Redefining the impact of preharvest factors on peach fruit quality development and metabolism: A review

Abstract

One primary reason worldwide peach consumption has been in steady decline throughout the past few decades is due to poor fruit quality. Fruit quality is developed in the orchard by optimizing preharvest factors and orchard practices. Several studies have been conducted to understand how these factors influence peach internal quality, but often fail to control for confounding variables. One particular confounding variable that is influenced by preharvest factors and directly impacts fruit quality is maturation. Pomological experiments investigating the impact of preharvest factors on internal fruit quality must compare fruit of equal maturity. Maturity assessment through destructive and subjective methods is not feasible nor efficient. The use of visual radiation (Vis) and near-infrared spectroscopy (NIRS) allowed the development of robust non-destructive tools for physiological maturity (index of absorbance difference, IAD) and internal fruit quality [dry matter content (DMC) and soluble solids concentration (SSC)] assessment simultaneously in a single scan. Recent studies investigated the impact of critical preharvest factors such as rootstock, canopy position, crop load and growing environment on peach fruit quality development and metabolism, while selecting for fruit of equal maturity. Studies on rootstock and canopy position revealed that the fruit's light environment was more influential in quality development and metabolic shifts than the genotype vigor or position alone. Fruit under sufficient carbon supply, which was determined by crop load, exhibited superior quality and phenotype when compared to carbon-starved fruit at harvest. Although, metabolite profile differences between distinct carbon supply conditions at harvest were minimal, when assessed at equal maturity. Early metabolic shifts under optimum carbon supply and optimum growing environment conditions may prime fruit quality at harvest. Catechin and sorbitol were associated with high-quality fruit, while amino acids and citric acid showcased relationships with inferior quality fruit.