Transplant Height Control and “Transplant Shock” Reduction with S-Abscisic Acid (S-ABA) in Vegetable Production

Transplanting is a standard cultural practice in vegetable production to improve seedling survival and cropping characteristics (earliness, yield, crop quality). The major objective of vegetable seedling production for transplanting is to produce a plant that has a compact shoot and well-developed, strong root system that provides a better chance of survival when it is moved from the protected environment to the field. S-ABA has been proven to successfully reduce undesirable excess shoot growth in the greenhouse with an increase in root-to-shoot ratio and improve seedling hardiness in a wide range of species. The dosage required varies between species or cultivars on a range of 200 to 2,000 ppm. Seedlings taken from the greenhouse and planted in the field often suffer transient water stress (i.e., transplant shock) due to root injury during transplanting and disturbed root-soil contact primarily in exposure to high evapotranspiration demand. Recently, foliar applications of S-ABA have gained interest in the vegetable industry as a method to improve post-transplant stress tolerance and increase transplant stand establishment. A series of greenhouse and field experiments was performed to determine the effects of exogenous applications of S-ABA on pepper, tomato, and watermelon transplants. Foliar applications of S-ABA significantly reduced water use, improved stand establishment and drought tolerance of the transplants. Latter seems important not just for seedling survival after transplanting but during shipping from the greenhouse to the field.