EFFECT OF AMBIENT-TEMPERATURE ON THE GROWTH AND DEVELOPMENT OF AMARYLLIS (HIPPEASTRUM-HYBRIDUM HORT.) BULBS

How different day/night temperature affect the growth and development of the vegetative and reproductive parts, including the bulbs of amary llis (Hippeastrum hybridum) plants in growth chambers for two years wa s investigated. One-year-old, 2-leafed seedlings were transferred to g rowth chambers set at 17 degrees/12 degrees C(low, L plot), 24 degrees /17 degrees C (middle, M plot) and 30 degrees/24 degrees C (high, H pl ot) under natural daylength. 1. High temperatures (H plot) hastened th e unfolding and elongation of leaves, and increased markedly the growt h of mother bulb and daughter bulbs,but the plants did not flower. 2. In plants exposed to low temperature (L plot), the leaves wore the slo west of the three plots to unfold and elongate; the mother bulbs were slow to enlarge but produced the most daughter bulbs. The temperature favored floral development. 3. Middle temperature (M plot) educed inte rmediate vegetative growth and the enlargement of mother and daughter bulbs. This condition was optimum for flower stalk elongation and flow ering. Thus, comparing the responses of amaryllis grown under low, mid dle, and high day/night temperatures, high temperature favored promoti on of mother bulb enlargement, but the moderate and low temperatures w ere optimum for bulb and flower production.