2017 ASHS Annual Conference

Earlier planting to take advantage of higher prices for early fruit has been proposed for stabilizing the Florida strawberry (Fragaria ×ananassa Duch.) industry from the effects of market incursions from California and Mexico. However, early planting in Florida exposes strawberry transplants to heat stress. Additionally, containerized strawberry transplants are of interest as a means of addressing the high sprinkler irrigation requirement for bare-root transplant establishment. Therefore, the objective of this study was to evaluate the effects of s-abscisic acid (s-ABA), kaolin, and white-on-black polyethylene mulch on the establishment, growth, and yield of containerized strawberry transplants. Trials were conducted in Citra and Wimauma, Florida using a split-plot design in which main plot treatments were either white-on-black mulch or black mulch; and a factorial arrangement of strawberry transplant type and stress-prevention application was randomly assigned to the subplots. ‘Florida Radiance’ plug and tray transplants were treated either with s-ABA (150 mg/L) as a 5-second root dip immediately before transplanting or with kaolin (56 kg/ha) as two consecutive sprays: the first shortly after transplanting and the second at 7 days after planting. Nontreated plug and tray transplants were included as controls. White-on-black mulch consistently resulted in plants that exhibited greater survival, vigor, photosynthesis, and vegetative growth than nontreated control plants on black mulch. Kaolin applied in combination with white-on-black mulch provided further protection against heat stress as indicated by increased photosynthesis rates within 3 days of transplanting, and higher leaf number and leaf area during the first 8 and 6 weeks after transplanting, respectively. Flowering occurred earlier in plants on white-on-black mulch than on black mulch and a further decrease in the days to first flower resulted with the combination of s-ABA and kaolin with white-on-black mulch that was more pronounced with plug transplants than with tray transplants. Early and total marketable yields were generally higher with white-on-black mulch than with black mulch. Compared to black mulch alone, early marketable yields in Wimauma were highest with black mulch + kaolin and with white-on-black mulch + either s-ABA or kaolin. At Citra the highest early yields occurred with white-on-black mulch in combination with either s-ABA or kaolin. Although early yield was unaffected by transplant type, total marketable yield was higher with plug transplants than with tray transplants. A combination of white-on-black mulch, plug transplants, and kaolin application appears to have the best potential for alleviating heat stress during early-season establishment of containerized strawberry transplants.