ETHYLENE INHIBITORS ENHANCE IN-VITRO ROOT-FORMATION FROM APPLE SHOOT CULTURES

Effects of the ethylene precursor 1-aminocyclopropane-1-carboxylic aci d (ACC) and three ethylene inhibitors, AgNO3, aminoethoxyvinyglycine ( AVG) and CoCl2, on root formation were tested in vitro using shoot cul tures of the apple (Malusxdomestica Borkh.) cultivar Royal Gala. ACC i nhibited root formation by delaying root emergence and increasing call us formation at the bases of shoots. In contrast, ethylene inhibitors promoted root formation. Both AgNO3 and AVG at the appropriate concent rations increased the percentage of shoots producing roots and reduced callus formation at the base of these shoots. AgNO3 stimulated root e mergence and enhanced root growth, while AVG increased the number of r oots per shoot. CoCl2 slightly increased root number and looting effic iency. These promotive effects may result from a reduction in ethylene concentration or inhibition of ethylene action. The results found in this study may be used to improve the rooting efficiency of other appl e cultivars and rootstocks, and possibly of other plant species.