オリエンタル系ユリ品種の球根品質に対する氷温帯での貯蔵条件の影響
氷温帯での長期貯蔵が比較的困難と言われるオリエンタル系品種の中からオランダ産カサブランカを選び、９ヶ月にわたる貯蔵実験を実施した。冷蔵倉庫の温度精度を±0.5℃とした場合、上限である-1.0℃の条件では、芽の伸長はより顕著であり、貯蔵９ヶ月後では約８cm以上に達する事が分かった。オリエンタル系の一般的な貯蔵温度-1.5±0.1℃では貯蔵期間が６ヶ月を越えると芽の伸長を抑制できず、９ヶ月後には約２〜３cmに芽が伸びる事が分かった。また、芽の伸長に伴い花芽の形成が認められた。よって、オランダ産球根を使用する場合、温度精度のよい冷蔵倉庫において、オリエンタル系品種で推奨される-1.5℃の貯蔵で９月以降に芽が数cm程度伸長していることは、正常な現象であり、オリエンタル系品種の貯蔵特性の限界を反映しているものと考えた。
キーワード： ユリ球根，氷温帯貯蔵，温度制御，球根発芽，長期貯蔵，オリエンタル系ユリ品種
＊１ 技術センター土木技術研究所水域生物環境研究室
＊２ 大阪府立食とみどりの総合技術センター
＊３ （株）日新
Study on the Long Term Storage of Bulbs for Cut Flower of Oriental Hybrid Lily at Termperatures below the Freezing Point
We quantitatively confirmed the effects of different storage temperatures (0, -0.5, -1.0, -1.5, -2.0 or -3.0℃; SD=±0.1℃) and storage terms (3, 6, 9 months) on the quality of hybrid Oriental lily bulbs (c.v. Casablanca) for cut flower production. Bulbs of Casablanca were produced in the Netherlands, stored, and transported at -1.5℃, and purchased from commercial stock in mid-March. They were divided into groups of twenty-five bulbs and stored again at different temperatures below the freezing point for three to nine months (mid-June to mid-December). After storage, the length of the sprouted shoot was measured. The condition of a half-cut surface of the bulb was also examined. Ninety-five percent of the bulbs had already sprouted after storage for 6 months at -1.5℃. The shoot length after 9 months was approx. 2-3 cm when the bulb was stored at -1.5℃ and approx. 8-9 cm when the bulb was stored at -1.0℃. The flower buds also differed according to the length of the shoot. These results clearly indicate that even storage at a precisely controlled temperature of -1.5℃ was not able to suppress the sprouting of 'Casablanca' bulbs after storage for more than 6 months. Storage at temperatures of -2.0 or -3.0℃, however, completely suppressed spouting. Vitrification of the flower stem was observed on the cut surface of bulbs after 6 to 9 months of storage, although black shoot of the flower stem was not observed. The relationship between this vitrification of the flower stem in the stored bulbs and the quality of bulbs for cut flower production remains to be determined.
Keywords: lily bulb, storage below 0℃, temperature control, sprouting of bulb, long-term storage, oriental hybrids
*1 Hydraulic and Bio Engineering Research Section, Civil Engineering Research Institute, Technology Center
*2 Agricultural, Food and Environmental Sciences Research Center of Osaka Prefecture
*3 Nissin Corporation