ChileanJAR

Callus formation and its differentiation on vascular tissue in walnut (Juglans regia L.) stock cuttings (Eureka type) , scion (Eureka and Payne type) and non-rooted grafts, stratified in sawdust under controlled temperature conditions were studied. The main observations were:
- A great variation in callus formation, both in cuttings as in non-rooted grafts, was observed; however no anatomical differences were detected. This suggests that the physiological stage of the tissues is important when grafting.
- Callus formation was always greater in stocks than in scion, both in non grafted as in grafted cuttings. A less homogeneous and intensive callus evolution being observed in the latter.
- Tissues involved in callus formation were phellogen, cortex, phloem parenchymatic cells and vascular cambium, being the latter the major callus generator tissue.
- Differentiation on vascular tissue was irregular and started after 16 days of stratifieation, both on stocks cuttings as on grafted stocks.