Grafted and non-grafted vines of the Red Globe cultivar were planted in May, 1985 in a randomized block design to determine the effects of grafting on different rootstock on vine growth, yield, and fruit quality. The rootstocks used in this trial were Harmony, Freedom, Couderc 1613, and Thompson Seedless; non-grafted vines included rooted cuttings and one-year-old rootings. Vines grafted on Freedom were more vigorous than any other vines. The levels of nitrogen and potassium were significantly higher in vines grafted on Freedom than non-grafted vines or those grafted on other rootstocks. Yield was significantly influenced by the different rootstocks. Vines grafted on Freedom produced significantly lower yield than other vines. Vines grafted on Harmony and Couderc 1613 were not significantly different from each other or non-grafted vines that were established from a rooted cutting.
Gibberellic acid (GA) applied as an aqueous spray to 4-year-old ‘Ascolano’ olive trees at concentrations of 250 or 500 ppm promoted shoot growth, mainly through internode elongation. Indoleacetic acid (IAA) at the same concentrations caused curling of young leaves and suppressed terminal bud growth for 10 to 14 days. Shoot growth promotion by GA was counteracted by IAA.
GA at 100, 250 or 500 ppm significantly promoted xylem differentiation and development in newly developed regions of olive shoots. GA + IAA, both at 250 or 500 ppm, had a synergistic effect. IAA at all concentrations had no effect in this respect. Xylem lignification was normal in all treated shoots. It is suggested that the endogenous gibberellin level was the limiting factor for xylem development and that a certain balance between auxin and gibberellin is required to stimulate cambial activity with subsequent xylem development. Secondary phloem development was not influenced by IAA and/or GA. GA alone or in combination with IAA stimulated precocious periderm formation