Growth and accumulation of phosphorus by bean plants treated with foliar phosphate and phosphite

Abstract

Currently the use of phosphite as fungicide in agriculture or as a supplementary source of phosphorus (P) has been widespread, however little is known about its effects on phosphate nutrition of important crops such as bean plants. The present work aimed to evaluate the effect of foliar applied phosphite and phosphate on the growth and phosphated nutrition of the bean plant cultivated under low and adequate P supply conditions. The experiment was conducted in an entirely random layout, in factorial scheme 2 x 3 x 2, where two phosphate concentrations were combined in the nutrient solution (1.5 mg L-1 = low phosphorous and 20 mg L-1 = adequate phosphorous), three foliar application products: KH2PO3 (monobasic potassium phosphite), KH2PO4 (monobasic potassium phosphate) and KCl (potassium chloride) as control and two treatments referring to the number of applications (one application, at the appearance of the first trifoliolate leaf and two applications: one at the appearance of the first trifoliolate leaf and the other application at the pre-flowering), with four repetitions. Overall the dry matter, fosfatase activity, phosphorus content and phosphorus use efficiency was not were affected by the foliar application treatments. Under low readiness of that nutritient the application of foliar phosphite had a negative effect on these variables. It was concluded that foliar applied phosphite has a depressive effect on the growth of the bean plant under low supply of P. The foliar phosphite slightly affects the total concentration of P in the roots and shoots, especially under low P supply, and provides no changes in levels of soluble fractions of P in leaves under conditions of low or adequate supply this nutrient.