Interaction effects of plant density and nitrogen rate on the growth and physiological traits of alfalfa in saline alkali soils

• LU Faguang, 
• GU Lifeng, 
• LIU Yuqian, 
• REN Zhen, 
• SHI Yu, 
• XU Zhenran, 
• ZHOU Guisheng, 
• LU Haitong, 
• WANG Xiaoshan, 
• ZHANG Wangding, 
• REN Zhiqiang, 
• ZHU Guanglong