Pre-plant Inhibition of Ethylene Signaling Alleviates Transplant Stress Responses and Improves Yield of Tomato

Shipping and transplanting can cause a high degree of mechanical stress in vegetable transplants. Ethylene biosynthesis is commonly increased under mechanical stress to induce downstream stress responses and reduce overall growth. In this study, it was hypothesized that ethylene is the primary hormone inducing stress responses during transplanting and limiting transplant performance in the field. Therefore, the objective of this study was to examine if inhibiting ethylene signaling prior to transplanting can improve field establishment and yield of tomato. 1-Methylcyclopropene (1-MCP) was used to inhibit ethylene signaling by blocking ethylene receptors. Tomato seedlings (‘Florida 47’) were treated with 1-MCP at 0, 12.5, and 50 mg/L one day before transplanting. Post-planting growth was significantly accelerated by 1-MCP, with plant height increasing by 7% to 12% at the flowering stage. At the time of harvest, the 1-MCP-treated plants had 17% to 19% larger shoot biomass and 10% to 14% more flowers than the control plants. Consequently, both extra-large fruit and total marketable fruit yields were significantly increased by 1-MCP by up to 51% and 25%, respectively. The magnitude of growth and yield promoting effects by 1-MCP was similar for the two tested concentrations. These results suggest that inhibiting ethylene signaling by 1-MCP is an effective strategy to alleviate undesirable stress responses and improve the performance of vegetable transplants.