Sclerotinia rot tolerance in oilseed Brassica

摘要

Sclerotinia rot of Brassica species incited by Sclerotinia sclerotiorum (Lib) De Bary is a devastating disease and proving threat to the cultivation of Brassica species in different oilseeds Brassica growing countries of the globe. The present study was carried out at CCS Haryana Agricultural University, Hisar (India) which is situated at 29° 10'N and 75°46E'. The efforts were made to identify sources lines tolerant to Sclerotinia rot. Ninety one (43 B. juncea, 48 B. napus) assembled germplasm accessions of Australia, China and India origin were screened by soil and stem inoculation techniques at seedling and 80% blooming stage (90 DAS old plants, siliquae development), respectively, under screen house conditions, to identify sources of resistance/tolerance at seedling and siliquae development stage, since the pathogen has systematic and aerial infection at both stages by myceliogenic and carpogenic germination of sclerotia. The symptoms of disease development appeared after 5-6 days of inoculation and seedlings collapsed within 15 days after inoculation. None of the assembled oilseed Brassica germplasm lines/accessions exhibited complete resistance to Sclerotinia rot. The genotypes of B. juncea namely, JO 009, JN 031 & JN 033 of Australian origin were observed tolerant whereas, none of the Indian and Chinese lines were observed tolerant at seedling stage. In B. napus, AG Outback, Rainbow, RQ 011 and RQ 011-02M2 of Australian origin, Neelam and GSL 1 of Indian origin and YU 178 of Chinese origin were observed tolerant at seedling stage. The variation in degree of incidence may be attributed due to the pathotype and plant age chosen for this study. The genotypes observed tolerant at seedling stage doesn't hold true at siliquae formation stage and vice-versa. However, the genotype RQ 011 was observed tolerant at both seedlings as well as at siliquae formation stage. The level of tolerance also varied among the genotypes. Based upon the available level of tolerace, it is advocated that the identified genotypes could be utilized to further enhance the level of resistance/tolerance rather than as donor parents for incorporating resistance against Sclerotinia rot.