球根アイリスの生育, 開花に及ぼす低温処理, 生育温度およびジベレリン処理の影響

Abstract

The author intended to examine the effect of cooling of bulbs, forcing temperature and gibberellin treatment on the growth and flowering of iris ‘Wedgwood’.The number of days to flowering differed little between the plants from bulbs cooled at 13°C for 40 days and those cooled at 8°C for 40 days. The number of leaves, height of plant and length of flower stalk at the flowering time increased in the plants cooled at 13°C than those cooled at 8°C. When the bulbs were cooled at 13°C for 28, 35, 42 or 49 days and were grown at 18°C, the number of days to flowering and the height of plant decreased as the cooling period was prolonged.In order to examine the effect of forcing temperature on the growth and flowering, the following two series of experiments were designed; (1) bulbs cooled at 13°C for 45 days were planted at 15°C, 20°C and 25°C on September 30, and (2) bulbs cooled at 13°C for 20 days were planted at 13°C, 18°C, 23°C and 30°C on June 15. None of the plants forced at 25°C in Exp. 1 and 30°C in Exp. 2 flowered at all and the flower buds blasted. The plants forced at the temperatures below 23°C flowered, though the flowering percentage was lower at higher temperatures. The number of days to flowering decreased remarkably and the height of plant increased and the length of flower stalk decreased as forcing temperature was raised. When the plants grown at 30°C for 5 or 10 days were shifted to 18°C, they did not blast and flowered with nearly the same percentage as plants forced continuously at 18°C.When the bulbs were soaked with gibberellin solution of 100 or 500mg/l and stored at 20°C without cooling, their flower bud initiation and development were accelerated. Although the flower bud formation was equally accelerated by gibberellin application and cooling treatment, the number of leaves increased in the bulbs treated with gibberellin and decreased in the cooled bulbs. When the bulbs were dipped in gibberellin solution of 100mg/l for 20 hours after cooling at 8°C for 45 days, the number of days to flowering decreased by 13.6 days with a slight increase in flowering percentage, comparing with those given cooling treatment only. The length of leaves and flower stalk increased by gibberellin treatment.