage, stem lodging had more significant effects than root lodging. There was no obvious difference between treatments with lodging at high node and low node. For yield loss, it was the largest for stem lodging at grain filling stage, and the lowest for root lodging at big flare stage.

Key words: root lodging, stem lodging, yield loss, summer maize