VEGETATIVE AND REPRODUCTIVE GROWTH POTENTIAL OF VITIS VINIFERA L. CV. MONTEPULCIANO GRAPEVINES TRAINED TO TENDONE SYSTEM

A study was conducted to evaluate the vegetative and reproductive capacity of 7Montepulciano9 grapevines trained to the Tendone trellis system. The study was conducted during 2001 and 2002 in a 6-year old drip-irrigated vineyard located in southern Italy. Vine density was 1,600 vines per ha. Three crop load treatments were imposed at fruit set: UT L unthinned control with approximately 70 clusters per vine (~ two clusters per shoot), T50 L in which 50% of the clusters were removed (~ one cluster per shoot) and T75 L in which 75% of the clusters were removed (~ one cluster every two shoots). Vegetative and reproductive growth was evaluated by measuring leaf area development, leaf gas exchange and water potential, canopy light interception and shoot and cluster growth. Leaf area development was measured by collecting shoots from mature vines on a monthly basis, beginning 15 days after budbreak until the end of September. Transmitted photon flux density (PFDt), on a 0.10 m by 0.20 m grid at the soil surface, and incident PFD (PFDi) above the canopy were measured with a Ceptometer (Decagon D., Accupar) to calculate the intercepted light (PFDin). Gas exchange parameters were measured on both shaded and sun-exposed leaves. Preliminary results indicate that vines trained to the Tendone system have a high capacity to produce vegetation and fruit. Intercepted light reached a maximum value of about 80% at maximum leaf area index (LAI). Thinned vines had significantly greater shoot leaf area, LAI and PFDin as compared to the unthinned control. There were no differences among treatments regarding leaf water potential, photosynthetic rate and apparent quantum efficiency.