Study of the phenological, vegetative and morphological characteristics of eight Populus nigra L. clones in the Albourz Research Station, Karaj, Iran

A set of phonological, vegetative and morphological data of eight clones of Populus nigra L. were collected and recorded on 9-year-old trees in the Alborz Research Station in Karaj during 2010 to 2019. The phenology results of poplar clones showed that the leaves were opened earlier in P.n.62/127 in mid-March and opened later in P.n.56/72 in mid-April than the other clones. The flowers were opened earlier in P.n.62/127 in early Marchand opened later in P.n.56/72 in early April than the other clones. Also, seed ripening and dispersal in P.n.62/149 began annually earlier than other female clones in late April. Full leaves fall were earlier in P.n.56/72 in early December and later in P.n.62/127 in late December than other clones. The shortest length of the growth period was in P.n.56/72 and longest was in P.n.62/127. The results of the vegetative characteristics analysis showed that there is the highest average volume growth increment in P.n.62/154 with 40.72 m3/ha/y. Also, study of morphological characterization showed that the trunk shape of all clones is straight except P.n.62/149 and their crown form are closed to somewhat open. There are maximum percentage of dry matter, leaf area and angle between the main vein and the second vein in P.n.62/191. Basic leaf base trait of clones is partially wedge-shaped to round wedge. There is considerable variation among the studied clones in terms of leaf and bud morphological characteristics.