Abstract
Phenology and leaf growth of the tropical maize hybrid Dekalb XL82 were examined as functions of photoperiod and temperatures. Data were collected from fully irrigated crops sown on three dates. The study was undertaken to obtain mathematical relationships describing phenology, and development and maintenance of leaf-area for use in crop-simulation models describing phenology, and development and maintenance of leaf-area for use in crop-simulation models describing the growth of maize in semi-arid tropical environments. The direct effect of photoperiod was on the thermal time from germination to tassel initiation, and subsequently on final leaf-number. Leaf appearance increased exponentially with thermal time, and the relationship was coincident for all sowings. The fully expanded area of each leaf was described as a function of leaf number, and the same relationship described each sowing, provided that account was taken of differences in final leaf-number across sowings. When account was taken of the leaves still expanding, the relationship between total per-plant leaf-area and leaf-number was similar across sowings. The relationship between leaf-area senescene and thermal time was significantly different among sowings, with the main difference accurring near maturity. The effects of water deficit on these relationships were also examined. Water deficit during early vegetative growth affected the rate of leaf appearance and leaf size, but not the final leaf-number nor leaf senescence. The main effect of water deficit during later growth was on leaf senescence.
Published Version
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