Abstract: Abstract: 【Objective】The objective was to find out when the difference of glucose/fructose (G/F) took place during fruit development in peach cultivars of two G/F types in fruits (G/F≈1 and High G/F) at maturity and if there was influence of end products in leaves on G/F in fruits. 【Method】Six peach cultivars were used as materials, which differ in G/F in fruits at maturity (G/F≈1 cultivars: ‘Hakuto’, ‘Shanyibaitao’ and ‘Yanhong’; High G/F cultivars: ‘Zhanghuang 7’, ‘Long 246’ and ‘Linbai 7’). Seasonal changes of soluble sugar contents in fruits and leaves were investigated by High Performance Liquid Chromatography method (HPLC). Moreover, soluble sugar in phloem at 74th day or 101st day after full bloom were measured for ‘Hakuto’, ‘Shanyibaitao’, ‘Zhanghuang 7’ and ‘Long 246’.【Result】Sucrose, main soluble sugar in fruit, was lower at the early stage, and accumulated quickly till maturity; Sorbitol content increased from early fruit development stage, and tended to decrease around the beginning of final fruit rapid growth stage; Glucose and fructose contents were high at the early fruit development stage, then decreased gradually. However, glucose and fructose contents were approximately equal to each other in G/F≈1 cultivars while bigger G/F values were observed for high G/F cultivars throughout fruit development. Sucrose and sorbitol were main soluble sugars in leaves, whereas G/F ranged 1-3 in leaves of G/F≈1 cultivars, and 2-7 in leaves of high G/F cultivars. There was significant correlation between G/F in fruits and G/F in leaves (r = 0.47***). Sorbitol was remarkably more than sucrose, glucose and fructose in phloem of 4 peach cultivars, accounting for 47-58% of the total soluble sugars. G/Fs in phloem were 0.8-0.91, and there were no obvious differences among the four peach cultivars.【Conclusion】Transportation of the assimilates through phloem from leaves to fruits should have no obvious effect on G/F in fruits. Different G/F in fruits for the two type cultivars should result from different sugar metabolisms in fruits. Sugar metabolisms in fruits and leaves might be independent, but could have similar regulation mechanisms.

Key words: Peach (Prunus Persica), Soluble sugar, Glucose, Fructose