Effect of medium darkening on in vitro rooting capability and rooting seasonality of olive ( Olea europaea L.) cultivars

• Published in: Scientia horticulturae Vol. 97; no. 2; pp. 129 - 139
• Main Author: Mencuccini, Massimo
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 31.01.2003; Elsevier
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Darkening; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Micropropagation; Olea europaea L; Rooting seasonality; Vegetative propagation. Micropropagation; Vegetative propagation. Sowing and planting. Harvesting; Olea europaea L; Rooting seasonality; Micropropagation; Darkening; Culture medium; Oleaceae; Olea europaea; Dicotyledones; Angiospermae; Blackening; Spermatophyta; Rooting; Oil plant (vegetal); Cultivar
• ISSN: 0304-4238; 1879-1018
• DOI: 10.1016/S0304-4238(02)00130-9

A new technique to obtain the darkening of the rooting medium and the effect on in vitro rooting of olive explants was studied. Olive shoots collected from cultivars ‘Frantoio’, ‘Dolce Agogia’ and ‘Moraiolo’ established in vitro 5 years earlier and having different rooting capability in vivo (high, intermediate and low, respectively) were used during three different in vitro rooting periods (January, May and September). The possibility of rooting seasonality of in vitro propagation for olive was also studied. The experiment was carried out using four dyes (Brilliant Black BN-SIGMA) concentrations (0, 10, 100, and 200 mg/l) added to the rooting medium ( MS+5 μM naphthalene acetic acid (NAA)+2% sucrose+0.7% agar and pH 5.5) to obtain a darkening effect. The dark control (cnt) treatment consisted of painting the outside of the vessel black and using it for comparison. Rooting percentage, number and length of roots were observed. As a result root formation was enhanced by about 100% due to darkening of the rooting medium at a dye concentration of 100–200 mg/l, independent of the period and cultivar. Explants not subjected to darkening seem to maintain their in vivo seasonal rooting variability with low rooting percentage in January (12–28%) in comparison with May and September (56–96%) which are also better in vivo. We can conclude that in vitro explants carry over the in vivo seasonal rooting ability of olive cultivars and that medium darkening could cancel this effect.