In vitro morphogenesis and growth of Narcissus in response to temperature

In vitro morphogenesis and growth of tissues of the Narcissus cultivar ‘Lord Nelson’ have been assessed in constant and alternating temperatures. Tissue of leaf-base and scape origin, producing leafy shoots and bulblets on a defined sterile medium, were grown at constant and alternating temperatures of 15, 20, 25 or 30°C and 15–25 or 20–25°C, respectively, in a 16-h daily photoperiod. The number of leaves, leaf length, volume of tissues, fresh weight (but not percentage dry matter), and the number of shoots that would ultimately produce bulbs, were maximal at a constant temperature of 25°C as compared with all other temperature-regimes tested.