This study aimed to evaluate the effects of winter and green pruning for obtaining two harvests per vegetative cycle for Niagara Branca, Niagara Rosada and Concord grapevine cultivars conducted by cordon training. The experiment was performed at the Agronomic Experimental Station of Eldorado do Sul, Rio Grande do Sul state, Brazil, during the 2007/2008 harvest. Grapevines were submitted to the following treatments: T1 (winter pruning on 07/20/07 and green pruning on 11/15/07), T2 (winter pruning on 07/20/07 and green pruning on 12/17/07), T3 (winter pruning on 08/22/07 and green pruning on 11/15/07) and T4 (winter pruning on 08/22/07 and green pruning on 12/17/07). The winter pruning was performed by means of a short pruning, while the green pruning was performed by pruning the shoot, starting from the fourth bud above the last grape cluster. The grapevine production, cluster weight, total soluble solids (SST), total titratable acidity (ATT), SST/ATT ratio, water potential in the leaf and leaf/fruit ratio were evaluated for the two crops. Results demonstrated that a winter pruning associated to a green pruning permitted to obtain two harvests of 'Niagara Branca', 'Niagara Rosada' and 'Concord' cultivars per vegetative cycle. The treatment T3 was the most efficient to obtain a second harvest in the same vegetative cycle. The Niagara Branca showed high potential for a second harvest when compared to the Niagara Rosada and Concord grapevines cultivars. Grapes under the green pruning had lower SST, larger ATT and smaller SST/ATT ratio compared to grapes from regular harvest.
pruning management; cultural practices; plant physiology; Vitis labrusca
