GENETIC VARIABILITY IN COWPEA Vigna unguiculata (L.) Walp UNDER VARIOUS CROP MANAGEMENT SYSTEMS

GENETIC VARIABILITY IN COWPEA Vigna unguiculata (L.) Walp UNDER VARIOUS CROP MANAGEMENT SYSTEMS

Abstract:

Twelve cowpea (“Vigna unguiculata (L.) Walp) genotypes (ten breeding lines and two local checks) were evaluated on station under different crop management systems for the estimation of their variability, the interaction between genotype and some environmental components such as cropping patterns, pesticide spraying regime, locations and years. Ten of the twelve genotypes were also evaluated on-farm under the farmers’ management systems at Gezawa and Minjibir local government areas in Kano State, Nigeria. The acceptability of the lines as crop and food by farmers was assessed. Considerable variation was observed for yield observed for yield and its components such as plant height, days to 50% flowering, days to maturity number of pods per plant, number of seeds per pod, 100-seed weight, fodder yield at harvest per plant and per hectare; dry fodder yield per plant and per hectare, number of Striga plants at harvest. Very wide range was observed for many traits on-station as well as on-farm. Breeding lines such as IT90K-59, IT89KD-374-57, IT86D-719, IT90K-277-2, IT89KD-391, IT89KD-355 and IT89KD- 319 performed better than the local varieties across locations for most of the traits. IT89KD- 319, IT89KD-391, IT88DM-867-11 and IT89KD-355 performed as poorly as the local varieties under heavy infestation of the crop by Maruca testulalis, pod sucking bugs, scab, Septoria and Striga for days to 50% flowering, days to maturity, grain yield, number of pods per plant. The performance of the genotypes evaluated varied from one location to another. Farmers’ local varieties performed as good as some of the breeding lines such as IT89KD-374-57 and IT89KD-319 for 100-seed weight, IT86D-719 for grain yield, IT89KD-374-57 and IT86D-719 for pod length, IT86D-719 and IT89KD-391 for number of seeds per pods. Some of the cowpea test lines such as IT88DM-867-11, IT89KD-374-57 and IT90K-277-2 performed better than the farmers’ local varieties and the local check ‘Danlla’ for grain yield per plant. Significant differences were observed among locations and in the interactions between genotypes and locations; genotypes, locations, pesticide spraying regime and cropping pattern; pesticide spraying regime and year; genotypes and pesticide spraying regime and years for many of the traits. Variance components estimates were computed using a set of data combined over locations, and another set of data combined over years. Genetic variance estimates had positive value for eleven traits out of thirteen for the data combined over years and for seven out of thirteen for the ones combined over locations. Most of the variance components estimates were associated with large standard errors. The negative variance components estimates were rather very small values than equal to zero. Broad sense heritability estimates were calculated. The estimates obtained from the data combined over years and the data combined over locations had similar magnitude for plant height, days to 50% flowering and days to maturity. Differences in the heritability estimates obtained by the two approaches for traits such as number of pods per plant, 100-seed weight and grain yield could have been due to the differences, observed in the level of heterogeneity in the environments (locations and years). The cowpea genotypes had no effect on the associated millet crop on-station even though 57% of the farmers reported an increase in the millet yield on their fields. A high proportion of farmers had a positive appreciation of the performance of the genotypes. They were acceptable and found suitable for cooking varied local dishes. The adoption of these breeding lines by farmers would increase the stability of grain production in their fields which are often under heavy attack by bacterial blight, aphids, thrips and other diseases to which these lines are resistant as against the local varieties which are susceptible. Farmers participation in varietal evaluation was found highly positive. Farmers wished that their involvement would be a permanent feature of the development of improved varieties

GENETIC VARIABILITY IN COWPEA Vigna unguiculata (L.) Walp UNDER VARIOUS CROP MANAGEMENT SYSTEMS