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

Abstract

SummaryThe process of florogenesis of Allium aflatunense (= A. hollandicum) and the effects of temperature and photoperiod on plant development were studied., Intrabulb development of the monocarpic shoot, and the formation of the renewal bulbs of A. aflatunense require a thermoperiodic annual cycle. Initiation of leaf primordia in the renewal bulb begins after planting of the parent plant. The vegetative meristem of the renewal bulb shifts to the reproductive stage during flowering of the parent plant, while the differentiation of individual flowers in the floral meristem begins during the rest period of the bulb, when temperatures are relatively high. New flower primordia are continuously being formed, while older flower buds have already been diferentiated. After floral differentiation, a prolonged period at low temperatures is required for further leaf and floral stalk elongation. After planting, the physiological response of the growing plants was affected by the temperature and length of preceding storage. Storage at 4˚C for 16 weeks, or a combination of 98C for eight weeks, followed by 4˚C for eight weeks, resulted in normal leaf and floral stalk elongation. Leaf elongation requires shorter cold treatment than that of the floral stalk. Storage conditions conducive to scape elongation also resulted in the formation of a renewal bulb and a few daughter bulbs. The development of the leaves, renewal bulbs and inflorescences was significantly affected by growth temperatures, but not by photoperiod. Leaf and renewal bulb growth was best at 17/98C (day/night temperatures), intermediate at 20/12˚C and 23/15˚C, and weakest at 26/18˚C, where leaves were narrower and shorter and renewal bulbs were smaller than in the other environments. Scape elongation was normal at 17/9˚C and 20/12˚C, and inhibited in plants subjected to higher temperatures.