Abstract

This study was conducted to determine the effects of host plant resistance in early, medium and late sown varieties of rice [2 non aromatic IR8 (P) and Sharshar, and 2 aromatic Basmati-370 (P) and Mehak] due to the incidence of rice stem borers. Treatments comprised the crop sown on 3 different dates at the fortnightly intervals starting from the last week of June till the end of July to note the rate of stem borer’s infestation. The data on the incidences of insect pests and yield performances of ricevarieties were studied. Rice yellow stem borer Scirpophaga incertulas (Walker)  (Lepidoptera: Pyralidae), was the most important insect pest of rice, attacking all stages of the crop causing substantial losses in early, medium and late-sown crops, and degree of stem borer infestation depended upon the planting time. The pest incidence was the least on early sown crop as compared to medium and late sown crops. Similarly, the highest yield was obtained in early sown crop, and the crop sown after this date showed drastic reductions in yield. Among different varieties tested, Sharshar showed best results in holding least pest infestation and increased grain yield approached by, IR8 (P), Mehakand Basmati-370 (P). Hence, use of tolerant rice varieties and their early sowing under agro climatic conditions of this region is recommended to protect the crop from borer’s invasion.

 Key words: Rice, yellow stem borer, resistance, planting time, Scirpophaga, Oryza sativa.