Allan M. Armitage

Photoperiod and cooling duration influence growth and flowering of six herbaceous perennials

SummarySeedlings of six taxa of herbaceous perennials were subjected to 0, 4, 8 or 12 weeks cold treatment at 2–38C followed by long or short day photoperiods after the cold treatment. Cold was not necessary for flowering in any taxa studied, but the duration of cold treatment was inversely related to forcing-phase days to flower for all taxa. Plant height at flowering increased due to cooling in Myosotis scorpioides (forget-me not) and Campanula carpatica (Carpathian harebell) while decreasing in Anchusa capensis (Cape bugloss). In M. scorpioides, the number of growing points also decreased as cooling duration increased. Photoperiod influenced flowering time in four taxa but not in M. scorpioides and Arabis blepharophylla (fringed rock-cress). Flower stems of M. scorpioides and A. capensis elongated more in long days than in short days. Short days reduced internode elongation in Gypsophila repens (creeping babys breath) and inhibited flowering of C. carpatica and Catananche caerulea (blue Cupids dart)....

Influence of cooling and photoperiod on growth and flowering of Aquilegia L. cultivars

Abstract Four cultivars of Aquilegia flabalata and four cultivars of Aquilegia×hybrida were cooled 0, 4, 8, or 12 weeks and forced in either long-day (LD) or short-day (SD) photoperiods. Cultivars of both species cooled eight or 12 weeks flowered in fewer forcing days than non-cooled plants, however, days to flower were similar for LD and SD photoperiods regardless of cooling level. Flower stem length increased with increasing cooling duration, and flowering stems were longer in LD photoperiod 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 four weeks. In this study, eight weeks cooling and LD photoperiod enhanced forcing phase growth and flowering of the columbine cultivars most efficiently.

Nitrogen and calcium nutrition of Petunia × hybrida ‘Coral Sea’

Abstract The effects of N and Ca nutrition on plant growth and shoot elemental content of Petunia × hybrida Hort. Vilm. - Andr. ‘Coral Sea’ were evaluated. Nitrogen and Ca were applied separately or in combination in three experiments: (1) N at 0, 100, 200 or 400 mg l−1; (2) Ca at 0, 75, 150 or 300 mg l−1; (3) N at 0 or 100 mg l−1 and Ca at 0 or 150 mg l−1 combined factorially. Shoot and root dry weights, branch length and flower number were highest when plants received 100 mg l−1 N. Plants treated with 150 mg l−1 Ca had the highest shoot and root dry weights. Branch length was maximal at 300 mg l−1 Ca. Nitrogen and Ca interacted to increase shoot dry weights, branch number and length, leaf area and flower number. Increasing N concentrations increased N and decreased P, Mn and Zn shoot contents. Calcium content of shoots increased while N, P and Mg decreased in response to increasing applications of Ca to petunia plants. Minimal N and Ca tissue concentrations for optimal P. × hybrida growth were 3.3 and 0.67%, respectively.