Abundance and Symbiotic Rhizobia Colonizing Soybean (Glycine max) in Soils of Kakamega County, Western Kenya

Samuel Mulama,John Muoma,Fredrick Odongo,Rose Onamu,Vera Popovic

doi:10.1155/2021/6627541

Samuel Mulama, John Muoma + Show 3 more

Open Access

https://doi.org/10.1155/2021/6627541

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Abstract

Identification of effective indigenous rhizobia strain nodulating soybean (Glycine max) was conducted in Kakamega County, Western Kenya. This study was carried out to establish the abundance and symbiotic efficiency of native rhizobia strains in soil samples collected from 12 sites in four agroecological zones within the region. The MPN enumeration technique was used to estimate the indigenous rhizobia numbers and showed that 54% of the sampled sites had high abundance. Rhizobia number in the soil collected from the six regions varied from 2.5 × 102 to 3.12 × 103 cells·g− soil. Thirty isolates from the soil collected in the four regions were tested for efficiency using soybean as the trap plant in Leonard jars containing sterilized vermiculite irrigated with nitrogen-free media. Determination of the relationship between rhizobial abundance and symbiotic efficiency with respect to the soil chemical conditions was performed using ANOVA, and the means were compared using Tukey’s honest significant difference test. Inoculation with bacterial isolates significantly ( P < 0.05 ) increased the nodule number and shoot dry weight, while weight of the seeds showed variations across the groups. The soil pH across the 4 regions ranged between 5.41 and 6.52.

Highlights

Soybean (Glycine max) is a grain legume providing dietary protein to millions of people, especially in sub-Saharan countries [1,2,3]. e crop is grown by both commercial and subsistence farmers
Rhizobia are bacteria that establish a symbiotic relationship with the host plant which results in the formation of plant root nodules through colonization and fixation of atmospheric nitrogen [10, 11]. ese bacteria can be divided into two broad groups: free-living rhizobacteria which live outside the plant and symbiotic endophytic bacteria which live inside the plant cell [12]
Both the free-living and endophytic bacteria are crucial in nutrient metabolism [13]

Summary

Introduction

Soybean (Glycine max) is a grain legume providing dietary protein to millions of people, especially in sub-Saharan countries [1,2,3]. e crop is grown by both commercial and subsistence farmers. Expansion and increase in soybean production in SSA since early 1970s to 2018 has rapidly grown popular [6]. Root nodulating bacteria strains are important property in soybean production since the strains must compete with each other in the rhizosphere for better yield production [7,8,9]. Ese bacteria can be divided into two broad groups: free-living rhizobacteria which live outside the plant and symbiotic endophytic bacteria which live inside the plant cell [12]. In this case, both the free-living and endophytic bacteria are crucial in nutrient metabolism [13]

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