ISHS Acta Horticulturae 109: III International Symposium on Flower Bulbs
THE USE OF ETHEPHON FOR CONTROL OF PLANT HEIGHT IN DAFFODILS AND TULIPS |
| Author: | R. Moe |
| Abstract:
The flower-stem and leaf length of eight daffodil and ten tulip cultivars were effectively reduced when ethephon (2-chloroethylphosponic acid) was applied to the soil. It controlled the growth of flower-stems better than leaves. The best time of application is when the shoots are about 8–10 cm in length. Too early application might cause blasting in sensetive cultivars of tulip. Spraying daffodils with ethephon reduced the plant height very little in 1978, but satisfactory in 1979. The optimum concentration of ethephon is about 1000 ppm (100 mg a.i./pot) for most of the cultivars of daffodil tested and 250–500 ppm (12.5 and 25 mg a.i./pot) for tulip. However, the amount of ethephon must be adjusted to the forcing temperature and the duration of cooling. The higher the forcing temperature, the stronger is the response to ethephon. Longer duration of cooling required higher concentrations. Too high ethephon concentration delayed days to flower with 1–3 days only when the bulbs were cooled for a short period of time. Ancymidol reduced flower stem length considerably more than leaf length. A concentration of 0.25–0.5 ppm (0.125–0.25 mg a.i./pot) reduced the plant height satisfactory for all cultivars tested. | |
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