GROWTH AND YIELD RESPONSE OF COWPEA (Vigna unguiculata L.) VARIETIES TO PLANT SPACING AT SIRINKA, NORTHERN b ETHIOPIA

Abstract

The production of cowpea (Vigna unguiculata L.) has been increasing in Ethiopia because of its high nutritive value for food and feed. Nevertheless, the yield is extremely low. One of the agronomic practices to increase its productivity is use of optimum plant density. However, there has been no recommended plant spacing regardless of variety and agro-climatic conditions. In view of this, a field experiment was conducted at Sirinka Agricultural research center, northern Ethiopia, during 2016 cropping season to assess the effects of different inter-row (40, 50, 60 cm ) and intra-row spacing (10, 15, 20 cm) on growth parameters, yield components and yield of two cowpea varieties namely Asebot and Bekur. Randomized complete block design in factorial arrangement with three replications was used. The result indicated that days to 50% flowering, days to 90% maturity, plant height, number of pods per plant, number of seeds per pod, hundred seed weight, harvest index and grain yield were highly significantly (p<0.01) affected by the main effect of varieties. There was also highly significant (p<0.01) main effect of both inter-row and intra-row spacing on days to 50% flowering, days to 90% maturity, number of seeds per pod and hundred seed weight. Highest number of seeds per pod (13.98) and hundred seed weight (18.1 g) were recorded from 60 cm inter-row spacing, while significantly the highest number of seeds per pod (13.98) and hundred seed weight (19.5) were recorded for 20 cm intra-row spacing. The interaction effect of 60 cm × 20 cm spacing resulted in significantly higher number of primary branches (4.16), number of pods per plant (9.14) and harvest index (37.5), whereas the highest above ground dry biomass (10584 kg ha-1) and plant height (46.73 cm) were recorded under 40 cm × 10 cm spacing combination. Interaction effect of variety, inter and intra-row spacing highly significantly (p<0.01) affected grain yield. Significantly the highest grain yield (1470 kg ha-1) was recorded for variety ‘Bekur’ established at a plant spacing of 40 cm × 15 cm, followed by 40 cm × 10 cm (1350 kg ha-1), while the lowest grain yield (985 kg ha-1) was recorded for the interaction of 60 cm × 20 cm plant spacing. From this study it can be concluded that among these spacing combinations 40 cm × 15 cm for variety Bekur and 40 cm x 10 cm for variety Asebot can be tentatively recommended for the area.