The introduction of successful poplar clones in the northeast of the country

This study was aimed at comparing the yield of native and non-native clones at the research site of Bojnourd in North Khorasan province. A total of 95 clones collected from different regions of the province and 45 non-native clones were investigated. Finally, 21 clones were divided into two groups of closed-crown and wide-crown and studied in the form of a complete randomized blocks design in three replications for 10 years. Vegetative traits including diameter at breast and height at the end of each vegetative season were measured, and the volume of wood production per hectare per year was calculated. The results of yield of 10 closed-crown clones including P.n.56/32, P.n.62/154,  P.a. 44/9, P.a.71/21 (native) with a yield of 41.5 and 34.5 m3/ha per year, had the highest yield as the first group, and P.n.56/32, P.n.62/191, P.n.62/127 with a yield of 32.8, 32.6 and 31.5 m3/ha per year were in the second group, showing no significant. The lowest yield belonged to the clones P.a. 49/39, P.n. 62/154 and P.n.71/23 (native), and P.n. betolifolia with a yield of 26.7, 25.3, 21.9 and 21.4 m3/ha per year, located in the last group. The results of the yield of 11 clones (9 wide-crown clones and 2 closed-crown clones) with 4 × 4 meter spacing including: P.e. 455, P.e. 262, P.e. 561/41, P.d. 69/55, P.e.vernirubensis, P.e triplo, P.a. 44/13, P.a. 17/60, P.d. 77/51, P.a. 71/23 and P.n. 71/28 showed that P.a.44/13, P.e. 455, and P.a.71/28, with a yield of 24.8, 20.65 and 20.12 m3/ha per year had the highest yield and also P.d. 69/55، P.e. 561/41, P.a 17/60 with a yield of 19.53, 18.5, and 17.8 m3/ha per year were in the second group, showing no statistically significant difference.The lowest yield was obtained in P.d 77/51, P.n 71/21
(native closed-crown clones) and P.e. 262.