SCREENING OF CANOLA GERMPLASM AGAINST ALBUGO CANDIDA AND ITS EPIDEMIOLOGICAL STUDIES

Abstract

White rust of crucifers is an important disease caused by Albugo candida (Pers. ex Lév.) Ktze. Twelve lines of Brassica juncea L. czern. et coss and Brassica napus L. var. oleifera were screened against white rust under field conditions. Correlation and regression studies were carried out between white rust severity and environmental factors (temperatures and relative humidity). There was a significant positive correlation of white rust severity with minimum, maximum temperature and relative humidity. Brassica juncea 44S01 and Brassica napus Sps-N7/26 were “highly resistant” lines. One degree increase in maximum and minimum temperature increased the maximum disease severity by 5.40, 5.88, 6.09, 6.87, 7.88% and 5.58, 6.04, 6.31, 7.06, 8.28% in B.juncea Sps-J10, B. juncea 44S45, B. juncea Pac-437, B. juncea Y065045 and B. juncea 7X1105-4 respectively and vice versa. Maximum disease severity 6.535, 7.119, 7.487, 8.385 and 9.390%  in B. juncea Sps-J10, B. juncea 44S45, B. juncea Pac-437, B. juncea Y065045 and B. juncea 7X1105-4 respectively was observed by one percent increase in relative humidity and vice versa. The present study revealed that one degree or one percent increase or decrease in environmental parameters change the severity of disease.