EFFECTS OF LODGING ON DRY-MATTER PRODUCTION, GRAIN-YIELD AND NUTRITIONAL COMPOSITION AT DIFFERENT GROWTH-STAGES IN MAIZE (ZEA-MAYS L)

To analyze the mechanism of damage to yield of maize by lodging, root lodging (RL) and stalk lodging (SL) were mechanically induced at four growth stages, and their effects on canopy architecture, dry matter and grain yield, and nutritional composition were investigated. Except for RL 15 days before silking, a decrease of dry matter and grain yield by treatment was observed. An uneven distribution of leaves in the narrow spaces of lodged canopy reduced the net assimilation rate (NAR). Increased reduction of the NAR occurred as the treatment stage advanced, more so by SL than by RL. Crop growth rate (CGR) correlated closely with the NAR. These results indicated that due to lodging, a reduction of the NAR was correspondingly the primary cause of a reduction of the CGR, and of subsequent yield reductions. Reduction of leaf area also decreased the CGR. Translocation of assimilates from foliage to ear was not inhibited by lodging. Being lowest by SL at silking, grain yield correlated with the number of grains per ear. It was concluded that lodging at silking decreased the number of grains per ear and caused the most serious damage to grain yield. All treatments caused a change in the nutritional composition of ear and foliage.