Growth and Yield of 'Budousanshou' Grafts on 'Fuyuzanshou' and 'Karasuzanshou' Rootstocks

The growth and yield of 'Budousanshou' (Zanthoxylum piperitum (L.) DC. f. inerme Makino) trees were compared between grafts on 'Fuyuzanshou' (Z. alatum Roxb. var. planispinum Rehd. et Wils.) seedlings and 'Karasuzanshou' (Fagara ailanthoides Engl.) seedlings. Comparisons were made for 8 years after transplanting. The tree height for grafts on 'Karasuzanshou' rootstock was greater than for 'Fuyuzanshou' grafts throughout the experimental period after transplanting. For both graft treatments, tree height did not increase beyond 6-7 years after transplanting, suggesting that the trees had reached maturity. In addition, the canopy volume of grafts on 'Karasuzanshou' rootstock was greater than that on 'Fuyuzanshou' rootstock at 2 years after transplanting. The yield per tree and canopy volume were higher for grafts on 'Karasuzanshou' than grafts on 'Fuyuzanshou' rootstock by 7 years post-transplanting (i.e., the mature stage). Due to its greater canopy volume, the per tree yield of mature 'Karasuzanshou' grafts has the potential to be greater than that from 'Fuyuzanshou'; therefore, 'Karasuzanshou' is a good candidate rootstock for the effective production of Japanese peppers.