Effects of the phosphorus content in a nutrient solution (15 or 50 mg P dm-3), growing substrate (rockwool or coconut fiber) and the plant growth stage (for roots: 71 or 113 days after transplanting DAT; for leaves: 71 or 92 DAT) on the chemical composition of roots, the phosphorus content in leaves and the expression of genes encoding proteins involved in the transport of phosphorus from the medium to the plant were investigated in tomato cv. Admiro F1 grown in a foil tunnel. A fertigation system without recirculation was used. Regardless of the plant age and growing substrate, tomatoes fertilized with a nutrient solution containing 50 mg P dm-3 had more phosphorus, iron, boron and copper in roots and more phosphorus in leaves. Irrespective of the stage of plant growth and phosphorus level in the medium, the content of almost all macro- and microelements was higher in roots of plants grown in rockwool than in coconut fiber. The stage of plant growth significantly affected the mineral composition of roots as well as the P content in tomato leaves. More phosphorus was stored in roots of younger plants, whereas the phosphorus content was lower in younger than in older leaves. Our analysis of the gene expression showed that transporters encoded by LePT1-LePT4 were involved in phosphate nutrition. Expression of the genes was generally (except LePT4) higher in plants treated by the solution containing 15 mg Pdm-3 than in plants treated by 50 mg P dm-3. The expression of genes LePT2, LePT3 in roots of older plants (113 DAT) was generally higher than in young plants.

20.2.2015