###### Abstract  
The cucumber is characterized by the presence of a wide range of volatile organic compounds (VOCs), which are recognized as the main responsible for its unique flavor. However, research on the types and contents of VOCs in different cucumber cultivars remains fragmentary. Here, using an automatic headspace solid-phase microextraction coupled with the gas chromatography-mass spectrometry method, the VOCs were analyzed in three representative cucumber cultivars, including YX, KX, and GX, with the best, middle, and worst flavor quality, respectively, which were selected from 30 cultivars after flavor quality evaluation. Principal component analysis revealed that the six biological replicates were grouped, indicating high reliability of the data. A total of 163 VOCs were detected. There were 28 differential VOCs in YX compared to GX, 33 differential VOCs in YX compared to KX, and 10 differential VOCs in KX compared to GX. Furthermore, K-means clustering analysis showed that 38 of the 43 no-overlapping differential VOCs were represented by the most abundant compounds detected in YX. The prevailing VOCs in YX included: hydrocarbons, aldehydes, and ketones. The data obtained in the present study extend our understanding the impact of cultivars on VOCs in cucumber and will help facilitate targeted breeding.  
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cultivars can be distinguished by their distinct abundance of monoterpenes, sesquiterpenes, and aldehydes. Through the correlation analysis between the VOCs and the sensory descriptors, [PERSON] et al. [11] found that the methyl butanoate, methyl 3-methylbutanoate, ethyl 2-methylbutanoate, methyl 2-butenoate, methyl 3-methylpentanoate, 3-carene, methyl (_E_)-2-methyl-2-butenoate, ethyl 4-methylpentanoate, 2-hexenal, butyl 3-methylbutanoate, butyl pentanoate, and 3-methyl butanoic acid were key factors in explaining differences in the characteristic fruit aroma and flavor of cashew apples.  
In melon, at least 500 VOCs have been identified and more than 100 of them can be found in a single accession [12]. Recently, [PERSON] et al. [13] found that the non-aromatic melon Piel de Sapo and the aromatic melon Vedrantais produced 88 different VOCs. For the first time, [PERSON] et al. [14] found that (_E_,_Z_)-2,_4-heptdalenal, (_E_,_E_)-3,5-octaiden-2-one, and 3-decyne were cucumber VOCs. [PERSON] et al. [15] qualitatively and quantitatively analyzed 85 volatile chemicals, including 36 volatile terpen, in 23 tissues of cucumber plants using solid-phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS). However, research on the types and content of VOCs in different cucumber cultivars is still lacking. To investigate differences in the composition and content of VOCs in cucumber fruits, three representative cultivars with distinct flavors were selected as test materials following the flavor-quality evaluation of 30 cultivars, and these were European greenhouse cucumber Yuxiu2 (YX), Northern Chinese-type cucumber Kangxiu4 (KX), and American pickling-type cucumber GX312 (GX). Automatic headspace SPME combined with GC-MS (HS-SPME/GC-MS) was used to analyze and compare the VOCs in the fruits of the three cucumber cultivars. The aim of this work is to study the impact of cultivars on the concentration and combination of VOCs in cucumbers, which could be integrated into breeding programs for future flavor improvement.