Screening of potential phosphate solubilizing bacteria inoculants should consider the contrast in phosphorus bio-solubilization rate along with plant growth promotion and phosphorus use efficiency

Abstract

Aims Although phosphate solubilizing bacteria (PSB) have been globally reported to improve soil phosphorus (P) availability and plant growth, technical gaps such as the lack of an ideal screening approach, is yet to be addressed. The potential of non-halo-forming PSB remains underestimated because of the currently adopted screening protocols that exclusively consider halo-forming and PSB with high phosphorus solubilization (PS) capacities. Yet, caution should be taken to properly assess PSB with contrasting PS rates regardless of the presence or absence of the solubilization halo. Methods and Results This study sought to examine the PS rate and plant growth promotion ability of 12 PSB categorized as high PSB (H-PSB), medium PSB (M-PSB), and low PSB (L-PSB) based on their PS rates of rock phosphate (RP). The non-halo-forming PSB Arthrobacter pascens was categorized as H-PSB, which might have been eliminated during the classical screening process. In addition, induction of organic acids and phosphatase activity in rhizosphere soils by H-, M-, and L-PSB was proportional to increased wheat P content by 143.22, 154.21, and 77.76 mg P g−1 compared to uninoculated plants (18.1 mg P g−1). Conclusions Isolates considered as M- and L-PSB could positively influence wheat above-ground physiology and root traits as high as H-PSB. In addition, non-halo-forming PSB revealed significant PS rates along with positive effects on plant growth as high as halo-forming PSB.

Whole genome sequencing and characterization of Pantoea agglomerans DBM 3797, endophyte, isolated from fresh hop (Humulus lupulus L.)

“…Siderophore as well as metalophore formation gene clusters were also identified by antiSMASH. This finding is consistent with recently published information (Elhaissoufi et al, 2023 ) that even bacteria not showing PS capability in a given test can in fact contribute significantly to plant phosphorus supply.…”

An insight into the role of the organic acids produced by Enterobacter sp. strain 15S in solubilizing tricalcium phosphate: in situ study on cucumber

“…Inoculation with PSB is considered a promising tool to promote plant growth and yield. These effects are produced by an increased P uptake at root level, that indeed results from OAs secretion by microbes and the P solubilizing property of such carboxylates [ 45 ]. Accordingly, citric acid (2.5 mM) supplementation in soil has already been shown to enhance P uptake and the yield of tomato plants [ 31 ].…”

“…A similar trend was also recorded for the apparent recovery efficiency (AREP), where oxalic acid induced the highest value, followed by citric acid and the bacterium. Indeed, the achievement of higher PUE in agricultural crops by applying eco-friendly approaches, as PSB, is becoming mandatory to guarantee, on one hand, the productivity and, on the other hand, the sustainability of the cropping system [ 45 ].…”

Bioinoculants as a means of increasing crop tolerance to drought and phosphorus deficiency in legume-cereal intercropping systems

“…Although, being unquestionably needed for crop production, large amount of these water-soluble P fertilizers may be rendered unavailable for plants due to fixation by cations such as Al 3+ , Fe 3+ , Ca 2+ , clay particles, or transformed into organic forms, hence their efficacy is reduced 14 , 15 . Chemical P-fertilizers are manufactured based on rock phosphate (RP), a non-renewable P source that has been recently exploited for its direct use in high P-retention soils 16 . However, thorough investigations are still needed to increase the RP agronomic efficiency.…”