(30(1):1-4)Physiological and biological studies of rice sheath rot pathogen

稻葉鞘腐敗病菌AO-3自典型稻葉鞘腐敗病病斑上，而AO-1係自不稔稻褐變葉鞘分離所得。兩種菌株在五種不同培此基上之生長，AO-1在稻藁培支基上之生長最佳，而AO-3則於玉米培養基上之生長最優。在五種常見的氮化合物中，AO-1以在硝酸鉀，AO-3在硝酸鈉上之生長最好。在不同碳素源中，兩種菌株均在蔗醣上之生長最優，又最適pH範圍為5.5~7.0；典型葉鞘腐敗病菌菌株（AO-3）之生長情形一般皆比自不稔稻分離的菌株（AO-1）為佳。 二菌株對九種作物或雜草之病原性，如果經刺傷接種法則在刺傷部位呈褐巴不擴展的斑點（小麥、高梁、稗子、牛筋草、狗牙根），在無刺傷接種法則均無病徵出現。Sheath rot pathogen AO-3 was isolated from typical lesion of rice sheath rot, AO-1 was from brown tissue of sterile rice sheath. Among the five media test, rice straw agar was the best one for the growth of AO-1 and corn agar was for AO-3 while in the five nitrogen sources tests, KNO3 was the best one for the growth of AO-1 and NaNO3 was for AO-3. Favorable carbon source was sucrose and optimun pH range was 5.5-7.0 for the growth of both isolates. The growth rate of AO-3 was better than AO-1 in all media used in the study. Both isolates failed to establish the disease on 9 kinds of plants