The characteristics of absorption，distribution and utilization to urea in branchesbefore sprout of Zhanhua winter-date(Zizyphus Jujuba Mill．Var．inermis Rehd．)

• ZHANG Jin, 
• JIANG Yuan-mao, 
• ZHAO Deng-chao, 
• ZHANG Xu, 
• LIU Wen-e, 
• LI Xin-xiang, 
• WANG Ling-ling, 
• ZHANG Lingl