Alleviating heat stress during early-season establishment of containerized strawberry transplants

BACKGROUND:Earlier planting under subtropical climatic conditions has been proposed as a means of increasing strawberry (Fragaria×ananassa Duch.) profitability but exposes transplants to heat stress. OBJECTIVE:Therefore, physical and chemical methods of ameliorating heat stress on the establishment, growth, and yield of containerized strawberry transplants were evaluated. METHODS:We used a split-plot design with white-on-black (white) mulch and black mulch as main plot treatments; and a factorial arrangement of transplant type and stress-prevention application was randomly assigned to the subplots. ‘Florida Radiance’ Jiffy plug and tray plug transplants were treated either with s-abscisic acid or with kaolin. RESULTS:White mulch resulted in greater plant vigor and vegetative growth than black mulch. Kaolin plus white mulch provided protection against heat stress as indicated by increased photosynthesis rates. At 4 weeks after transplanting, plant vigor and shoot growth were higher and flowering occurred earlier with Jiffy plug transplants than with tray plug transplants. Early marketable yields were higher with white mulch than with black mulch in three of the four site years. CONCLUSIONS:A combination of white mulch, Jiffy plug transplants, and kaolin application appears to have the best potential for alleviating heat stress during early-season strawberry establishment under subtropical conditions.