Studies on Phosphate Solubilizing Bacteria (PSB) in Rhizosphere and Non-Rhizosphere Soils in Different Varieties of Foxtail Millet (Setaria italica)

摘要

Phosphorus is a vital nutrient for plants and microorganisms next to nitrogen. The populations of phosphate-solubilizing bacteria were isolated from the non-rhizosphere and rhizosphere soil samples of the three varieties of foxtail millet viz., Chitra, Lepakshi and Prasad varieties planted to black and red soils on Pikovskaya's medium. The phosphate-solubilizing bacteria were purified. Identification of PSB was limited to very high efficient isolates numbering 8 of which 7 were isolated from the rhizosphere samples while one was from non-rhizosphere sample. The PSB count varied from 14-15 X 10~5 cfu/g in non-rhizosphere and 16-18 X 10~5 cfu/g in rhizosphere samples. Phosphate solubilization of these isolates varied from 14% in non-rhizosphere and 15-19% in rhizosphere samples in semi solid Pikovskaya's media and 25-94 (ig/mL in Pikovskaya's broth. Rhizosphere samples of all the varieties viz., Chitra, Lepakshi and Prasad of foxtail millet harboured higher populations of phosphate-solubilizing bacteria when compared to the non-rhizosphere samples. Phosphate-solubilizing bacterial isolates from black soil were more efficient in solubilization of phosphate when compared to the phosphate-solubilizing bacterial isolates from red soil. The percentage ofoccurrence of phosphate-solubilizing bacterial isolates with different solubilization rates followed the order: medium (63.28) > high (23.44) > very high (12.50) > low (0.78).