Phenological characteristics of different Poplar species at Yassoj Experimental Station

In order to collect and study the morphological- phenological characteristics and ecological requirements of different poplars, 40 most successful clones were selected from Selection Nursery and transferred into Mother Individual collection by 5*5 and 4*4 m intervals for open and closed crown species, respectively, using five seedlings for each planting line. The collection is located in western Iran, near Yasooj in Kohgiluye and Buyerahmad province. The studied growth characteristics contained of diameter and height which recorded at the end of growth period. The phenological phenomena consisted of were flower, leaf, seed development and leaf fall. Furthermore, daily maximum and minimum temperature data was recorded all over the growth period. The results showed that the poplar biotic activity usually starts at March and ends at November. The phenological phenomena at different poplar species and clones started in different dates due to variation in species and clones genetic characteristics and climate condition which varied from few days to few weeks. Beginning of phenological phenomena of a species is usually correlated to air temperature (maximum, minimum and average) at beginning of growth period, whereas its end is often correlated to photoperiodism and minimum air temperature. Leaf discolor and fall date at different poplar species varied from 6th September to 6th November due to shorter day time and cooler air temperature. The species P. alba and P. euramericana started their phenological activities earlier than the other species and the clones of P. alba and P. deltoides had longest biotic activities. The clones of P. alba were more sensetive to forest, whereas the clones of P. euramericana and P. deltoides were very sensetive to pests, particularly to beetle xylophagus (Melanophila sp.). About 70% of P. euramericana clones were complete died due to damage caused by this pest.