Timing and concentration of abscisic acid applications affect the quality of 'Crimson seedless' grapes.

摘要

Crimson Seedless is a table grape cultivar that often fails to develop adequate colour, particularly in warm regions such as the San Joaquin Valley, California. Growers generally apply ethephon to Crimson Seedless grapes to improve their colour but results are erratic. Abscisic acid (ABA) stimulates anthocyanins production in some other varieties of grape, so applications of ABA may help improve the colour of cv. Crimson Seedless. Application of ABA at veraison maximized anthocyanins accumulation in cv. Crimson Seedless, but later applications also increased pigmentation and, at the same time, reduced the negative effect of ABA on berry puncture resistance. 150 and 300 mg l-1 ABA increased anthocyanins levels more than 75 mg l-1. Relationships between the anthocyanins content of berry skins and colour characteristics lightness (L*) and hue angle (ho) were well described by 2 functions. At skin anthocyanins contents >=0.03 mg cm-2, relatively large increases in anthocyanins content had relatively small effects on L* and ho. Similar results were obtained with other grape cultivars. For this reason, it is suggested to include direct colour measurements, rather than relying only on anthocyanins content, when evaluating grape colour.