STUDIES ON PROPAGATION OF OLIVES BY GRAFTING AND TISSUE CULTURE

Abstract

A comprehensive study was undertaken in two objectives. The first one was planed to investigate the best combinations of scion and rootstock in olive) Olea europaea L.). Three olive cultivars characterized by their little rooting capacity i.e. Kalamata, Picholin, and Sevillano used as scions. Each scion was side-veneer grafted during the l st. week of May 2000 and April 2001 on one-year-old plants used as rootstocks, namely: Chimlali seedlings, rooted cuttings of Picual and Coratina. Grafting success significantly varied according to rootstock , scion and grafting date. Grafting during the l st. week of April resulted in more success percentage than that at the l st. weak of May. Chimlali seedling rootstock . was the most promising rootstock for grafting the three olive cultivars under study due to it was the most vigorous rootstock, giving the highest averages of grafting success, length and diameter of scion shoot, leaf area of scion, fresh and dry weight of scion shoot and leaves, and chlorophylls A, B as well as it showed the best development of union-zone. On the other hand, Picual as rootstock was the least promising rootstock due to it gave the least averages of the above studied items. Meanwhile, Coratina rootstock was intennediate. Dry weight of rootstock roots and whole grafted plants varied according to the scions and rootstocks. The <;econd objective was undertaken to obtain somatic embryogenesis from Kalamata olive cotyledon callus, and shoot organogenesis from mature somatic embryos. Mercuric chloride at 0.05% was the best. treatment for surface sterilization of olive cotyledon explants as it gave the highest average of survived explants and the lowest average of explants developed browning. Dark conditions was more effective for callus induction (as callus fresh weight) than light conditions.2,4-D treatments produced friable callus converted to browning color. IBA treatments gave white and compact callus used for testing its embryogenic capacity. Casein hydrolysate at 700 mg\1 stimulated callus induction of olive cotyledon explants. Somatic embryos induction was affected by type and concentration of experimented cytokinins (Zeatin or 2ip ). Zeatin at 0.1 mg\1 and clark conditions stimulated more somatic embryos induction as compared with 2ip or light conditions. Somatic embryos completely inhibited by Zeatin or 2ip at concentrations higher than 0.5 mg\1. For shoot organogenesis, Zeatin at 1.5 mg\1 was the most effective cytokinin, followed by 2ip then BA at the same concentration. Woody plant medium supplemented with 2.5 mg\1 GA3 gave more satisfactory growth for somatic embryos and regenerated shoots as compared with MS medium. The highest rooting percentage of

regenerated shoots was achieved in '12 MS medium supplemented with IBA at 0.75 or 1.00 mg\1 ;meanwhile NAA was less effective. Olive plant\ets, which regenerated in vitro were sensitive to dehydration during acclimatization stage. Plant survival was about 80% when these plantlets transferred from aseptic culture in vitro to greenhouse conditions.