Comparison of Chandler walnut grown on both Paradox and northern California black rootstock that were planted as seed, seedling or grafted trees.

摘要

In 1986 Paradox (Juglans hindsii x J. regia) and northern California black (J. hindsii) walnut trees were planted either as seed, ungrafted seedlings or Chandler grafted trees in a replication trial. The ungrafted trees were grafted in 1987 to Chandler cultivar. Eight year yield data showed that trees on Paradox were higher yielding at 23727 kg/ha compared to 21290 kg/ha for trees on northern California black. The Paradox trees planted as seed were the highest yielding at 27105 kg/ha followed by Paradox grafted trees at 25196 kg/ha, northern California black walnut grafted trees at 24027 kg/ha and northern California black trees planted as seed at 21524 kg/ha. When the yield of trees planted on both rootstocks was averaged there was no differencebetween trees planted as grafted trees (24597 kg/ha) and trees planted as seed and grafted one year later (24428 kg/ha). The trees planted as seedlings were the lowest yielding (18618 kg/ha). Trunk cross sectional area was largest for the grafted trees on northern California black and next largest on trees of both rootstocks planted as seed. Yield efficiency was highest on the trees growing on Paradox rootstock. Crown gall (Agrobacterium tumefaciens) was highest on the Paradox rooted trees planted as seedlings and next highest on the Paradox rooted trees that were grafted prior to planting. In 1996 no crown gall was visible on the Paradox trees planted as seed and only one tree of twenty had visible crown gall in 1998. The difference in incidence of crown gall may account for some of the yield and growth differences between the Paradox rooted trees planted as seed compared to those trees planted as seedlings or as grafted trees.