Impact of sodium azide on maturity, seed and tuber yields in M1 African yam bean [Sphenostylis stenocarpa (Hochst ex A. Rich) Harms] generation

Abstract

Mutation breeding has been recognized as a valuable supplement tool to conventional breeding and it has contributed significantly to crop improvement. This study therefore, evaluated the effects of sodium azide (NaN₃) on maturity, tuber and seed yields related traits of African yam bean (AYB) accessions, with the aim of creating genetic variation. Six promising AYB accessions in term of their earliness to maturity and high yield potentials from previous evaluation across agro-ecologies in Southwest Nigeria were selected for this study. Seeds of AYB were presoaked in distilled water at room temperature (25±2⁰C) for 6 hours. Then, presoaked seeds were treated with varied NaN₃ concentrations (0.02%, 0.04%, 0.06%, 0.08%) for 9 hours while control was also soaked for 9 hours in distilled water. The treated seeds were sown in the field for evaluation of M₁ generation. The results obtained revealed that genotypes, NaN₃ concentrations and their interaction exhibited highly significant differences in most of traits measured. Also, as the NaN₃ concentration increased, germination, flowering, maturity and other yield related traits decreased. However, germination inhibition increased as NaN₃ concentration increases. Hence, NaN₃ was effective in inducing earliness to flowering and maturity, but it hampers seed and tuber yields. TSS-79 accession produced highest seed yield, when treated with 0.04% concentration, hence it is regarded as good candidate for nomination for further improvement in mutation studies for increased seed yield. Therefore, NaN₃ is capable of inducing variability in AYB genotypes and can therefore be exploited for the genetic improvement of AYB in breeding programs.