influence of partail defoliation on yield and chemical composition of grape variety 'Cabernet sauvignon' (Vitis vinifera L.)

Defolijacija je zahvat zelenog reza kojim se uklanja 3-4 bazalna lista, kako bi se poboljšala mikroklima trsa. Defolijacijom dovodimo više svijetlosti u zonu grožđa, smanjujemo zelenu masu, stvaramo uvjete za bolje provjetravanje, te tako smanjujemo opasnost od bolesti. Istraživanje je provedeno na način da su se uklanjala četiri bazalna lista na svakoj mladici u četiri različita termina: prije cvatnje (D1), neposredno nakon cvatnje i oplodnje (D2), u fazi zatvaranja grozda (D3) i u trenutku šare (D4). Rezultati su pokazali da je za povedanje prinosa najbolje obavljati defolijaciju u trenutku šare (D4), a za povedanje ukupne kiseline, antocijana i flavonola defolijaciju najbolje obavljati neposredno nakon cvatnje (D2). Sadržaji šedera i flavanola smanjeni su u svim varijantama defolijacije.Defoliation is an operation where we remove 3-4 basal leaves to improve microclimate parameters around berry clusters. By doing this, more light comes to berry clusters, we reduce the amount of shoots surrounding them and we reduce the posibility of developing grape diseases. Research was conducted by removing 3-4 basal leaves in 4 different periods: pre-bloom (D1), after blooming (D2), pre-veraison (D3) and at veraison (D4). Results showed us that increased yield was accomplished by removing basal leaves at veraison (D4), but to increase acidity, anthocyanins and flavanols we have to do this post blooming (D2). Results also showed that content of sugars and flavanols are decreased in all variations of defoliation