Phosphate solubilization and multiple plant growth promoting properties of rhizobacteria isolated from chickpea (Cicer aeritinum L.) producing areas of Ethiopia

Abstract

Chickpea is one of the major legume crops widely grown in Ethiopia. The low availability of phosphorus in soil is among the stresses that constrain the production of this crop in the country. However, there are rhizobacteria capable of solubilizing insoluble forms of phosphorus in soil and make it available to the plant. Thus, this study was aimed at isolation and characterization of phosphate solubilizing bacteria from chickpea rhizosphere. Fifty phosphate solubilizing bacterial strains were isolated from the soil samples, characterized biochemically and identified by 16S rDNA sequences analysis. The results indicate the presence of genera Acinetobacter, Bacillus, Brevibacillus, Burkholderia, Empedobacter, Enterobacter, Pseudomonas, Ralstonia, Sphingomonas and Stenotrophomonas. Phosphate solubilizing efficiencies of the strains were analyzed using different insoluble phosphorus sources and the results show that most isolates released a substantial amount of soluble phosphate from tricalcium phosphate, rock phosphate and bone meal. Screening for multiple plant growth promoting attributes showed that 44 and 18% of them were capable of producing indole acetic acid and inhibiting the growth of Fusarium oxysporum under in vitro conditions, respectively. A direct impact of several strains (Bacillus flexus (PSBC17), Pseudomonas fluorescence (PSBC33), Enterobacter sp. (PSBC35), Enterobacter sakazaki (PSBC79) and Enterobacter sp. (PSBC81)) on the growth of chickpea in pot culture has been demonstrated by the increase in the number of root nodules, shoot dry matter, nitrogen and phosphorus concentration of shoot. Based on the results, we conclude that chickpea rhizosphere harbor phosphate solubilizing bacteria which are diverse in taxonomy and phosphate solubilizing efficiencies. Thus, consecutive studies should focus on field studies on those strains due to their potentially high importance for the phosphorus nutrition of crops in this area and in this context for the improvement of the sustainability of crop production in the country.

Rhizospheric bacterial isolates of grass pea (Lathyrus sativusL.) endowed with multiple plant growth promoting traits

“…The phylogenetic tree was constructed using 16S rRNA sequence of the isolated strains with other genus and species of Enterobacter, Enterococcus, Kluyvera, Pantoea and Serratia forming four clades. Mulissa et al (2015Mulissa et al ( , 2016 reported the sequencing and clustering of E. cloacae, Enterobacter kobei, P. agglomerans and E. ludwigii from lentil rhizosphere all of which were identified in this study in the related grass pea rhizosphere. The sequences of the native isolates showed 30-99% similarity with each other and with sequences of related organisms obtained from NCBI forming four clusters, suggesting the existence of molecular diversity.…”

“…Rhizobacterial isolates screened from the rhizosphere of lentil and chickpea also produced solubilization indices of 1·34–2·25 cm and 1·44–3·06 cm, respectively (Mulissa et al . , ).…”

“…Muleta et al (2013) reported coffee rhizobacterial strains that solubilized TCP at the range of 2Á05-5Á82 cm which is close to the findings of this study. Rhizobacterial isolates screened from the rhizosphere of lentil and chickpea also produced solubilization indices of 1Á34-2Á25 cm and 1Á44-3Á06 cm, respectively (Mulissa et al 2015(Mulissa et al , 2016. The selected strains solubilized TCP with a solubilization potential of 288-340 lg ml À1 with a significant drop in pH showing moderate to weak correlation (r = À0Á333, P = 0Á05 and r = À0Á358, P > 0Á05) between phosphate solubilization and broth pH, which may indicate the acidic condition required for phosphate solubilization.…”

“…All the selected grass pea isolates produced IAA that ranged between 12Á01 and 56Á55 lg ml À1 . Mulissa et al (2015Mulissa et al ( , 2016 reported 14Á3-47Á5 and 12Á3-58 lg ml À1 IAA from lentil and chickpea rhizobacteria, respectively. IAA production by PGPR could vary among different species and strains of rhizobacteria, but also depend on culture medium conditions (Kumar et al 2012a,b).…”

Isolation and Characterization of Phosphate Solubilising Rhizobia Nodulating Wild Field Pea (Pisum sativum var. abyssinicum) from Southern Tigray, Ethiopia

“…The multifunctionality exhibited by R. leguminosarum makes it important in food production in terms of reducing cost and improving efficiency of P fertilization, especially in P-limited soils [14]. So far, phosphate solbilizing of fababean and chickpea nodulating rhizobial isolates from Ethiopian soils have been done by several authors [15], [16] and [17]. According to Feredegn [18] also assessed the phosphate solubilization of rhizosphere and endophytic bacteria from sugarcane (Saccharum officinarum L.).…”