EFFECTS OF EARLY WATER STRESS ON GRAPEVINE (VITIS VINIFERA L.) GROWING IN CV. SYRAH

Water deficit is a major issue in grapevine production. The purpose of this research was to identify the effects of early water stress on the growing and yield of grapevine. The research was performed in SupAgro/INRA in Montpellier using the ECOTRON System, France. Syrah/SO4 graft combination was used as a plant material. 7 years old and potted grapevines were grown/kept in natural vineyard conditions. A completely randomized block design was used: WS0(control) 0; -0.2 MPa, WS1 -0.2; -0.4 MPa, WS2-0.4; -0.6 MPa, and WS3 -0.6; -0.8 MPa respectively. The limitation of water was started the 15th of May in the 17th E-L stage and ended about the 15th of June in the 27th E-L stage. Analysis of variance was performed on the agronomic data using the MSTAT-C. Means were separated using the LSD test (P < 0.01). It was determined that there was a reduction in vegetative growth. Also the predawn leaf water potential results showed differences between the irrigation levels. These results indicated that the lowest psi(pd) in WS3 was -0.80 MPa. There was an approximately 55 cm difference determined between the control and other groups in shoot lenghts. Besides that the average cluster weight was reduced by about 41% and the yield by about 28% under the early water deficit conditions.