Night-temperature effects on rate of apple fruit maturation and fruit quality

Abstract

Potted ‘Red Chief’ apple trees were exposed to 26°C day and either 22°C (warm) or 11°C (cool) night temperatures during fruit development and maturation. The onset of fruit ethylene (C 2H 4) production occurred at approximately the same time regardless of temperature. ACC (1-aminocyclopropane-1-carboxylic acid) levels in the fruits were not statistically different between temperature treatments during fruit maturation. Ethylene-forming enzyme (EFE) activity was measured by applying saturating amounts of exogenous ACC to fruit tissue and measuring C 2H 4 production. Cool-night fruit developed EFE activity earlier than warm-night fruit. Firmness and soluble solid content of the fruit were not statistically different between the temperature treatments. Although fruit maturity was unaffected by night temperature, fruit abscission occurred earlier in cool-night fruit. Warm-night fruit had less red skin color than cool-night fruit. Fruit diameter and length were not affected by night temperature.