Inter-disciplinary approach to selection in mutation breeding in local sorghums for adaptation and disease resistance

The present report of Mutational rectifications in local Sorghums involved improvement in adaptation and disease resistance. After seed treatment at 20, 30 and 40 kr the material now in the M6 generation has given promising response to the above selection. Similarly, chemical mutagens with Na Azide + 5 kr γ-radiation of seeds also gave valuable mutants now in M4 generation. More than 20 promising mutants are isolated with dwarf habit (100-125 cms), good head size, resistance to charcoal rot, good seed size and root development, more heads/unit area and yield increases (40%-100%) over the parents and much higher than the hybrids under cultivation. The mutants were also superior or equal to the parent in micronutrient uptake (Zn), protein content, nutrient uptake, light interception, photo-synthetic rate, and transfer to grain for N and P, root activities, regeneration capacity and disease resistance under artificial inoculation with better yield potential under close spacing (50 cm x 10 cm vs 75 cm x 10 cm). The multilocation test for wide adaptation in 3 locations revealed that at least 4 of the mutants have a wide range of adaptation. Biochemical studies of seed proteins by gel electrophoresis revealed distinct differences between the mutants and also the parents. Similar results were obtained for tannin content, Zn, phosphate (p32 tracer) N uptake, indicating the presence of diverse mechanisms of adaptation and yield. Differences between the mutants in tillering, regeneration capacity rooting pattern, panicle no. and size, grain size and threshing % were observed. The integrated selection for the above attributes from M3 to M6 involved both field and laboratory testing demonstrating the utility of interdisciplinary approach in mutation breeding for effective selection in problem areas with complex ecological conditions and cropping patterns. The results of these studies are discussed with emphasis on selection methodology for the multiple traits involving different disciplines, and the scope of nuclear and allied technicians, and the possible use of these mutants for basic studies on mechanisms of wide adaptation, nutrient uptake and host-pathogen relations