© 1992 Heron Publishing—Victoria, Canada
Carbon dioxide exchange of developing avocado (Persea americana Mill.) fruit
A. W. Whiley (1, 2), B. Schaffer (1) and S. P. Lara (1)
1. University of Florida, Tropical Research and Education Center, 18905 S.W. 280 Street, Homestead, Florida, USA / 2. Department of Primary Industries, Maroochy Horticultural Research Station, P.O. Box 5083, Sunshine Coast Mail Centre, Queensland,
Australia / Received August 6, 1991
Summary
Net efflux of CO2 from attached avocado (Persea americana Mill.) fruit was measured periodically from three weeks after anthesis to fruit maturity. Net CO2 exchange was determined in daylight (light respiration, Rl) at a photosynthetic photon flux (PPF) greater than 600 μmol m–1 s–1, and in the dark (dark respiration, Rd). Dark respiration and Rl were highest during the early cell division stage of fruit growth (about 25 and 22 nmol CO2 gdw–1 s–1, respectively) and decreased gradually until fruit maturity to about 1 and 0.5 nmol CO2 nmol CO2 gdw–1 s–1, respectively. Fruit photosynthesis, calculated from the difference between Rd and Rl, ranged from 0.5 to 3.1 nmol CO2 gdw–1 s–1. Net rate of CO2 assimilation on a fruit dry weight basis was highest during the early stages of fruit growth and reached the lowest rate
at fruit maturity. Net rate of CO2 assimilation of fruit exposed to light was 0.4 to 2.5% of that for fully expanded leaves. Although the relative amount of
carbon assimilated by the fruit was small compared with the total amount of carbon assimilated by the leaves, the data indicate
that avocado fruit contribute to their own carbon requirement by means of CO2 assimilated in the light.
