Use of Rhizobium Biofertilizer for Increasing the Production of Food Legumes

Abstract

Under the project response of nitrogen biofertilizer was studied on different cultivars of chickpea, lentil, mungbean and blackgram, at different agroclimatic areas of Pakistan. During the first year, biofertilizer response and application of different nitrogen fertilizer doses were studied in a chickpea cultivar C-44 at Faisalabad, Peshawar and Tandojam. A significant increase in nodule number was present in inoculated treatments, but data on shoot dry weight, grain, yield, biomass production and plant total nitrogen indicate towards the establishment of effective symbiosis by inoculated strains at Faisalabad and Tandojam only. Whereas, at Peshawar no response of inoculation may have been due to ineffective symbiosis or higher soil nitrogen levels prevailing in the area. During second and third year of project mode of seed inoculation and its response in two different cultivars of chickpea were studied, at four sites Kundian, Faisalabad, Peshawar and Tandojam. Seed pelleting by carrier-based inoculum had more nodules on the tap root than by broth seed pelleting. Overall, nodulation was comparatively higher in MB-72 than C-44, except at kundian. A positive response of biofertilizer for shoot dry weight, grain, yield, biomass production and plant total nitrogen were observed at Faisalabad, Kundian and Tandojam. A significant increase in nodule number in inoculated treatments was observed, at Peshawar but n response at Peshawar for all other parameters may have ben due to ineffective symbiosis. The effect of single super phosphate (SSP) application before, after and at the time of seed sowing was also studied at Faisalabad. SSP application before and after seed sowing gave better nodulation and grain yield rather than its application at the time of seed sowing. Rhizobia applied in the form of broth came in direct contact with SSP and were killed due to its acidic effect before their entry into the host root cells. Effect Of Rhizobium biofertilizer on thirteen mungbean and nine blackgram genotypes were evaluated for their nitrogen fixing potential at Bhakkar, Khanewal and Faisalabad. The response in inoculated treatment at Faisalabad was relatively poor as compared to Bhakkar and Khanewal. A compatible indigenous rhizobial population and total soil nitrogen may have been the limiting factor. In addition, biofertilizer response on lentil, studied only at Faisalabad, showed significant increase in nodule number in inoculated treatments, but a non-significant difference in fresh and dry weight of nodules. Also, the inoculum tested for lentil, prepared in sterilized and unsterilized carrier, showed that unsterilized carrier can also be used effectively. Attempt have also been made for the isolation of rhizobial strains from the chickpea nodules using different isolation media/carbon sources. Fluorescent antibodies (FA’s) against cowpea (Brady) rhizobial strain Ma 8 and M 55, and chickpea strain Ca34 were also developed to study nodule occupancy of the strains in competition experiments. It is concluded through these studies that selection of efficient nitrogen fixing strain (s) should be made, keeping in mind soil N level, indigenous rhizobial population and the genotype of the host.