How nitrogen supply affects growth and nitrogen uptake, use efficiency, and loss from citrus seedlings
How nitrogen supply affects growth and nitrogen uptake, use efficiency, and loss from citrus seedlings
复制标题
DOI：
10.21273/jashs.121.1.105
复制
发表时间：
1996-01-01
影响因子：
1.9
通讯作者：
Syvertsen, JP
中科院分区：
文献类型：
--
作者：
LeaCox, JD;Syvertsen, JP
我们研究了氮供应如何影响植物生长以及四种柑橘砧木品种细沙土壤中氮的吸收、分配和淋失损失。 “Cleopatra”柑橘 (Citrus reticulata Blanco) 和“Swingle”柑橘 (C. paradisi x P. trifoliata) 的幼苗在温室中 2.3 升 Candler 细沙盆中生长，每周用含有 200 mg N/升（20 mg N/周）的完全营养液施肥，单次施用 (NH4)-N-15当幼苗仅 22 周龄（第 0 天）时，(NO3)-N-15（17.8% 原子过量的 N-15）取代了正常的每周施氮量。在施用 N-15 后 0.5、1.5、3.5、7、11 和 30 天收获每个物种的六株重复植物。在第二个实验中，向 14 周龄的“Volkamer”柠檬 (C. volkameriana Ten. & Pasq.) 和酸橙 (C. aurantium) 提供 NH4NO3，剂量为 18、53 和 105 mg N/周。 L.) 幼苗在完全营养液中培养 8 周，如第一个实验，在第 22 周（第 0 天）时单次施用 (NH4)-N-15 (NO3)-N-15 (23.0% N-15) 进行替代，并在施用 N-15 后 3、7 和 31 天收获幼苗，每个速率内的物种间氮吸收和分配相似，但受总氮供应量的强烈影响以及新生长对氮的需求。在最高速率（105 mg N/周）下，没有 N-15 重新转移到新组织，但低于该速率的 N 供应限制了植物生长，而没有短期 N-15 重新分配到其他组织，叶 N 浓度随着 N 供应线性增加至最高速率，而叶绿素浓度在 53 mg N/周时不会增加到以上。本研究中光合CO2同化不受N的限制；叶片氮素浓度超过100mmol。 m(-2) 在所有处理中，因此，较高施氮量下净生产力的差异似乎是叶面积增加的函数，而不是叶氮浓度的函数。因此，无论是在气体交换还是干重基础上表示，在施氮量范围内，氮利用效率显着下降。 31 天后，植物 N-15 的平均吸收效率从 18、20 和 53 毫克氮/周施用 N-15 的 60% 降至 47%，在 105 毫克氮/周施用量时降至低于 33%。 淋溶损失随着施氮量的增加而增加，植物生长速度和这些柑橘品种随后的氮需求与残留土壤氮和潜在淋溶损失相互作用。
We examined how N supply affected plant growth and N uptake, allocation and leaching losses from a fine sandy soil with four Citrus rootstock species. Seedlings of 'Cleopatra' mandarin (Citrus reticulata Blanco) and 'Swingle' citrumelo (C. paradisi x P. trifoliata) were grown in a glasshouse in 2.3-liter pots of Candler fine sand and fertilized weekly with a complete nutrient solution containing 200 mg N/liter (20 mg N/week), A single application of (NH4)-N-15 (NO3)-N-15 (17.8% atom excess N-15) was substituted for a normal weekly N application when the seedlings mere 22 weeks old (day 0). Six replicate plants of each species were harvested at 0.5, 1.5, 3.5, 7, 11, and 30 days after N-15 application, In a second experiment, NH4NO3 was supplied at 18, 53, and 105 mg N/week to 14-week-old 'Volkamer' lemon (C. volkameriana Ten. & Pasq.) and sour orange (C. aurantium L.) seedlings in a complete nutrient solution for 8 weeks, A single application of (NH4)-N-15 (NO3)-N-15 (23.0% N-15) was substituted at 22 weeks (day 0), as in the first experiment, and seedlings harvested 3, 7, and 31 days after N-15 application, Nitrogen uptake and partitioning were similar among species within each rate, but were strongly influenced by total N supply and the N demand by new growth. There was no N-15 retranslocation to new tissue at the highest (105 mg N/week) rate, but N supplies below this rate limited plant growth without short-term N-15 reallocation hom other tissues, Leaf N concentration increased linearly with N supply up to the highest rate, while leaf chlorophyll concentration did not increase above that at 53 mg N/week. Photosynthetic CO2 assimilation was not limited by N in this study; leaf N concentration exceeded 100 mmol . m(-2) in all treatments, Thus, differences in net productivity at the higher N rates appeared to be a function of increased leaf area, but not of leaf N concentration, Hence, N use efficiency decreased significantly over the range of N supply, whether expressed either on a gas-exchange or dry weight basis. Mean plant N-15 uptake efficiencies after 31 days decreased from 60% to 47% of the N-15 applied at the 18, 20, and 53 mg N/week rates to less than 33% at the 105 mg N/week rate, Leaching losses increased with N rate, with plant growth rates and the subsequent N requirements of these Citrus species interacting with residual soil N and potential leaching loss.