Variability and relationship among cuttings' rooting characters for eastern cottonwood

The influence of genotype, year and genotype x year interaction on variation of 14 characters of hardwood cutting rooting ability in field conditions, as well as relationship among them was examined in four dates of observation during the first half of vegetation period for fifteen genotypes of Populus deltoides Bartr. are presented. The influence of year rose throughout the examined period, while influence of genotype x year interaction was usually weak. Most of characters had high heritability in second date of observation (second half of May). Beside total number of first-order roots, results signify number of roots on middle and basal part of cutting, as well as shoot characters (number of leaves and shoot height), while characters describing wound roots (roots on basal cut) appeared insignificant. Examined characters were grouped according to PCA(Principal Component Analysis) in two groups, defined by number of roots in the middle part of cutting and number of roots on basal part of cutting.