Growth and assimilates partitioning in rice cultivars difering in grain yield potencial

The growth, assimilate partitioning and grain yield in BRS Pelota (high yield) and BRS Firmeza (low yield) rice cultivars were evaluated. The experiment was conducted in greenhouse (Department of Botany, Federal University of Pelotas) with complete randomized design composed by two cultivars, nine plant sampling times and four replicates. BRS Pelota rice cultivar exhibited higher accumulation of total dry matter (Wt), mainly at the end of life cicle, as well as higher leaf area (Af). The dry matter allocated toward culm + sheath and panicles was higher in BRS Pelota. However, the Wt percentage accumulated in panicles at 125 DAE was the same between cultivars. In BRS Firmeza the increase in Wt in the roots may had influenced photoassimilates partitioning toward grains, and also contributed to delay of in plant senescence. Grain yield was higher in BRS Pelota than in BRS Firmeza (17.4 versus 11.8 g vaso), and also panicle number was three times greater in relation to BRS Firmeza. The yield component which exhibited higher relevance for productivity was the panicle number. The higher grain yield of BRS Pelota could be related to higher leaf area and leaf area duration, which allows the provision of elevated quantity of photoassimilates during longer period time.

Dry matter; growing analysis; leaf area; BRS Firmeza; BRS Pelota