Temperature affects leaf unfolding rate and flowering of cyclamen

The rate of leaf unfolding for Cyclamen persicum Mill. was determined at 8 to 24 degreesC. Temperature treatments started 9 weeks from seeding and after 8 weeks all plants were moved to 16 degreesC. The cultivars Miracle Salmon, Miracle Scarlet, and Miracle White produced leaves at a similar rate. The relationship of (leaves/d) = - 0.01727 - 0.02284 * degreesC + 0.005238 * (degreesC)(2)- 0.000162 * (degreesC)(3) (R-2 = 0.99) best described the leaf unfolding rate in response to temperature. The maximum leaf unfolding rate was estimated to 0.329 leaves/day at 19.1 degreesC. Flower buds (2 mm diameter) developed within 60 days from the start of temperature treatments except at 8 degreesC. Thirty-five additional days at 16 degreesC were required for cyclamen initially grown at 8 degreesC for 8 weeks to produce flower buds. Despite similar conditions during bud development, flowering was delayed 14 to 18 days for plants initially grown at 24 degreesC compared to those grown at 12 to 20 degreesC. Plants initially at 8 degreesC did not flower within 70 days at 16 degreesC. Leaf and flower numbers at first open flower increased as initial temperature increased from 12 to 24 degreesC while dry weight and height only increased to 20 degreesC. No correlation between Leaf unfolding and rate of flowering or flower number was detected. Recommendations for 20 degreesC during early cyclamen growth can be expected to support rapid rates of leaf unfolding and development, and large flower numbers.