Estimation of LD50 and effect of sodium azide on germination and seedling parameters of different cultivars of Cajanus cajan (L.) Millspaugh

Objective The present investigation was undertaken for determination of LD50 and studying response exhibited by selected cultivars of pigeon pea for various seedling parameters. Methods Five promising cultivars of pigeon pea viz., 'Manak,' 'PAU 881,' 'Pusa 992,' 'PA 291' and 'VLA 1' were induced with different doses of sodium azide (SA). SA was diluted to different concentrations (1 mM, 2 mM, 3 mM, 4 mM and 5 mM) in 0.1 M phosphate buffer of pH 3.0. Seeds were soaked in each concentration of mutagen for 6 h followed by germinating treated seeds in towel paper. Observations regarding various parameters were collected according to International Seed Testing Association (ISTA) guidelines. Probit analysis based on seed germination percentage was done for determination of LD50. Results The results revealed that cultivars exhibited differential response for seedling parameters when induced with varying concentrations of SA. LD50 ranged between 1.60 mM and 2.69 mM SA. The cultivar 'Manak' exhibited the highest degree of tolerance against inhibitory effect of SA whereas 'VLA 1' was the most sensitive cultivar as it had the lowest LD50. Seed germination and other seedling parameters followed a general repressive trend with a related increase in concentrations of SA with quite a few exceptions. Estimates of cultivar 'Pusa 992' were not fully consistent with the repressive trend for a few seedling parameters. Conclusion The present study strengthened the fact that interaction between particular genotype and specific mutagen exclusively determines the rate of mutation and chances of obtaining viable, distinctive and favorable mutants to diversify the breeding material. The findings of the present investigation will serve as a benchmark for growers and plant breeders who intend to produce fruitful mutations to increase genetic variability in the primary gene pool of pigeon pea. Further, it is recommended to carry out respective field evaluation to screen out favorable mutants with higher crop value.

Automated summary

The study determined LD50 and seedling parameters response of pigeon pea cultivars to varying concentrations of sodium azide. Different cultivars showed differential tolerance to SA, with 'Manak' being the most tolerant and 'VLA 1' being the most sensitive. Further research is recommended to identify favorable mutants for increased crop value.