ISHS Acta Horticulturae 451: VI International Symposium on Integrated Canopy, Rootstock, Environmental Physiology in Orchard Systems
APPLE FRUIT RESPIRATION IN THE FIELD: RELATIONSHIPS TO FRUIT GROWTH RATE, TEMPERATURE, AND LIGHT EXPOSURE |
| Authors: | M. Bepete, A.N. Lakso |
| Keywords: | relative growth rate, computer model |
| Abstract:
Total carbon requirements for growth of the apple fruit consist of carbon for dry matter growth and for the respiratory cost of growth and maintenance. Growth data for apple is plentiful, respiration data are not. This study measured the development of attached 'Empire' apple fruits in the field and measured the fruit respiration rates during the day in the dark at intervals with a portable gas analysis system. Light response curves were done in the field, and a temperature response curve and a diurnal pattern of fruit respiration at constant temperature were done in growth chambers with potted trees. In general, the specific respiration rates (per g fresh weight) declined as reported previously. Fruit respiration increased with temperature as expected, but there was no striking diurnal pattern of respiration in the constant temperature chamber. However, in the field, shaded fruits showed increases over the light period in excess of that expected due to temperature. Light exposure decreased net respiration and 29 mm fruits showed no significant net gas exchange under full sunlight. No simple relationship for fruit respiration to growth rate was found. These results, diurnal measurements of fruit temperature and exposure patterns, and other data from the literature were used to develop an initial diurnal fruit respiration model to estimate the effects of fruit development, daily temperatures, and fruit exposures on apple fruit respiration. | |
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