Growth and wood production of 10 poplar clones (Populus nigra) at the second harvesting period in Kermanshah

Kermanshah province is one of the main regions of poplar cultivation in Iran. Therefore, in order to study of growth situation and wood production of poplar clones, this research was carried out in Mehregan station of Agricultural and natural Resources Research Center of Kermanshah province. Ten poplar clones (Populus nigra) were selected from selection nurseries and cultivated in a Randomized Complete Block Design (RCBD) layout with 3 replications on 3m3m distance in station and then studied in the first stage during 1993–2001. After first harvesting operation in winter 2002, we started a new investigation which lasts from 2002 to 2007. All shoots were cut except the most vigorous ones. At the end of each growth season diameter at breast height (dbh), height, diameter and height increment and mean wood volume per hectare and annual volume increment were recorded and calculated. Analysis of variance, combined analysis variance and mean comparisons were conducted for all traits over 6 years. Results indicated that P. nigra 56/75, P. nigra 63/135, P. nigra 56/52, P. nigra 56/32 and P. nigra mehregan revealed the highest productive clones which could be recommended for further cultivation in the Kermanshah province.