| In order to explore the effect of day and night temperature on the quality of wine grape berries,this study used "Cabernet Sauvignon" as the test material and set up 3 experiments on day and night temperature.Experiment 1 studied the effect of Cover Gravel(CG)between rows on the micro-environment and berry quality of vineyard by using the natural properties of sands and gravel that absorb heat quickly during the day and cool down quickly at night,and taking clean tillage between rows as control(CK1);Experiment 2 compared and analyzed the differences of berry quality indexes in three different day and night temperature processing areas in Shihezi,Shandong,Penglai,and Yinchuan,Ningxia(hereinafter referred to as Xinjiang,Shandong and Ningxia)during the ripening period of grapefruit;Experiment 3 studied the effects of different temperature on the physical and chemical properties of Cabernet Sauvignon leaves,berry quality and volatile aroma components by using the method of building a greenhouse above the grapevines and regulating night temperature,simulating low temperature at night(LT)and high temperature at night(HT),and taking the natural environment as control(CK2)The experimental results showed that:(1)CG changed the micro-domain temperature environment of grape plants.Compared with inter-row ploughing,CG had some effects on air humidity and the variation of reflected light day,while it significantly increased the daytime vineyard canopy temperature and caused a larger diurnal range of air temperature.Because sand obstructed the direct contact between the ground and solar radiation,so as to the soil temperature of CG was significantly lower than CKI.(2)CG significantly improved the quality of grape berries.CG accelerated the accumulation of soluble sugars,anthocyanins and flavonoids,grape berries were higher than CKI of 12.2%,23.3%and 12.7%(at ripening),respectively.At the same time,CG also slowed down the degradation of titratable acids,tannins and total phenols,so as to grape berries were higher than CK1 of 18.1%,22.3%and 7.4%(at maturity),respectively.45 and 44 kinds of aroma were detected by CG and CKI respectively,and 11 kinds of aroma substances were detected together.CG increased the relative content of aldehydes,ketones and terpenes,which was higher than CKI of 10.7%and 60.6%.Compared with CK1,lipids and alcohols decreased by 25.6%and 45.6%,respectively.(3)A significant difference in the quality of grape berries among the three producing areas.The sugar content of fruit in the Xinjiang Uygur Autonomous Region was the highest,reaching 240.82 mg/kg,and the content of anthocyanin was the rank of the Xinjiang Uygur Autonomous Region>the Ningxia Hui Autonomous Region>Shandong province.The titratable acid content of fruit was the highest in the Ningxia Hui Autonomous Region,reaching 7.21 g/L,and the rank of tannin and total phenol contents were Shandong province>the Ningxia Hui Autonomous Region>the Xinjiang Uygur Autonomous Region.There were significant differences in volatile aroma components of fruits from three producing areas.For example,the species number and relative content of aldehydes and terpenes in Shandong province’s fruits were the highest,while the species number and relative content of lipids in Xinjiang Uygur Autonomous Region’s fruits were the highest.However,the species number and relative content of alcohols in the Ningxia Hui Autonomous Region’s fruits were the highest.(4)During the night temperature regulation,LT reduced the chlorophyll content,but when the treatment was finished,the chlorophyll content of LT would increase.The diurnal changes of photosynthetic rate were measured on the 20th day of regulating night temperature.Compared with CK2,LT would reduce the photosynthetic rate of leaves on the next day;HT reduced the soluble sugar content of leaves,and LT increased the soluble sugar content of leaves.(5)At different night temperatures,the quality of berries is also different.LT accelerates the accumulation of soluble sugars,anthocyanins and flavonoids,which were 11.7%,51.7%and 27.9%higher than CK2at maturity;LT slows down the degradation of titratable acid and tannins,which were 16.1%and 16.1%higher than CK2 at maturity.16.5%;HT has no effect on other quality indicators except that it significantly reduces the total phenols of the fruit.A total of 103 aroma components were detected in the 3 treatments,44,38,and 43 respectively for LT,HT and CK2;high temperature at night reduced the number of aroma substances,while low temperature at night increased aldehydes,terpenes and lipid compounds the relative content.Therefore,day and night temperatures have a significant effect on the berry quality of Cabernet Sauvignon grapes.Both covering sand in rows and the low temperature at night can improve the quality of the berries.The high temperature at night will reduce the quality of the berries.The local conditions and regional characteristics of three different producing areas lead to the differences of berry quality among the same wine grape varieties.This research can provide a theoretical basis for the selection of suitable microclimate cultivation areas for wine grapes and the production of high-quality grape berries and brewing wine with unique styles. |
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