Scion and Rootstock Affect on the Performance of Grafted Black Walnut Cultivars

摘要

Eastern black walnut (Juglans nigra L.) is prized for both its timber and edible nuts and has been suggested as a desirable tree species to use in agroforestry-based systems in the Midwestern U.S.A. (Garrett and McGraw, 2000). New plantings of improved cultivars will be required to fully realize the economic gains expected when managing for nut production (Jones, Mueller, and Van Sambeek, 1998). Grafting is currently the most effective method used to vegetatively propagate eastern black walnut (Coggeshall and Beineke, 1997). Yet to be defined, however, are the long-term effects of different rootstock sources on scion survival, growth, and nut productivity for this species. In California, scions of Persian walnut (J. regia) can exhibit increased vigor and pest resistance when grafted on specific rootstocks (McGranahan and Leslie, 1990). Likewise, it is possible that the use of rootstocks grown from seeds of popular black walnut cultivars might also convey some advantages in terms of growth and survival. If so, then significant amounts of seeds would be readily available for use as rootstock sources for future orchard establishment in Missouri. Our objective in this investigation is to determine the long-term effects of different rootstock sources on scion growth and nut productivity in an orchard setting at two locations.