Defoliation at seedling stage enhances maize yield by reducing lodging

Lodging greatly reduces maize (Zea mays L.) grain yield and harvest efficiency. We conducted a 3-year (2018-2020) field experiment in Fengcheng city, Liaoning, China to investigate the effects of maize seedling defoliation on lodging resistance and grain yield. Two cultivars, Liangyu99 and Hongshuo, were tested without (control treatment) and with defoliation at seedling stage (V4 stage: DS treatment). Compared with the control, DS significantly (p < 0.05) decreased stalk lodging by 63.2%-77.9% and 51.0%-75.1%, contributing to the increase in grain yield by 4.94%-7.76% and 9.75%-19.6% for Liangyu99 and Hongshuo, respectively, during 2018-2020. The improvement of maize lodging resistance by seeding defoliation was mainly due to changes in plant morphology. On average, 12.0% and 21.9% declines in plant and ear heights, respectively, were observed and the number of internodes below the ear was reduced by 1-2 units for both cultivars with DS. A comparison of cultivars revealed that the increase in grain yield with defoliation was approximately twofold greater for Hongshuo than for Liangyu99. The greatest yield increase due to seedling defoliation was observed in 2018, when the yield was lowest with the nontreated control. However, in environments where lodging is less common, suppression of early vegetative growth would probably make little, if any, contribution to maize yield. These results suggest that defoliation of maize seedlings could be a profitable agronomic practice for maize grown in areas that experience frequent lodging.