Methyl jasmonate effects on table grape ripening, vine yield, berry quality and bioactive compounds depend on applied concentration

Abstract

In the present research the effect of preharvest metyil jasmonate (MeJA) treatment on the ripening process and fruit quality parameters at harvest was evaluated, for the first time, in two table grape cultivars, ‘Magenta’ and ‘Crimson’, during two years, 2016 and 2017. MeJA treatments (applied when berry volume was ca. 40% of its final one, at veraison and 3 days before the first harvest date) affected grape ripening process and vine yield differently depending on applied concentration. Thus, MeJA at 5 and 10mM delayed berry ripening and decreased berry weight and volume as well as vine yield, in a dose-dependent way, in both cultivars, although the effect on ‘Crimson’ was more dramatic than in ‘Magenta’. However, treatments with MeJA at 1, 0.1 and 0.01mM accelerated ripening and increased total phenolics and individual anthocyanin concentrations, the major effects being obtained with 0.1mM concentration. In addition, total soluble solids (TSS) and firmness levels were also increased by these MeJA treatments. These results might have a great agronomic and commercial importance since fruit with higher size and harvested earlier would reach higher prizes at markets and berries with higher firmness and TSS would be more appreciated by consumers. Moreover, MeJA treatments increased the content of antioxidant compounds, such as phenolics and individual anthocyanins, leading to enhance the homogeneous pigmentation of the whole cluster, with additional effects on increasing the health beneficial effects of grape consumption.