Fruit degreening in different cultivars of kiwifruit
The global trade in kiwifruit (Actinidia chinensis) developed with the green-fleshed Hayward as the predominant cultivar. More recently, alternative cultivars have become available, including those with yellow flesh. Hayward is largely considered not to degreen, despite evidence that it does so slowly. In contrast, yellow-fleshed cultivars degreen fully to reveal their background pigmentation. The degreening of five cultivars of kiwifruit, Zesy002, Zesy003, Zesh004, Tomua and Hayward, on and off the vine, has been investigated with respect to fruit development on the vine and temperature when off the vine. Zesy002 and Zesy003 fruit may degreen fully on the vine, while Zesh004, Tomua and Hayward show less colour change. This may be associated with both the genetics and timing of fruit development. Off the vine, Zesy002 and Zesy003 fruit harvested when green continued to degreen, although the rate was temperature dependent. In contrast, off the vine there was little degreening in Zesh004 fruit and virtually no degreening in Tomua and Hayward. However, there was significant chlorophyllase activity in the fruit of all cultivars. In Zesy002 and Zesy003 fruit, chlorophyllase activity decreased as fruit fully degreened. In Hayward and Tomua fruit, the coexistence of high levels of chlorophyll and chlorophyllase activity suggests that chlorophyllase activity is not the only determinant of fruit degreening. There appear to be two aspects to the differences in degreening among cultivars: the inherent genotype difference in capacity to degreen, and the temperature dependence of the degreening process.
Ghasemnezhad, M., Fullerton, C., Billing, D., Ampomah-Dwamena, C., Burdon, J. and Atak, A. (2022). Fruit degreening in different cultivars of kiwifruit. Acta Hortic. 1332, 285-294
Actinidia, fruit, quality, maturation, chlorophyll