| Improving fruit quality is the theme of fruit cultivation in 21 century. Of all, the composition and content of flavor matter have main effect on the fruit internal quality. Recently, although the studies on fruit flavors have made great progress, the studies on apricot remains little, especially on the flavor of North China ecogeographical group and F1 progenies of North China ×Europe ecogeographical group have not been reported. In this paper, the effect of different extraction methods on the apricot aroma constituents, the changes of the constituents of aroma, sugar and acid were studied at different developmental stages with "Katy"and "Xinshiji"varieties by gas chromatography-mass spectrometry (GC-MS) and Capillary Electrophoresis (CE). The difference in constituents of aroma, sugar and acid among 10 apricot cultivated varieties were also studied, including "Hongyu", "Tai'anshuixing", Jintaiyang, "Shajinhong", "Kaixin NO.1", "Huaxiandajiexing", "Hongfeng", "Yingxiangbai", "Jifu". Based on this, the inheritance of main flavor compounds in apricot was further studied with "Katy", "Xinshiji"and 65 seedlings of F1 progenies. The destination of this experiment was to give theoretical support and reference for evaluation, regulation of apricot quality and fruit quality breeding. The main results were as follows: 1. The effect of 4 extraction methods on apricot aroma constituents had been compared, with samples analyzed by GC-MS. Comparing distillation–extraction (DE) with solvent extraction (SE), the results indicated that a total of 74 components were identified in DE sample, of which C6 aldehydes, C6 alcohols, lactones, terpenic alcohols, ketones and hydrocarbons were the major constituents, and representing 99.5% of the total peak area. A total of 32 components in SE sample, of which hydrocarbons were the dominant constituents representing 99.6% of the total peak area. The results indicated that SE was not an effective method for extracting aroma components from apricot fruit because of little amount of aroma compounds, neither was SE because of its solvent and time-consuming. 2. The effect of headspace solid-phase microextraction (HS-SPME) and simultaneous steam distillation-extraction (SDE) on aroma compounds extracting was further compared. The results indicated that a total of 70 components were identified in the SPME sample including 23 esters, 19 hydrocarbons, 5 alcohols, 5 carbonyls, 4 acids, 4 lactones, 3 aldehydes, and 13 miscellaneous components, of which the esters were clearly the dominant constituents. Based on the Uo, 8 compounds identified in SPME sample were probably the characteristic compounds to the fresh apricot aroma such as hexyl acetate, β-ionone, butyl acetate, (E)-2-hexenal, linalool, limonene, γ-decalactone, and hexanal. Meanwhile, 48 components in the SDE sample, including 12 hydrocarbons, 9 alcohols, 7 aldehydes, 7 esters, 4 ketones, 4 lactones, 2 acids, of which the monoterpene alcohols were the dominant constituents. Odor unit values indicate that 14 compounds identified in SDE sample were the characteristic compounds to boiled apricot aroma: β-ionone, linalool, hexyl acetate, γ-dodecalactone, γ-decalactone, (E)-2-hexenal, hexanal, γ-octalactone, phenyl-acetaldehyde, butyl acetate, limonene, α-terpineol, δ-decalactone, and geranylacetone. The results showed that HS-SPME is a simple, rapid, solvent-free, and effective method to apricot aroma, which is an alternative to the classical SDE. 3. This current study focused on the aroma components which presented in "Xinshiji"and "Hongfeng"cultivars at the commercial ripe stage. The fruit was sampled by steam distillation-extraction. The results indicated that a total of 74 compounds were identified in "Xinshiji", and 72 compounds in "Hongfeng". Alcohols, aldehydes, lactones, ketones were the major constituents in the two extracts. The common constituents included β-ionone,hexanal, hexanol, hexenal, hexenol, lactones, terpineols ,etc, which were major contributors to apricot aroma. There were more concentration of these compounds in "Xinshiji"than in "Katy", this may caused "Xinshiji"more aromatic than "Hongfeng". Therefore, the presence and content of β-ionone, linalool, and lactones could probably be considered as the criterion to apricot aroma evaluation. 4. Sugar and acid compounds in apricot were studied with 10 cultivated varieties. The relationship between sugar/acid values and fruit quality was also studied. The results indicated that there were great differences in the components and total content of sugar among apricot varieties; fructose, glucose and sucrose were the main sugar components in the fruit. Of these three components in all tested varieties, the level of sucrose was the highest,the lowest in fructose. Meanwhile, malate and citrate were the main acid components. There were great differences in the components and the total content of acid among varieties. According to the components of acid, the apricot varieties could be divided into two types: citrate and malate. The ratio of sugar and acid were obviously different among the varieties. The sugar/acid values relied on the contents of sugar and acid. According to the sugar/acid values and fruit quality evaluation, the fruits that contained moderate acid (10～20 mg·g-1FW), high sugar (60～75mg·g-1FW) and moderate sugar-acid proportion (3.0～5.0) could be considered as having strong flavor and good dessert quality and were suitable to fresh-consuming. 5. The aroma constituents presented in apricot fruit during three different developmental stages had been studied, including mature green stage, commercial ripe and tree ripe stage. The fruit was sampled by simultaneous distillation-extraction. The results indicated that the aromatic constituents behaved differently during the fruit developmental period. Alcohols, aldehydes, ketones, lactones, esters and acids were the major constituents in the sample extracts. A total of 35 compounds were identified in the mature green stage, including (E)-2-hexenal, linalool, α-terpineol, (E)-2-hexen-1-ol, hexanal, 1-hexanol. 45 compounds in commercial ripe stage, among the important compounds were (E)-2-hexenal, linalool, α-terpineol, hexanal, ocimenol and geraniol. Meanwhile, 44 were found in tree ripe stage, the main components including linalool, (Z,Z,Z)-methyl 9,12,15-octadecatrienoate, α-terpineol, γ-decalactone , γ-dodecalactone, butyl acetate, hexyl acetate. The maximum of C6 aldehydes and alcohols were found in the mature green stage, diminishing in concentration as ripening proceeded. Several terpenic alcohols had been found in the different stages of ripening. The maximum was found in the commercial ripe stage. To the contrary, the presence of lactones and ketones was not detectable until the commercial ripe stage. Some esters had also been found such as butyl acetate, 3-hexenyl acetate, hexyl acetate, 2-hexenyl acetate, etc. Except 2-hexenyl butanoate and 2-hexenyl hexanoate, levels of others increased during fruit maturation. 6. The changes of sugar and acid components were studied with two cultivated varieties during fruit development. The results indicated that the changes of the components and total content of sugar were almost similar in "Xinshiji"and "Katy"varieties at different fruitdevelopment stages, the level of sucrose and total sugar increased constantly, whereas the content of fructose and glucose kept relatively steady, which indicated the increasing of total content of sugar was caused by sucrose. The change patterns of the content of total acid and components were different obviously in two varieties, but the change of malate and total acid was completely similar in "Xinshiji". Malate content increased slowly at higher level, whereas the level of citrate was lower during fruit development. The level of citrate at early development stage was lower than at later development stage, increasing rapidly while stoning finished and decreasing slightly during fruit maturation. The changing pattern showed "S"curve, contrast to citrate, the change of malate showed a reverse "S"curve. 7. Aroma components from "Katy"and "Xinshiji"and their F1 generations were analyzed. The results indicated that there were 37 compounds shared with parents and not segregated in F1 generations, of which 20 components with quatitative character inheritance was probably governed by multiple genes, including 9 characteristic aroma compounds such as (E)-2-hexenal, linalool, ocimenol, myrcenol, a-terpinenol, γ-decalactone, γ-dodecalactone, acetic acid hexyl ester, benzaldehyde and hexanal. The means of characteristic aroma compounds, such as (E)-2-hexenal, γ-decalactone, hexanal, γ-dodecalactone, were over mid-parent values, which indicated the inheritance of these compounds had the trend of over-parent and exhibited not only additive genetic effect but also inadditive genetic effect. The progenies with these compounds had great potential to be chosen. There were 17 compounds shared with parents and segregated in ratio of 1:1, 1:3 ,1:7 or 1:15 in F1 generations, which exhibited qualitative character inheritance governed by one or several pare genes. Of all, there were 8 characteristic aroma compounds including hexyl hexanoate, hexyl butanoate, butyl acetate, (Z)-3-hexen-1-ol acetate, benzene-acetaldehyde, δ-decalactone. There were 12 compounds shared with single parent and segregated or not segregated in F1 generations, of which 2 compounds with quatitative character inheritance were probably governed by multiple genes, whereas 10 compounds segregated in the ratio of 1:1, 1:3 or 1:7 in F1 generations were probably governed by one or several pare genes.
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