Elevated Atmospheric Ethylene and High Temperature Independently Inhibit Fruit Set But Not Vegetative Growth in Tomato

Ethylene is an essential plant hormone at low concentrations. Concentrations in the field rarely exceed 5 nmol center dot mol-1 (0.005 ppm), but it can accumulate as a gas in closed, indoor environments. These elevated levels can reduce growth and yield. Temperature alters ethylene synthesis and has the potential to influence ethylene sensitivity of crop plants in sealed greenhouses and indoor environments. We studied ethylene sensitivity of tomatoes (Solarium lycopersicum L. cv. MicroTina) using a unique, 12-chamber system. Ethylene levels of 0, 20, and 40 nmol center dot mol-1 (parts per billion) were maintained throughout the life cycle, at an air temperature of 22 or 28 degrees C. Yield of red fruit was three times higher at 22 than at 28 degrees C. There was a steady decrease in yield with increasing ethylene concentration, but vegetative growth was reduced less than 10% in any treatment. The highest ethylene concentration reduced yield to 11% of the control at 22 degrees C and to 4% of the control at 28 degrees C; the intermediate ethylene level reduced yield to 51% of the control at 22 degrees C and 37% at 28 degrees C. Regardless of temperature, filtering of ethylene in indoor environments to below 20 nmol center dot mol-1 is necessary to achieve normal fruit set and yield in tomato.

Automated summary

Elevated ethylene levels in closed indoor environments can reduce tomato yield, especially at higher temperatures. By studying ethylene sensitivity in a 12-chamber system, it was found that maintaining ethylene levels below 20 nmol/mol-1 can result in higher fruit yield.