Influence of partial defoliation on the chemical composition of grapes of the 'Graševina' variety in conditions wine growing region Srijem

Defolijacija je zahvat zelene rezidbe kojim se uklanjaju listovi vinove loze. Ovaj zahvat može se koristiti u različitim periodima vegetacije vinove loze. Ovisno o periodu defolijacija može biti rana ili kasna. Rana defolijacija podrazumijeva period uklanjanje lišća prije cvatnje, do zametanja bobica, dok se kasna defolijacija izvršava početkom šare bobica. U ovom radu istraživana su tri termina defolijacije te njihov utjecaj na kemijski sastav grožđa. Defolijacija nakon cvatnje rezultirala je s najvišim sadržajem ukupnih polifenola, defolijacija u zoni grožđa početkom šare postigla je najviši sadržaj šećera i ukupnih kiselina, dok defolijacija iznad zone grožđa početkom šare sveobuhvatno imala je statistički najmanje značajan utjecaj na kemijski sastav grožđa sorte Graševina.Defoliation is operation of leaf removal from the vine. This operation can be used during various periods of vegetation. Depending on period defoliation can be early or late. Eary defoliation preformed in the period before blooming until berry development, while late defoliation is preformed at the verasion. In this research defoliation was preformed at three stages and the impact on chemical composition of grape was evaluated. Defoliation after berry development had the highest amount of total polyphenols, defoliation in zone of grapes at the begining of verasion had the highest amount of sugar and total acids, while apical defoliation did not significantly affected chemical composition of 'Graševina' grape