| Late frost is a major agricultural meteorological disaster in the wine producing areas on the eastern foothills of Helan Mountain. Studying the supercooling and freezing points of different grape varieties and organs is of great significance for revealing the formation mechanism of late frost disasters in wine grapes and scientifically formulating defense measures.Using five widely planted wine grape varieties, "Cabernet Sauvignon", "Chardonnay", "Merlot", "Pinot Noir", and "Marceline", from the eastern foothills of the Helan Mountains as materials, the supercooling and freezing points of winter buds, new shoots, and inflorescences were measured using a frost simulation test chamber. The results showed：The supercooling points of winter buds of five grape varieties for wine making are significantly lower than those of new shoots and inflorescences, mostly around -5 to -6 ℃. The supercooling points of new shoots and inflorescences are relatively close, around -4 ℃; In the three developmental stages of winter buds, the supercooling point during the open stage is significantly higher than that during the swelling and pilling stages, and the swelling and pilling stages are relatively close. The freezing points of various organs of the five grape varieties for winemaking are, from low to high, winter buds, inflorescences, and new shoots. The three developmental stages of winter buds increase from front to back, with the swelling stage below -4.5 ℃, the pilling stage between -4.6 ℃ and -3.1 ℃, and the opening stage between -3.1 ℃ and -2.5 ℃. The range, frequency distribution of supercooling points, and supercooling capacity vary among different varieties, organs, and developmental stages.In the eastern foothills of Helan Mountain production area, there are differences in the threshold size and frequency distribution of supercooling and freezing points for different grape varieties, organs, and winter buds at different developmental stages, which confirms the complexity of the mechanism of late frost damage in wine grapes. When formulating comprehensive defense measures against late frost damage in wine grapes, it is necessary to fully consider the cold resistance of different varieties, organs, and even the same organ at different developmental stages. |