Graig J. Pearson, Said Masduki, Jody Moenandir
Soybean (Glycine max (L.) Merr.) cultivars 29 (local origin) and Orba (national origin) were grown at four populations in two experiments during the dry season in East Java (8° S latitude). In the second experiment, a treatment of turning the canopy at flowering to admit more light to the pods and adjacent leaves was imposed. In both experiments, grain yields of the two cultivars were the same at the lowest population, which approximates that used by farmers. Cv. Orba showed a strong response in grain yield to increased population in both experiments, while cv. 29 showed no response in experiment 1 and only a weak response in experiment 2. Turning the canopy at flowering had no effect on cv. Orba, but improved the response of cv. 29 to a population/yield curve similar to that of cv. Orba. The lack of responsiveness of unturned cv. 29 was attributed to excessive leaf area, low dry weight increment per unit area of leaf and a strong effect of increased population on rate of leaf senescence. In cv. Orba, vegetative and seed dry weight increments with population increase were highly correlated with leaf area index. Thus seed yield response to population was governed in cv. 29 by leaf area efficiency and in cv. Orba by total leaf area. © 1980.
Departemen Agronomi, Universitas Brawijaya, Malang, Jawa Timur Indonesia
