Resumen
In this study the compatibility for grafting of root stocks and buds of three recognized leaf phenotypes of Ilex paraguarensis St. (mate) Hil. from south Brazil was investigated. Special regard was given to the anatomical structure and the sap flow in the secondary xylem of the grafted plants. Significant differences of the wood structure expressed in terms of vessel portion, vessel member length, and intervessel perforations were found in low compatible phenotypes, while highly compatible phenotypes had a very similar wood structure. In grafts of highly compatible phenotypes six months after grafting the water conducting system of root stocks and buds was strongly linked to each other, while in grafts of low compatible phenotypes the formation of connecting vessel elements was rare. In the first month after grafting the xylem sap flow in the buds of all grafts was significantly higher compared to their root stocks, while in the second month in grafts of highly compatible phenotypes, the water transport in the root stocks and in the buds was balanced. In contrast, in grafts of low compatible phenotypes even in the second month the water transport in the root stocks was lower compared to the buds causing the dieback of a high portion of these plants.