Aluminium Application and Rhizobia Inoculation Effects on Growth, Yield and Nutrients Uptake of Three Kenyan Soy Bean Genotypes

Abstract

Soy bean (Glycine max L.) grains are important legume crops commonly grown in Kenya. Soy bean genotypes are grown in western Kenyan soils that are highly saturated with aluminium ions. Aluminium toxicity mainly limits crop production. Many soy bean genotypes do not tolerate high acidity in soils. Aluminium stress have effects on root growth, which limits plant growth and development. Inoculation of plants with Rhizobia can restore nitrogen under acid affected soils to produce competitive crop yields. There is little information on response of soy bean genotypes grown in Western Kenya to aluminium toxicity under rhizobium inoculation. This study was designed to determine the effect of aluminium application and Rhizobia inoculation on growth, yield and nutrients uptake of soy bean genotypes. Eight treatments of Al (AlCl3.6H2O) levels and Rhizobia were imposed. Randomized Complete Block Design with three replicates was used. Parameters determined included; number of branches, days to 50% flowering, pod clearance, number of pods, days to harvest maturity and nitrogen, phosphorus and potassium contents. Tukey’s HSD test at 5% level was used to separate treatment means. Mean of branches for NAMSOI was significantly higher compared to mean branches for GAZZELLE and TGX at treatment 4 (T4) on 61 DAT, respectively. Mean number of days to 50% flowering of NAMSOI was significantly higher than that of GAZZELLE and TGX genotypes, respectively at T3.There was a statistically significant interaction between the effects of treatments and genotypes on NPK concentrations in plants. These findings show that Bradyrhizobium japonicum inoculation alleviates Al effects to a level that is significant to improve soy bean yield. Therefore, genotypes GAZELLE and NAMSOI under Rhizobia inoculation were identified to be more tolerant to Al-stress, hence are recommended for growing in Al prone soils. It provides the best conditions in improving soy bean production under Al stress prone soils.