The effect of soil-water stress on the absorption of soil phosphorus by wheat plants

A study of the effect of soil-water stress and phosphorus level on the efficiency of phosphorus absorption (micrograms phosphorus per milligram oven-dry root per day) and growth by young wheat plants grown on a lateritic podzolic soil showed that absorption was not affected by increasing soil-water stress, provided the plants were not damaged by wilting. In experiments where the water-stress treatment was imposed for only a few days it was found that the rate of phosphorus absorption was reduced after the plants had been subjected to a period of wilting. The results indicate that available soil phosphorus was derived mainly from fine pores undrained at suctions approaching 15 atm. The concentration of available phosphate in these pores may have been considerably higher than earlier estimates of the phosphate concentration in the soil solution. The absorption of phosphorus increased with increasing soil phosphorus potential for all levels of water stress.