Spontaneous hybrids within the genus Abies are considered to be better in growth and vitality in comparison with Abies alba and parental species. Three plantations with this material were established in the Czech Republic. These plantations are regularly measured and examined. The results show a very high potential of this material for the purposes of Czech forestry practice. Abies concolor, Abies procera and Abies nordmanniana grew faster than intraspecific hybrids. Mergen and Gregoire (1988) measured the height and diameter of 17-years-old hybrids that originated from crossing realized in 1960 and 1962 in Connecticut, USA. Abies cephalonica, Abies firma, Abies homolepis, Abies koreana, Abies lasiocarpa, Abies mariesii, Abies procera, Abies sachalinensis and Abies recurvata were used in this experiment. The results showed better growth and vitality compared to the control material (Abies balsamea). French researchers (Arbez et al. 1990) studied Mediterranean fir species and their hybridization. They recommended the utilization of fir progenies from selfing because of their inbreeding tolerance. Kantor and Chira (1971) investigated fir hybridization in former Czechoslovakia using Abies alba, Abies cephalonica, Abies nordmanniana, Abies pinsapo, Abies cilicica, Abies concolor, Abies grandis for interspecific and intraspecific hybridization.
Keywords: genusGreguss (1986, 1988a,b, 1992) and Kormuťák (1985Kormuťák ( , 1986Kormuťák ( , 1992 studied fir hybridization in Slovakia. Greguss (1986) reported slower growth of silver fir in comparison with fir hybrids and increasing differentiation between hybrid progenies and progenies of individual species from open pollination. Kormuťák (1986) presented similar results. He recommended primarily these combinations for planting in our conditions: Abies alba × Abies cephalonica, Abies cephalonica × Abies numidica, Abies nordmanniana × Abies alba, Abies pinsapo × Abies cephalonica, Abies pinsapo × Abies alba, Abies numidica × Abies nordmanniana, Abies numidica × Abies cephalonica and Abies concolor × Abies grandis. That means mainly the use of Abies alba and Mediterranean tree species. The same species already played the most important role in experiments of Kantor and Chira (1971) and Greguss (1988aGreguss ( ,b, 1992.
MATERIAL AND METHODSAccording to findings mentioned earlier comparative plantations with spontaneous hybrids within the genus Abies were established in the Czech Republic. There are three plantations there -one in Kostelec nad Černými lesy (Central Bohemia) and two in Forests of the Town of Prostějov (Central Moravia). They were established to evaluate possibilities of hybrid utilization in Czech forestry practice. Plantation characteristics are shown in Table 1.The material on these plots originated from Kysihýbel' Arboretum in Slovakia. Seeds of spontaneous hybrids within the genus Abies were obtained there in 1990. Seeds were collected from 21 trees. Trees number 1-3 and 6-21 incline in phenotype to Abies cephalonica, tree number 4 to Abies cilici...
