ABCTRACT
In tropical regions, the vine needs different care than those required in temperate regions because of its continuous growth. Techniques such as the application of growth regulators and the alternation of pruning become essential for a satisfactory exploitation of viticulture, providing two or more crops per year. The objective of this study was to evaluate the effect of different pruning times, coupled with Etefom doses, on the 'Isabel' grapevine growth in two production cycles. Two experiments were carried out using a randomized block design, composed of 16 treatments, arranged in the 4 x 4 factorial scheme, with four replications. Four seasons of pruning were evaluated in two vintages: Winter (08/March, 22/March, 05/April and 19/April 2013) and Summer (25/August, 8/September, 22/September and 06/2013). The second variation factor consisted of four doses of Etefom (0, 720, 1440, 2160 mg L-1). The evaluated variables were the duration of the productive cycle of the vine, the diameter of the base of the branches, the length of branches, the percentage of sprouting and the number of shoots per gem. The pruning seasons factor was evaluated by the Tukey test, at 5% probability, and the factor Etefom concentrations, by regression analysis. In the Winter crop, the Isabel vine presented the smallest cycles, while in the Summer crop the cycles were longer. In the Summer harvest, pruning performed in early October provided a longer length of branches, while in the Winter season this occurs in the pruning performed in April. Concentrations of Etefom influenced vine growth only in the Summer crop, with positive linear effect for branch length and quadratic effect, increasing sprouting up to the dose of 1440 mg L-1.
Key words:
Vitis labrusca L.; Isabel cultivar; thermal demand; growth regulator.