Concurrent action of salinity and water stress on leaf gas exchange and water relations in tomato

Abstract

Tomato plants (Lycopersicon esculentum Mill.) grown in pots were irrigated for four weeks with 0.04,0.08,0.12 molai NaCl solutions and a control solution. Half the plants in each salt treatment were water stressed for five days. Single leaf gas exchange at near ambient C02, water consumption and plant water relations were measured. Both salt and water stress reduced growth, water potential and gas exchange rates. Well watered plants were only slightly stressed by a salt concentration of 0.04 molai, while plant growth continued at a concentration of 0.08 molai. Short-term water stress imposed greater stress than long-term salt stress; carbon exchange rate (CER) was partially limited by stomatal closure in the case of water stress and by mesophyll limitation with longer-term salinity treatments. Osmoregulation in response to salt stress did not impart particular tolerance to transient water stress.