Solubilization of Phosphate Rocks and Minerals by Wild Type and UV Induced Mutants of Aspergillus Tubingensis

Abstract

Phosphorus (The Morning star- Vallentyne, 1974) is an essential nutrient for plant growth and development. It is classified as a macronutrient because of the relatively large amounts of P required by plants. Despite its wide distribution in nature, it is a deficient nutrient in most soils. Many soils are defined as having high P-fixation capacity, since a substantial amount of any applied P fertilizer is rendered unavailable and frequent applications of soluble forms of inorganic P are needed to maintain adequate P levels for plant growth. With the current tendency for a reduced use of agrochemicals and efficient application of natural materials in agro ecosystems, a renewed interest in direct application of rock phosphate (RP) has arisen (Rajan et al., 1996). Phosphorus plays a key role in the balanced nutrition of plants (Hayman, 1975). Phosphorus is second only to nitrogen as an essential macronutrient for plant growth and development (Scheffer et al., 1998). Pierre (1938) referred to it as the ‘Master Key’ element in crop production. It is associated with several vital functions and is responsible for several characteristics of plant growth such as utilization of sugars and starch, photosynthesis, nucleus formation and cell division, fat and albumin formation, cell organization and the transfer of heredity (Arnon, 1956 and McVicker et al., 1963).