Istraživanja su provedena u Orahovici na tri sorte lijeske: Istarski duguljasti, Rimski i Haleški. Pojedinačno je promatrana cvatnja muških i ženskih cvjetova prema čemu je izrađen fenogram cvatnje. Cilj istraživanja je utvrđivanje fenofaza cvatnje lijeske, pojave homogamije i dihogamije te ovisnost cvatnje o klimatskim prilikama. Pokazalo se da pojava protandrije, protoginije i homogamije nije isključivo sortno svojstvo već je ovisna o sezonskim klimatskim prilikama. Na području Orahovice najčešće se pojavljuje protoginija. Protandrija se pojavljuje rjeđe i to u godinama s većom sumom srednjih dnevnih temperatura u dekadi koja prethodi cvatnji. Na osnovi izrađenog fenograma cvatnje vidljivo je da se tri odabrane sorte dobro nadopunjuju i međusobno osiguravaju dobro oprašivanje bez obzira na nepovoljne klimatske prilike koje vladaju za vrijeme cvatnje.Research was conducted on three hazel cultivars: Istarski duguljasti, Romische Zellernuss and Hallesche Riesen in Orahovica. Flowering of male and female inflorescences was observed individually according to which flowering phenogramme was completed. The aim of this research was to determine the flowering pattern of hazel, occurrence of homogamy and dichogamy and influence of weather conditions on flowering.
It was observed that appearance of protandry, protogyny and homogamy is not solely varietal characteristic, but depends on seasonal climatic conditions as well. In the Orahovica area protogyny mostly occurs. Protandry occurs rarely, mainly in the years with higher sum of average daily temperatures in a decade that precedes the flowering. Based on created flowering phenogramme it is visible that all three cultivars complement each other and guarantee good pollination irrespective of possible adverse climatic conditions that can occur during flowering
