engleski

Canopy management practices for cv. Istrian Malvasia

The impact of shoot thinning and timing and severity of partial defoliation on yield components, vegetative growth and fruit composition of cv. Istrian Malvasia (Vitis vinifera L.) was investigated. The investigation was divided in two separate studies. In the first study two intensities of shoot thinning (approximately 7 or 11 shoots per vine left after shoot thinning) were combined with two options of partial defoliation (control vines without defoliation and vines with four leaves per shoot removed at berry set). In the second study a combination of defoliation severity (four or eight leaves per shoot removed) and defoliation timing (pre-bloom or at berry set) were investigated and compared to control treatment on which defoliation was not performed. Treatments with lower number of shoots per vine had lower yield per vine, lower number of clusters per vine, higher cluster weight, higher yield per shoot and slightly higher soluble solids than treatments with higher number of shoots per vine. The defoliation of four leaves per shoot had not any effect on the productive characteristics of Istrian Malvasia vines, while pre-bloom removal of eight leaves per shoot reduced yield per vine, yield per shoot, cluster weight and number of berries per cluster. Lateral regrowth was in most cases higher on defoliated vines and it was more intensive with higher severity of defoliation, while total leaf area per vine did not vary significantly among treatments. Leaf area/yield ratio was not affected by defoliation of four leaves per shoot, while it was higher in treatments with eight leaves removed and especially in pre-bloom treatment, which also had significantly higher Brix than control and treatments with four leaves per shoot removed. Defoliation of four leaves per shoot performed either pre-bloom or at berry set had only a mild effect on Brix in comparison to control treatment. It is concluded that the practices of shoot thinning and pre-bloom defoliation of eight leaves per shoot reduce yield and improve Istrian Malvasia basic grape composition, while defoliation of four leaves per shoot affects only slightly yield components and basic fruit composition of Istrian Malvasia vines.

partial defoliation; shoot thinning; Istrian Malvasia

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