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ŠUMARSKI LIST 5-6/2012 str. 17     <-- 17 -->        PDF

of medium productivity and a tendency to adapt to all environments (´I-214´, ´M 1´, ´S 6-36´, ´S 6-20´; b) moderately stable clones, of moderate productivity which manifest a tendency to adapt to all environments (‘710’, ´Bl Constanzo´, ´Pannonia´); and c) phenotypically very instable clones of high production capacity, with specific adaptation to optimal sites (´S 1-8´). Levels of the genetic control for the growing stock, heritability values (h2) and genetic gain (∆G) were assessed on the basis of selecting five or one of the best clones. The expected genetic gain was compared with the obtained experimental data. Assessment of the heritability values (h2) ranged from 0.40 to 0.90, which indicates that the traits of production and adaptability is under a high degree of genetic control. The obtained genetic gain (∆G) in growing stock production for the best five selected clones was somewhat higher than expected and ranged from 15.30 to 45.12 %, whereas it was between 30.88 and 81.03 % for one best selected clone. In order to minimize the risk of cultivating one clone (monoclonal culture) and increase plantations stability, we will favour the cultivation of a mixture of five clones of divergent genetic constitution. The results of this research confirm that even at such a young plantation age the quality of a particular habitat has conditioned modifications in average clone values of growing stock and survival. They also indicate the amount of production to be expected from the mixture of these clones or from the cultivation of a particular clone.

Key words: poplar clones, genetic parameters, genotype × environment interaction, adaptability.