## 4 Discussion  
VOCs are essential factors controlling the quality of fresh and storage-processed oranges. Studies related to VOCs in oranges have mainly focused on varieties such as brocade orange, sour orange, and naval orange varieties, while little has been reported on 'hongjiang'. [PERSON] et al. [26] detected a total of 127 VOCs from ten orange juice samples by HS-SPME-GC-MS, mainly consisting of alkenes, alcohols, esters, aldehydes, and ketones, with alkenes and alcohols accounting for a relatively proportion of their large content. Consistent with the results of this study, it was further confirmed that alkenes, alcohols, esters, aldehydes, and ketones were the typical aroma compounds constituting orange juice. In addition, this study revealed that two factors (location and cultivation mode) had strong effects on the percentage of orange VOC composition: largest share of aldehydes was found in half-net room cultivation (PRHN) oranges, the largest shares of ketones, esters, and alkenes were found in little-net room cultivation (PRGN) oranges, and the largest percentage of alcohols was found in Chengyue town (PCON) oranges. [PERSON] et al. [10] used the HS-SPME-GC-MS technique to isolate and identify 65 VOCs from five commercially available naval orange fruits, which were dominated by limonene, \(\beta\)-watercressene, \(\beta\)-laurelene, and linalool, with limonene accounting for 70-81%. This study proved that limonene, valencene, \(\alpha\)-panasinsen, linalool, and Selina-4,11-diene were the main VOCs in 'hongjiang', with limonene and valecene ranging from 30-60% and 1-30%, respectively. The composition of limonene in 'hongjiang' was much lower than that in naval oranges. Still, the composition of valencene in red river orange was higher than that of navel orange, indicating that the aroma characteristics of red river orange and navel orange differed significantly. Naved orange fruits were dominated by limonene, \(\beta\)-watercressene, \(\beta\)-laurelene, and linalool, among which limonene accounted for 70-81%. At the same time, this study showed that limonene, valencene, \(\alpha\)-Panasinsen, linalool, and Selina-4,11-diene were the main VOCs of 'hongjiang', with limonene accounting for 35-67% and valencene accounting for 10-20%. The composition of limonene in 'hongjiang' was much lower than that of navel oranges, while that of valencene and other components in 'hongjiang' exceeded that of navel oranges, indicating that the aroma characteristics of 'hongjiang' and navel oranges were different. Net room cultivation is one of the important measures for green vegetable and fruit production. It plays a pivotal role in integrated pest management, and the results have been applied to cultivating fruits and vegetables, flowers, and so on [27; 28]. [PERSON] et al. [29] showed that the intrinsic quality (vitamin C, soluble solids, acidity, solid-acid ratio, and juice rate), extrinsic quality (fruit shape index, peel thickness, fruit hardness, peel rate, and residue rate), and some coloring qualities (yellow value \(b\), color saturation \(C\), and brightness value \(L\)) of the fruits cultivated in net room cultivation were not significantly different from those of the open-air cultivation (\(p>0.05\)). Still, the red value of citrus fruits in the net room cultivation was considerably smaller than that in the open-air cultivation area (\(p<0.05\)), and the hue angle (describing the relative. amounts of redness and yellowness) was significantly larger than that in the open-air cultivation (\(p<0.05\)). [PERSON] et al. [30] revealed the effect of net room cultivation on the quality of late-ripening citrus in Guinan, with a significant decrease in the total sugar content of wogon and a substantial increase in the vitamin C content of Maugu tangerine compared to open-air cultivation, with no substantial changes in other quality indicators.