EFFECTS OF SUPRA-OPTIMAL TEMPERATURE ON COREOPSIS AND GAILLARDIA

Coreopsis grandiflora ‘Sunray’ and Gaillardia x grandiflora ‘Goblin’ are commonly grown in the southern United States because of their ease of culture, showy daisy-like flowers and long blooming season.
High temperatures however, can often cause early decline resulting in a life cycle similar to that of annuals.
Objectives of this experiment were to determine the effects of high temperature combinations (30, 35 or 40 °C) on growth of Coreopsis and Gaillardia over a seven month period.
The plant growth rate (PGR) of Gaillardia control plants grown at warm temperature treatment (WTT, 35 °C) and hot temperature treatment (HTT, 40 °C) was significantly lower than those grown at mild temperature treatment (MTT, 30 °C), whereas Coreopsis displayed even more adverse affects in both WTT and HTT. The greatest effects on PGR occurred in the first 3 months when plants were moved into the HTT from either the MTT or the WTT. This research indicates that Gaillardia is more heat tolerant than Coreopsis, however both species are affected by temperature over 35 °C.

XXVI International Horticultural Congress: Environmental Stress and Horticulture Crops

M.K.D. Vige, J.S. Kuehny, J.E. Board, G. McClure

plant growth rate, Coreopsis grandiflora ‘Sunray’, Gaillardia x grandiflora ‘Goblin’

https://doi.org/10.17660/ActaHortic.2003.618.18