Responses of soybeans (Glycine max (L.) Merrill) associated with variable plant density stress applied at different phenological stages: Plasticity or elasticity?

摘要: The study evaluated developmental responses associated with plant population density stress applied at different phenological phases and effects on grain yield in determinate indeterminate soybean (Glycine max L.). A split-split plot design four replications, variety (main plot), (sub plot) thinning time (sub-subplot) was adopted. Two genotypes (Lukanga SC Semeki) an type (Mwembeshi) were used. Plant imposed by planting supra optimal densities (700, 600 500 K plants ha-1) (K representing 1000) removed to the recommended (400 stages. had little effect yield. Thinning influenced root shoot ratio, number of grains per pod, harvest Index (HI). Lukanga highest (2.43 tons ha-1), followed Mwembeshi (1.95 lastly Semeki (1.17 ha-1). exhibited reproductive plasticity, while showed vegetative plasticity. suggested non-plastic or ‘elastic’ response. lack exemplified constant suggests that maintaining low seed rates is more economical given high cost seed.   Key words: Partitioning, determinate, indeterminate,