Phosphite supply affects phosphorus nutrition and biochemical responses in maize plants

Abstract

Phosphate (Pi) is the major phosphorus (P) form used for plant nutrition, whereas phosphite (Phi) is effective in controlling important plant diseases caused by Oomycetes pathogens. However, Phi-based products also have been widely marketed as either P fertilizer or biostimulant, such as elicitor of biochemical responses to abiotic and biotic stress agents, although these effects are not as yet well understood. This investigation has aimed to evaluate the effect of Phi supply as part of the P fertilization, and its influence on the guaiacol peroxidase activity and contents of total fenolics and lignin in maize plants. This study was conducted in an experimental design completely randomized, with 2 P concentrations (52 µM = low P concentration, and 644 µM = adequate P concentration) and 2 P forms (100% phosphate, and 75/25% as Pi/Phi, respectively). Based on studies of uptake kinetics of the 31P, it was shown Phi inhibits Pi uptake competitively in maize, regardless of the plant Pi status. Replacement of 1/4 of Pi by Phi decreased the biomass production of the plants grown under low Pi supply, but no effect was observed in the plants grown under adequate Pi supply, with the advantage of eliciting biochemical responses to stress agents, such as stimulation of the guaiacol peroxidase activity and lignin biosynthesis.