The effect of daylength and temperature on the growth and reproduction of six strains of Townsville lucerne (Stylosanthes humilis)

Abstract

Growth studies of Townsville lucerne were conducted in the phytotron at Canberra to gain an understanding of the relative response of six strains to daylength and temperature. Vegetative growth was promoted by long days in all strains. Some strains flowered under these conditions but other strains appeared to require short days before they were induced to flower. The effect of daylength was reflected in seed yield and in the relative effort that plants devoted to reproduction. In these characters, various strains showed differential responses. For most other characters, a response to daylength was detected, but all strains reacted in a common manner. Weights of roots, stems, and leaves were significantly higher under the lower temperature treatment. A tendency in this direction was also detected in several other characters. Variation among strains in plant morphology and response to photoperiod were pronounced. This suggests a relation between growth characteristics and the ecological background of these strains of Townsville lucerne.