Maize is primarily cultivated as a monoculture in Northeast China where the growing seasons are relatively longer Lower temperatures at the vegetive stage couple with seasonal droughts during the repr

按照《Field Crops Research》期刊的标准，检查上述句子的语法。

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"Maize is primarily cultivated as a monoculture in Northeast China, where the growing seasons are relatively longer. Lower temperatures during the vegetative stage, coupled with seasonal droughts during the reproductive stage, are critical limitations for increasing maize density in this region (Liu et al., 2012)."