engleski

GENETIC DIFFERENTIATION OF PEDUNCULATE OAK (Quercus robur L.) SEED STANDS BASED ON HEIGHT AND SURVIVAL ANALYSIS IN A FIELD TRIAL ‘JASTREBARSKI LUGOVI’

Previous studies of morphological and physiological traits of pedunculate oak in Croatia have indicated genetic differentiation of populations as well as high level of intrapopulation genetic diversity. However, reported patterns of genetic differentiation vary by different authors. Research of the pattern of genetic differentiation and diversity of oak populations in Croatia was conducted by analysis of height growth and survival in a filed trial established with progeny from 17 seed stands. Analysis of variance for the studied traits revealed significant differences between populations, which confirm their genetic differentiation. Multivariate regression tree analysis (MRT) was used to determine the pattern of genetic differentiation. The populations were grouped in clusters based on climate variables of their habitats of origin and standardized arithmetic means of the studied quantitative traits in the genetic test. Populations were divided into three clusters for height trait based on beginning of frostfree period and the number of frost-free days. Populations originating from habitats where period free of spring frosts begins relatively later had lower mean heights. Populations that were highest on average originate from the habitats where early autumn frosts occur earlier on average. For the survival populations were firstly separated due to Hargreaves’s reference evaporation. This variable indicates the potential evapotranspiration of an area, and points to the aridity or humidity of a habitat. Two populations originating from relatively most humid habitats had lowest mean survival. Remaining populations were clustered based on the average temperature in winter. Populations originating from relatively arid and warmer habitats in winter performed highest mean survival. Therefore, climate in the trial during the analyzed period probably was not favorable for the populations originating from moister habitats. MRT analysis indicates ecotypic pattern of the population’s genetic differentiation driven by environmental differences in the habitats of origin. This study is part of research projects “Forest tree breeding and seed husbandry” 024- 0242108-2099 (Ministry of Science, Education and Sports of the Republic of Croatia) and “Conservation of genetic resources forest trees in the light of climate change” ConForClim 8131 (Croatian Science Foundation).

genetic test, intrapopulation diversity, pattern of genetic differentiation, quantitative traits

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