Temperature and Photoperiod Effects on Fuchsia × hybrida Morphology

Abstract

Fuchsia × hybrids `Dollar Princess' plants were grown under 35 day/night temperature (DT/NT) environments ranging from 10 to 30C over 2 years. Plants were grown under short days (SD) (9-hour 15-minute photoperiod) or long days (LD) (9-hour 15-minute photoperiod plus a 4-hour night interruption) within each environment. The influence of temperature on Fuchsia stem elongation and leaf expansion was best described by the relationship or difference (DIF) between DT and NT (DT - NT) rather than actual DT and NT between 10 and 25C. Both internode length and leaf area increased linearly as DIF increased from - 15 to + 15C with DT and NT between 10 and 25C. Internode length increased 0.129 and 0.071 cm/1C increase in DIF for LD- and SD-grown plants, respectively. Individual leaf area increased 0.52 and 0.40 cm 2 /1C increase in DIF for LD- and SD-grown plants, respectively. DT or NT above 24C reduced stem elongation and leaf expansion, regardless of DIF. The response of stem elongation and leaf expansion to DIF was greater on a percent basis when plants were grown under SD and LD, respectively. On an absolute basis, both internode length and leaf area were greater on LD-grown plants. Branching increased as average daily temperature decreased from 25 to 12C. Photoperiod did not affect branching.