Effect of varying combination of P and Zn in chelater-buffered solution on P-Zn interaction in wheat seedling

A nutrient solution experiment with chelater-buffered solution was conducted to investigate the interactions of Zn and P nutrients in wheat seedlings. Zn rates were supplied at three levels of deficient (0 μmol·L^-1), normal (3 μmol·L^-1) and excess (30 μmol·L^-1), while P was supplied at 0 mmol·L^-1 (insufficiency), 0.6 mmol·L^-1 (normal) and 3.0 mmol·L^-1 (excess). The results show that wheat seedling growth slows under deficient or excess P and Zn. Growth retardation is greater under deficient P than under excess P, and under excess Zn than under deficient Zn. The effects of deficient P and excess Zn mainly embody at tillering and shoot biomass accumulation. An obvious antagonism exists in wheat seedling roots under excessive P supply, resulting in decreased Zn content of roots. However, Zn translocation rate to shoots increases under normal and excess P dose. Large amounts of P accumulate in wheat leaf under Zn deficiency. The rate of P translocation to shoots decreases with increasing supply of Zn. Under normal P and Zn supply, P-Zn interaction benefits Zn absorption and translocation. It, however, inhibits P translocation to leaves.While chlorophyll SPAD decreases under deficient P and Zn dose, it increases under normal P and Zn supply. Wheat leaf SOD and POD activity is high while CAT activity is low under deficient P. SOD activity is low under both deficient and excess Zn. The activities of POD and CAT are high under deficient Zn, which decrease with increasing Zn dose. The study shows distinct antagonism between Zn and P in the root system, which might be the case for the other part of the wheat crop. The antagonism does not only occur under abnormal supplies of P and Zn, but also under balanced P and Zn doses.