在日本,从1927年起开展了系统的水稻育种工作。1935年育成农林6号,1936年育成农林8号。在当时,这两个品种米质好、产量高,是日本西部长时期内主要的栽培品种。农林6号高度抗穗颈稻瘟,但不抗叶稻瘟。另一方面,农林8号抗叶稻瘟,但不抗穗颈稻瘟。为了培育既抗叶稻瘟又抗穗颈稻瘟的品种,1935年在国立农事试验场把农林 In Japan, systematic rice breeding has been carried out since 1927. In 1935 bred agriculture and forestry on the 6th, 1936 bred into agriculture and forestry on the 8th. At the time, these two cultivars were good in quality and high in yield and were the main cultivars in western Japan for a long period of time. Agriculture and forestry on the 6th highly resistant panicle blast, but not resistant to rice blast. On the other hand, agricultural and forestry 8 leaf blast resistant, but not resistant panicle blast. In order to cultivate both the resistance to rice blast and panicle rice blast varieties, in 1935 in the National Agricultural Experimental Station of Agriculture and Forestry