百葉枯病 發病 常習地에서 벼 品種間 抵抗性의 差異

Varietal response to bacterial blight of rice in field condition

This study was conducted to get necessary information to develop new resistant cultivars for bacterial blight. The disease index by natural infection of bacterial blight for fifty seven cultivars (Japonica 39, Tongil 18) was investigated in frequently flooding rice field at Haenam, Chonnam during the period 1985 to 1989. Ninety one isolates collected from natural infection field were tested their virulence to five differential rice varieties. The distribution ratio of K₁, K₂, K₃ and K₄ races was 28.6, 27.5, 38.5 and 5.5%, respectively. But K₄ race was not isolated from 1987 to 1989. On the other hand, K₁, K₂ and K₃ races showed nearly similar distribution ratio in 1989. The disease incidence of cultivars tested trended to decrease year by year. Among the cultivars possessing true resistance, the degree of natural infection of japonica group differed from that of tongil groups. This suggests that resistant genes of japonica cultivars differ from those of tongil cultivars. Yeongsanbyeo, Gehwabyeo, Seomjinbyeo and Daecheongbyeo(Japonica) ; and Baegyangbyeo, Taebaegbyeo, Samgangbyeo, Seogwangbyeo and Baegunchalbyeo(Tongil) showed resistant reaction in natural infection field.