Sanjeev Kumar, Archana Joshi Saha and Sapalika Dogra
GNG 1958 is a popular desi chickpea variety released for commercial cultivation in the North west plain zone (NWPZ) of India though the All India Coordinated Research Project (AICRP) on chickpea. Mutation breeding is an important tool not only to enhance genetic variability but also for specific trait improvement in elite varieties. However, the effect of a mutagen, either physical or chemical is dependent not only on the type of mutagen but also on the genotype of the plant material. Therefore, the present study was conducted to determine the effect of radio sensitivity (gamma rays) and chemical mutagenicity (ems) on biological traits of cultivar 1958 and the lethal dose (LD50) and growth reduction (GR50) doses for creation of genetic variability in this variety. Seeds of GNG 1958 were exposed to variable doses of gamma irradiation (0, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, and 700 Gy) and (ems) concentrations (0.0, 0.1,0.2, 0.3, 0.4, 0.5,0.6, 0.7, 0.8, 0.9 and 1.0%). The effect of mutagens on biological parameters like germination (%), shoot length(cm), root length (cm), shoot fresh weight (g), shoot dry weight (g), root fresh weight (g), root dry weight (g), stem diameter (mm), leaf length (cm), and leaf width (cm) were studied under controlled conditions in the M1 generation. The growth pattern correlated inversely with the gamma-irradiation doses or EMS concentrations and appeared to be inhibitory at higher doses. In contrast, low doses of gamma rays and EMS concentrations initially stimulated certain growth and development of traits. Root length showed a positive and significant correlation with all the biological parameters except stem diameter whereas stem diameter showed a negative significant correlation with all the biological parameters except leaf width and shoot fresh weight and positive with root fresh weight in case of gamma irradiated doses. The diameter of the stem showed a negative significant correlation with leaf length, shoot dry weight and root dry weight. LD50 dose is an important to understand the sensitivity of genotype GNG1958 to the critical doses of mutagens creating 50 percent mortality or lethality. It was established that GNG1958 for germination by using probit analyses of germination data the lethal dose (LD50) was determined as 468.60 Gy with gamma rays and 0.56% with ethyl methane sulphonate while seedling growth. In M2 generation of chickpea, 129 chlorophyll mutants were identified viz., Albina-23, Chlorina-58, Xantha-30 and Virids-18 out of which 47 chlorophyll mutants were observed under 350 Gy (LD50) and 82 chlorophyll mutants in 300 Gy (slightly
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