Ability of Emericella rugulosa to mobilize unavailable P compounds during Pearl millet [Pennisetum glaucum (L.) R. Br.] crop under arid condition

Abstract

Phosphate solubilizing microorganisms are ubiquitous in soils and could play an important role in supplying P to plants where plant unavailable P content in soil was more. A phosphatase and phytase producing fungus Emericella rugulosa was isolated and tested under fi eld condition (Pearl millet as a test crop) in a loamy sand soil. In the experimental soil 68% organic phosphorous was present as phytin; less than 1% of phosphorous was present in a plant available form. The maximum effect of inoculation on different enzyme activities (acid phosphatase, alkaline phosphatase, phytase, and dehydrogenase) was observed between 5 and 8 weeks of plant age. The depletion of organic P was much higher than mineral and phytin P. The microbial contribution was signifi cantly higher than the plant contribution to the hydrolysis of the different P fractions. A signifi cant improvement in plant biomass, root length, seed and straw yield and P concentration of root and shoot resulted from inoculation. The results suggest that Emericella rugulosa produces phosphatases and phytase, which mobilize P and enhance the production of pearl millet.

Phosphate Solubilization and Mobilization in Soil Through Microorganisms Under Arid Ecosystems

“…In certain cases phosphate solubilization is induced by phosphate starvation ( Gyaneshwar et al, 1999). Organic phosphates is catalysed through hydrolysis of C-O-P ester bond by phosphatase and phytase released by PSMs (Tarafdar & Rao, 1996;Tarafdar et al, 2001;Yadav & Tarafdar, 2007;Yadav & Tarafdar, 2010;Yadav & Tarafdar, 2011). The efficiency of different phosphatase and phytase secreating fungi isolated from arid soils of Rajasthan, India to hydrolyse different organic P compounds were reported (Tarafdar et al, 2003;Aseri et al, 2009) and presented in Table 6.…”

“…Most of the PSMs solubilize Ca-P complexes and only a few can able to solubilize Fe-P and Al-P ( Kucey et al, 1989).Hence, these PSMs could be effective in calcareous soils in which Ca-P complexes are present, but not in other soils such as Alfisols in which phosphates are complexed with Fe and Al ions. Most P-solubilizing bacteria (Baya et al, 1981;Venkateswarul et al, 1984) and fungi (Venkateswarul et al, 1984;Tarafdar et al, 2003;Tarafdar & Gharu 2005;Achal et al, 2007;Yadav & Tarafdar 2007;Aseri et al, 2009;Yadav & Tarafdar 2010;Yadav & Tarafdar 2011) were isolated from the rhizosphere of various plant and are known to be metabolically more active than those isolated from sources other than rhizosphere. The phosphate solubilizing ability in bacteria was lost upon repeated sub culturing but no such loss has been observed in the case of phosphate solubilizing fungi.…”

“… phosphate from organic P compound (inositol hexaphosphate) (Tarafdar & Gharu, 2005;Yadav & Tarafdar 2007;Yadav & Tarafdar 2011). Some heterotrophic micro-organisms are also capable of solubilizing phosphates combined with calcium or magnesium (Atlas & Bartha, 1998).…”

“…The role of phosphate solubilizing microorganisms in native P solubilization and increasing crop yield under arid ecosystem of India has been studies (Tarafdar et al, 1992;Tarafdar et al, 1995;Tarafdar & Rao, 1996;Tarafdar & Graru, 2005;Yadav & Tarafdar, 2007;Yadav & Tarafdar, 2010;Yadav & Tarafdar, 2011). The work on P solubilization in soil using plant growth test have been carried out under green house conditions (Tarafdar et al, 1992;Tarafdar et al, 1995;Tarafdar & Rao, 1996;Tarafdar & Graru, 2005;Yadav &Tarafdar, 2010), although the results of field studies are also available (Tarafdar & Graru, 2005;Yadav & Tarafdar, 2007;Yadav & Tarafdar, 2010;Yadav & Tarafdar, 2011).…”

“…The soils being poor in organic matter (1.5-4.2 mg kg -1 ), most of these phosphorous is present in inorganic form as calcium and aluminium phosphatase. About 20-25% of total phosphorous in arid soils of India is organic in nature and 68% organic phosphorous in the soil is present as phytin (Yadav & Tarafdar, 2007), which are not directly available to plants. Therefore application of phosphatic fertilizers to the soil is essential to maintain adequate amount of soluble P in the soil solution for optimum plant growth as well as to maintain soils sustainability.…”