Photosynthetic response of drought- and salt-stressed tomato and turnip rape plants to foliar-applied glycinebetaine

The effect of foliar application of glycinebetaine (50 and 100 mM) on photo synthesis, stomatal conductance, photorespiration and transpiration in toma to cv. Bos 3155 (Lycopersicon esculentum Mill.) and summer turnip rape cv. Kulta (Brassica rapa L. ssp. oleifera) plants subjected to drought and sali nity are reported. Glycinebetaine application increased net photosynthesis of stressed plants. This was mostly due to increased stomatal conductance f ollowing glycinebetaine application as there mere no marked changes in ligh t and CO2 saturated rates of O-2 evolution. Moreover, glycinebetaine applic ation resulted in a significant decrease of photorespiration both in drough t- and salt-stressed plants.