Comparison of growth and morphological traits among rooted cuttings of Populus caspica Bornm. provenances

In a study of growth and morphological differences among Populus caspica Bornm., trees within Hyrcanian biogeographical region, 15 stands were selected from which one-year cuttings were cut from three plus-trees in each stand. The cuttings were planted in March 2017 at Chamestan Research Station, and the rooted cuttings were cut from the collar base after one year. Cuttings were separated from the one-year sprouts in the next winter and planted based on Randomized Complete Block Design with three replications. We sampled five leaves of each stand-tree seedling on late June and 17 leaf morphological and growth traits as well as collar diameter and height of the rooted cuttings. Data were analysed by hierarchical cluster analysis, two-way ANOVA and Duncan comparison of means test. Four groups were separated according to cluster analysis, among which rooted cuttings from Golestan province showed the highest morphological diversity. The maximum and minimum collar diameters and height growth were observed in seedlings originated from Rostam-Abad (Guilan province) and Golestan National Park (Golestan province) respectively, yet they were similar in some of their morphological traits like their minimum leaf width at 10% of the total length, maximum leaf width, lobe depth and number of veins, which id presumably due to the location of their mother stands at the border of Hyrcanian and Irano-Turanian regions. Thus, they can be considered as morphological traits of P. caspica in the ecotone regions. However, the two regions had a high value for conservation, especially in Rostam-Abad due to high growth rate as well as prominent morphological differences in comparison with the other genotypes. Therefore, they are suggested for being integrated in tree improvement programs in the future.