Effects of fertilization area size on absorption and utilization of ¹⁵N and growth of young peach trees

【Objectives】In this study, the effects of fertilization area size on absorption and utilization of nitrogen and suitable fertilization pattern in peach orchard were evaluated to provide the beneficial reference for peach cultivation production.【Methods】Two-year-old peach trees, Spring Snow, and 15N isotope tracer technique were used to investigate the effects of fertilization area changes on the absorption and the utilization of 15N and growth of young peach trees. The tree plate was evenly divided into four areas in the horizontal direction using the tree backbone as a center. Seven treatments was designed, including 1/4, 2/4, 3/4 and 4/4 root zone fertilization, fixed root-zone fertilization, root-zone alternative fertilization and the no fertilizer treatment. Peach tree stem was regularly measured during growing season, and the plant was collected and subdivided into abover-ground and under-ground parts corresponding to fertilization area and nonfertilization area at the end of the test. Aboveground part is subdivided into shoot, leaf and stem corresponding to different root area, and under-ground part is subdivided into coarse roots (0.2 cm diameter), fine roots (0.2 cm diameter), and dry matter biomass of different organ is weighed.【Results】The result showed that the nitrogen utilization rate in the 4/4 root zone (full tree plate) is 4.16%, which is respectively 3.62, 1.65 and 1.24 times of those in the 1/4, 2/4 and 3/4 root zones. The nitrogen utilization rate in the fixed root-zone fertilization is 1.24 times of that in the root-zone alternative fertilization. After the local fertilization treatment, Ndff value in the root system and 15N distribution rate in fertilization area are significantly higher than those in the non-fertilization area. There are no significant differences between the15N distribution rate and Ndff value in above-ground part from new born organ in the fertilization area and the non-fertilization area. The total root try matter in fertilization area is less than that in the non-fertilization area. Generally, the plants growing in the full tree plate fertilization have the maximum growth rate, the plants growing in the fixed root-zone fertilization and the root-zone alternative fertilization are similar in the growth rates. The plant growth rate in the 4/4 root zone (full tree plate) is 0.57 cm/month, which is respectively 1.19, 1.14 and 1.04 times of those in the 1/4, 2/4 and 3/4 root zones. 【Conclusions】Nitrogen utilization rate and plant growth rate in the full tree plate fertilization are the highest, i.e. the uniform fertilizer treatment is recommonded for nutrient utilization and morphogenesis of young peach trees.