Studies on the Physiologic Races of Piricularia Oryzae Cav. (II)

Abstract

A total of 354 cultures of P. oryzae isolated from 95 varieties or selections of rice grown in five localities of Taiwan were grouped into 6 distinct cultural types according to their cultural characteristics on yeast-starch agar. Using 16 rice varieties as differentials, these isolates were identified as to compose 19 physiologic races which could further be conveniently distinguished into seven race groups on the basis of their ability to attack the differentials. The distribution of the major races in the five areas is as follows: Ilan, Races 13 and 17; Tunshu, Races 9, 10, 12 and 13; Chiayi, races 12 and 13; Pingtung, races 10, 13, 14 and 17; Taitung, races 12 and 17. Of the 7 groups, group P could be considered as the most prevalent and widely spread. 1. 從1959年起，自全省稻熱病測定試驗病圃（宜蘭、東勢、嘉義、屏東、臺東等地）及臺北、桃園、新竹、臺中、臺南、高雄等地區採集稻熱病病害標本。經人工純系單胞分離後，在酵母培養基上鑒別其培養型，並於溫室內舉行人工接種在十六鑒別稻品種上，以測定各菌株之感病反應。 2. 純系分離之稻熱病病原菌，在酵母培養基上，可分為6種培養型，以A , B , C , D , E 及 F 等表之。C , D , E 三型常具強之病原性； A , B 兩型之病原性較弱； F 型之病原性不定。 3. 354個純系分離之稻熱病病原菌，接種於鑒別稻種上，得到19種不同之生理小種，以1 , 2 , 3~19 等表示之。並以品種間感病反應之差異，可組成為7個小種羣。 4. 19生理小種中，1960年發現13小種；1961年12小種；1962年l7小種。宜蘭臺北區共15種生理小種，以13及17最多；臺中東勢區共14種生理小種，以9 , 10及13最多；嘉義地區共13種生理小種，以12及13最多；屏東地區共17種生理小種，以10 , 13, 14及17最多；臺東地區共18種生理小種，以12及17最多。