Estimation of Leaf Area in Tropical Maize

Abstract

Leaf area development at regular time intervals during the growing season is estimated by many crop growth models and is needed for competition studies. In plant breeding programs, observation is generally restricted to a single leaf area estimate or assessment of the plant type. Two procedures that build on earlier studies are presented to estimate total plant leaf area of maize (Zea mays L.). Leaf area development of six tropical maize cultivars grown in 1995 and 1996 in several tropical environments in Mexico (both favorable and moisture‐ and N‐limited) was observed and analyzed. 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.