The influence of root-zone temperature on strawberry species has not b
een thoroughly studied. Two experiments were conducted to determine th
e effect of root-zone temperature on vegetative growth, runner number,
runner plant development, and water relations in Fragaria chiloensis
Duch., F. virginia Duch., and F. viridis Duch. In Experiment I, clones
of F. chiloensis 'FRA 366' that originated in California, F. chiloens
is 'FRA 606' (Alaska) F. virginiana 'FRA 67' (Maryland), and F. virgin
iana 'FRA 104' (Wyoming) were grown hydroponically for 21 days with ro
ot zones at 23, 29, or 35 degrees C. All clones with roots held at 35
degrees C had less fresh mass gain over time, fewer runners, fewer run
ner plants, less leaf area on mother and runner plants, and less root
dry mass than plants at 23 or 29 degrees C. Plants at 29 degrees C had
less runner plant leaf area than plants at 23 degrees C. F. virginian
a exhibited greater vegetative growth and produced mere runners and ru
nner plants than F. chiloensis, but there were no species-temperature
interactions. In Experiment II, F. chiloensis 'FRA 366' (mother plants
originating in California) and F. viridis 'FRA 333' (Germany) were gr
own hydroponically for 56 days with root zones at 23, 29, 35, 20/26 (n
ight/day), 26/32, or 32/38 degrees C. F. viridis was more sensitive to
high root-zone temperature than F. chiloensis, and most growth reduct
ions were with reduced transpiration and leaf water potential. A low t
emperature (23 degrees C) promoted maximum growth of F. viridis, where
as exposure to root-zone temperatures as high as 32 degrees C fostered
maximum growth of F. chiloensis.