Life Cycle and Temperature Requirements of Seven Herbaceous Species

Abstract

A series of observations were made on the life cycle, phenology, and germination capacity of Galantbus nivalis L., Corydalis cava Schw. et Krt., Anemone nemorosa L., Symphytum tuberosum L., Allium ursinum L., Aegopodium podagraria L., and Campanula rapunculoides L. The studies were conducted in field, in the Arboretum of the Botanical Garden of Padua, in experimental field chambers, and in growth cabinets maintained at temperature of 4°, 15° and 25°C. The various stages of life cycle of plants require different optimal thermoperiods. High temperature induce dormancy in A. nemorosa and S. tuberosum, while in G. nivalis and A. ursinum the rest period at the end of the vegetative cycle, is not broken by temperature treatments. A. podagraria and C. rapunculoides respond with a different morphogenesis to different temperatures. Temperature change (in the controlled conditions from one constant temperature to another) induced subsequent stage development. Vernalization is essential for all the species under study. However the minimum temperature for vernalization and the duration of exposure at this temperature varies in different species.

The life cycle observed of the various species may be considered as examples of different types of adaptation to a same environment.