Abstract
To identify effective ways of increasing the yield of crops grown in nutrient-poor calcareous soils, the combined effects of biochar addition and inoculation with plant growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) on wheat growth and soil properties were investigated under rhizobox conditions. Measured soil properties included pH, electrical conductivity (EC), organic matter content (OM), the availability of P, Fe, and Zn in the rhizosphere, and the uptake of these elements by plants. Combined biochar addition and microbial inoculation were shown to significantly increase the concentration of available forms of P, Fe, and Zn in the soil when compared to non-biochar treatments. The highest soil pH (7.82) was observed following biochar addition without microbial inoculation. The EC following biochar addition and PGPR inoculation was significantly higher than the other treatments, and the soil OM content was highest when combining AMF inoculation with biochar addition. The available P content after AMF inoculation combined with biochar addition was 27.81% higher than the control conditions, and AMF inoculation increased Fe and Zn bioavailability by factors of 2.38 and 1.29, respectively, when combined with biochar addition relative to AMF inoculation alone. The simultaneous biochar addition and PGPR inoculation significantly increased P uptake by the plants. The highest shoot Fe and Zn uptake rates were observed after a simultaneous application of biochar and PGPR inoculation. Under these conditions, shoot uptake was higher than seen when combining biochar addition with AMF inoculation by factors of 1.64 and 1.21, respectively. In general, it can be concluded that combining inoculation with growth-promoting bacteria and biochar addition can effectively improve nutrient availability to plant and soil conditions.
Highlights
Soils in the arid and semi-arid regions of Iran are alkaline, deficient in organic matter, and mostly calcareous
Plant-growth promoting rhizobacteria (PGPR) enhance plant growth via mechanisms, including the production of metabolites that are important for plant growth, such as plant hormones, N fixation in the rhizosphere, increasing the solubility of insoluble or sparingly soluble nutrients, and thereby improving their availability by releasing organic and inorganic acids, producing phosphatases, synthesizing siderophores, and regulating ethylene synthesis in roots [32]
Due to the strategic importance of wheat in human nutrition and the common deficiency of P, Fe, and Zn in wheat farms, this work investigates the effect of treatment with growth-promoting microorganisms and biochar derived from tree-pruning waste on P, Fe, and Zn bioavailability in the wheat rhizosphere under rhizobox conditions
Summary
Soils in the arid and semi-arid regions of Iran are alkaline, deficient in organic matter, and mostly calcareous. Plant-growth promoting rhizobacteria (PGPR) enhance plant growth via mechanisms, including the production of metabolites that are important for plant growth, such as plant hormones (auxin, cytokinin, and gibberellin), N fixation in the rhizosphere, increasing the solubility of insoluble or sparingly soluble nutrients, and thereby improving their availability by releasing organic and inorganic acids, producing phosphatases, synthesizing siderophores, and regulating ethylene synthesis in roots [32]. Hacisalihoglu and Kochian [35] reported that grains could release phytosiderophores from their roots into the rhizosphere soil, thereby increasing Zn and Fe solubility and their availability for uptake by plants. Despite extensive research on the effect of organic matter on the bioavailability of P, Fe, and Zn, we do not yet comprehensively understand the interactions of roots and biochar or their interactions with microbial inoculation and the resulting effects on the bioavailability of key nutrients in calcareous soils, due to the complex relationships between these factors under rhizobox conditions. Due to the strategic importance of wheat in human nutrition and the common deficiency of P, Fe, and Zn in wheat farms, this work investigates the effect of treatment with growth-promoting microorganisms and biochar derived from tree-pruning waste on P, Fe, and Zn bioavailability in the wheat rhizosphere under rhizobox conditions
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