Climate and weather conditions are important factors influencing grapevine growth and fruit quality. Cooler regions are expected to be unsuitable for grape growing due to insufficient maturation and variability of quality parameters. Therefore, a field trial was conducted, aimed to determine the effect of pruning time on low cordon cane (CP) and spur pruned (SP) grapevines of the hybrid cultivar Hasanski Sladki in a cool climate conditions. A vineyard, with the low double trunk (25 cm in height) training system, was established at the experimental station of the Estonian University of Life Sciences (58°23’17’’ N, 26°41’50’’ E) in June 2007. The treatments were carried out in autumn after leaf fall and in spring at the two leaf phase in 2010/2011 and 2011/2012. Pruning time affected grape maturity parameters depending on pruning method. Autumn SP increased the soluble solids content from 18.5 to 19.8 °Brix in 2011 and from 17.1 to 18.0 in 2012. Titratable acids content was high in both experimental years ranging from 1.3 to 2.1 g 100 g^-1, and only autumn CP decreased it. Pruning in spring significantly decreased the soluble solids/ titratable acids for both pruning methods. The timing of SP affected the maturity index (MI = °Brix × pH²) variably; in 2011, spring pruning decreased the index whereas; the index was increased in 2012. Spring pruning decreased the total phenolics up to 22% in both treatments in the two years mean. In CP, spring pruning increased anthocyanins content from 31 to 77 mg 100 g^-1 in 2012.

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