2018 ASHS Annual Conference

Florida’s soils for vegetable production are rich in insoluble phosphates tied up with aluminum, calcium, iron, magnesium, etc. Mobilizing the insoluble phosphates is critical for crops such as tomato (Solanum lycopersicum) to use phosphorus efficiently. The objective of this experiment is to expound the mechanisms of P bioavailability adjustment with three typical P-efficient and P-inefficient tomato genotypes – Great White Og, Japanese Black Trifele, Mariana F1 in hydroponics. Seedlings of the genotypes will hydroponically grow in modified Hoagland solution using tric-calcium phosphate (TCP) as the only P source with different concentrations of calcium or chelates such as EDTA until two sets of leaves fully expand. Chlorophyll content, pH, height, biomass, and concentration of N, P, and Ca will be determined. Our expected results will be (1) Great White Og and Japanese Black Trifele will be more P-efficient than Mariana F1; (2) Extra calcium added to the culture solution will significantly downregulate P bioavailability of TCP; (3) Great White Og, Japanese Black Trifele can absorb more calcium than Mariana F1, and hence can mobilize more P from TCP; (4) adding chelate to the solution will greatly upregulate P bioavailability of TCP. This means that calcium should not be applied with phosphate fertilizer on soil rich in calcium to enhance P use efficiency. As compared with ordinary genotype, elite genotypes may release more organic acids such as citric acid to the rhizosphere to mobilize the insoluble phosphates in soil.