Phosphate-Solubilizing Bacteria as a Panacea to Alleviate Stress Effects of High Soil CaCO3 Content in Phaseolus vulgaris with Special Reference to P-Releasing Enzymes

Atif A Bamagoos,Mostafa M Rady,Hesham F Alharby,Esmat F Ali,Mahmoud A Abdelfattah,Eman E Belal,Ahmed E A Khalaf,Gaber A M Mersal

doi:10.3390/su13137063

Abstract

The present study examines the role of leguminous compost (LC), humic acids (HA), and phosphate-solubilizing bacteria (P-SB) in alleviating the stress effects of high soil CaCO3 content in Phaseolus vulgaris. Two pot trials for two consecutive seasons; fall 2019 and summer 2020 were implemented in an open greenhouse. A mixed three-way ANOVA, two independent factors (season and soil treatments) and one within factors (time) were used with four replicates. Residual maximum likelihood (REML) analysis was used for the mixed model of the studied traits. Inoculation of calcareous soil with P-SB (a 1:1 mixture of two Pseudomonas sp.; Ps. mallei and Ps. cepaceae) significantly exceeded LC, HA, or even LC+HA for the positive results obtained. P-SB facilitated nutrient solubility (e.g., N, K, Fe, and Mn), including conversion of insoluble phosphorous into a form available in the tested soil due to increased soil enzymatic activities (e.g., phosphatases and phytases). This mechanism, combined with a decrease in soil calcium carbonate content and an increase in cation exchange capacity (CEC) and organic matter (OM) content, increased the availability of various nutrients to plants, including P, in the soil, which contributed to the increased plant output. Adequate P content in plants led to a marked decrease in plant acid phosphatase activity under high content of CaCO3. The study concluded that the use of P-SB promotes biological activities, nutrient availability, and thus the productivity of calcareous soils, enabling Phaseolus vulgaris plants to withstand stress produced by high CaCO3 content through the development and/or adoption of potentially effective mechanisms. Strong highly significant interactions between the treatments and time were observed using the Wald’s statistics test, which indicates a positive correlation.

Highlights

This article is an open access articleThe availability of essential nutrients for plant production, especially phosphorus (P), in defective agricultural lands such as calcareous soils, is very important due to the large global extent of these lands [1]
29%, and sand is about 20%), pH is more than 8.15 which indicates that the soil is alkaline, salinity is somewhat low within the range of 2.3 dS m−1, organic matter (OM) content is low, calcium carbonate is high and exceeds 19% which indicate that the soil is calcareous as per Leytem and Mikkelsen [12], who defined calcareous soil as containing
Results indicated that the effects of main effects, first order interaction, and second order interaction were highly significant for most traits under the present study

Summary

Introduction

The availability of essential nutrients for plant production, especially phosphorus (P), in defective agricultural lands such as calcareous soils, is very important due to the large global extent of these lands [1]. The availability of P, especially in calcareous soils, is largely controlled by rates of immobilization and mineralization as biological-mediated processes [7]. Unlike N, P supply is not replenished, so it is necessary to preferably utilize P reserves and rectify chemically bound P [8]. It is quickly restricted into unavailable forms resulting in lower P utilization efficiency regardless of the amount applied to soil [9]. In the absence of mechanisms leading to the release of P in the soil, bio-fixation and chemical precipitation would rapidly deplete every supply of available

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Conclusion