Effects of salinity on grain yield and yield components of rice at different seeding densities

One possible management option for growers in dealing with decreases in rice (Oryza sativa L.) production caused by salinity is to compensate yield reduction by increasing seeding density. Our objectives were to investigate the effects of salinity and seeding density on grain yield and yield components, and analyze the relationships of the yield components to final grain yields at different seeding densities under salinity. Plants were grown in the greenhouse in sand irrigated with nutrient solutions. The treatments included seeding densities of 400, 600, and 720 seeds m(-2) and salt levels of 1.0, 3.9, and 6.5 dS m(-1). Salinity effects were highly significant on grain yield, plant stand, seed weight per plant, seed weight per panicle, and spikelets per panicle, but not significant on panicle density, kernel weight, and shoot weight per plant at seeding densities tested. Grain yield was not significantly increased with an increase of seeding density, Plant stand and panicle density were significantly increased, while seed weight per plant, fertility, and harvest index were significantly decreased with increases of seeding densities. The density-dependent seed weight per plant under salinity was explained by the competition within and among plants at high-density populations affected by salinity. Seed weight per panicle accounted for 62% of total variation and contributed more than panicle density to the grain yield under salinity. It was concluded that yield loss under moderate salinities may not be compensated for by increasing seeding density above normal density levels.