Lower doses of sodium azide and methyl methanesulphonate improved yield and pigment contents in vegetable cowpea [Vigna unguiculata (L.) Walp.

Abstract

Cowpea, often categorized as an orphan crop, is an essential member of the Fabaceae family and is recognised as a primary crop by Food and Agriculture organisation. It is adapted to a wide range of dry ecologies; however, its yield is low compared to other grain legumes. Considering its low yielding potential, a traditional cowpea variety Gomati VU-89 was treated with lower (0.01%) and higher (0.04%) sodium azide (SA) and methyl methanesulphonate (MMS) doses. An extensive phenotyping selection on traits such as plant height, days to flowering, branches, pods, seeds, and seed yield, resulted in the isolation of two high yielding putative mutants. Among the mutagen doses, the highest increase in mean seed yield was recorded in 0.02% SA (65.00 gm) and 0.02% MMS (65.07 gm). One-way analysis of variance and post hoc Duncan's multiple range test showed that mutagenized populations deviated significantly from the control population. Correlation analysis showed seed weight and plant height possesses a strong positive correlation with yield; therefore, these characters could be used in indirect selection for yield improvement. Hierarchical cluster analysis revealed mutagen-induced divergence by classifying five populations into four groups, each with 1–2 clusters. Principal component analysis showed that two principal components explained more than 95% of the total variation in mutagen treated populations. Seeds per pod and pod length showed maximum positive loading on PC1 in MMS (0.359) and SA (0.371) treated populations, respectively. In contrast, days to flowering revealed maximum positive loading on PC2 in MMS (0.707) and SA (0.635) treated populations. Putative mutants showed high yielding potential compared to the control plants and could be employed in future cowpea breeding programs for genetic enrichment of existing varieties.