EXOGENUS ‘GA3’ AND ‘GA4+7’ EFFECTS ON PHENOLOGICAL INDICES, FROST HARDINESS AND QUALITY PROPERTIES OF ‘ENGLISH MORELLO’ SOUR CHERRY (Prunus cerasus L.)

Exogenous gibberellins GA3 and GA4+7 treatments on ‘English Morello’ sour cherry trees 58 days after anthesis were evaluated in relation to their effect on fruit firmness, size distribution, colour development, titratable acidity to firmness ratio, yield, efficiency indices as well as leaf fall senescence. Moreover in the season following the applications their effect on flower bud characteristics including frost hardiness, fruit set and fruit drop, were examined. Foliar GA3 treatment had the most positive effect on ‘English Morello’ fruit size in the year of application and in the following season. GA4+7 treatment in the first experimental year increased sour cherry fruit firmness. Both GA3 and GA4+7 delayed leaf senescence process in the autumn. GA3 application had a positive effect on flower buds survival in comparison to control trees after frost occurred in spring. No GAs subsequent effect on next year fruit set and yield compared to control was found.