EUROPEAN JOURNAL OF HORTICULTURAL SCIENCE, cilt.70, sa.3, ss.142-148, 2005 (SCI-Expanded)
Effects of sucrose and maltose at the concentrations 0.5 and 1.0 M, availability of the phloroglucinol (PG) at the concentrations 0 and 10 mu M, and three levels of pH (5, 6 and 7) in a basic medium containing 1.63 mM H3BO3, 1 mM KNO3, 1.27 mM Ca(NO3)(2).4H(2)O and 0.45 mM CaCl2 on the pollen germination in vitro of globe artichoke (Cynara scolymus L.) were studied. A separate experiment for each type of sugar was carried out. Analyses of percentages for pollen germination showed that main effects of sugar concentrations and availability of PG in the media were significant only in the sucrose experiment where 1.0 M sucrose and 10 mu M PG resulted in a germination of 49.8 and 38.9 %, respectively. The main effect of pH however was significant only in the maltose experiment where pH 5 resulted in 29.5 % germination while pH 7 gave only 15.3 %. Regarding the two factor interactions, statistical significance was found only for the combinations of sucrose concentrations x pH and PG x pH in the maltose experiment and sucrose concentrations x PG in the sucrose experiment. The interaction of all three factors was significant only in the maltose experiment where the highest pollen germination was 40.8 % for the combination of 0.5 M maltose x 10 mu M PG x pH 6, whereas in the sucrose experiment interaction of the three factors was not significant and the highest pollen germination was 68.9 % for the combination of 1.0 M sucrose x 0 PG x pH 5. Bursting of the pollen tube as well as elongation of the tube in a spiral manner occurred in all the media tested. Overall, more favourable germination was obtained from the sucrose media to which addition of phloroglucinol at 10 mu M concentration was useful. The factors influencing pollen germination of the globe artichoke and their relevance for its improvement were discussed.