Inducing genetic variation in growth related characteristics of poplar germplasm, by producing inter-specific hybrids between P. alba and P. euphratica

Crosses were made between two Populus species to create two hybrid groups, P. alba ♀ * P. euphratica ♂ and P. euphratica ♀ * P. alba ♂. Aseptic immature hybrid seeds were first grown on MS medium. Hybrid seedlings were then acclimatized and grown in greenhouse conditions and transplanted to an experimental field. Growth related characteristics were recorded on 307 three years-old seedlings of new inter-specific hybrids of six half-sib families, in order to assess possible potentials of the two hybrid groups. Double nested analysis of variance revealed significant differences between the hybrid groups and siblings based on majority of the studied characters. The hybrid groups formed two distinct groups for some of the studied characteristics which implied maternal effects of inheritance on the traits. The first hybrid group had more but shorter and closer branches than the second group. Adaxial stomata number for the two hybrid groups varied between 4.7 to 123. Whereas, there were no such strong differences between vegetative characteristics of the two groups. The second hybrid group had a very condense layer of white fuzz on its abaxial leaf surface, inherited from its female parents. This may lead to suggest some kinds of photosynthesis and respiration functions such as leaf sub-stomatal chambers’ functions for the mentioned fuzzy trichomes of the second hybrid group and their female parental species, P. alba. In essence, 307 new divergent poplar hybrid genotypes were produced by which ecological zone of poplar species could be extended in the country as well as high yielding genotypes would be promising.