Genetic divergence and selection indices among the micromutant lines in blackgram [Vigna mungo (L.) Hepper]

Forty five micromutant lines of blackgram variety PU-30, developed by single and combination treatments with Gamma-rays, ethyl methane sulphonate (EMS), N-methyl-N-nitroso guanidine (NG) and maleic hydrazide (MH) were evaluated for yield and component traits. The mutant lines showed significant differences in all 9 traits indicating that the different mutagenic treatments were effective in inducing changes in all the quantitative characters, though magnitude, direction and frequency of changes varied with treatments. Genetic divergence among the mutants and the parent was estimated by D² analysis.100-seed weight, plant height and pod length had high contribution to genetic divergence indicating induction of more micromutations in these traits. The genetic diversity D² estimates among the 45 mutant lines and the parent were significant indicating the effectiveness of mutagenic treatments in isolation of mutant lines with diverse changes in multivariate traits from the parent. Using Tocher’s method the mutants grouped in to 11 diverse genetic clusters. 31 of the 45 mutant lines grouped into 10 different clusters away from the parent. These lines not only exhibited genetic diversity from the parent but also among themselves. The mutant lines derived from the same mutagenic treatment often grouped into different clusters indicating that there was no mutagen specific trend in clustering. On the basis of D² values and character complementation, hybridization of mutant line PM 3-3 with PN 3-2 or PGN 2-2 is expected to produce promising and desirable segregants in subsequent generations. The use of index selection on multiple traits including yield proved to be an effective and efficient method for selection of high yielding productive mutant lines such as PE2-3, PGN 2-3, PGN 2-2, PGM 2-2, PG2-1 and PG 3-2. These productive mutants showed changes in some growth and productivity traits from the parent variety and had 38.5 to 28.7 % yield superiority over parent. Three of these six mutants were derived from combined treatments and other three from single treatment with Gamma-rays or EMS.