Geographic variability among estreme European wild chestnut populations

The long range distribution of Castanea sativa indicates the probable existence of some adaptive variation among populations from extreme conditions. However their introduction in some European areas as well as the evidence of founder effects and the influence of grafted varieties on wild populations, pose the question about the existence of adaptations to local environments and of enough variability within populations. The variation of several traits related to adaptation was studied in a multi-site provenance–progeny test, for six European chestnut populations populations originating from contrasting environments of Spain, Greece and Italy. The experiment was established at six sites of contrasting European chestnut climate. At each site every population was represented by 26 open-pollinated progenies. The experimental design was a randomised complete block design with 20 blocks and one-tree plot. Assessment of height growth, flushing and bud set was carried out during the first three years after planting. The populations originated from Greece initiated growth earlier, followed by the populations from South Italy and South Spain, while the populations from North Spain and North Italy initiated growth later. Cessation of the height growth occurred during summer and prior to reduction of day length. The North Italian population, growing in conditions of Central European climate, stopped growth later than the other five populations from Mediterranean conditions. Height growth of the northern populations was higher than growth of the southern ones.