Method for studying trunk radial increment on clementine trees in Corsica. First results and research prospects.

摘要

In an attempt to detect possible correlations between tree growth variations and certain exogenous factors, the development of clementine (cv. Clementine Commune, on on Poncirus trifoliata or citrange rootstocks) trees grown on the eastern plain ofCorsica was studied by dendrochronology. Tree age was calculated by counting the rings on trunk and primary branch sections, and the cumulated increment of the axes was measured. The logs were observed with the naked eye and using a counter. On a given section of trunk, the step produced by the rootstock above the grafting line resulted in the coexistence of areas in which the tissues of the two varieties anastomose and others where they remain individualized. Scion and rootstock growth differs depending on whether or not there is anastomosis. In anastomosed areas, clementine tree radial increment is ensured by the rootstock. In the absence of anastomosis, radial growth of the scion continues, but slows abruptly. Primary branch growth is identical to that of the trunk section to which they are attached. This approach established a link between step development and stress, for instance waterlogging or a significant reduction in foliage volume. Step development appears to be a sign of a decay process that will in all probability kill the tree. These observations open the way for new lines of research, and for the development and (or) adaptation of new crop management sequences.