© 1994 Heron Publishing—Victoria, Canada
Carbohydrate requirements for dark respiration by peach vegetative organs
Yaffa L. Grossman (1, 2) and Theodore M. DeJong (1)
1. Department of Pomology, University of California, Davis, CA 95616, USA / 2. Department of Land, Air and Water Resources, University of California, Davis, CA 95616, USA / Received May 26, 1993
Summary
The specific respiration rate at 20 °C (R20) of peach leaves and stems declined rapidly from a high value in the early spring (22.5 nmol CO2 gdw–1 s–1) to relatively constant rates by July (3.1 nmol CO2 gdw–1 s–1). Leaf R20 declined more rapidly than current-year stem R20, but leaf and current-year stem R20s were similar by July. The R20 of current-year stems in July was approximately 2.5 times greater than that of one-year-old stems (1.3 nmol CO2 gdw–1 s–1), and about 30 times greater than that of the trunk R20 (0.1 nmol CO2 gdw–1 s–1). The Q10s of leaves and stems were approximately 2 for a temperature increase between 20 and 30. The Q10s above 30 were 2.03 for leaves but only 1.61 for stems. Leaves and current-year stems accounted for 2 and 17% of the aboveground
vegetative biomass in April and August, respectively, but accounted for 59–80% of total daily (24 h) respiration. Although
trunk biomass accounted for 91 and 77% of aboveground vegetative biomass, in April and August, respectively, trunk respiration
accounted for only 8–15% of daily aboveground respiration. Before harvest, during a period when fruit growth was source-limited,
daily fruit respiration exceeded respiration by all aboveground vegetative organs.
Keywords:
biomass, daily respiration, Prunus persica, Q10, specific respiration rate, temperature.
