Abstract

The effects of potassium (K) application rates on population build up of rice stem borers and rice yield were evaluated using cultivar “Shua-92”. The treatments were consisted of K applications at 40, 50 and 60 kg/ha at the top dressing, andno K fertilizer application along with normal doses of nitrogen and phosphorous.The results showed that compared with the untreated control, K fertilizer significantly reduced the rate of rice borers’ infestation and increased paddy yield. The treatments 50 and 60 kg K significantly reduced the incidence of pest and increased the grain yield of rice, but none significantly followed by application at 40 kg compared to control treatment. This assures that at low level of K application, biomass of rice plants were significantly less than the plants grown in the higher levels, but, further increase in the amount of K from 50 to 60 kg/ha did not significantly increase the pest growth and biomass of rice plants. Based on observations, it is possible to make sure that by considering cost benefit ratio application of K by adopting the rate of 50 kg/ha might be the most effective strategy in inhibiting rice pest’s incidence. The results suggest that application of K fertilizer could be useful in the recovery of plants damage when attacked by larvae of borers which can be safely and successfully managed to contribute larger volume of yield and reduce the environmental pollution.

Key words: Plant nutrition, K fertilizer, herbivore, insect pests, rice, Oryza sativa.