Narges Mojtahedi - Agriculture Biotechnology Research Institute of Iran (ABRII), Seed and Plant Improvement Institutes Campus, Mahdasht Road, Karaj, Iran, P.O. Box ۳۱۵۳۵-۱۸۹۷
Parisa Koobaz - Agriculture Biotechnology Research Institute of Iran (ABRII), Seed and Plant Improvement Institutes Campus, Mahdasht Road, Karaj, Iran, P.O. Box ۳۱۵۳۵-۱۸۹۷
Mohammad Fathi - Agriculture Biotechnology Research Institute of Iran (ABRII), Seed and Plant Improvement Institutes Campus, Mahdasht Road, Karaj, Iran, P.O. Box ۳۱۵۳۵-۱۸۹۷
Omid Dabirashrafi - Agriculture Biotechnology Research Institute of Iran (ABRII), Seed and Plant Improvement Institutes Campus, Mahdasht Road, Karaj, Iran, P.O. Box ۳۱۵۳۵-۱۸۹۷

One of the most effective ways to propagate Lilium is by using tissue culture techniques, preferably through bulblet production. In addition to the surviving percentage of Lilium bulbs after transplantation, the small size of in vitro bulblets compared to commercial bulbs and bulblets‟ dormancy are the most important constraints to commercializing Lilium micropropagation. Different concentrations of sucrose or sorbitol as carbohydrate sources were investigated as maturation and enlargement factors on in vitro bulblets of Lilium longiflorum cv. „Ceb-dazzle‟. Five concentrations of gibberellic acid and 4°C cold treatment for 6, 7, 8, 9, 10 and 11 weeks in the greenhouse were studied in relation to the dormancy breaking of three in vitro Lilium bulblets cultivars: „Simplon‟, „Navona‟ and „Ceb-dazzle‟, which belong to the Oriental, Asiatic and LA hybrids. The results showed that 3% of sucrose and two weeks of culture significantly increased the bulblet maturation and enlargement of „Ceb-dazzle‟. One mg L-1 gibberellic acid for six weeks, or cold treatment for six to eight weeks, had significant positive effects on the dormancy breaking of in vitro bulblets of Lilium cultivars.