Ethephon-mediated Changes in Gas Exchange of Tomato Plants

Abstract

The gas exchange of tomato (Lycopersicon esculentum Mill cv. Spring Giant VF) plants exposed to an ethephon root drench of 5 μl·liter -1 or 50 μl·liter -1 was examined for 9 days. Photosynthesis showed a biphasic response to ethephon, wherein elevations of 13.2% and 16.7% were observed over control plants for two of the measurement days for the 50 and 5 μl ethephon/liter concentrations, respectively. Stomatal conductance showed a large increase at 50 μl ethephon/liter on day 2, while 5 μl·liter -1 did not show this difference. A biphasic response of photosynthesis may explain some of the intraspecific variation found in the literature describing ethylene-induced gas-exchange alterations.