The impact of leaf removal on mechanical and chemical composition of Merlot grape variety

Vrijeme izvođenja zahvata djelomične defolijacije još uvijek je tema brojnih istraživanja. Ukoliko se provodi u periodu cvatnje smatra se ranom, a između oplodnje i šare kasnom defolijacijom. Cilj ovog rada bio je istražiti utjecaj djelomične defolijacije provedene u četiri različita termina (prije cvatnje i oplodnje, neposredno nakon cvatnje i oplodnje, u fazi zatvaranja grozdova i u šari) na uvometrijske vrijednosti i mehanički sastav grozda sorte Merlot u uvjetima Zagrebačkog vinogorja, podregije Prigorje-Bilogora, proizvodne godine 2016. Djelomična defolijacija nakon cvatnje i oplodnje utjecala je na smanjenje prosječne mase grozda te prosječne mase bobica koje su povezane sa boljom kvalitetom grožđa. Djelomična defolijacija u fazi šare pokazala je najviši prinos po trsu te broj grozdova u odnosu na ostale varijante djelomične defolijacije, a u moštu te varijante izmjerena je viša koncentracija šećera te niži pH u odnosu na kontrolu.Timing of partial defoliation is still the subject of numerous studies. Partial defoliation conducted during the flowering period is considered to be early, and if it is conducted between fertilization and veraison is considered to be late. The aim of this research was to investigate the influence of partial defoliation (which was conducted in four different periods: before flowering and fertilization, after flowering and fertilization, in the pea size of the berry and at the veraison) on the uvometric values and the mechanical composition of the Merlot cultivar under the ecological conditions of the Zagreb vineyard, subregion Prigorje-Bilogora, year 2016. Partial defoliation after flowering and fertilization resulted in a decrease of the average cluster weight and the average weight of berries associated with more quality. Partial defoliation in the period of veraison affected the highest yield per vine and the largest number of clusters per vine when compared to other variants of partial defoliation. Also, the higher concentration of sugar and the lower pH value was measured in must