Study On The Characteristics Of ¹⁵N Absorption, Distribution And Utilization Of (?) (Prunus Avium L.)

The experiment using the stable isotope15N-labelled urea was carried out in Shandong Agricultural University fruits research institute of sweet-cherry from 2006 to 2007. The characteristics of 15N absorption, distribution and utilization at different growth stages when fertilizer before sprout and the characteristics of 15N absorption, distribution and utilization after fertilizering in defferent phases and depth and 15N-urea daubing on the trunk before sprout under the condition of field cultivation by using five-year-old sweet-cherry (Prunus avium L.)were studied. The main results were as follows:1. 15N-urea fertilized before sprout in'zao daguo'sweey-cherry tree,Ndff% value gradually increased in different organs over time. The value was higher in fine roots and storage organs at full-blooming stage, it increased quickly in long shoots and the leaves, reaching 0.72% and 0.59% respectively at fruit core-hardening stage; and it increased quickly in fruits from fruit core-hardening stage to harvest stage, reached the highest point (1.78%) at harvest stage. However, the value increased slowly in neonatal organs after harvest while it increased quickly in storage organs. At full-blooming stage, 15N absorbed by roots was firstly distributed to the storage organs, and the distribution rate in thick roots was the highest (54.91%). At fruit core-hardening stage, the distribution rate in fine roots and storage organs decreased from 85.43% to 55.11% while in the neonatal branches and the leaves it increased to 44.89%. At harvest stage, the distribution rate in different organs had no significant change. After fruit harvest, 15N translocated to the storage organs quickly and the distribution rate in fine roots and storage organs reached the highest point (72.26%) at flower differentiation stage. Its distribution rate in the neonatal branches and the leaves decreased 19.31% compared with that at harvest stage. From full-blooming stage to flower differentiation stage, the utilization rate of 15N-urea was on the rise, which reached the highest point (16.86%) at flower differentiation stage. 2. 15N-urea fertilizered before sprout, 15N translocation in'zao daguo'sweet-cherry was in accordance with the rule of stored N nutrition distribution in deciduous fruit trees, and 15N was transported with the growth center transporting. In the early growth and development period, the 15N absorbed by roots was firstly distributed to the storage organs(76.91%), and the distribution rate in thick roots was the highest (54.91%). At fruit core-hardening stage, the distribution rate in long shoots was the hightest, that is 26.56%. At flower differentiation stage, 15N translocated to the storage organs and the distribution rate in thick roots reached the highest point (26.76%).3. Fertilizered in different phases, the characteristics of 15N absorption, distribution and utilization in sweet-cherry at harvest stage were different. When fertilizered in the autumn, the Ndff% in fine roots was the highest, that is 4.87%. The value in spur leaves, fruits and thick roots was higher, reaching 1.37%, 1.26% and 1.21% respectively. When fertilizered before sprout, the Ndff% in fine roots was the highest (2.36%), then are the spur leaves, long shoots and fruits, the values are 1.27%, 1.26% and 1.18%. Fertilizered at full-blooming stage, the Ndff% in fruits was the highest, it reached 1.18%, then are the long shoots the spur leaves, reaching 0.96% and 0.86% respectively. When fertilizered in the autumn, before sprout and at full-blooming stage, the distribution rate of 15N in thick roots was the highest, it reached 39.08%, 22.23% and 38.43% respectively. When fertilizered in the autumn, the 15N absorbed by roots was mainly distributed to the storage organs such as thick roots, and 41.80% of the nitrogen was distributed to roots. When fertilizered before sprout,39.08% of the nitrogen absorbed by roots was distributed to the spurs and fruits in order to promote sprouting and the growth of leaves and spurs, and to increase the fruiting rate. Fertilizered at full-blooming stage, the distribution rate in the fruits was higher(15.66%). It indicated that fertilizering at full-blooming stage can promote the fruits development, improve fruiting rate to a certain extent. The 15N utilization rate of 15N-urea fertilizered in the last autumn was higher(24.61%) than that before sprout(14.74%) than that at full blossom stage(9.24%).4.When fertilizered in the deep soil, Ndff% was low in each organ. The value in neonatal organs was1.86%, it is only 1/3 of the plants fertilizered in the shallow soil. Ndff% of storage organs was 0.59%, it is only 23% of that fertilizered in the shallow soil. Ndff% of fruits is less than 1/2 of the fruits fertilizered in the shallow soil. When fertilizered in the deep soil, Ndff% of fine roots was the highest, that is 0.91%, while the value in fine roots of fertilizered in the shallow soil was 2.36%. At harvest stage, the ability to absorb and mobilize nitrogen of the plants fertilizering in the deep soil was lower. It is because the roots of sweet-cherry were low, they mainly concentrated in the 0～20 cm soil. The distribution rate of every organ was similar when fertilizering in different depths. At harvest stage, the distribution rate of storage organs in deep-fertilizering-plants was 43.22%, a little more than that of shallow-fertilizering-plants(39.03%). The15N utilization rate of 15N-urea fertilizered in the deep soil(3.75%) significantly lower than that in the shallow soil(14.74%). As a result, fertilizering in the deep soil is not conducive to the absorption of fertilizer. The 15N utilization rate was low in the same time period.5.When daubing 15N-urea on the trunk before sprout, branches have a stronger absorption capacity. The distribution rate of xylem and cortex reach 17.68% and 36.16%. The value of storage organs are 61.44% while it is 22.55% in nutrition organs. The distribution rate of fruits is 13.59%. It indicated that daubing 15N-urea on the trunk, cortexes are the main part of accumulating nutrogen. The distribution rate of storage organs such as xylem and cortex of trunk, cortex of perennial branches are significantly higher than that fertilizered in the soil.