RESPONSE OF MUNGBEAN [Vigna radiata (L.)Wilczek] VARIETIES TO PLANT SPACING UNDER IRRIGATION AT GEWANE, AFAR REGION, NORTHEASTERN ETHIOPIA

Production of mungbean has been increasing in Ethiopia because of its high importance as a source of protein and foreign exchange earnings. Determination of appropriate plant density for the varieties of mungbean can increase its productivity. Therefore, an experiment was conducted to determine the effect of inter and intra row spacing on growth, yield components and yield of mungbean varieties under irrigation during 2016 cropping season at Gewane, Northeastern Ethiopia. The treatments consisted of factorial combinations of three inter row spacing (30, 40, and 50 cm), three intra row spacing (5, 10 and 15 cm) and two mungbean varieties (N-26 and MH-97) laid out in randomized complete block design with three replications. Significant differences were obtained on days to 50% flowering, days to 90% physiological maturity, number of seeds per pod and hundred grains weight (g) due to the main effect of the variety. Variety MH-97 was earlier in attaining flowering (43.30 days), physiological maturity (74.49 days), produced higher number of seeds per pod (10.08) and hundred grain weight (6.78 g) than variety N-26. The main effect of inter row spacing and intra row spacing were significant on plant height, secondary branches and above ground dry biomass. The tallest plant in height (41.71 cm) was produced from 5 cm intra row spacing and maximum numbers of secondary branches were recorded from intra row spacing of 15 cm (9.53), inter row spacing of 50 cm ( 9.30 ) and the highest above ground dry biomass yield of 4867.0 kg ha-1 and 4834.4 kg ha-1 were recorded unde intra row spacing of 5 cm and inter row spacing of 30 cm, respectively. The interaction effect of the variety, inter and intra row spacing were highly significant on the number of primary branches per plant and number of pods per plant, where as the highest number of primary branches (7.00) was recorded from variety MH-97 at 50 cm inter row spacing and the highest number of pods per plant (30.15) and (31.34) were record by variety MH-97 at 40 cm inter row and at 15 cm intra row spacing recpectively The main effect of variety, inter row spacing and intra row spacing were significant on crop stand count at harvest, harvest index and grain yield. The highest crop stand count at harvest was recorded from variety MH-97 (95.86%), inter row spacing of 40 cm ( 98.59% ) and intra row spacing of 10 cm (95.43%), the highest harvest index was recorded from variety MH-97 (32.38%), inter row spacing of 50 cm (33.38 %) and intra row spacing 15 cm (32.72%) while the highest grain yield (1317.94 kg ha-1) was produced by Variety MH-97, under inter row spacing of 40 cm (1413.74 kg ha-1) and under intra row spacing of 10 cm (1351.67 kg ha-1). Thus, using of the variety MH-97 with inter row spacing (40 cm) and intra row spacing (10 cm) can be tentatively recommended for mungbean production under irrigation in the study area