Effect of Varying Rate of Leaf Defoliation on Maize Growth, Development and Yield Components and Yield

Pot trial was conducted at the Faculty of Agriculture, Kogi State University Anyigba, within the southern Guinea savanna agro ecological zone of Nigeria, with daily temperature range between 250C - 350C. The experiment, a Randomized Complete Block Design (RCBD) with eight treatments (defoliation at 25% above the ear, 25% under the ear, 50% above the ear, 50% under the ear, 75% above the ear, 75% under the ear, 100% defoliation and no defoliation as control) was replicated four times. Treatment was imposed at ear initiation. Growth and yield parameters collected were: number of leaves per plant, leaf area, plant height, stem girth, days to ear initiation, number of cobs/plant, days to crop maturity, cob weight, cob length, seed rows per cob, 100-seed weight as well as total cob yield/ha. All data collected were subjected to analysis of variance (ANOVA) and New Duncan Multiple Range Test (NDMRT) was used to estimate the differences among significant means at 5% level of probability. Prior to imposition of the treatment, analyzed results indicate no significant differences between number of leaves at 2, 4 and 6 WAS, as well as plant heights and stem girth at 2, 4, 6, 8 and 10 WAS. However there were significant differences between leaf areas at 4 and 6 WAS. In addition, there were significant effects of defoliation on cob length and dry cob weight with the highest cob weight obtained in 25% defoliation carried out above the ear. In addition, there were significant differences in the number of rows per cob and grain yield per ha with 0% defoliation giving the highest result while the least was in 100% defoliation. Generally, it was observed that defoliation at any rate and position influenced maize yield, notwithstanding that the treatment was imposed at cob initiation, an indication that harvest of solar radiation post cob initiation plays important role on eventual maize yield.