Tillage, Seeding, and Nitrogen Rate Effects on Rice Density, Yield, and Yield Components of Two Rice Cultivars

Abstract

Research was conducted for 2 yr on a Crowley silt loam soil (fine, smectitic, thermic Typic Albaqualfs) near Crowley, LA to evaluate the main effects of tillage, seeding and N rate and potential interactions on rice (Oryza sativa L.) density, yield, and yield components. Two tillage systems (conventional and fall‐stale seedbed), four seeding rates (162, 323, 484, and 646 seed m−2) and four N rates (101, 134, 168, and 202 kg ha−1) were evaluated. ‘Jupiter’ and ‘Cheniere’ a medium and long grain cultivar, respectively, were evaluated in separate experiments. Conventional tillage reduced rice plant density as compared with fall‐stale seedbed tillage due to crusting following flush irrigation during seedling emergence. A tillage by N rate interaction was not observed, suggesting optimal N rates are similar for rice grown using a conventional or fall‐stale seedbed. Rough rice grain yield was optimized at 202 and 168 kg N ha−1 for Jupiter and Cheniere, respectively. Grain yields were optimized for Jupiter at 323 seed m−2, while Cheniere required a seeding rate of more than 323 seed m−2 Panicle density was found to be the single most influential yield component on rice yield and was able to explain 49 and 51% of the variation in yield for Jupiter and Cheniere, respectively. Filled grain panicle−1 was inversely related to panicle density highlighting the ability of rice to tiller as a yield compensatory measure when less than optimum rice densities exist. However, total yield compensation may not be feasible at low seeding rates.