Abstract

In 2016, rice cultivated areas in the central region of Thailand were 4,799,114 rai, comprise of 2,164,392 rai (45.10%) for wet broadcast paddy field. Farmer highly use seeding rates for rice plantation around 28.62 kilograms rai⁻¹, resulted in high costs in seed and farm management. The RD49 rice cultivar, providing high yield and tolerance to brown planthoppers, planting in both irrigated and rainfed areas. The method for the most of efficiency. Therefore this study aims to evaluate effects of different seeding rates on yield components and grain yield of the RD49 rice cultivar. The experiment was conducted at Sanap Thuep district, Phra Nakhon Si Ayutthaya province, by using Randomized Complete Block Design (RCBD) with 4 replications. The treatments were three seeding rates; 7.5 kg rai⁻¹, 15 kg rai⁻¹ and 25 kg rai⁻¹. The results showed that tillers hill⁻¹, panicles plant⁻¹, grains panicle⁻¹, for planting rate of 7.5 kg rai⁻¹, were higher than those of the planting rate of 15 and 25 kg rai⁻¹, respectively. The grain yield at 14 percent moisture content of planting rate 7.5 (894 kg rai⁻¹) was higher than yield from planting rate 15 kg per rai (872 kg rai⁻¹) and 25 kg per rai (656 kg rai⁻¹). Harvest index of each planting rate were not statistically different. Therefore, rice cultivation using the seed rate of 7.5 kilograms rai⁻¹ is recommended that can provide good yield and reduce seed costs.