EFFECTS OF Rhizobium INOCULATION AND PHOSPHORUS FERTILIZER RATE ON NODULATION, YIELD COMPONENTS AND YIELD OF CHICKPEA VARIETIES (Cicer arietinum L.) AT HARAMAYA, EASTERN ETHIOPIA

An experiment was conducted at Haramaya University, eastern Ethiopia in 2016 main cropping season, to assess the response of chickpea varieties to Rhizobium and P fertilizer rate. Factorial combinations of three ‘Kabuli’ chickpea varieties (Arerti, Ejere and Habru), four rates of phosphorus (0, 10, 20 and 30 kg P ha-1) with and without rhizobium inoculants were laid out in a randomized complete block design with three replications. The main effects of variety had significant effect on stand count at harvest and harvest index. The variety Arerti had the highest stand count at harvest while Ejere had the highest harvest index. The interaction effect of variety and P rate showed that Ejere treated with 20 kg P ha-1 produced significantly the highest number of total nodules (34.00), effective nodules (28.00), dry weight of total nodules (0.33 g), number total pods per plant (80.55) and number of seed per pods (1.44). Similarly, the interaction of variety with Rhizobium inoculants indicated that Ejere inoculated with rhizobium produced significantly highest number of primary branches (3.79), total number of nodules (30.33), effective number of nodules (24.33), and dry weight of total nodules per plant (0.30 g). Moreover, the interaction effect of P rates and Rhizobium inoculants gave significantly highest number of days to flowering and physiological maturity from the application of 0 kg P ha-1 with seed inoculation. On the other hand, the highest number of total nodules (33.11), numbers of effective nodules (25.33), dry weight of total nodules (0.31 g), total number of pods (74.94), number of seeds per pod (1.47), 100 seed weight (35.55 g) and aboveground dry biomass yield (5411 kg ha-1) were recorded for seeds inoculated with rhizobium inoculants and treated with 20 kg P ha-1. The three-way interaction effect of variety, phosphorus rate and rhizobium inoculants showed that variety Arerti treated under 0 kg P ha-1 with seed inoculation took significantly the longest days to flowering and physiological maturity, whereas the same variety receiving 20 kg P ha-1 with rhizobium inoculants also produced the highest number of secondary branches per plant (14.77). On the other hand, Ejere receiving 20 kg P ha-1 with rhizobium inoculants produced the highest number of primary branches per plant (4.0), number of total nodules per plant, numbers of effective nodules per plant, dry weight of total nodules per plant, seed yield and highest net returns (49793.00 Birr ha-1). Based on the results, it can be concluded that Ejere at application rate of 20 kg P ha-1 with seed inoculation was found to be superior in the study area. Similar studies should be conducted by including more others chickpea varieties at different locations during different growing seasons among different rhizobium inoculants with consideration of economic analysis to come to a conclusive recommendation