华北寒旱区作物轮作的生产效应

姚兆磊, 张继宗, 杜玉琼, 刘玉华, 张立峰

Productivity evaluation of crop rotation in cold and arid region of Northern China

Zhao-Lei YAO, Ji-Zong ZHANG, Yu-Qiong DU, Yu-Hua LIU, Li-Feng ZHANG

图1 各茬口马铃薯、甜菜的病情指数

Fig. 1 Disease index of potato and beet at different croppings