Evaluating Hybrid-Maize Simulation Model for Grain Yield Estimation in Hybrid Seed Maize Production

Abstract

The study was carried out to determine the effect of Male Planting Date (MPD) and Female Plant Population (FPP) on the Grain Yield (GY), yield components and flowering of a three-way hybrid. The study also evaluated Hybrid-Maize simulation model for grain yield (GY) estimation in hybrid seed maize production. Seed grading of harvested three-way hybrid seed was also carried out to determine the seed grades based on the principle of length and thickness of the seed according to the Zimbabwe screen sizes. A CIMMYT three-way hybrid, with pedigree of (CML395/CML444//CML443) was used in this research. The experiment was laid out in (5 x 3) two-way factorial arrangement in a Randomized Complete Block Design (RCBD) at CIMMYT-Harare research station. Fifteen treatment combinations of five MPD as a deviation from the female planting date and three FPP replicated three times were used. The Hybrid-Maize simulation model programme was used to forecast the possible GY outcomes for the fifteen treatments of the experiment using estimated parameters and weather data for the 2006/7 season. The field experiment produced significant (P<0.005) main effects but non-significant interaction effects for grain yield, yield components and ASI. Female seed yield was affected by time of male pollen shed relative to female silking (Anthesis-Silking Interval, ASI), with highest yields associated with close synchrony (ASI= +/-3 days). ASI had a significant effect on the number of Kernels Per Ear, KPE, with the greatest KPE (318) associated with an ASI of +/-3 days. FPP effects on yield are typical for maize, showing a curvilinear response from low to high density. The optimum population density for grain yield was 5.4 plants m-2. Simulation output from the Hybrid-Maize model showed an overestimation of GY compare to the observed yield. Furthermore, the model was unable to predict yields for the low FPP of 2.7 plants m-2. This model would need to be modified for estimating seed yield of a three-way hybrid through the inclusion of male and female components. Seed grading data produced significant (P<0.005) difference for main effect FPP for medium size kernel weight but non-significant effects for the other FPP grades, MPD and interaction effects.