tailieunhanh - Evaluation of pathogenicity of four different Alternaria brassicae isolates on three brassica coenospecies

Indian mustard (Brassica juncea) is the second most important edible oilseed crop in the country after soybean. Mustard is an important source of healthy edible oil in the northern states of the country viz., Uttar Pradesh, Rajasthan, Uttarakhand, Haryana, Punjab and Bihar. The production of edible oil in the country is lagging behind the growing demand by ever increasing population and therefore increasing its import. Preventing the loss by various biotic and abiotic stresses is one of the ways to increase the production of mustard oil. Among the various biotic stresses faced by mustard crop in the country, Alternaria blight caused by a necrotrophic fungal pathogen Alternaria brassicae is an important economic disease. To develop the disease-resistant cultivars, it is important to select the genotypes against most virulent pathogen. For this, we have studied the pathogenicity of four different isolates DEL, PNT, MRT and ND (named according to place of collection) of A. brassicae on three different Brassica coenospecies viz., B. juncea, Sinapis alba and Camelina sativa, having different degree of resistance against this pathogen. Highest pathogenicity was observed in PNT isolate of A. brassicae producing largest size lesion [ cm (±)] in B. juncea whereas, DEL isolate produced smaller size lesion [ cm (±)] at 12 days post inoculation. Highest number of secondary spots and distal infected leaves were observed with PNT [(±) and (±) respectively]. C. sativa never produced any secondary infection or distal infected leaves against any isolate upto 12 dpi. These results concluded that among the four different A. brassicae isolates, the PNT isolate was highly pathogenic followed by ND and MRT isolate. The DEL isolate was found least pathogenic in B. juncea. | Evaluation of pathogenicity of four different Alternaria brassicae isolates on three brassica coenospecies