CORESTA Meeting, Agronomy/Phytopathology, 2019, Victoria Falls, AP 07

Evaluation of a biodegradable plastic greenhouse float tray

Virginia Tech, Southern Piedmont Center, Blackstone, VA, U.S.A.

The Trilogy tray was introduced in 2015 as the first commercially available plastic greenhouse float tray for tobacco transplant production in the United States. Modifications to the original design have been made in subsequent years. More recently, for research purposes, an additive has been included in the plastic to promote biodegradability of the tray. The additive allows photodegradation of the plastic through oxidation or the addition of carbonyl groups to the polypropylene plastic molecule when exposed to sunlight. This oxidation is necessary to facilitate the biodegradation of the plastic once the trays are exposed to an active microbial environment. The objectives of this study were to quantify the degradation of Trilogy float trays under laboratory and greenhouse conditions and to propose how such tray technology may be incorporated into sustainable greenhouse tobacco transplant production.

Laboratory testing was conducted to measure plastic degradation under accelerated ultraviolet (UV) light exposure conditions of plastic tray samples to which three rates of a proprietary additive had been added. The physical integrity of the plastic was evaluated as well as laboratory quantification of the addition of carbonyl groups to the plastic. Results suggest a useable life for the plastic of 5 to 6 years of outdoor exposure. The response in degradation was dependent on the rate of the additive in the tray. The lifespan of trays in actual use would be expected to be longer since UV exposure is significantly reduced once the seedlings grow to cover the trays and trays would typically be stored out of the sun when not in use. Greenhouse trials are currently under way to evaluate the degradation of the plastic under actual greenhouse conditions.