Genotypic Differences in Mobilizing Insoluble Phosphates by Potato Grown in Sandy Soil

Crop production has been challenged by economic constraints, environment concerns and mineral resource depletion. Phosphorus (P), as a macronutrient, has involved in all of the above aspects. Potato is one of the widely grown crops over the world. It is imperative to improve P-use efficiency, reduce P fertilizer requirement, and minimize negative impacts on the environment. The morphological characteristics of potato are different between genotypes and play a key role in phosphate acquisition while grown under low P condition. An insoluble phosphate source, tri-calcium phosphate [Ca₃(PO₄)₂] was used to indentify P-efficient genotypes out of potato germplasm banks in hydroponics. In this research, different Ca concentrations were used to adjust the bioavailability of P in growing solution. Potato plants would need to either decrease the pH of the solution or uptake more Ca²⁺ in order to release the phosphorous from tri-calcium phosphate. We have found that increasing Ca²⁺ concentration results in decreasing plant size and increasing root/shoot ratio.  In soil, most of the phosphates are presented as non bio-available forms, mostly bind with iron, aluminum or calcium. The effective mobilization of insoluble phosphates by elite potato genotypes will contribute to improving P use efficiency. To screen potato germplasm for P-efficient genotypes, 0% and 100% of recommended P rates were applied in a pot experiment at Hastings, Florida. Chlorophyll content, photosynthesis rate and harvest index were evaluated upon seven potato genotypes.