INTRODUCTION However, the available deposits contain low grade phosphorus. Phosphorus is a macro nutrient required for plant growth. The phosphate form of phosphorus is one of the least soluble The recent research in crop production has shown that Rock mineral nutrients in soil. Available phosphorus in soil is phosphate is found to be agronomically inferior to super seldom sufficient for optimum growth and yield of crops phosphate when applied at the same ratio. Therefore it is where no phosphatic fertilizers are applied. However, the always better to inoculate the soil or seeds of crop plants with application of organic matter and humus to soil improves the phosphate solubilising organisms. availability of phosphorus to the plants. Modern agriculture ROLE OF SOIL MICROBES AND FUNGI IN 'P' which is characterised by intensive cultivation method is SOLUBILIZATION totally dependent on regular input of numerous types of inorganic fertilizers. Shortage of raw materials compelled Microorganisms play an important role in the solubilisation of with energy crisis has forced to accept the challenge under various insoluble organic and inorganic phosphates present in such circumstances for increased production of crops, by the soil (Kapoor et al., 1989). Such application of microbes economic and direct use of indigenous rock phosphate. As results in increased availability of phosphorus for plant plant root grows through the soil, it introduces change to its growth (Tomar et al., 1993). Systematic studies on microbial surroundings. The affected zone is known as rhizosphere solubilisation of inorganic phosphates were reported by which differs biologically, chemically and physically from Pikovskaya (1948). Since then voluminous literature has non-rhizosphere soils (Katznelson and Bose, 1959). The accumulated reporting the ability of different groups of essential growth requirements are obtained by plant roots. microbes to solubilize the insoluble phosphates in soil and in Hence, though the soil-root interface of a root exerts a degree culture. The organisms includes bacteria, cyanobacteria, of influence over its growth environment. One such actinomycetes and fungi (Table-1). Arthobacter, Azotobacter, rhizosphere effect concerns changes in phosphate availability Bacillus, Bradyrhizobium, Brevibacterium, from organic and inorganic sources. Corynebacterium, Enterobacter, Escherichia, Flavobacterium, Micrococcus, Pseudomonos, Rhizobium, 'P' STATUS IN INDIAN SOILS Anabaena, Nostoc, Scytonema, Tolypothrix, The records of Indian soils have shown that 70-90% of soils Micromonospora, Nocardia, Streptomyces, Candida, have a low or medium available P-status (Ghosh and Hasan, Alternaria, Aspergillus, Curvularia, Cephalosporium, 1979). The availability of phosphorus can be increased by Chaetomium, Humicola, Myrothecium, Paecelomyces, adding water soluble Phosphatic-fertilizers, enzymatic Penicillium, Phoma and Trichoderma have been reported as decomposition or mineralization of the organic form of phosphate solubilizing microbes (Bardiya and Gaur, 1972; phosphorus in the soil and solubilisation of inorganic Gaur et al., 1973; Halder et al., 1991; Katznelson et al., 1962; phosphates by phosphate solubilising microbes. Nateshan and Shanmugasundaram, 1989; Sardina et al., 1986; Subba Rao and Bajpai, 1965; Surange, 1985). Phosphatic fertilizers such as single super phosphate and triple super phosphate are applied nearly to half of the area in Number of soil factors like pH, moisture, organic matter and India. But the efficiency of water soluble phosphatic fertilizer NPK were found to influence microbial solubilization does not exceed 30% (Kapoor et al., 1989). Further, there is a (Thakkar et al., 1993; Gaur, 1990). Generally Pikovskaya greater shortage of phosphorus fertilizers and these are also agar medium is used for isolation of phosphate solubilising very expensive. The high cost of these fertilizers is a major microbes. However, the presence of soluble 'P' in culture constraint for Indian farmers. Rock phosphate deposits are medium has been found to have reducing effect on the available in Uttar Pradesh, Rajasthan, Madhya Pradesh, solubilisation of Ca (PO ) by some fungi (Chhonkar and 3 4 2 Bihar, West Bengal, Tamil Nadu, Orissa and Andhra Pradesh. Subba Rao, 1967). Phosphate solubilising microbes differ in KAVAKA 48(2): 33-40(2017) Role of Phosphate Solubilizing Fungi and Microbes for sustainable Agriculture and Agro forestry C. Manoharachary* and D. Nagaraju *Mycology and Molecular Plant Pathology Laboratory, Department of Botany, Osmania University, Hyderabad - 500007, Telangana, India Department of Botany, Govt. Degree College, Eturnagaram-506165, Distt. Warangal, Telangana, India. Corresponding author Email: nagaraj.bot9@gmail.com (Submitted in March, 2017; Accepted on July 10, 2017) ABSTRACT Phosphorus is an important nutrient required for plant growth, yield and adaptability to different ecological conditions. Many Indian soils are deficient in phosphorus. The organic form of available phosphorus is meagre and mineral phosphorus such as rock phosphate is found in large quantities. The mineral phosphorus needs to be solubilized by varied groups of microorganisms, thus making 'P' available for crop plants and forestry. This review presents information on role of phosphate solubilizing fungi and microbes for sustainable agriculture and agro-forestry. KEYWORDS: Agriculture, agroforestry, fungi, microbes, phosphorus, rock phosphate. 33