Phosphite and phosphate in the accumulation and translocation of nutrients in common bean

Abstract

Although used as an additional nutritional source of phosphorus in agriculture, little is known about the effects of phosphites on plants. In order to evaluate the influence of phosphite and phosphate on the accumulation and translocation of phosphorus and cationic nutrients, in common bean, three experiments were conducted. In the first experiment, five concentrations (0.5 mg L^-1, 10 mg L^-1, 20 mg L^-1, 30 mg L^-1 and 60 mg L^-1) were studied in a nutrient solution combined with two forms of phosphorus [phosphate (Pi) and phosphite (Phi)]. In the second one, five Phi/Pi ratios were tested (0/100, 25/75, 50/50, 75/25 and 100/0). In the third experiment, two phosphate levels (1.5 mg L^-1 = limiting and 20 mg L^-1 = adequate phosphorus) and three treatments related to foliar fertilization (KH₂PO₃, KH₂PO₄ and KCl solutions) were combined in the nutrient solution. Phosphite via roots caused a decrease in the accumulation of phosphorus and cationic nutrients, under phosphate deficiency. P-Phi decreased the Zn/P ratio more than P-Pi, increased the translocation of P and decreased the translocation of Fe. The foliar supply of P-Phi did not affect the phosphorus nutrition of bean plants or the translocation of nutrients, but decreased the accumulation of K, Ca, Mg, Fe and Mn. Foliar P-Pi, at an adequate P supply in the nutrient solution, increased the accumulation of this nutrient.