Variation of chlorophyll index and dry mass in Quercus robur L. trees from different provenances

In the comparative forest cultures of the "Plaiul Fagului” Scientific Reserve, an evaluation of the chlorophyll index and dry mass in the leaves of pedunculate oak descendants from the northern, central, and southern regions of the Republic of Moldova was carried out. The obtained data showed significant variations within trees in terms of minimum and maximum values, as well as the position of the median value relative to the mean in the distribution of the chlorophyll index in the investigated provenances. The analysis of the variation indicates significant differences in the distribution of the chlorophyll index of the leaves of trees originating from different ecological zones. Within this variation, two trends can be observed. The first trend refers to the fact that descendants from more distant areas (in the north and south) have a higher chlorophyll index than those from the central area (including local provenance). This difference due to the fact that descendants from ,,foreign” zones are exposed to different environmental conditions than optimal ones, which makes adaptation processes more pronounced compared to descendants from the central zone with similar conditions to the cultivation area. The second tendency consists of the uniformity in the response of different genotypes of non-locally provenance descendants from remote areas in the north and south, in relation to the specific environmental conditions of the common arboretum. This uniformity is indicated by lower coefficients of variation in the chlorophyll index of descendants from ,,foreign” zones compared to local provenance ones. Therefore, descendants of non-local provenance developed adaptation processes in new environmental conditions reflected by differences in the distribution of chlorophyll content. In descendants of northern and southern origin, these differences are lower than those characteristic of local provenance descendants. This view is supported by the fact that the dry mass rate of the leaves of local provenance descendants tends to be lower compared to those from the northern and southern parts of the Republic of Moldova.