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Production Potential of Faba Bean (Vicia faba L.) Genotypes in Relation to Plant Densities and Phosphorus Nutrition on Vertisols of Central Highlands of West Showa Zone, Ethiopia, East Africa

Tekle Edossa Kubure and Cherukuri V Raghavaiah

Faba bean is an important grain legume grown on vertisols of central high lands in Ethiopia, and is constrained by low yielding varieties, soil acidity, besides scanty information on optimum plant density and phosphorus nutrition. Field experiment was therefore conducted at Ambo University research farm during 2014 rainy season with the objective to determine optimum P rate and population densities for Faba bean (Vicia faba L.) genotypes grown on vertisols under rain fed conditions. The treatments comprised three genotypes (Hachalu, Walki and Local), three spacings (30 cm × 7.5 cm, 40 cm × 5.0 cm and 60 cm × 5.0 cm) and two phosphorus levels (0 kg P205/ha and 46 kg P205/ha), which were combined factorially and laid out in a split –split plot design with three replications. The results showed that the improved genotype, Walki (3,407 kg/ha) being comparable with Hachalu (3,037 kg/ha) gave substantially greater seed yield than the local cultivar (2,833 kg/ha). Seeding at 44 plants/m2 resulted in significantly higher seed and biological yields (3,815 kg/ha and 7,894 kg/ha) than 50 plants/m2 (3,074 kg/ha and 6,570 kg/ha) and 33 plants/m2 (2,388 kg/ha and 4,696 kg/ha); although the harvest index was unaltered. Fertilization of faba bean with 46 kg P205/ha resulted in substantial increase in seed (3,531 kg/ha) and biological yields (7,172 kg/ha) over no fertilizer check (2,654 kg/ha seed and 5,602 kg/ha haulm yield). The harvest index tended to improve with P nutrition (49.7) over no phosphorus (47.4). Correlations worked between yield and growth and yield components showed a significant positive relation between seed yield and plant height, leaf area/plant, leaf area index, biological yield and seed yield/plant. Biomass yield is correlated with leaf area/plant, leaf area index, and plant height. Cultivation of improved varieties of faba bean Welki and Hachalu with a plant density of 44 plants/m2 (30 cm × 7.5 cm spacing) was found to be better than the local cultivar in terms of yield and yield attributes. Phosphorus fertilizer application at 46 kg P2O5/ha improved the growth, yield and yield components of faba bean on Vertisols of high lands.