Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: February 1, 1996
Publication Date: N/A
Technical Abstract: Field experiments were conducted to evaluate dry matter (DM) accumulation and partitioning during the growing season in rice. Three high yielding rice cultivars, Rosemont, Gulfmont and Teqing, were evaluated at three plant densities. Sampling frequency was twice a week prior to panicle differentiation, and then every one or two weeks thereafter depending on the treatment. Rice plants were removed from the soil to a depth of 40 cm to collect all roots. Samples were washed and divided into 4 groups of tillers depending on their age. Tillers in each group were separated into root, stem, leaf blade, panicle vegetative component, and grain structures. DM partitioning among tiller groups depends on a cultivars tillering ability and plant density. The higher the tillering ability and lower the plant density, the greater the mass and grain yield partitioned to the subtiller groups. However, total DM per unit area at harvest was very similar for all densities. This indicated that compensation or competition among tiller groups provides considerable yield stability. DM partitioning to the different plant parts was similar for each tiller group and cultivar. Accumulation of vegetative DM in both years for the 3 cultivars significantly increased before heading. After heading, root mass reached a plateau, while leaf and stem mass decreased due to tissue death and carbohydrate and nitrogen remobilization. DM loss from stem tissues was greater for the main tillers than in the subtillers. The amount of mass loss increased with later maturity. This stem mass loss suggested remobilization of stored nonstructural carbohydrates to grain, which is one of the major factors accounting for main crop yield difference between treatments and years.