ISHS Acta Horticulturae 398: Postharvest Physiology of Fruits
REGULATION OF RESPIRATION IN APPLE, AVOCADO AND CITRUS ORANGE FRUIT |
| Author: | M. M. Blanke |
| Keywords: | Apple, Avocado, Orange, Fruit ripening, Phosphoenol-pyruvate carboxylase, Respiration, Stomata |
| Abstract:
Anatomical, physiological and biochemical features which regulate fruit respiration were examined in apple, avocado and Citrus orange. The number of stomata or lenticels at harvest ranged from 1 mm-2 in apple, 3–5 mm-2 in avocado to 50–75 mm-2 in Citrus orange fruit. Most guard cells lost their regulatory ability at harvest. The smallest stomata were observed in avocado fruit. Stomata when open were the preferred sites of gas exchange. Respiration rates were 10 to 220 mg CO2 kg-1 fruit fresh matter h-1 or 0.1 to 19 mg CO2 dm-2 fruit surface h-1. The slowest respiration rate was shown by apple and the fastest by avocado. Intercellular space volumes of the three fruits ranged from 5% to 25% (v/v). Mitochondrial and seed respiration resulted in intercellular CO2 concentrations of between 2 % and 20 % CO2. A large proportion of the CO2 respired by mitochondria was refixed within the fruit by | |
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-carboxylation of the enzyme PEPC and recycled into the carbon and organic acid metabolism.
