Abstract
Groundnut (Arachis hypogaea L.), produced in the traditional small-scale rainfed sector of Western Sudan, accounts for 80% of the total annual groundnut acreage, producing 70% of the total production. Low productivity of groundnut is a characteristic feature in North Kordofan State, which is characterized as the most vulnerable state to the impact of climate change. Terminal drought stress resulting from reduction in rainfall amount and distribution at the end of the season is the most deleterious drought period, as it coincides with groundnut pod filling and maturation periods. High and stable yields under subsistence farming conditions in North Kordofan State could be realized only by using adapted high-yielding, drought-tolerant genotypes. Mutation induction by gamma-rays of 200 and 300 Gy was utilized to irradiate 500 dry seeds of the Spanish-type groundnut genotypes, Barberton, Sodari, ICGV 89104, ICGV 86743, ICGV 86744 and ICG 221, aiming at increasing the chances of obtaining genotypes with the desired drought-tolerant traits. Mutants were selected from the M3 plants using visual morphological traits. Groundnut mutants at the M4 and M5 generations, advanced by single seed descent, were evaluated for end-of-season drought tolerance. A terminal drought period of 25 days was imposed after 60 days from planting, using a rainout shelter. Mutants that survived 25 days of terminal drought stress were further evaluated for agronomic performance under rainfed field conditions. The groundnut mutant, Barberton-b-30-3-B, produced 1024 kg/ha, a significantly higher mean pod yield over 12 seasons compared with 926 kg/ha for 'Gubeish', the widely grown released check cultivar, showing overall yield advantage of 11%. Under 5 years of participatory research, Barberton-b-30-3-B was ranked the best with yield increment of 21% over 'Gubeish' under the mother trials. The GGE biplot analysis for 12 and five seasons, respectively, showed that Barberton-b-30-3-B was stable and produced a good yield in both high and low rainfall situations. Hence, Barberton-b-30-3-B was found to be a suitable mutant for sustainable profitable yields in the marginal dry lands of North Kordofan State and was officially released as 'Tafra-1' by the National Variety Release Committee during its second meeting of April 2018.