Maturity of apple cv. Elstar as affected by temperature during a six-week period following bloom
In two experiments under controlled conditions, the effect of temperature (16, 20 and 24°C, experiment 1; 16 and 22°C, experiment 2) during a six-week period immediately following bloom on the progress of ripening around the normal picking time was evaluated for fruits of cv. Elstar. After six weeks, the temperature in experiment 1 was kept at 20°C throughout. In experiment 2 the temperature was 22°C from week 6 to 14, and 16 or 22°C from week 14 to 22. Post-bloom temperature clearly affected the rate of fruit ripening as reflected in ethylene production, background colour, starch content, firmness and red blush, but these variates did not respond to the same degree. The effect of temperature late in the season on ripening (just during the maturation period) was almost absent when the post-bloom temperature was 16°C. However, when post-bloom temperature was 22°C, fruits were greener, firmer, contained more starch and showed more red blush at 16 than at 24°C given from week 14 to 22. The acid content at ripening was lower at the higher post-bloom temperatures. Irrespective of the post-bloom temperature, acid content was also reduced at the higher temperature given during the maturation period. The content of soluble solids showed no consistent pattern.