Identification of resistant sources against bud-blight disease of soybean [Glycine max (L.) Merrill]

Abstract

Bud blight of soybean [Glycine max (L.) Merrill) is caused by a strain of groundnut bud necrosis virus (GBNV). GBNV has been identified very recently as the causal organism based on serology and nucleic acid hybridization [1) and further confirmed by nucleocapsid protein gene sequence identities [2). Although its incidence in India was noticed as early as in 1970 [3), it is emerging as a major disease of soybean and its incidence has been reported from almost all major soybean growing regions in India such as Maharashtra, Rajasthan, Uttar Pradesh, Madhya Pradesh, Andhra Pradesh and Delhi [1, 3, 4) Information on sources of resistance and genetics of resistance to causal virus is lacking. Identification of sources of resistance is the first and most important step towards development of resistant varieties for effective management of the disease. Therefore, to identify sources of field resistance, observations were taken on a total number of 48 genotypes in three trials namely, Initial Varietal Trial (IVT -34 genotypes), Advanced Varietal Trial I (AVT-I 6 genotypes) and Advanced Varietal Trial II (AVT-II 8 genotypes) at IARI, New Delhi, during kharif-2001. Total number of plants and infected plants (based op visible symptoms) were counted in the central row of' each plot of IVT (3 rows of 3m each), AVT-I (8 rows of 5m each) and AVT-II (12 rows of 5m each). The percentage incidence was calculated and the data was subjected to suitable transformation before analysis (Table 1, 2 and 3)