Rice seeding and nitrogen rate effects on yield and yield components of two rice cultivars
Field research was conducted for 2 yr to investigate the relationship between rice (Oryza sativa L.) seeding rate and preflood nitrogen (N) rate utilizing long-grain rice cultivars planted into clay and silt loam soils. Rice cultivars included ‘Cheniere’ and ‘Wells’ seeded at 162, 323, and 646 seeds m–2. Nitrogen was applied before flooding at 67, 134, and 202 kg ha–1. No response to soil texture and no interaction between seeding rate and N rate were detected for the parameters examined. The lowest applied N rate had lower yield than the other two N rates. Rough rice yields were 7564 for 67 kg N ha–1, 8520 for 134 kg N ha–1, and 9000 for 202 kg N ha–1 averaged over all cultivars, seeding rates, and soil textures. Similarly, when head rice yield was pooled across soil texture and seeding rate, head rice yield of Cheniere was independent of N rate, but head rice yield of Wells increased when the N rate was increased from 67 to 202 kg ha–1. Panicle density responded to N rate similar to rough rice yield. Panicle density increased with seeding rate up to 418 panicles m–2 at a seeding rate of 646 seeds m–2. Filled grain panicle–1 was highest at a seeding rate of 162 seeds m–2. Cheniere produced more filled grain panicle–1 while Wells had a higher 1000-grain weight. Grain yield and yield components of Cheniere and Wells respond to seeding rates and N rates independently when planted into clay or silt loam soils.