Effect of low phosphorus and iron-deficient conditions on phytosiderophore release and mineral nutrition in barley

To investigate the effect of low phosphorus (P) conditions on phytosiderophore (PS) release and mineral nutrient status in graminaceous plants, an experiment was conducted in a phytotron with barley plants grown in iron-deficient (Fe0) nutrient Solutions with four P levels (0.5, 5, 50, 500 [control] mu mol L-1) at pH 6.5 for 21. days after treatment (DAT). The results showed that the growth and chlorophyll index of plants cultured under low P conditions (0.5, 5 and 50 mu mol L-1) were higher than those of the control plants. The accumulation amount (mg or mu g/plant) of mineral nutrients in shoots was higher for potassium, iron and copper in plants in the low P treatment than in the control plants. The accumulation of PS in roots and the amount of PS released from the roots at 14 DAT were lower in plants in the Fe0 and low P treatments. These results indicated that low P depressed PS release from roots and PS accumulation in roots in Fe0 barley. This might result from the higher Fe content in shoots and the alleviation of Fe chlorosis with low P treatment of plants. These results showed that low P treatment enhanced the growth, chlorophyll index and Fe mobilization to shoots in Fe0 barley. Low P conditions alleviated Fe-deficiency symptoms, suggesting that P is physiologically competing with Fe in plant tissues.