Screening of nitrogen fixers from root nodules associated with Albizia procera

Abstract

The rhizosphere contains a host of microorganisms that are affected by both abiotic stress and biotic stress. Low fertility is a major problem in establishing vegetation in degraded areas. Nitrogen (N) is an important plant nutrient needed for plant growth in abundance in the earth’s atmosphere however; most tropical soils are deficient in available N. In low-lying ecosystems and without human fertilization or supplementation, the nutrients found in plants come from organic matter or organic matter. The amount of fixed nitrogen depends on the nitrogen level of the soil, the type of rhizobia that attacks the pods, the growth of the plant and the length of the growing season. Nitrogen-fixing tree species can play an important role in stabilizing sandy and eroded soils, utilizing deep groundwater due to its broad roots and thus helping to increase soil fertility. Among the indigenous legume species Albizia procera is best known for the traditional legume species, which are associated with Rhizobium and this association leads to nitrogen fixation in the atmosphere. Soil rhizobial value calculations showed high number of bacteria in the soil sample of Baddi (297.21 cfu g-1) and a small amount in Solan (243.46 cfu g-1). On the basis of verification tests namely, congo red test, ketolactose testing and plant infection testing in all isolated areas, more than 70.58 per cent (26 of 34) were confirmed as rhizoba. All isolates are tested for factors that promote the growth of different plants, namely, p-solubilizers, siderophore producers and IAA producers. Of these 26 rhizobial isolate, 82.38 per cent were p-solubilizers, 54.45 per cent were siderophore producers and 75.47 per cent were IAA producers. This approach was to improve the bio-inoculum to increase soil fertility by injecting the most suitable type of bacteria that would bring the best plant into the natural environment without adding fertilizer from the outside. Rhizobia is very important in improving the availability of nitrogen in the soil.