Investigation on phenolory of different poplar clones in collection at Karaj research station during 1997 1998 period

The prerequist in planning and implementing any research project is possession of preliminary and basic data and information. Phenological information are required by researchers of various poplar trees research projects. The purpose of this study was to obtain and collect such essential information. In this study the phenology of 30 Poplar clones at Karaj collection during 1997 and 1998 were studied. Factors such as anthesis, foliation, seed ripeness, defoliation, daily minimum and maximum temperature at the site were considered. The results of this study may be summarized as follows: Living activity of various poplar clones starts in the period between early Mars until late April and ends up between middle of November until late December. The time difference of few days up to few weeks exist in the appearance of various life phenomenas. Initiation data for poplar living activities at the start of growth season depends on the daily temperature. Therefore due to the fact that mean, minimum and maximum temperature of early period of growth season in 1998 was higher than relevant temperature for 1997, life phenomenas of this year appeared one week earlier than 1997. However defoliation is mostly influeneced by photoperiod and minimum temperature and as a result of shortening the daylight time and dropping the temperature from middle of September up to middle of October, leaf color changes and sheding of different poplar clones starts. Furtheremore time difference of the appearance of living phenomenas and period of any phenomenas in different poplar clones was shorter in 1998 compared to 1997. Investigated poplar clones were groupped based on living activities periods. These clones such as P. e. arges grandis and P. e. marilandica with short growth periods are suitable for cold regions and clones such as P. d. 69/55 and P. e. triplo with longer growth periods are suitable for planting in the warmer regions of our country.