低温処理温度の違いがフリージアの開花に及ぼす影響

Abstract

In Japan, freesia corms after root emergence are precooled at 8 to 10°C under moist condition for 5 to 7 weeks to advance flowering. Because flower initiation and differentiation occur under these conditions, low temperatures enhance it directly. In these experiments, we tested the effects of chilling temperatures on flowering were direct or an indirect ones on freesia corms of 'Elegance' and 'Blue Heaven' by keeping the corms at 5, 8, 10, 12, or 15°C under moist condition. They were then moved to 24/18°C (day/night) at the same stage of floral development. Corms chilled at 5°C for 13 weeks did not initiate flower buds, and were excluded from the experiments. Within a range of 8 to 15°C, not only a direct effect but also some after-effects on flowering were noticed. The number of florets per main inflorescence was determined as a direct effect of chilling temperature ; it decreased as corms were chilled at lower temperatures. Corms, chilled at lower temperatures, also had a higher flowering percentage and longer flower stem, and required fewer days from the end of chilling to flowering ; an after-effect of the chilling temperature.