Partitioning of photosynthates between panicle and vegetative organs of rice under different planting densities

Abstract

When the supply of photosynthates is reduced, various organs compete for photosynthates during the young-panicle development stages. Under such conditions, panicle growth is more strongly impaired in a tall than in a short rice variety because the culm of the tall variety has a greater sink size than the panicle. In the tall variety, the leaf sheath has a larger sink size than the culm at a low plant density but its competitive ability is weaker at a high plant density. In the short variety, the relative sink size of culm and leaf sheath remain about the same. Tillers and roots act as sinks for photosynthates produced by the main shoot but they are weak competitors. In a tall variety a larger amount of the photosynthates assimilated during panicle development is respired than in a short variety, particularly at a high plant density.