Estimation of leaf area in tropical maize

Leaf area development of six tropical maize cultivars grown in 1995 and 1996 in several tropical environments in Mexico (both favourable and moisture-and N-limited) was observed and analysed. First, the validity of a bell-shaped curve describing the area of individual leaves as a function of leaf number was investigated. When individual cultivar-environment combinations were normalized for area of the largest leaf and for total leaf number, one parameter set described all combinations. It remained difficult, however, to estimate these parameters in advance, which limits predictive applications in crop growth models. Analytical application after flowering, when parameter values can be determined, is possible. Second, a method was developed to directly estimate total leaf area when total leaf number and area of the largest leaf are known. The method makes use of the facts that the area of the largest leaf relative to total plant leaf area is constant and that this constant is linearly related to total leaf number. This study has shown that approaches previously presented by others are applicable in modified form over a wide range of environmental conditions