CALCIUM AND NITROGEN EFFECTS ON D’ANJOU PEAR FRUIT RESPIRATION AND ETHYLENE EVOLUTION

Calcium concentration in D’Anjou pear fruit was increased significantly by preharvest sprays (up to 30%) by postharvest dips (up to 150%) or by vacuum infiltration (up to 54%) with CaCl₂ solutions.
Increased Ca concentration in the fruit caused a significant reduction in respiration rate and ethylene evolution, and fruit Ca concentration was significantly inversely correlated with respiration rate (r = -0.83) and ethylene evolution (r = -0.87) during ripening at 20°C. An even greater correlation (r = -0.91) existed between water-soluble Ca and respiration rate than did total (acid-extractable) Ca and respiration rate (r = -0.87). Fruit firmness was increased by 1.1 kg from increased fruit Ca, but internal ethylene was also slightly increased by 5% CaCl₂ dips.
Fruit low in Ca (less than 7 mg per 100 g fresh weight) required a much shorter duration of cold storage before acquiring the ability to ripen compared with fruit having greater Ca.
Fruit with N:Ca greater than 10:1 also had shorter storage durations to ripen.
This rapid ripening of low Ca, or high N:Ca ratio fruit was related to greater initial and peak ethylene evolution.
High Ca fruit required a longer cold storage period to begin ripening, and after six months at -1°C the fruit retained firmness and stronger ethylene synthesis during 20°C ripening better than fruit with lower Ca.

III International Symposium on Pear Growing

D.G. Richardson, A.M. Al-Ani

https://doi.org/10.17660/ActaHortic.1982.124.25