ABSTRACT
Green cowpea is an important alternative for generating employment and income for family farmers and helps broaden production and consumption of the grain. However, biotic factors such as insects, fungi, bacteria, nematodes and viruses have hampered production, especially the Cowpea Severe Mosaic Virus (CPSMV) and Cowpea Aphid-Borne Mosaic Virus (CABMV). The most efficient control of these viruses is via the use of resistant varieties, but few varieties intended for green-grain production are resistant. As such, the aim of this study was to develop and identify superior strains of cowpea in terms of joint resistance to the CPSM and CABM viruses that show characteristics associated with green-grain production. Crosses were carried out in a greenhouse at the Agronomic Institute of Pernambuco (AIP) between the following genotypes: Sempre Verde Salgueiro (susceptible), CNC-0434 (immune to CPSMV) and TVu-966 (resistant to CABMV). From these crosses, fifty F2:5 strains with the Sempre Verde type of grain colouring were selected, their resistance to the viruses assessed in a greenhouse, and their agronomic characteristics for green-grain production evaluated in an experiment at the Experimental Station of the AIP in Belém do São Francisco, Pernambuco. The experimental design was of completely randomised blocks, with three replications. The L300.026, L300.039, L300.040 and L300.049 strains proved to be resistant to both viruses, with a high potential for green-grain production. The Mulamba-Mock selection index facilitated the selection of superior strains that are promising for the future launch of new resistant varieties destined for the production of green grains.
Key words:
Vigna unguiculata; Plant breeding; Resistance; Plant viruses.