Integrated Effect of Heavy Metal-Tolerant Rhizobacteria and Phosphorus on Maize Growth and Phosphorus Bioavailability in Contaminated Soil

Journal of Soil, Plant and Environment Pub Date : 2023-07-19 DOI:10.56946/jspae.v2i1.180

Aman Nawaz, M. Tariq, K. Khan, Mauz Ul Haq, H. Khan

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Abstract

Toxic metals significantly influence agricultural crop yields and adversely affect animals and humans. Hence, in the current study impact of different strains of phosphorus-solubilizing bacteria (PSB) and levels of phosphorus on the solubility of phosphorus and the stabilization of heavy metals in contaminated soil were studied in a greenhouse pot experiment in 2022. The PSB strains included Bacillus CUM6, Bacillus DUM7, and Bacillus PIS7. Phosphorus was applied at rates of 40, 60, and 80 kg P2O5 ha-1 using single superphosphate, with a basal dose of 120 kg N and 60 kg K2O ha-1. The experiment followed a randomized, two-factorial design. Maize plants (variety "Azam") were inoculated with the PSB strains. Consequently, combining Bacillus PIS7 with 80 kg P2O5 ha-1 significantly increased both fresh and dry maize biomass (35.33 and 24.56 g pot-1) compared to the control (unspiked soil). Phosphorus bioavailability (7.07 and 5.14 mg kg-1) significantly improved with 80 kg ha-1 phosphorus and Bacillus PIS7. Heavy metal concentrations in soil (Cd, Pb, Cr, and Ni) decreased significantly at 80 kg ha-1 phosphorus and Bacillus PIS7, and Cd concentrations in plants decreased to 3.31 mg kg-1 with Bacillus DUM7 and to 2.96, 0.42, and 1.33 mg kg-1 with Bacillus PIS7. The application of PSB strains and phosphorus fertilizer reduced heavy metal concentrations. Notably, 80 kg P2O5 ha-1 with Bacillus PIS7 showed the best performance. Phosphorus uptake increased significantly (0.106 mg pot-1), while heavy metal uptake (Cd, Pb, and Cr) decreased linearly with increasing phosphorus levels and PSB strains. Bacillus PIS7 with 80 kg P2O5 ha-1 had the lowest heavy metal translocation, doing better than the control and other PSB strains (Bacillus CUM6 and Bacillus DUM7). Soil characteristics indicated increased organic matter content (0.73%) and decreased pH (7.61) and electrical conductivity (0.17 dSm-1) with applied phosphorus and PSB strains, suggesting enhanced phosphorus bioavailability and reduced heavy metal concentrations. In conclusion, adding 80 kg P2O5 ha-1 with Bacillus PIS7 helps plants grow better when they are stressed by heavy metals and keeps Cd, Pb, Cr, and Ni stabilized in the soil.

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耐重金属根瘤菌与磷对污染土壤中玉米生长及磷生物有效性的综合影响

有毒金属严重影响农作物产量，并对动物和人类产生不利影响。因此，本研究将于2022年在温室盆栽试验中，研究不同溶磷菌菌株(PSB)和磷水平对污染土壤中磷溶解度和重金属稳定的影响。PSB菌株包括芽孢杆菌CUM6、芽孢杆菌DUM7和芽孢杆菌PIS7。磷的施用量为40、60和80 kg P2O5 hm -1，使用单一过磷酸钙，基础剂量为120 kg N和60 kg K2O hm -1。实验采用随机、双因子设计。用PSB菌株接种玉米(Azam品种)。结果表明，芽孢杆菌PIS7与80 kg P2O5 ha-1配施显著提高了鲜玉米生物量和干玉米生物量(分别为35.33和24.56 g -1)。施用80 kg ha-1磷和芽孢杆菌PIS7显著提高了磷的生物利用度(7.07和5.14 mg kg-1)。施用80 kg ha-1磷和芽孢杆菌PIS7后，土壤重金属(Cd、Pb、Cr和Ni)浓度显著降低，植物Cd浓度分别为3.31 mg kg-1和2.96、0.42和1.33 mg kg-1。施用PSB菌种和磷肥降低了土壤重金属浓度。其中，80 kg P2O5 ha-1添加芽孢杆菌PIS7效果最好。磷吸收量显著增加(0.106 mg -1)，重金属(Cd、Pb和Cr)吸收量随磷水平和菌株的增加而线性降低。施用80 kg P2O5 ha-1的芽孢杆菌PIS7的重金属迁移量最低，优于对照和其他PSB菌株(芽孢杆菌CUM6和芽孢杆菌DUM7)。土壤特征表明，施用磷和PSB菌株提高了土壤有机质含量(0.73%)，降低了pH值(7.61)和电导率(0.17 dSm-1)，提高了磷的生物利用度，降低了重金属浓度。综上所述，添加80 kg P2O5 ha-1和芽孢杆菌PIS7有助于植物在重金属胁迫下更好地生长，并保持土壤中Cd、Pb、Cr和Ni的稳定。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Journal of Soil, Plant and Environment Agricultural Sciences-Environmental Sciences

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期刊介绍： Journal of Soil, Plant and Environment is an open peer-reviewed journal that considers articles and review articles on all aspects of agricultural sciences. Aim and Scope Journal of Soil, Plant and Environment (ISSN: 2957-9082) is an international journal dedicated to the advancements in agriculture throughout the world. The goal of this journal is to provide a platform for scientists, students, academics and engineers all over the world to promote, share, and discuss various new issues and developments in different areas of agricultural sciences. All manuscripts must be prepared in English and are subject to a rigorous and fair peer-review process. Accepted papers will appear online within 3 weeks followed by printed hard copy. Journal of Soil, Plant and Environment (ISSN: 2957-9082) publishes original papers including but not limited to the following fields: Soil–plant relationships; crop science; soil science; biometry; crop, soil, pasture, and range management; crop, forage, and pasture production and utilization; turfgrass; agroclimatology; agronomic models; integrated pest management; integrated agricultural systems; and various aspects of entomology, weed science, animal science, plant pathology, and agricultural economics as applied to production agriculture. We are also interested in: 1) Short Reports– 2-5 pages where the paper is intended to present either an original idea with theoretical treatment or preliminary data and results; 2) Book Reviews – Comments and critiques of recently published books in agricultural sciences.