Respiratory Response of Detached Roots to Lower Temperatures in Cucumber and Figleaf Gourd Grown at 20°C Root Temperature

Abstract

Respiratory response of detached roots to lower temperatures was compared between a chilling-sensitive species, cucumber (Cucumis sativus L. cv. Suyô) and a less sensitive species, figleaf gourd (Cucurbita ficifolia Bouchè), which were grown at a root temperature of 20°C. Respiration of figleaf gourd roots was less susceptible to low temperature than that of cucumber roots. It was mainly the cytochrome respiration that was responsible for the differential susceptibility of root respiration. Experiments with 2, 4-dinitrophenol(DNP) indicated that the oxidative phosphorylation rate was higher in figleaf gourd than in cucumber roots at low temperature. These results strongly suggest that the response to low temperature of the cytochrome respiration of roots, coupled with oxidative phosphorylation, is an important aspect of differential root-chilling tolerance between cucumber and figleaf gourd.