포장조건하에서 수잉기와 출수기에 벼멸구를 인위적으로 가해시킨 후 출수후 고사시기별로 수량수율을 조사하여 다음과 같은 결과를 얻었다. 1. 출수후 23일경에 고사된 벼는 무접종구에 비하여 등숙율은 $32.2~37.5\%$ 현미천립중은$ 3.2~3.5g$ 감소되었다. 2. 고사시기가 같아도 수잉기부터 가해구는 출수기부터 가해구보다 등숙율 현미천립중, 현미수량이 낮았다. 3. 고사된 벼의 감수율은 무접종에 비하여 고사시기에 따라 $24~62\%$였으며 출수후 고사일수(X)와 수량(Y)간에는 다음과 같은 관계가 있었다. o 수잉기이후가해 : $hat{Y}=10.145X-16.374(r=0.9726^{**})$ o 출수기이후가해 : $hat{Y}=9.792X+26.936(r=0.8850^{**})$.
The present work was designed to study the yield loss on rice at different appearance days of hopperburn caused by the brown planthopper(BPH), Nilaparvata lugens Stal, when rice plants were infested with BPH on booting and heading stages. Dead plants were colleted from 23 days after heading stage with intervals of 5 days. Yield losses by the initation of BPH infestation was greater at tooting than at heading stage. Compared to the uninfested plot, there was a reduction in 1,000 grain weight and filled grain percentage at both stages. Positive relationship was observed between rice yield(Y) and the number of days from heading to the appearance of the hopper-burn. Regression equations calculated were; for BPH feeding from booting $hat{Y}(g)=10.145X-16.374(r=0.9726^{**})$, and for BPH feeding from heading $hat{Y}(g)=9.792X+26.936(r=0.8850^{**})$.
