1Department of Microbial, Cellular and Molecular Biology, Addis Ababa University, P.O. X-1176, Ethiopia
2Department of Plant Sciences, Wollega University, Shambu Campus, Shambu, P.O.X.-38, Ethiopia
3Department of Biology, Wollega University, Nekemte, P.O. X-395, Ethiopia
*Corresponding Author: Email: girmayek@gmail.com
Online published on 22 July, 2021.
Phosphorus is one of the limiting plant nutrients in most soil due to its fixation with metal ions both in acidic and alkaline soil. However, some soil bacteria have potential to solubilize the cation-fixed phosphorus and make it available to plants.
Sixty-six cowpea root nodule bacterial species were tested for inorganic phosphate solubilization (PS).PS potential of the isolates from Ca3 (PO4), AlPO4 and FePO4 were tested on four different kinds of agar media. Solublization efficiency was determined as Solubilization Index (SI) on agar media and quantity of bioavailable phosphorous on broth media.
About 30% of the bacterial isolates, out of which 60% endophytes were Ca3 (PO4)2 solubilizers on Pikovskaya medium but did not grow on media containing AlPO4 and FePO4 as sole P sources. Isolates showed significant variation (p<0.05) in Ca3 (PO4)2 solubilization efficiency on the different culture media and ECE-21 (Pseudomonas putida) was versatile in solubilizing Ca3(PO4)2 from the four test media. However, ECE-26A (Bacillus subtilis) showed the highest PS in broth media (140.8 ug ml1) indicating the moderate correlation (r=0.5578; p<0.05) of PS between solid and liquid media. Amounts of P solubilized and pH change of the culture filtrate was inversely correlated (r=-0.731; p<0.01). In general, ECE-21 was the most efficient P solubilizer (SI=2.67±0.1; P=87.74±7.4ug ml−1) solublizers and hence can be an ideal candidate as inoculants for the crop production in Ethiopia after field evaluation.
Endophytes, Nodule bacteria, Phosphate solubilization, Rhizobia, Solubilization Index
