Changes during the last ripening stage in pomological and biochemical parameters of the ‘Redhaven’ peach cultivar grafted on different rootstocks

The development of the ‘Redhaven’ peach [Prunus persica (L.) Basch.] fruit grafted on six rootstocks (Adesoto, GF 677, Monegro, Ishtara, Penta, Tetra) was evaluated in 2011. Several quality indices (fresh weight, flesh firmness, ground, blush color and flesh color measurements, and soluble solids content) were measured. The chlorophyll a content and total carotenoid content were measured using a spectrophotometer, and HPLC analyses were performed for numerous chemical parameters (quantification of individual phenolic compounds and carotenoids in the skin and flesh). Sampling was carried out on three dates (94, 100 and 107 days after full bloom – DAFB) during the last 15 days of fruit development, to determine changes in fruit quality. Fruit weight as well as the a* value of ground, blush color and flesh color increased, while fruit firmness decreased with the progress of ripening. This indicates a transition from green to red in the case of ground and blush color and a gradual absence of green tones in the case of flesh color. All metabolites and pigments were more concentrated in the skin than in the flesh tissues regardless of the development stage or rootstock. In general, contents of metabolites followed similar patterns during ripening in both tissues. Chlorophyll a decreased, while anthocyanins, total carotenoids, lutein and β-carotene increased with ripening. Phenolics generally presented the highest content levels at 94 DAFB, which then decreased by 100 DAFB and again increased by 107 DAFB. Rootstocks had no influence on chlorophyll a level in the last 15 days of fruit development, but did influence individual carotenoid and phenolic compound levels in peach skin in ripe fruit.