Abstract:

The characteristics of the absorption, distribution and utilization to ¹⁵N-urea fertilizer before bud-break were studied using four-year-old pot-cultivated Ziziphus jujuba var. inermis ‘Zhanhua_Dongzao’ tree. The main results were as follows: ¹⁵N-urea applied before bud-break had the feature of the effect of stored N in dongzao trees. That is to say, ¹⁵N absorbed by root was distributed firstly and mostly to the storage organs (including the trunk, the perennial branch and the large root), then to the construction of the new organs (including the deciduous spur and leaf, neonatal branch, fine root and fruit), and began to flow back to the storage organs after fruit harvest. The ¹⁵N-urea applied before bud-break was mainly translocated to the growth centre. Analysed during the leaflet, Ndff% of ¹⁵N-urea was highest in the large root and xylem of the trunk. During full blossom, Ndff% of the leaf of deciduous spur (including flower) became the highest. During the rapid fruit growth, Ndff% of the fruit became the highest. And analysed after fruit harvest, Ndff% of the root became the highest. With the development of the tree, the ratio of utilization to ¹⁵N-urea increased gradually, in the rapid fruit growth phase it was the highest,and after fruit harvest it decreased appreciably.

Key words: Ziziphus jujuba var. inermis &lsquo, Zhanhua-Dongzao&rsquo, ¹⁵N-urea, bud-break, distribution, utilization