Reaction of some Soybean Advanced Lines to Charcoal Rot Disease,



In order to determine the tolerant cultivars to charcoal rot disease,caused by Macrophomina phaseolina,121 soybean lines were evaluated in field conditions during 2001 and 2002. Initial densities of the fungal inoculum was 35 microsclerotia per gram of soil. The experiment was carried out in a simple lattice square design with 121 plots in two replications. In each plot one soybean line was planted on three rows (5m long). Distance between rows was 50 cm and between plants 10 cm. Infected plants were differentiated from healthy ones, based on the level of colonization and presence of microsclerotia on the lower parts of stems and roots. The results of combined analysis of variance showed significant differences between soybean lines in reaction to the disease. Lines exhibited reactions from moderately resistance to high susceptibility (up to 100% infection). Generally,the late maturity groups of soybean were more tolerant to the disease. Lines B.P-692, J.K-695 and K.S-69035 showed the highest tolerance to charcoal rot. Based on the results in this study and the qualitative and quantitative agronomy characteristics, two lines J.K-695 and B.P-692 were selected as the suitable cultivars and introduced as Sari and Telar for cultivation in Mazandaran region.