Deying Zhao

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1. Introduction Apples (Malus domestica) are an economically important fruit in China, with major apple-producing regions including the traditional Bohai Bay and northwest Loess Plateau regions, as well as distinctive apple-producing regions such as the southwest cool highlands, Xinjiang, and the northeast. The climatic characteristics of apple-producing regions vary substantially, with the northeast region being a high-latitude area with a cold climate [1].