根际施肥位置变化对桃树^(15)N吸收分配的影响

Effects of the Change of Rhizosphere Fertilization Location on Characteristics of Absorption and Distribution of ^(15)N for Peach Trees

以2年生‘春雪’桃和13年生‘中华寿桃’为试材,研究不同施肥位置对桃树15 N吸收分配的影响。结果表明:在垂直方向上,下层施肥处理各器官的Ndff(%)显著低于表层施肥处理;下层施肥处理新梢15 N分配率显著高于表层施肥处理;下层施肥处理根系15 N分配率显著低于表层施肥处理;表层施肥的氮肥利用率是下层施肥的3.75倍。在水平方向上,环状沟(树冠外围施肥)与放射沟(树冠内膛施肥)比较,环状沟施肥有利于氮素分配到营养器官,放射沟施肥有利于氮素分配到贮藏器官;环状沟施肥氮素当季吸收利用率达21.41%,而放射沟施肥氮素当季吸收利用率仅为16.12%。可见,桃树生长势较强的外围根系吸收的氮素,主要分配到新生器官,近树干部位根系吸收的氮素,主要分配到贮藏器官,提高树体贮藏营养水平。

Two-year-old peach trees ＂spring snow＂ and thirteen-year-old peach trees ＂China Birthday peach＂ were used to explore the effects of the change of fertilization location on characteristics of absorption and dis- tribution of 15N for peach trees. Results showed that in the vertical direction, Ndff （%） of the organs through deep fertilization treatment was significantly lower than that of sur{ace fertilization treatment, lS N distribution ratio of new growth branch through deep fertilization treatment was significantly higher than that of surface fertilization treatment. 15N distribution ratio of root through deep fertilization treatment was sig- nificantly lower than that of surface fertilization treatment. The nitrogen use efficiency of surface fertilization was 3.75 times than that of the lower fertilization treatment. In the horizontal direction, comparing circular canal （peripheral fertilization to crown） with radial canal （internal fertilization to crown）, it found that circu- lar canal fertilization was more conducive to distribute nitrogen to nutrient organ, radial canal made it more conducive to distribute nitrogen to storage organ. The nitrogen absorption use efficiency in season of the cir- cular canal fertilization was 21.41%, while that of radial canal fertilization was j,ust 16.12 %. Overall, those suggested that nitrogen absorbed by the outer root with strong growth potential of peach trees mainly allocated to new organs, while nitrogen absorbed by the root near trunk mainly allocated to storage organs, impro- ving the level of tree storage nutrition.