Effect Of Different Spacing Intervals On Growth And Yield Of Cowpea Varieties In Kilifi County, Kenya

ABSTRACT

Cowpea (Vigna unguiculata [L.] walp) is an ancient leguminous plant that is indigenous to Africa. Cowpea is commonly cultivated in the Middle East region, South United States, Asia, Africa, and throughout the sub-tropics and tropics. In Kenya, cowpea is the most important grain legume after common beans and pigeon peas. In Kilifi County and the entire Coastal Kenya, cowpea crop is considered as the most crucial African leafy vegetable (ALV), being the main source of dietary protein, especially for the urban and rural poor. The major constraints facing cowpea production in Coastal Kenya include unavailability of quality seed, lack of technical packages, low plant population and general lack of awareness of the potential the crop holds in mitigating poverty and malnutrition challenges in the community. A field experiment was carried out at Mtwapa Agricultural Training Centre-(ATC) demonstration farm to determine the effect of different spacing intervals on growth and yield of cowpea varieties. The experiment was laid out as a randomized complete block design (RCBD), with 12 treatment combinations consisting of 4 (four) cowpea varieties namely Ken kunde, Katumani 80 (K80), KVU 27-1 and Machakos 66 (M66) and 3 (three) spacing intervals, 40x20 cm, 50x20 cm (Control) and 60x20 cm. It was replicated three times. The specific objectives of the study were to assess the effect of different plant population on growth and yield of cowpea, to evaluate growth and yield of different cowpea varieties and to determine the interaction effect between cowpea varieties and plant population density. The yield parameters investigated were pod length, number of seeds per pod, number of pods per plant, 100 seed weight, seed weight per plant, total seed weight per plot and harvest index. Plant height, number of branches and above ground biomass were the growth parameters investigated. The results revealed significant differences (P < 0.05) between the treatment means for pod length, 100 seed weight, above ground biomass, total seed weight per plot and harvest index. There were no significant differences (P >0.05) between treatment means for height of plant, number of branches, number of pods per plant, number of seeds per pod and weight of seeds per plant. Different responses were noted as a result of spacing variations. The mean number of branches, mean number of pods per plant, mean number of seeds per pod, mean seed weight per plant and the mean above ground biomass increased with variation of spacing intervals from 40x20 cm to 60x20 cm. The mean plant height and mean total seed weight per plot decreased with variation of spacing intervals from 40x20 cm to 60x20 cm. KVU 27-1 had the highest mean pod length, mean 100 seed weight and highest grain yield of 2,310 kg/ha. The yields of Machakos 66, Katumani 80 and Ken Kunde were 2,120 kg/ha, 1,860 kg/ha and 1,050 kg/ha respectively. Machakos 66 had the highest mean above ground biomass. The highest mean pod length was realized at the spacing interval of 40x20 cm whereas the highest mean above ground biomass was at the spacing interval of 60x20 cm. For agricultural practitioners with cowpea maximum biomass yield as the motive, the spacing interval of 60x20 cm is recommended. Cowpea variety KVU 27-1 and spacing interval 40 x 20 cm are recommended for maximum cowpea grain yield in Kilifi County.