Item: Evaluation of salt stress and acidity tolerance of selected indigenous strains of Mungbean (Vigna radiata) Rhizobia isolated from the Philippines [manuscript]
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Date
2020
Authors
Czarina V. Elemencio
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Abstract
Salinity and acidity decreases legume growth and decreases the activity, growth and symbiotic efficiency of rhizobia. In this study, seven indigenous Bradyrhizobium strains isolated from different provinces of the Philippines were evaluated for their ability to tolerate specific acidity and alkalinity concentrations under laboratory condition. These strains were inoculated to a mungbean plant and were subjected to rtwo salt stress level (50 and 100 mM). Then, eleven indigenous Bradyrhizobium strains and two Bradyrhizobium USDA reference strains were streak using spot method at culture media that have four salt stress level (1.0%, 1.5%, 2.0 and 2.5%) and acidity level (4.0, 5.0, 6.8 and 8.0 pH).
The results of the study show that the growth performance of mungbean was limited by salt stress. Increasing the salt stress inhibited mungbean plants as well as the effectivity and infectivity of the Bradyrhizobium strains in roots, shoots and number of nodules formed in the root plant. In pot experiments the indigenous strain BA-11 showed the highest tolerance at 50mM among all the strains while no strain was able to tolerate a salinity level of 100mM. In culture media, the strain B)-10 was the most tolerant to both acidic and alkaline condition. For the salinity test in the culture media. SK-11 showed the highest tolerance at 1.0% and 1.5% whereas LT-1 showed the highest tolerance at 2.0% at 2.5%. As a whole, this indicated that some indigenous strains isolated from the Philippines can be utilized as potential inoculant to problem soils with high acidity and salinity concentrations. This is the first study characterize the specific strains and further evaluation on field in recommended.