Mutagenic effectiveness and efficiency of gamma rays and combinations with EMS in the induction of macro mutations in blackgram (Vigna mungo (L.) Hepper)

Abstract

Blackgram, an important pulse crop of India and other Asian countries, is a rich source of protein. Genetic improvement in this crop is generally slow-paced due to the lack of wide genetic variability available for selection. To create variability for important morphological traits and yield, induced mutagenesis was attempted in a popular blackgram cultivar CO 6 using gamma rays (γ rays-60Co) and a combination of ethyl methanesulphonate (EMS) and gamma rays. In M1 generation, the mutagenic treatments of 200 Gy γ rays and 200 Gy + 20 mM EMS showed a high percentage of viable and chlorophyll mutants. However, in M2 generation, 400 Gy + 20 mM EMS generated a higher proportion of viable mutations. A broad spectrum of viable macro mutants namely variation in growth habit, duration, size of leaf and pod, nature of pod and seed, seed yield and protruded stigma mutant were observed. The combination treatments exhibited a maximum frequency of viable macro mutations. Among viable macro mutations, the growth habit mutants recorded maximum frequency, followed by leaf mutants and pod mutants. The protruded stigma mutant was isolated at the higher dose of 400 Gy of γ rays. Studies on palynological traits among fertile and sterile plants using Scanning Electron Microscopy (SEM) revealed variations in pollen and anther length and shape among the mutants. The pollen lumina and muri shape in the fertile plant were observed as polygonal and narrow straight, whereas it was collapsed in the sterile plant. The inheritance pattern for most of the viable macro mutants was true-breeding which was further confirmed in the M3 generation. These viable mutants could be used for the blackgram improvement program.