Biofertilizers for enhancing groundnut productivity

Abstract

Groundnut is one of the major oilseed crops of the tropics and subtropics, grown in an estimated area of about 25 million ha in about 90 countries with an average yield of about 1600 kg. In India, groundnut is cultivated in around 6 million ha with an annual production of around 7 million tonnes and with an average productivity of around 1270 kg/ha in rainfed situation. There is a fluctuating trend in area, production and productivity of groundnut in India. As around 90% of the crop is grown under rainfed conditions, productivity is affected due to erratic rainfall and frequent occurrence of droughts. One of the reasons of poor productivity in India is the cultivation of groundnut in marginal lands with suboptimal nutrient supply. However, being a legume crop most of its N requirement should be met from biologically fixed nitrogen. But promiscuity of groundnut allows nodulation by all the different strains of rhizobia present in the tropics and sub-tropics resulting in erratic biological nitrogen fixation. The situation is compounded further as native rhizobia often out-compete the inoculants strains. Because of insufficient biological nitrogen fixation in groundnut, very often yield is badly affected. Thus, application of highly competitive and efficiently nitrogen fixing strains of groundnut rhizobia would help in enhancing the biological nitrogen fixation vis-à-vis groundnut yield. The soils of groundnut growing areas are very often affected by acidity or alkalinity coupled with deficiency in available P, Fe, Zn, Mo, and other micronutrients. Therefore, with the application of phosphate solubilizing microorganisms, plant growth promoting rhizobacteria and other beneficial bacteria having multiple plant growth promoting traits, transformation and availability of P, Fe, Zn, Mo and other micronutrients can be improved substantially. Biofertilizers hold promise in improving the productivity of groundnut in a sustainable way, though their potential in increasing yield has not been exploited yet. With the sincere efforts of the microbiologists of the ICARDirectorate of Groundnut Research, a number of highly competitive strains of groundnut rhizobia, plant growth promoting rhizobacteria, consortia of beneficial bacteria and phosphate solubilizing bacteria have been identified and their potential demonstrated throughout the country through FLDs and demonstration. There is a need for further popularization of the biofertilizers. To provide valuable information to the farmers and extension worker about the biofertilizers of groundnut and the benefits that can be accrued from biofertilizers usage, this bulletin has been compiled. Hope this will benefit the groundnut growers of the country.