Influence of Soil Water Stress on Wilting and Water Relations of Differently Osmotically Adjusted Wheat Plants

S ummary During a pretreatment period of 1 week, spring wheat plants ( Triticum aestivum , L., cv. ‘Sappo’) grown in a sandy soil in pots were adjusted to three levels of soil water osmotic potential induced by watering the plants with a nutrient solution (minus 0·5 bar) and further additions of KNO 3 (minus 3 and minus 6 bar). After leaching of the soil, the plants were exposed to two drying cycles separated by rewetting. With severe water stress at the end of drying cycle 1, reduction of wilting was highly correlated with lowering of leaf osmotic potential due to the KNO 3 pretreatment. Turgor potential was highest and decreased at lowest soil water matric potentials in KNO 3 pretreated plants. Recovery after rewatering was seemingly most accelerated in KNO 3 pretreated plants due to a larger potential difference between leaf and soil water. The leaf and soil water matric potentials at which stomata closed were lowered as a result of both KNO 3 pretreatment and the effect of previous water stress on leaf osmotic potential.