Induced Mutation Studies For Crop Improvement In Cowpea (Vigna Unguiculata (L.) Walp.)

ABSTRACT

Elite cowpea varieties IT84E-124 and Vita 7 of the International Institute for Tropical Agriculture, Ibadan, were exposed to varying doses of chemical and physical mutagens. Optimum doses of 10mm EMS for 6 hours and 0.1mM and 1.0mm NaN, for 2 hours, determined from seedling growth tests, and 100R and 200R gamma radiation were applied to seed samples of cach genotype. A total of 2000 seeds from each cultivar/treatment were planted. The suitability and efficacy of the treatment regimes were expressed in the germination percentages and the broad spectrum of morphological, physiological and biochemical changes observed in the two cultivars. The 1.0mm NaN, for 2 hours treatment was more adequate for induction of mutation than the other treatment regimes, and Vita 7 was found more amenable to induced mutation breeding. Vita 7 produced more lines with beneficial changes in their agronomic features while the 1.0mm NaN, treatment induced higher increases in yield parameters of the two cultivars.

These would lead to increased yield per hectare. The IT84E-124 mutant progeny lines with aphid and bruchid resistance qualities will reduce yield loss due to these insect pests in the field and during storage without detrimental effect on the environment. The change in the seed coat pattern might be responsible for the resistance in the bruchid resistant line. Nutritional evaluation and assessment of yield attributing traits of selected lines indicated the production of mutant lines without loss of quality while the SDS-PAGE and IEF of seed storage protein confirmed induced molecular variation and distinctness of the lines.