Effects of auxins and cytokinins on graft union of grapevine (Vitis vinifera)

Abstract

The aim of this study was to determine the effects of some auxins and cytokinins on graft union and root formation of grafted cuttings of four different grapevine (Vitis vinifera) graft combinations (41B‐Erenköy Beyazi, 41B‐Italia, Rupestris du Lot‐Erenköy Beyazi, and Rupestris du Lot‐Italia). The cut grafting surfaces of both the scion and rootstock were first dipped into either 1 ‐naphthaleneacetic acid (NAA), indole‐3‐butryic acid(IBA), benzyladenine (BA), or kinetin (Ki) for 20 s. NAA and IBA were applied at concentrations of 500, 1000, and 2000 mg/litre and BA andKi were applied at rates of 250, 500, and 1000 mg/litre. Following this treatment the cuttings were grafted, stratified, and hardened. Control group cuttings were grafted without any application. Results showed that the physiological effects of cytokinins differed from auxins. In general, Ki and BA stimulated rapid proliferation of callus between the scion and rootstock whereas NAA and IBA increased root formation at the basal end of grafted cuttings compared with the control. The best results were obtained from treating the graft cut‐surfaces of graft combinations with 250 and 500 mg/litre Ki or BA. Except for the 1000 mg/litre concentrations, Ki and BA showed better callusing rate and callusing degree at grafting point of all tested graft combinations compared with the control, whereas rooting rate and rooting degree were enhanced by application of IBA and NAA compared with the control. In all graft combinations, the highest success rate (100%) was obtained from 250 mg/litre Ki application. Significant increases in success rate and callus formation as callusing rate and callusing degree at the grafting zone indicated that the Ki and BA may have the potential to improve graft union formation.