Effect of Spacings on Rice Yield and Ragged Stunt Disease

Abstract

The study on effect of s[acomg amd mi,ber pf seed;omgs per hill on grain yield as related to damages of rice ragged stunt disease transmitted by brown planthopper Nilaparvata lugens (Stal) was conducted in both dry and wet seasons in 1981 , at the Pathumthanee Rice Research Center. RD 7 and RD 9 varieties have been reported to be susceptible to rice ragged stunt disease while RD 9 has been found to be resistant to its vector, N. Lugens complete block design. Results indicated that RD 7 and RD 9 produced higher grain yield when they were transplanted at the rate of 3 seedlings per hill with spacing of 30 x 10 cm between rows and hills, respectively. This was due to the fact that damages from the ragged stunt disease was least in this treatment.