Abstract
Phosphate is one of the most important nutrients for plant growth and development, and only 0.1% of the phosphate in soils is available to plants. Currently, the use of excess phosphate fertilizer has caused surface and ground water pollution and water eutrophication, resulting in algal blooms in lakes and oceans. Therefore, it is imperative to explore alternative ways to solve these problems for sustainable agricultural production and improvement of soil fertility, while protecting the environment. Microorganisms from the rhizosphere and within plants are able to solubilize insoluble soil phosphate, making it available to plants. Five high phosphate solubilizing bacteria from our bacterial endophyte library were chosen for this study and identified as Pantoea vagans IALR611, Pseudomonas psychrotolerans IALR632, Bacillus subtilis IALR1033, Bacillus safensis IALR1035 and Pantoea agglomerans IALR1325. All five bacteria significantly promoted tall fescue growth in vitro. Greenhouse experiments showed that IALR1325 significantly promoted pepper and tomato growth, and IALR632 was the best in promoting tomato growth. In addition, all these bacteria had extracellular acid phosphatase and phytase activities. One of the mechanisms for phosphate solubilization by bacteria is pH reduction caused by gluconic acid production. Our results indicate that P. agglomerans IALR1325 is a promising bacterium for future applications.
Highlights
Accepted: 9 September 2021Phosphate is one of the most important nutrients for plant growth and development and plays important roles in all metabolic processes [1,2]
Based on our preliminary results for phosphate solubilization and 16S rRNA sequences, five high phosphate solubilizing bacteria representing different species were chosen for further study
The phylogenetic tree constructed with verified bacterial species from GenBank confirmed the species level identity of bacterial endophytes used in this study (Figure 1)
Summary
Accepted: 9 September 2021Phosphate is one of the most important nutrients for plant growth and development and plays important roles in all metabolic processes [1,2]. Phosphate is abundant in soil but is mostly insoluble due to P fixation [3], which causes P deficiency. 0.1% of phosphate in soils is available to plants [4]. In order to increase yields, the use of excess phosphate fertilizer has caused surface and ground water pollution and promoted water eutrophication due to running off, which results in algal blooms and adversely affects water quality. Most soluble chemical P fertilizers can be fixed with Ca2+ , Fe3+ and Al3+ to form insoluble calcium phosphate, ferric phosphate and aluminum phosphate, respectively, which leads to the rapid formation of poorly available P for plants after fertilizer application [6]. There is a dilemma with respect to phosphate in soil. The total phosphate content is abundant in soil; only a minor amount is available to plants
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