عنوان مقاله [English]
The expansion of Poplar plantations has been stated to play a decisive role by increasing the amount of wood production, reducing the wood import as well as by creating employment rate in wood and paper industry. Here, a number of 34 native and exotic Poplar clones were explored in a two-year study in a selected nursery of the Chalaki research station in Gorgan. The aim was to examine the effects of stump cutting on the growth in different ages (1/1 and 1/2 age), the results of which will support the decision making process when choosing the suitable clones for Poplar plantations. The sample seedlings were provided by planting 100 cuttings in 20×130 cm spacing grid. The examined clones were selected from 6 species including Populus nigra (12 clones), P. alba (6 clones), P.x.euramericana (9 clones), P. deltoids (5 clones), P. trichocarpa (one clone) and P. caspica 80.4 (one clone). Following the first growth period, all seedlings were cut from the ground level. In the subsequent year, half of the seedlings (i.e. one-year old stems and two-year old roots) were bred. Then, Collar diameters and heights were measured for all the seedlings, followed by calculating the mortality rate and the rate of growth change. The one-way analysis of variance (ANOVA) and Duncan test were used for comparing the means. The stump cutting was shown to bear a significant positive effect on the growth rate as well as on the uniformity of the seedlings in different clones. The changes in height growth among different poplar groups showed a significant difference (P<0.05). Moreover, the maximum and the minimum changes in height were returned by P. euramericana (70%) and P. nigra (46%), respectively. Native clones of P. caspica 80.4 and P. alba showed maximum percent of height growth changes with their substantial rates of 143% and 109% respectively.