M. GOSPODINOVA1, D. DOCHEV1, V. DJOVINOV1, K. KOLEV1, A. ZHIVONDOV1 and P. BOXUS2
1 Fruit Growing Institute, BG - 4004 Plovdiv, Bulgaria
2 Experimental Station of Vegetable and Fruit Crops, B - 5030 Gembloux, Belgium
GOSPODINOVA, M., D. DOCHEV, V. DJOVINOV, K. KOLEV, A. ZHIVONDOV and P. BOXUS, 2006. Effect of regulated deficit irrigation, soil and nitrogen application rate on some biological properties of young sweet cherry trees on clonal rootstock GM9. Bulg. J. Agric. Sci., 12: 743-750
The need for intensifying sweet cherry production in Bulgaria necessitates the use of dwarfing rootstocks, such as the recently developed clonal rootstock Grand Manil. Experiments were carried out with cv. Stella/GM9 on three soil types - Fluvisol, Chromic-Luvisol and Vertisol, using drip irrigation. A RDI (Regulated Deficit Irrigation) regime, used in Southern France, was verified and rated under the climatic conditions in S. Bulgaria. The soil water potential (ψsoil), stem water potential (ψstem), stomatal conductance, photosynthesis and transpiration rate, growth and yield were studied. In the pre-planting application of PK + N, an induced plant water stress, as a result of a ψsoil and ψstem increase, was established. In Fluvisol, this negative effect of the N-application rate was not noted. Critical values of the ψsoil and ψstem, indicating a disturbance of the water balance of the plants, and a water stress were established as well as the optimum N-application rate on the three studied soils. The assessed RDI regime proves adequate for the Fluvisol and insufficient for the Chromic-Luvisol and Vertisol.