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Abstract
Solutions of (2-chloroethyl) phosphonic acid (ethephon) at 1000, 1500, and 2000 ppm were sprayed on trees of ‘Giarraffa’ olive (Olea europaea L.) time midway between the onset of pit hardening, and the maximum respiratory rate induced early pigmentation of drupes. Treatment modified anthocyanins, respiratory ratio (CO2/O2), polyphenols, redox potential, total sugars and their composition, linoleic/palmitoleic acid ratio, and dry weight. Pulp/stone ratio, respiratory rate, pH, uronic acids, oil, principal fatty acids, and protein content did not differ from the control. Ethephon applied after the occurrence of the maximum respiratory ratio only reduced the fruit detachment strength. These results confirm the hypothesis which attributes a climacteric model to the attached fruits and a nonclimacteric model to the detached ones. The physiological modifications of fruits ripened with ethephon were similar to those found in the last stage of natural maturation.
Abstract
Clonal plants of four olive (Olea europaea L.) cultivars that originated in cool, moderately hot, and hot climates were examined for their photosynthetic potentials. Within 3 to 4 weeks, plants had fully expanded leaves; by 3 months the apparent photosynthesis, A, increased to a maximum of 5.4 µmol CO2/m2 per sec, while the water use efficiency (WUE) was 2.6 mmol CO2/mol H2O. The mean chloropohyll content was 0.564 mmol/chlorophyll (a + b)/m2. Mean assimilation rate was negatively correlated to leaf area. The values of A were three to four times less than those reported for apple and almond, whereas WUE was 22% greater. A values were proportional to stomatal conductance. Mesophyll resistance was higher than several C3 plants and the optimum temperature for photosynthesis varied among cultivars, seemingly according to the climate where they originated. Stomata opened and closed within 10 min in response to changes in humidity. Gas exchange properties were not affected by peltate removal.