R.D. DHORE, S.S.PANDE AND P.M.TUMANE
Abstract
The country has witnessed yield stagnation despite use of increased doses of chemical fertilizers, deterioration of soil organic stock and imbalance in NPK ratio, etc. At the moment, although different microbial organisms occur in the soil habitat but their number is often inadequate to support the requirement of crop nutrients. Under these circumstances, it was the real challenge before bioscientists to rescue the dying agriculture by investigating the alternative sustainable means. In market, ready to use biofertilizers are available in the solid state. These carrier-based bio-fertilizers are used in agriculture since the long time. For this, carrier materials like lignite, charcoal, soil or press-mud are charged by pure cultures of desired bacteria. At the moment, these biofertilizers too are very costly and beyond the buying capacity of small and marginal farmers. Secondly, the effectiveness of carrierbased bio-fertilizers which are normally available in market in a solid state has short shelf life due to the thermal sensitivity of the microorganisms used. The user has no way to know whether the product has been stored and transported under appropriate conditions before reaching him. Hence, due to all these facts the idea of replacing present carrier-based bio-fertilizer with liquid bio-fertilizer has come up. Liquid bio-inoculants are more convenient to use as seed treatment as well as foliar sprays. In the present studies, therefore, Azotobacter Spp. inoculants have been used as liquid biofertilizer to check various stress effects. Cyst based Azotobacter were thought to be ideal for dispensing as liquid bioinoculants. On considering the probabilities of cheapness of the process, the liquid bio-fertilizer may be advantageous to maximizing their use and utilization for the fiber yielding crop like cotton. Therefore, in the present study the microorganism Azotobacter chroococcum has been selected to formulate the liquid biofertilizer and its application on the cotton crop. Cyst initiation in Azotobacter has the ability to withstand adverse conditions of desiccation, sonic treatments, heat treatments and ultra-violet radiation, which are hardly tolerated by vegetative cells.