Rhizobium leguminosarum bv. viciae sp. inoculation improves the agronomic efficiency of N of common bean (Phaseolus vulgaris L.)

Anteneh Argaw,Ayele Akuma

doi:10.1186/s40068-015-0036-z

Abstract

Due to common bean derives lower nitrogen (N) from symbiotic N2-fixation, it requires N either from inorganic fertilizer or soil N. Field experiments were conducted at four locations to evaluate the effect of Rhizobium leguminosarum bv. phaseoli inoculation on agronomic efficiency of N of common bean var. Dursitu major growing areas of eastern Ethiopia. Six levels of inorganic N (0, 20, 40, 60, 80 and 100 kg N ha−1) and two inoculation treatments (uninoculated and inoculated) were factorially combined and laid out in randomized completely block design, replicated three times. AE-N, nodule number per plant (NN) and nodule dry weight per plant (NDW) decreased with N rates of application beyond 20 kg N ha−1. The highest AE-Ns at Babillae, Fedis and Haramaya sites were obtained from 20 kg N ha−1 applied with Rhizobium inoculation while 40 kg N ha−1 supplied with Rhizobium inoculation at Hirna site. Regardless of experimental sites, inoculation improved AE-N. A positive relationship between AE-N and NDW was also observed in all experimental sites. Significant increase in grain yield with increasing rates of N application was also observed. Hence, it can be concluded that inoculation is recommendable to increases the efficient utilization of applied Mineral N.

Highlights

Due to common bean derives lower nitrogen (N) from symbiotic N2-fixation, it requires N either from inorganic fertilizer or soil N
Regardless of the experimental sites and inoculation treatments, Agronomic efficiency of N (AE-N) was significantly decreased with increasing rates of N application
Reduction of AE-N could be due to the amount of grain yield of common bean increases reduced with increasing rates of N application (Rebeschini et al 2014), leading to lower AE-N at higher rate of N application

Summary

Introduction

Due to common bean derives lower nitrogen (N) from symbiotic N2-fixation, it requires N either from inorganic fertilizer or soil N. In Ethiopia, common bean is one of the major grain legumes cultivated, with its production centred in small farmers’ fields where the use of N fertilizer is limited and average yields are low, usually less than 1 ton ha−1 (CSA 2013). In Latin American, the yield losses due to N deficiency has been recorded up to 45% when compared to the N fertilized plants (Thung and Rao 1999). This indicates the need for inorganic N application and/or a search for more effective rhizobial strains to enhance the growth and grain yield of common bean

Methods

Results

Conclusion