水稻恶苗病苗性状变化及对产量的影响

水稻亚苗病徒长苗有３个显病高峰，稻苗３叶期、拔节初期、破口初期，徒长苗 明显的症状隐蔽现象。太隐蔽始于秧龄１３ｄ时，高峰发生酝水稻分蘖盛期，武育粳５号与寒优１０２７分蘖盛期的症状隐蔽率分别达９２．６％，８９．７％。部分症状隐蔽病 重新转化为徒长苗，其转化高峰发生于水稻拔节初期、破口初期。未出现症状隐蔽的徒长苗及移栽１５ｄdisplay structure

CHANGE IN TRAIT OF BAKANAE DISEASE-INFECTED LEGGY RICE SEEDLINGS AND ITS INFLUENCE ON RICE YIELD

Bakanae disease-infected leggy rice seedlingsin our experiment in 1998 showed three symptom display peaks in total at three-leafseedling stage, early jointing stage and early earing stage. The leggy rice seedlingsshowed also an obvious phenomenon of symptom hiding. The symptom hiding began at the 13days age of seedlings and attained to a peak at full tillering stage when the symptomhiding rates of Wuyujing No.5 and Hanyou 1027 seedlings were 92.6% and 89.7% respectively.A part of hidden-symptom seedlings might retransform into leggy seedlings, thetransformation peaks occurred at early jointing stage and early earing stage. The leggyseedlings which did not show symptom hiding and which showed symptom hiding 15 days aftertransplant died all successively before early earing. A part of leggy seedlings whichentered into symptom hiding state within 15 days could form ears. Opportunely applyingfertilizer, especially applying supplementary organic fertilizer, will increase obviouslythe ear formation rate of diseased plants and decrease the yield loss.