Northeast China is a commodity grain base with strategic role in China, so researches on the change of grain yield per hectare in northeast China is of significance for ensuring China's grain security.
Northeast China is a commodity grain base with strategic role in China, so researches on the change of grain yield per hectare in northeast China is of significance for ensuring China's grain security.
摘要东北地区是我国具有战略意义的商品粮墓地，粮食单产变化的研究对确保我国粮食安全具有重要意义。