Phosphate-solubilizing microorganisms of a lateritic soil: III. Effect of inoculation of some tricalcium phosphate-solubilizing microorganisms on available phosphorus content of rhizosphere soils of rice (Oryza sativa L. cv. IR-20) plants and their uptake of phosphorus

Abstract

Summary Three efficient phosphate-solubilizing microorganisms, isolated from a lateritic soil (Typic Ochragualf), LCB 9 , a mixed culture of Bacillus circulans and B. subtilis (B-7648), LCS 4 , a Streptomyces sp., and LCF 4 , Aspergillus niger van Tieghem were inoculated either alone or in combinations of two with rock phosphate (RP), farm yard manure (FYM), FYM + RP, rice straw (RS), and RS + RP to study their role on the available phosphorus content of the rhizosphere soils and uptake of phosphorus by rice plants ( Oryza sativa L. cv. IR-20) and their dry weight at early tillering and preflowering stages of growth in a pot culture experiment with the same soil. Available phosphorus content of the rhizosphere soils of IR-20 rice increased with application of FYM + RP and with the inoculation of LCB 9 , either alone or with LCF 4 . Inoculation of LCB 9 + LCF 4 with RS induced the highest uptake of phosphorus by the rice plants and that of LCB 9 + LCS 4 with RP the dry matter content of the plants at early tillering stage, while inoculation of LCB 9 + LCF 4 with RS + RP resulted in the highest uptake of phosphorus as well as dry matter content at preflowering stage. But on an overall basis, the highest uptake of phosphorus and dry weight of the plants were obtained with the inoculation of LCB 9 + LCF 4 , whereas in the case of manures the former was obtained with FYM + RP and the latter with FYM alone. Thus, application of FYM, either with or without RP, and inoculation of LCB 9 , either alone or with LCF 4 , had beneficial effect with regard to accumulation of available phosphorus in the rhizosphere of rice plants, to their uptake of phosphorus and dry matter content. Incidental accumulation of available phosphorus in the rhizosphere was significantly correlated with the uptake of phosphorus by the plants, but not with the dry weight of the plants at early tillering stage, while there was a constantly significant correlation between the uptake of phosphorus by the plants and their dry weight.