The influence of varying gamma irradiation doses on the growth and yield of selected cowpea (Vigna unguiculata Walp) genotypes.

Abstract

Cowpea is an annual legume which is commonly referred to as southern pea or lubia it is one of the vital nourishment legumes and a valuable part of the old harvesting schemes in the semi-arid tropics. A field study was conducted at Omahenene Research Station, Northern Namibia to examine the influence of varying gamma irradiation doses on the growth and yield of cowpea (V. unguiculata L. Walp) genotypes. The experiment was done under rain fed conditions from January to April 2015. The experiment was conducted with two cowpea genotypes (Bira and Shindimba) treated with varying gamma irradiation doses of 200. 450. 600 and 0 Gy which served as a control. The data analysis was done using GenStat version 14. Data on pod length, seed yield and dry biomass of cowpea was collected. The outcomes demonstrated that increasing varying gamma irradiation doses significantly (P<0.05) improves the growth and yield of cowpea genotypes. Pod length, dry biomass and seed yield started to increase at 0 Gy and the highest pod length, dry biomass and seed yield was observed at 450 Gy in Bira and at 200 Gy in Shindimba. While 600 Gy resulted in a decreased pod length, dry biomass as well as seed yield in both cowpea genotypes. Increasing the dose level up to 450 Gy is advisable and resulted to be the optimum dose for Bira while 200 Gy was observed to be the optimum dose in Shindimba. Increasing the dose levels to 600 Gy is not advisable for cowpea production with respect to Bira and Shindimba in the experimental area. Though further investigation with the same experiment should be conducted in different regions of the country to put the recommendation on a strong basis. Depending on the crop of choice, farmers are ought to use Bira 450 Gy or Shindimba 200 Gy in order to achieve high seed yield.