两种施肥模式下柑橘树体氮素吸收与运转机制的研究

Study on nitrogen absorption and operation mechanism of citrus tree in two fertilization modes

以石棉县8年生黄果柑为材料,通过关键物候期(萌芽期、夏梢旺长期、果实迅速膨大期、转色期)施肥和常规施肥(谢花期、夏梢旺长期)两种模式施入^(15)N-尿素和普通尿素,测定夏梢旺长期、果实迅速膨大期以及转色期果实和叶片中的Ndff值以及成熟期树体不同器官的Ndff值、^(15)N分配率以及^(15)N利用率的差异情况。结果表明:在果实迅速膨大期、转色期以及成熟期3个关键时期,关键物候期施肥模式下柑橘果实的Ndff值显著大于常规模式下果实的Ndff值,两种模式下叶片的Ndff值在果实转色期均显著低于其他三个物候期,分别为2.04(关键物候期施肥)和2.01(常规施肥);成熟期两种施肥模式均表现为果实中^(15)N分配率最高,其中关键物候期施肥模式果实的^(15)N分配率为50.2%,显著高于常规施肥模式的45.7%,关键物候期施肥模式下柑橘树体的^(15)N利用率为35.7%,显著高于常规施肥的27.8%,表明关键物候期施肥能够使柑橘树体更充分地吸收、利用氮素。

With 8-year-old Huangguogan in Shimian as materials,^15N-urea and urea were fertilized through two modes including the key phenophase（ germination period,strong period of summer shoot,rapid enlargement of the fruit,veraison） fertilization and conventional（ the falling period,strong period of summer shoot） fertilization. The difference in Ndff value in fruits and leaves during the strong periods of summer shoot,rapid enlargement of the fruit and veraison,and Ndff value,the distribution rate of^15N,the utilization rate of^15N in different parts of the tree during the maturity period were measured. The results showed that： in the three key periods of rapid enlargement of the fruit,veraison and maturity,the Ndff value of citrus fruit in the key phenophase fertilization mode was notable higher than that in conventional fertilization mode,the Ndff value of citrus leaves in veraison was notable lower than the other three phenophases in the two modes,which were 2. 04（ the key phenophase fertilization） and 2. 01（ conventional fertilization） respectively. In the maturity period,the distribution rates of^15N were the highest in fruits both in the two modes,in which the distribution rate of^15N in fruits in the key phenophase fertilization mode was 50. 2%,significantly higher than 45. 7% in the conventional fertilization mode; Meanwhile,the utilization rate of^15N of citrus tree in the key phenophase fertilization mode was 35. 7%,which was also significantly higher than 27. 8% in the convention-al fertilization mode. It was indicated that nitrogen could be absorbed and utilized much more fully by citrus trees in the key phenophase fertilization mode.