ISHS Acta Horticulturae 297: II International Symposium on Kiwifruit
THE EFFECT OF TEMPERATURE ON THE RATE OF KIWIFRUIT MATURATION USING CONTROLLED ENVIRONMENTS. |
| Authors: | N.G. Seager, E.W. Hewett, I.J. Warrington, E.A. MacRae |
| Keywords: | Soluble solids concentration, flesh firmness, maximum daily temperature, minimum daily temperature |
| Abstract:
In New Zealand, kiwifruit can be harvested for export once the fruit soluble solids concentration exceeds a minimum of 6.2%. There is a difference in the timing of commercial maturity in the different kiwifruit production areas in the country and from year-to-year and these variations may be due to the different temperatures prevailing throughout a growing season. Two controlled environment projects have been undertaken to determine the effect of various maximum and minimum temperatures on the accumulation of soluble solids concentration in kiwifruit. Five pot-grown kiwifruit vines were placed in each of four controlled environment temperature treatments in 1989 where the maximum daily temperature in all treatments was 18 C with four different minimum temperatures at night. After 9 weeks, the soluble solids concentration in the fruit was 14.9, 13.6, 11.5 and 10.4% from vines exposed to 4,8,12 or 16 C night temperatures, respectively. Low temperatures at night increased the rate of kiwifruit maturation as measured by the rise in soluble solids concentration. The decreases measured in flesh firmness were not directly related to the night temperatures. In 1990, vines were placed in six controlled environment temperature treatments where the maximum and minimum temperatures were 14/8, 18/8, 22/8, 26/8, 14/12 or 22/12 C. The soluble solids concentration increased fastest with the coolest mean temperatures, irrespective of the day/night combination. After 10 weeks the final soluble solids concentration in the fruit was 15.0, 13.0, 12.8, 10.3, 9.7 and 9.1% from vines grown at 11, 13, 13, 15, 17 or 17 C mean temperature, respectively. Mean temperature affected the rate of change in soluble solids concentration more than it affected changes in flesh firmness. | |
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