Phosphorus nutrition and water stress tolerance in wheat plants

The effect of phosphorus (P) nutrition and soil water availability (W) on the growth of wheat (Triticum aestivum L.) plants was studied in two pot experiments. Several levels of P supply were applied once before sowing. Before seedling establishment, the pots were kept near 100% of field capacity (FC). Afterwards, half of the pots were maintained between 60-70% FC. Control pots were kept at 85-95% FC by weighing and watering every two to three days. Several harvest of shoots were done before anthesis. At each harvest, dry matter and total P accumulation were measured in shoots. The main differences between both experiments were the way the drought stress was imposed, the levels of P supply, and the developmental stage of the plants at each harvest. In Experiment 1, no additional P resulted in a reduction of the shoot dry matter of 24 and 48% for well watered and drought-stressed plants, respectively. In Experiment 2, these reductions were of 33 and 65% for well-watered and drought-stressed plants, respectively. In both experiments, the effect of the drought-stress treatment was different at different levels of P supply. Interactions between P and W treatments were attributed to both, a less intense drought stress in PO plants, and to the enhancement of drought-stress tolerance in P100 plants (Experiment 1), and P60 plants (Experiment 2).