Enhancing Fodder Oat (\u3cem\u3eAvena sativa\u3c/em\u3e) Production in Problem Soils Using Phosphate Solubilizing Fungi Isolated from Acid and Salt Affected Soils of India
Tropical and subtropical soils are predominantly acidic, and often extremely phosphorus-deficient with high phosphorus sorption (fixation) capacities. Phosphorus (P) is one of the major essential macronutrients for plants, present at levels of 400–1200 mg/kg of soil. One of the drawbacks of fertilization is that only a fraction of the P added is eventually assimilated by plants, due to high reactivity of soluble phosphate with other elements the rest becomes unavailable to plants by forming complexes with either, Al, Fe, Ca or Mn depending on soil type (Rodríguez and Fraga, 1999). Even though some soils may have high levels of total P, they can still be P-deficient due to low levels of soluble phosphate available to plants. Available P concentrations for maximum pasture production are estimated to be between 20 and 50 µg/g. Because of the spiraling cost of phosphatic fertilizers coupled with low recovery (10- 30%) of phosphorous applied in the field, the developing tropical countries are attempting to utilize their indigenous reactive ground phosphate rock as a cheap alternative (Sabannavar and Lakshman, 2009). Many soil bacteria, Pseudomonas, Bacillus, Burkholderia, Arthrobacter, Alcaligenes, Serratia, Enterobacter, Acinetobacter and Flavobacterium and fungi especially Aspergillus, Penicillium, Trichoderma have the ability to solubilize elemental phosphate (Pi) and make it available to plants. They are used as biofertilizers for supplying the P requirement of the plants. However, scanty information is available on the occurrence of PSMicroorganisms (PSMs) in acid and salt affected soils. The present investigation was aimed to isolate PSMs from acid and salt affected soils that could survive and solubilize insoluble phosphate efficiently in the presence of higher salt concentration and acidic medium so as to obtain efficient isolates for application as a potential biofertilizer in acid and saline or problematic soils
