SEASONAL EFFECTS OF WOUNDING AND GROWTH-SUBSTANCES ON DEVELOPMENT OF TRAUMATIC RESIN DUCTS IN CEDRUS-LIBANI

The development of traumatic resin ducts, in response to wounding and to hormone [napthalene acetic acid (NAA) and gibberellic acid (GA)] application at various times of the year was studied in the secondary xylem of Cedrus libani Loud. Resin duct formation was associated with enhanced cambial activity. As a result of wounding or of application of NAA or NAA together with GA3, a system of longitudinally oriented ducts developed around the treated area. In most cases the ducts reached their greatest length above the treated area. Application of GA3 alone did not normally cause the formation of ducts. Wounding and auxin application, at the time of highest cambial activity, led to duct formation shortly after treatment. Ducts did not develop during the period of cambial dormancy. When auxin was applied during dormancy, duct systems developed in the following season of cambial activity, but wounding during the same period produced no ducts or only short ones in the following season. Copyright © 1979, Wiley Blackwell. All rights reserved