The effects of root pruning on the vegetative growth and fruit quality of six-year-old Zhanhuadongzao (Ziziphus jujuba Mill.) trees were evaluated. Three root pruning treatments (severe, moderate and light degree) were conducted at the distance of 3, 5 and 7 times trunk diameter from trunk on both inter-row sides of the trees, respectively. The results showed that the severe root pruning decreased the length of primary branch by 27.9% and the number of primary branches by 12.1% in contrast to the control of no root pruning. Compared to the control, both severe and moderate root pruning had no apparent effects on nitrogen, phosphorus and potassium contents of leaves after 35 days, but had significant effects after 161 days. Severe root pruning had larger effectiveness of controlling vegetative growth than the moderate one. By root pruning, the contents of vitamin C and total sugar were increased but the content of cypermethrin was decreased in fruits and no effects were found on total acid content of fruit and yield at harvest. In the rhizosphere soil, root pruning decreased the microbial populations and enzymes activities but increased the concentrations of cypermethrin, available nitrogen, phosphorus and potassium. It is proposed that the removal of root at 3 times trunk diameter distance from trunk was feasible to regulate the vegetative growth and fruit quality of Zhanhuadongzao tree.

Li B., Xie Z., Zhang A., Xu W., Zhang C., Liu Q., Liu C., Wang S., 2010. Tree growth characteristics and flower bud differentiation of sweet cherry (Prunus avium L.) under different climate conditions in China. Hort. Sci. (Prague), 37: 6-13.The phenological stages, flower characteristics, shoot growth and flower bud differentiation of sweet cherries, cv. Hongdeng and Van, were investigated in different climatic zones in China, subtropical monsoon climatic zone (Shanghai, 31°14'N, 121°29'E) and temperate climatic zone (Qingdao, 37°09'N, 121°20'E). Sweet cherry trees grown in subtropical monsoon climatic zone had earlier phenological stage and longer blooming duration than those grown in temperate climatic zone. Fruit growth periods of Hongdeng and Van in Qingdao were 38 days and 51 days, respectively, but only 29 days and 45 days in Shanghai. Both cultivars showed more abnormal flowers under subtropical monsoon climate. The percentage of fruit set under open pollination in Hongdeng and Van were 31% and 24% in Qingdao, respectively, but only 0.4% and 3.2% in Shanghai. The trees grew more vigorous in Shanghai; flower bud differentiation was delayed by high temperature and superabundant rainfall in subtropical monsoon climate zone and more easily affected by the overlap of current shoot growth.