The influence of temperature on growth and development of chrysanthemum cultivars

SummaryThe effects of temperature, especially in the sub-optimal temperature range, on growth and development of chrysanthemum (Dendranthema grandiflorum syn. Chrysanthemum morifolium) are reviewed with special emphasis on cultivar differences. The developmental aspects analysed in this paper are leaf unfolding rate, stem elongation, time to flowering, and the number and sizes of flowers. Growth is studied as biomass production and partitioning to different plant organs. Temperature has a significant effect on development, especially on leaf unfolding rate and time to flowering, both of which show an optimum response to temperature. The optimum for time to flowering is cultivar-dependent and lies between 17º – 22ºC. Also, for the other developmental traits, there are clear differences between cultivars in their response to temperature. The effect of temperature on biomass production is less clear. When leaf area index is low, sub-optimal day temperatures decrease biomass production due to the formation of thicker leaves. Biomass produced up to flowering is highly variable and depends on cultivar and the interaction between temperature and other growing conditions. More research is required to determine whether differences in biomass produced between cultivars are related to differences in the duration of the cultivation period, growth rate, or both. The possibilities for breeding for low energy demand are also discussed.