Growth and yield of rice (Oryza sativa L.) as affected by cultivars, seeding depth and water deficits at vegetative stage

This study investigates the effects of different seeding depths and water stress on growth and yield of direct-seeded rice. The experiment was a 3x2x2 factorial in a randomized complete block design with four replications. The main factors (03) were seeding depths (0, 1 and 5 cm), water level (well watered and water stress at 30 days after seeding (DAS) and rice cultivars (Pathum Thani 1 and Suphan Buri 1). Above-ground biomass and root length density were significantly affected by rice cultivars, seeding depths and water stress. The Suphan Buri 1 had a higher above ground biomass and root length density than the Pathum Thani 1. At the first 7 days of water stress, maximum above-ground biomass was obtained at 1 cm seeding depth. But at a later stage, the highest above ground biomass was observed with a seeding depth of 5 cm at both 60 and 90 days after seeding. The greatest root length density was obtained at a seeding depth of 5 cm. Grain yield was significantly affected by seeding depths and water stress. The highest grain yield was obtained in 5 cm seeding depths compared with other low depth under water stress at vegetative stage (30 DAS). It was concluded that yield loss under water stress at vegetative stage may be compensated for by increasing seeding depth above shallow depth levels. (Résumé d'auteur