Effects of Potassium Fertilizer on the Photosynthesis and Root Morphology of Trifolium repens L.cv.Haifa in Squaring Stage

• Meizhang JIAO, 
• Shiming XUE, 
• Xin LUO, 
• Ming CAI, 
• Lan MU, 
• Meifen HUANG, 
• Jieqiong HOU, 
• Meiyan ZHANG