Influence of cane girdling and plastic covering on leaf gas exchange, water potential and viticultural performance of table grape cv. Matilde

Canes of field-grown uncovered and covered (plastic film) table grapes, cv. Matilde, were girdled at veraison. Leaves of girdled vines displayed lower rates of transpiration on a leaf area basis and lower rates of CO2 uptake; stem and leaf water potentials were decreased. Both, covering and cane gir dling stimulated vegetative growth and increased leaf area per vine. Howeve r, sugar accumulation in berries and fruit quality were not affected by can e girdling and were slightly reduced by covering. Therefore, harvesting dat es were not advanced. Cane girdling appeared to influence carbohydrate part itioning by stimulating shoot growth at the expense of fruit production. It is concluded that the stage of rapid sugar accumulation was not yet reache d by the time girdling took place. The development of a larger transpiring leaf surface area per vine is supposed to have lowered the vine water statu s.