Effects of fertilization on growth and seasonal dynamic of leaf nutrients of close planting pear-jujube trees

To investigate the influence of different fertilization on jujube nutrients, field experiments were conducted in loess hilly-gully mountains, and pear-jujube (Zizyphus jujuba Mill. cv. Lizao) was used as experimental materials. The seasonal dynamic changes of eight kinds of nutrition elements (N, P, K, Ca, Mg, Mn, Zn and Fe) of pear-jujube leaves were studied, and plant development, productivity and fruit quality of pear-jujube in different fertilizer application conditions were also examined. The results show that the contents of N, P and K of the pear-jujube at the blossom and fruit-set period (from early May to early July) are in higher levels, compared with Mg, Fe, Mn and Zn. Besides, the contents of N and P in leaves are relatively stable at the fruit enlargement period (from early July to late August); at the same time, K is declined drastically, while trace elements (Fe, Mn and Zn) have rising trends. At the fruit maturation stage (from early September to early October), the contents of N, P and K in leaves are decreased, whereas Fe, Mn and Zn are increased slowly or remained basically unchanged. So we conclude that there are positive correlations between N, P, K and Mn and between Ca, Mg, Fe and Zn in leaves of jujube in the growth period. Furthermore the contents of N, P and K have significantly positive correlations, however, the content of N, P and K correlate negatively to Ca, Mg, Fe fertilizer can improve fruit yield to 33210 kg/ha; K fertilizer can improve fruit quality. Therefore, P and K fertilizer cooperating application can increase both yield and quality of the pear-jujube.