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 photosynthesis, stomatal conductance, photorespiration and transpiration in tomato cv. Bos 3155 (Lycopersicon esculentum Mill.) and summer turnip rape cv. Kulta (Brassica rape L, ssp. oleifera) plants subjected to drought and salinity are reported. Glycinebetaine application increased net photosynthesis of stressed plants. This was mostly due to increased stomatal conductance following glycinebetaine application as there were no marked changes in light and CO 2 saturated rates of O 2 evolution. Moreover, glycinebetaine application resulted in a significant decrease of photorespiration both in drought- and salt-stressed plants.