The relationship of dwarfing and IAA oxidase activity in sweet cherry (Prunus avium L.) rootstocks

Greenhouse experiments were conducted on mazzard (Prunus avium L.),Giessen (Gi) 148/1(Gisela 6) (Prunus cerasus x Prunus canescens) and Gi148/8 (Gisela 7) (Prunus cerasus x Prunus canescens) rootstocks to determine the relationship of their dwarfing potentials with IAA oxidase activity. Trunk bark was sampled and analysed for indole-3-acetic acid (IAA) oxidase activity at 1 day and 7 days after initial treatment. At the end of the experiment, both root and trunk bark were analysed for IAA oxidase activity. The effects of the inhibitors, scopoletin (7-Hydroxy-6-methoxy-2H-1-benzopyran-2-one) and 2,3,5triiodobenzoic acid (TIBA) on IAA oxidase activity were examined. The IAA oxidase activities in these clonal sweet cherry rootstocks varied significantly in all the samples. The most vigorous mazzard rootstock had the lowest enzyme activity. Both Gi148/1 and Gi148/8 rootstocks had significantly higher enzyme activity than mazzard. Scopoletin (100 ppm) and TIBA (100 μM) treatments increased IAA oxidase activity significantly at 1 day and 7 days but not 30 days after initial treatment.