Abstract: In order to study the influence of night temperature in the greenhouse on the fruit quality of Cabernet Sauvignon, we controlled night temperature in the greenhouse to the high night temperature (HT, the average temperature is 21.8 ℃), the low night temperature (LT, the average temperature is 17.1 ℃), and the natural environment temperature (CK, the average temperature is 18.9 ℃) for 35 consecutive days starting before veraison, and we monitored the temperature and humidity during this period. We measured and compared chemical components and volatile aroma composition of the three treatment groups. The results showed that LT accumulated 11.7%, 51.7% and 27.9% more soluble sugar, anthocyanins and flavonoids in mature grape berries than CK, respectively. LT degraded 16.1% and 16.5% less total acids and tannins than CK, respectively. HT significantly decreased total phenol content, despite having no effect on other quality indexes tested. The night temperature had a significant effect on the composition and proportions of volatile aroma components. A total 103 volatile compounds were detected, 44, 38 and 43 of them being found in LT, HT and CK, respectively. Eleven volatile components were common to all three groups. HT reduced the kinds of volatile compounds, but increased the relative content of aldehydes. LT increased the relative contents of aldehyde, terpenes and esters. HT and LT reduced the relative contents of alcohol compounds. Therefore, these results indicated that LT can improve berry quality while HT has an opposite effect.

Key words: greenhouse; regulation; night temperature; Cabernet Sauvignon; berry quality; aroma components