عنوان مقاله [English]
In this research, the effect of tension wood formation in Populus nigra on its anatomical characteristics was studied. Vessel element and ray frequency (N/mm²), vessel diameter and ray dimensions were measured in both normal and tension wood. Furthermore, the formation of gelatinous layer (G-layer) in the fibers of tension wood was studied. The results showed that the vessel proportion and diameter in normal wood were greater than those in tension wood but ray proportion in tension wood was higher. Unlike ray length, ray width in tension wood was greater than that in normal wood. The SEM studies also revealed that most of the fiber cell lumens in tension wood were blocked by gelatinous layer. The tree response to growth stresses is one of the main causes for anatomical variation in tension wood.