عنوان مقاله [English]
Poplar as fast growing tree with a great potential of coppicing at consecutive periods is the most suitable tree species to provide wood at short period. The high volume of wood at short periods (2-5years) produced under the short rotation system is used in different industries such as particle board, pulp and paper.
In this study, 18 poplar clones of various groups and species were being examined in two 4 year rotation period. A randomized complete blocks design with three replications was applied. Overall, cuttings of each clone were planted in each plot including 10 cuttings on each planting row.
At end of the first year, the seedlings were clear-cut to produce vigorous shoots and roots (to provide more nutrition for shoots). The annual measurements contained: survival, height, stem diameter, total number of shoots and those more than two meters height and shoots diameter at breast height. At the end of each rotation period, the measurements including: intermediate diameter, collar diameter and classification of wood products, based on different parts of crown, wet and dry weights of the wood were determined under field and laboratory conditions.
The results for two consecutive harvesting showed that:
- P.e . vernirubensis, P.e . 561/41, P.e . triplo and P.e. costanzo were able to produce the highest yield of 24 to 27 tone/ha/year dry matter.
- In terms of survival rate , the four above mentioned clones and P.nigra clones achieved the highest and both P.deltoides and P.alba achieved the lowest percentage.
- The second rotation period produced higher volume of wood (about double) compared to the first period due to the optimal establishment, vast and vigorous roots and modified growing conditions.