2018 ASHS Annual Conference

Phosphorus is the second most essential nutrient element for plants, following nitrogen. Phosphorus fertilizer is made from mining phosphate rock, however, these reserves are finite and depleting. With increasing global demand for fertilizer and a shrinking supply, it is imperative to find efficient means to utilize phosphorus. Phosphorus occurs in soils as organic (Po) and inorganic (Pi) forms, all mainly insoluble and unavailable. Growers commonly use fertilizer as an insurance for crop production, but over-fertilization commonly occurs as a result which causes eutrophication. Some cultivars are able to mobilize insoluble phosphates due to mechanisms such as changing root architecture, microbial associations, or exuding organic acids. The objective of this experiment is to examine seven tomato (Solanum lycopersicum) genotypes collected from a pre-identification trial– Great White Og, Japanese Black Trifele, Mariana F1, Juliet F1, Cherokee Green, Chef’s Choice Orange, and Pink Bumble Bee – under conditions of insoluble phosphate, tri-calcium phosphate, to identify elite genotypes. This trial will be carried out by growing tomato seedlings in a 10% Hoagland solution-based hydroponics system until two sets of leaves fully expand. Chlorophyll content, pH, height, biomass, and concentration of N, P, and Ca will be determined. Based on the pre-identification data, we hypothesize that Great White Og, Japanese Black Trifele, and Mariana F1 will have the lowest P content, highest P content, and highest Ca content respectively. We also hypothesize that the P-efficient tomato (Japanese Black Trifele) will have greater height, greater biomass, greater root to shoot ratio, greater chlorophyll content, and lower pH. These results will help to aid breeders in selecting for traits that are associated with phosphorus use efficiency. Growing phosphorus efficient crops can minimize environmental damage from over-fertilization and can slow depletion of the finite phosphorus reserves.