Gamma rays induced moisture stress tolerant long root mutant in mungbean (Vigna radiata L. Wilczek)

The mutation breeding programme was undertaken to improve the root characters of variety Samrat in mungbean. It is high yielding and MYMV resistant variety but its shallow root system limits the grain yield under moisture stress. Seeds of variety Samrat were irradiated with 450 Gy gamma rays. One long root mutant (LRM) having root length up to 71cm as compared to average 19.5 cm of Samrat was identified and isolated in M2 generation. LRM was tested in laboratory using various concentrations of polyethylene glycol and also in the field under simulated water stress condition. With increase in concentration of PEG, water uptake, germination, root and shoot length significantly reduced in both LRM and Samrat. The LRM showed significantly greater water uptake, root and shoot length as compared to control Samrat. In the field experiment, LRM recorded better root length along with yield and yield contributing characters as compared to Samrat. The results indicated that a strong root system of LRM will help the genotype to draw comparatively more water to survive and reproduce normally under drought.