Leaf area Index and yield of upland rice. II. Manifestation through yield components

Abstract

- The relationship between leaf area index (LAI) and yield, through its components, was studied in the upland rice cultivar, IAC 47, in two field experiments with different planting dates. Rains were abundant and well distributed during the reproductive stage of the first experiment (EXP I), whereas were scarce for the second one (EXP II), resulting in water stress to the plants. In order to achieve variation in LAI, five defoliation levels (O, 25, 50, 75 and 100%) were performed at the stage of spikelet differentiation. Before cutting, LAI was 6,5 for EXP I, and 5,5 for EXP II. An additional treatment was tested in EXP II, in which 50% of the leaf area was removed through detillering. Covariance analysis showed that LAI effect on yield was exerted through spikelet number in EXP I, and through spikelet fertility in EXP II. Comparison of the detillering treatment with the standard 50% defoliation showed that the number of tillers can be increased without decrease in drought resistance if leaf area per tiller is reduced