Florogenesis and the effect of temperatures on the development of Allium aflatunense

The process of florogenesis of Allium aflatunense (= A. hollandicum) and th e effects of temperature and photoperiod on plant development were studied. , Intrabulb development of the monocarpic shoot, and the formation of the r enewal bulbs of A. aflatunense require a thermoperiodic annual cycle. Initi ation of leaf primordia in the renewal bulb begins after planting of the pa rent plant. The vegetative meristem of the renewal bulb shifts to the repro ductive stage during flowering of the parent plant, while the differentiati on of individual flowers in the floral meristem begins during the rest peri od of the bulb, when temperatures are relatively high. New flower primordia are continuously being formed, while older flower buds have already been d iferentiated. After floral differentiation, a prolonged period at low tempe ratures is required for further leaf and floral stalk elongation. After pla nting, the physiological response of the growing plants was affected by the temperature and length of preceding storage. Storage at 4 degreesC for 16 weeks, or a combination of 9 degreesC for eight weeks, followed by 4 degree sC for eight weeks, resulted in normal leaf and floral stalk elongation. Le af elongation requires shorter cold treatment than that of the floral stalk . Storage conditions conducive to scape elongation also resulted in the for mation of a renewal bulb and a few daughter bulbs. The development of the l eaves, renewal bulbs and inflorescences was significantly affected by growt h temperatures, but not by photoperiod. Leaf and renewal bulb growth was be st at 17/9 degreesC (day/night temperatures), intermediate at 20/12 degrees C and 23/15 degreesC, and weakest at 26/18 degreesC, where leaves were narr ower and shorter and renewal bulbs were smaller than in the other environme nts. Scape elongation was normal at 17/9 degreesC and 20/12 degreesC, and i nhibited in plants subjected to higher temperatures.