Response of cowpea lines to inoculation with four seed transmitted viruses of cowpea.

Abstract

This study evaluated the performance cowpea genotypes in the field in Ibadan, Nigeria for response to infection induced by four seed transmitted viruses of cowpea. The experiment was laid out in split plot design with
three replicates. Cowpea mottle virus genus Carmovirus (CMeV) produced infection in 14 of the 15 lines, Bean common mosaic virus genus Potyvirus - blackeye cowpea strain (BCMV – BlC) in 12, Cowpea aphid-borne mosaic
virus genus Potyvirus (CABMV) in 11 and Southern bean mosaic virus genus Sobemovirus (SBMV) in 6. BCMV – BlC significantly reduced (p <  0.05) the grain yield, number of pods per plant, number of seeds per plant and shoot length than CMeV, and CMeV reduced the same traits than CABMV and SBMV. Percentage reduction in the grain yield induced by BCMV – BlC infection ranged from 62.6% in CP-VAR8 to 87.7% in IT86D-371, CMeV from 49.9% in IT90K-284-2 to 91.4% in IT82D-889, CABMV from 20.2% to 87% and SBMV from 31.8% to 69.2%. Similar trend was observed in the reduction of the number of pods per plant, plant height and number of seeds per pod. The four viruses did not affect the number of days from planting to 50% flowering and the number of days from planting to maturity. IT90K-284-2, IT82D-889, TVu 11426 and IT86D-880 were resistant to infection caused by BCMV – BlC, CABMV and SBMV but were tolerant to CMeV infections. CP-VAR8 was resistant to infections induced by CMeV and SBMV. The cultivation of these lines should be encouraged in the areas where the viruses are endemic.

KEY WORDS: Cowpea, Vigna species, Virus infections, Cowpea Diseases, Seed Transmitted Viruses