P. N. Murumkar, Ashok M. Chavan
Abstract: Economic losses in cotton due to foliar diseases in cotton have been confirmed by many workers. In intra- hirsutum hybrid H4, losses in yield up to 68 percent have been reported in chemically unprotected crop in disease endemic areas of Akola district of Maharashtra (Shivankar and Wangikar, 1992). Screening of foliar disease has been done by several workers to identify resistant donors for disease management through host plant resistance. In present study, 49 genotypes comprising 36 iso-hybrids, 10 parents and 3 commercial checks were evaluated for Alternaria leaf spot at Aurangabad. Thirty Six crosses were prepared by using cytoplasmic male sterility (CMS), genetic male sterility (GMS) and conventional methods were studied for Alternaria leaf spot (ALS) in natural field condition. After pooled analysis of two years data of PDI of Alternaria leaf spot at 120 days stage five crosses C10346B BGIIXR11, C10346G BGIIXR11, C10346A BGII XR11, C10026A BGIIXR14 & C10346B BGII XR14 found relatively resistant than commercial check Mallika BGII, Jai BGII and NHH44. Effect of G. harknessii cytoplasm for Alternaria leaf spot reaction was studied at 120 days stage of crop growth in natural condition by comparing AXR crosses and BXR crosses. It was found that presence of crosses with G. harknessii cytoplasm & normal (G. hirsutum) cytoplasm in extreme classes of resistant and susceptible establish the fact that cytoplasm had no direct influence on reaction of genotypes to Alternaria leaf spot.
Keywords: Alternaria Leaf spot, CMS, GMS, Conventional, iso-hybrids