INFLUENCE OF COOLING AND PHOTOPERIOD ON GROWTH AND FLOWERING OF AQUILEGIA L. CULTIVARS

Four cultivars of Aquilegia flabalata and four cultivars of Aquilegia x hybrida were cooled 0, 4, 8, or 12 weeks and forced in either long-d ay (LD) or short-day (SD) photoperiods. Cultivars of both species cool ed eight or 12 weeks flowered in fewer forcing days than non-cooled pl ants, however, days to flower were similar for LD and SD photoperiods regardless of cooling level. Flower stem length increased with increas ing cooling duration, and flowering stems were longer in LD photoperio d than in SD. Plants cooled eight or 12 weeks were either larger than or similar in size at flowering to non-cooled plants or those cooled f our weeks. In this study, eight weeks cooling and LD photoperiod enhan ced forcing phase growth and flowering of the columbine cultivars most efficiently. (C) 1998 Elsevier Science B.V.