Moderate water stress affects tomato leaf water relations in dependence on the nitrogen supply

Abstract

The responses of water relations, stomatal conductance (gs) and growth parameters of tomato (Lycopersicon esculentum Mill. cv. Royesta) plants to nitrogen fertilisation and drought were studied. The plants were subjected to a long-term, moderate and progressive water stress by adding 80 % of the water evapotranspirated by the plant the preceding day. Well-watered plants received 100 % of the water evapotranspirated. Two weeks before starting the drought period, the plants were fertilised with Hoagland's solution with 14, 60 and 110 mM NO3- (N14, N60 and N110, respectively). Plants of the N110 treatment had the highest leaf area. However, gs was higher for N60 plants and lower for N110 plants. At the end of the drought period, N60 plants showed the lowest values of water potential (Ψw) and osmotic potential (Ψs), and the highest values of pressure potential (Ψp). N60 plants showed the highest Ψs at maximum Ψp and the highest bulk modulus of elasticity. © 2007 Institute of Experimental Botany, ASCR.