###### Abstract  
Covering crops was a commonly used viticultural technique to adjust the vineyard microclimate, thus affecting the grape and wine quality. In this two-year study, the purslane (_Portulaca oleraca_ L.) was used to cover the lands between rows in the vineyards located in the semi-arid Northwest China, Xinjiang. Results showed that the photosynthetically active radiation around the fruit zone and the temperature with the purslane covering treatment decreased. Compared with the clean tillage, covering purslane had lower TSS and higher TA in the grape berries, while lower alcohol content and higher TA was also found in their corresponding wines. Covering purslane treatment significantly increased the contents of anthocyanin and flavonoid in the grapes and wines in the year 2018, but no significant effect on flavanols was observed in the wines. Norisoprenoids, esters, and C\({}_{6}\) alcohols in the grapes and wines were increased in the purslane covering treatment, respectively. Additionally, compared to the clean tillage, the purslane covering treatment significantly improved the sensory value of the wines, especially the floral aroma and the complexity of the wines. This study helped us to better understand the feasibility of applying covering purslane in viticulture in the semi-arid climate of Northwest China. c 20  
The effects of the canopy microclimate on the grape and wine composition were also important [7; 8; 9]. The canopy microclimate of the vineyard had become one of the key focuses of current researches. The common cultivation measures to change the microclimate of the vineyard included leaf removal, canopy shading, crop covering, spur-pruning, etc. The vineyard canopy microclimate and its management has become one of the key focuses of current researches [10; 11]. In various attempts, covering crops might have the potential to improve the wine quality by changing the microclimate of the grape growing, especially in arid environments [12]. Furthermore, in the sustainable or the organic vineyard systems, the introduction of covering crops could represent a powerful tool for viticultural practices to positively influence the agro-ecosystem by promoting the whole soil-plant system equilibrium. Furthermore, covering crops practice might be capable of controlling the soil erosion, reducing the ground pressure, improving the soil structure, and easing the viticultural mechanization [13; 14]. There were more than 30 species of plants that were used as inter-row covering crops in the vineyards, mainly including grasses and legumes [15]. Furthermore, after the agronomic strategy of covering crops was introduced into China, according to the current situation of the drought and cold weather in winter and spring, in Northwest China, alfalfa (_Medicago sativa_ L.), white clover (_Trifolium repens_ L.), and purslane (_Portulaca elencaa_ L.) were often selected to carry on as the covering crops in their vineyards [16]. Covering purslane usually led to the decrease of the total soluble solids, the increase of the tittatable acid, the phenolic contents of the treated grape berries, especially those of the tannins and anthocyanins, and was also beneficial to the accumulation of the aroma components of grapes [17; 18; 19]. This was because in the semi-arid North China, wine grapes often ripened quickly in the latest years, as a result of global warming, where the heatwaves frequently occurred in the grape development stage. Thus, the grape berries often matured with extremely high sugar contents (TSS \(\geq\) 27\({}^{\circ}\)Brix) and low tittatable acid (\(\leq\)3 g/L) without special viticultural treatments. Besides, due to the wine grapes maturing too quickly, they often could not accumulate enough flavor compounds, especially the flavonoids and the aroma compounds, which limited their potential for finest winemaking.