Effects of different diurnal temperatures on the growth of sandersonia (Sandersonia aurantiaca Hook.) plants

Effects of day and night temperatures on the growth and the tuber formation of Sandersonia aurnntiaca plants were investigated. Seedlings with 1 or 2 leaves were transferred to growth chambers. controlled at day / night temperatures of 17 / 12 degrees C, 24 / 17 degrees C, and 30 / 24 degrees C: under natural daylength. On plants kept at 30 / 24 degrees C, the unfolding of leaves, stem elongation, and the branching from the main stem were enhanced, whereas those at 17 / 12 degrees C were retarded. At 24 / 17 degrees C, intermediate vegetative growth and optimum growth for flower stalk elongation and flowering were educed. At the time of shoot die back, the fresh and dry weights of new tubers were greatest at 24 / 17 degrees C, moderate at 30 / 24 degrees C, and smallest at 17 / 12 degrees C. At 17 / 12 degrees C and 24 / 17 degrees C, normal fingerlike or fork shaped tubers developed, while at 30 / 24 degrees C, secondary tubers formed and developed. These results indicate that 24 / 17 degrees C is optimum for tuber and flower development of sandersonia plants.