Location: Horticultural Crops ResearchTitle: Evaluation of bacillus seed coatings on soybean phosphorus uptake in an oxisol fertilized with 32P-labeled hydroxyapatite
|LI, CHONGYANG - University Of Illinois|
|MANAVALAN, LAKSHMI - Bayer Cropscience|
|PARIKH, SANJAI - University Of California, Davis|
Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2021
Publication Date: 4/21/2021
Citation: Li, C., Rippner, D.A., Manavalan, L.P., Parikh, S.J. 2021. Evaluation of bacillus seed coatings on soybean phosphorus uptake in an oxisol fertilized with 32P-labeled hydroxyapatite. Plant and Soil. https://doi.org/10.1007/s11104-021-04941-w.
Interpretive Summary: Phosphorus is a limiting nutrient for plant growth in many soils. In the current study, seeds were coated with a bacteria to help increased available phosphorus from fertilizers. To determine the source of phosphorus in the plants, we used radioactive phosphorus. In acidic soils, the bacillus seed coatings helped the plants take up more fertilizer P than the uncoated seeds. In non-acid soils the seed coating did not help the plants take up more fertilizer P than the uncoated seeds. Our results show that bacterial seed coatings may help growers produce better crops in acid soils with low inherent phosphorus fertility.
Technical Abstract: Aims Phosphorus (P)-solubilizing microorganisms (e.g. Bacillus species) paired with modern seed coating techniques are promising biological tools to promote crop growth via stimulating beneficial microorganisms that effectively colonize the seedling rhizosphere. This study evaluated P uptake of four soybean seed treaments in an oxisol fertilized with isotopically (32P) labeled hydroxyapatite. Seeds included: no coating (NC), fungicidal coating (FC), Bacillus coating (BC), and fungicidal + Bacillus coating (FBC). The bacterial strain was Bacillus velezensis strain EX180863. Treatments also included soil with and without lime amendment (as Ca(OH)2), pH ~6 and ~4.8, respectively. Methods Soybeans were grown in a growth chamber. A non-destructive method was used to measure 32P uptake from labeled fertilizer during the soybean vegetative stages by autoradiography. Plants were harvested before entering reproductive stages and plant performance, together with various post-harvest soil properties, were evaluated at harvest. Total P and radioisotope (32P) in plant tissues were quantified using different techniques to distinguish soil- and fertilizer-derived P. Results Without lime, BC and FBC treatment assimilated more 32P than NC, starting from late vegetative stage (V4). Assuming the ratio of 32P/31P was constant when P flowed from the labeled hydroxyapatite to plant tissues, BC and FBC contained 50-60% more fertilizer derived P than NC at harvest. Post-harvest soil pH decreased by ~0.2 units from BC and FBC compared to NC. In contrast, when limed, soybean plants from BC seeds did not take up more P, but the bacteria enhanced root biomass. Conclusions Effect of B. velezensis strain EX180863 coatings on soybean growth were pH dependent with FBC providing additional benefits compared to BC alone: when unlimed, P uptake was maximized under FBC while FBC had the greatest root biomass when liming the soil.