美国研制成功一种能使大豆增产30—40％的新方法。具体做法是:大豆播种前,先用20℃左右的水浸泡大豆种子6—8小时。当种皮开始出现皱折时,把种子转入0.5—1％的食盐和20ppm铜酸的混合液中浸泡 The United States has successfully developed a new method that will increase soybean yields by 30-40%. Specific approach is: Sowing before sowing, soak the soya seeds with water about 20 ℃ for 6-8 hours. When the seed coat begins to wrinkle, the seeds are immersed in a mixture of 0.5-1% salt and 20 ppm cupric acid