Response of Snap Bean Cultivars to Rhizobium Inoculation under Dryland Agriculture in Ethiopia

Abstract

High yield in snap bean (Phaseolus vulgaris L.) production requires relatively high nitrogen (N) inputs. However, little information is available on whether the use of rhizobial inoculants for enhanced biological dinitrogen fixation can provide adequate N to support green pod yield. The objectives of this study were to test the use of rhizobia inoculation as an alternative N source for snap bean production under rain fed conditions, and to identify suitable cultivars and appropriate agro-ecology for high pod yield and N2 fixation in Ethiopia. The study was conducted in 2011 and 2012 during the main rainy season at three locations. The treatments were factorial combinations of three N treatments (0 and 100 kg·N·ha−1, and Rhizobium etli (HB 429)) and eight snap bean cultivars. Rhizobial inoculation and applied N increased the total yield of snap bean pod by 18% and 42%, respectively. Cultivar Melkassa 1 was the most suitable for a reduced input production system due to its greatest N2 fixation and high pod yield. The greatest amount of fixed N was found at Debre Zeit location. We concluded that N2 fixation achieved through rhizobial inoculation can support the production of snap bean under rain fed conditions in Ethiopia.

Keywords

• snap bean
• Rhizobium
• nitrogen fixation
• 15N
• Dryland Agriculture