How do plums ripen in two weather different years? A deep insight into the metabolomic profile

Abstract

The aim of this study was to analyse the ripening process of two European plum cultivars, ‘Nada’ and ‘Stanley’. As the effects of climate change are becoming increasingly evident, plum producers are facing new challenges. Therefore, the study was conducted in two consecutive years (2021 and 2022) characterised by different weather conditions during the ripening of the plum fruit. The first harvest was performed when 70 % of the fruit surface was covered with cultivar characteristic colour, while the last sampling date coincided with fruit drop. In addition to the basic fruit quality parameters (fruit weight, firmness, total soluble solids), 35 primary and secondary metabolites (sugars, organic acids and phenolics) were identified and quantified by HPLC analysis. Certain trends such as the decrease in fruit firmness, the accumulation of sucrose and anthocyanins and the degradation of malate, were observed during the ripening of two cultivars studied. No clear trend was observed for hydroxycinnamic acids, flavonols, flavanols and flavanones, although the most dominant phenolic compound in all ripening stages was 3-caffeoylquinic acid. Principal component analysis showed that ripening was largely cultivar-dependent and that the behaviour of the same cultivar differed between growing seasons. It was found that heat waves in combination with drought periods accelerated the ripening process, which had a particular effect on the softening rate.