Increase in phosphorus concentration reduces the toxicity of copper in wheat roots (Triticum aestivum L.)

The increase in the availability of phosphorus (P) can reduce the toxicity of copper (Cu) to plants because it favors the formation of complexes and precipitates, reducing the bioavailability of this metal. The objective of this study was to investigate the capacity of P supplementation to decrease the phytotoxicity of excess Cu in the growth and in physiological parameters of wheat plants. Plants of wheat (Triticum aestivum L.) were cultivated on sand substrate and, for 30 days, submitted to the control treatments - Hoagland & Arnon solution 100% (H & A); H&A + 47 mg P L-1 (H&A + P); H&A + 28 Cu mg L-1 (H&A + Cu); H&A + 47 mg P L-1 + 28 mg Cu L-1 (H&A + P + Cu). Plant growth, tissue nutrient concentration, photosynthetic pigment concentration, chlorophyll a fluorescence and superoxide dismutase enzyme activity in the leaves were evaluated. We observed that the treatments H&A + P and H&A + Cu provided higher height, while H&A + P + Cu provided higher dry matter yield of shoots and roots in plants. A higher Cu content in the leaves was observed in the plants cultivated with addition of 28 mg Cu L-1, however the application of Cu did not cause loss of photochemical energy and energy dissipation in the PSII antenna complex. The addition of 47 mg P L-1 provided a higher rate of electron transport in wheat plants. Therefore, wheat plants were tolerant to increasing the concentration of Cu in the culture medium and the addition of P attenuated the toxic effects caused by Cu, mainly in the roots of plants.