Photosynthesis and growth responses of Fraxinus mandshurica Rupr. seedlings to a gradient of simulated nitrogen deposition
Photosynthesis and growth responses of Fraxinus mandshurica Rupr. seedlings to a gradient of simulated nitrogen deposition
复制标题
水曲柳的光合作用和生长反应。
DOI：
10.1007/s13595-017-0678-2
复制
发表时间：
2017
影响因子：
3
通讯作者：
Guang-You Hao
中科院分区：
文献类型：
--
作者：
Miao Wang;Wei-Wei Zhang;Na Li;Yan-Yan Liu;Xing-Bo Zheng;Guang-You Hao
关键信息在氮沉降模拟试验中，我们发现低到中等水平的氮添加对水曲柳的生长和光合速率有有利的影响。幼苗，而超过阈值80公斤N ha− 1 year −1，性能趋于平稳，甚至下降在更高immissions.ContextTemperate森林正在从自然N有限向N饱和的状态与增加N沉降。然而，我们的知识，关于幼苗生长和生理反应过度N输入温带树种仍然非常有限。方法通过4年的试验，研究了不同氮沉降梯度对水曲柳幼苗生长和光合作用的影响。mandshuricaseedlings到模拟N沉降的大梯度（0、20、40、60、80、100和120 kg N ha− 1 year −1）。在第四生长季测定了生物量积累和分配、光合气体交换、核酮糖-1，5-二磷酸羧化酶/加氧酶（Rubisco）的表达和活性。土壤的生化特性进行了测定，将它们连接到整个N添加gradient. Results幼苗生长和光合作用性状的变化依赖于N沉降的速率。最大羧化速率（Vc，max）和饱和光下净光合速率（Asat）在60 kg N ha− 1 year −1下达到最大值。相比之下，高水平的N输入（100和120 kg N ha− 1 year −1）导致生物量和光合活性的次优值。氮沉降还调节了叶片中Rubisco的活性和表达，最大值约为80-100 kg N ha− 1 year −1。RDA分析表明，幼苗生长和光合作用沿着氮沉降梯度的变化主要归因于土壤pH和全氮含量的变化。mandshuricaseedlings在这个地区。过量的氮素输入降低了幼苗的生长和光合性能。
Key messageDuring an N-deposition simulation experiment, we showed that low to medium addition of N had beneficial effects on growth and photosynthetic rates ofFraxinus mandshuricaRupr. seedlings, while beyond a threshold of 80 kg N ha−1year−1,performance plateaued and even declined at higher immissions.ContextTemperate forests are shifting from naturally N-limited toward N-saturated status with increasing N deposition. Yet, our knowledge regarding how seedling growth and physiology respond to excessive N input in temperate tree species remains very limited.AimsThe objective of this study was to examine growth and photosynthetic responses ofF. mandshuricaseedlings to a gradient of simulated N deposition.MethodsWe conducted a 4-year study to investigate growth and photosynthetic responses ofF. mandshuricaseedlings to a large gradient of simulated N deposition (0, 20, 40, 60, 80, 100, and 120 kg N ha−1year−1). Biomass accumulation and allocation, photosynthetic gas exchange, expression, and activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in leaves were determined during the fourth growing season. Soil biochemical properties were measured to link them to the alterations in growth and photosynthetic traits across the N addition gradient.ResultsSeedling growth and photosynthesis were dependent upon the rates of N deposition. The maximum rate of carboxylation (Vc,max) and the net photosynthetic rate under saturating light (Asat) reached a maximum under 60 kg N ha−1year−1. By contrast, high-level N inputs (100 and 120 kg N ha−1year−1) resulted in suboptimal values in biomass and photosynthetic activity. Nitrogen deposition also modulated the activity and expression of Rubisco in leaves with a maximum around 80–100 kg N ha−1year−1. Redundancy analysis (RDA) showed that the changes of seedling growth and photosynthesis along the gradient of N deposition were mostly attributed to the variations of soil pH and total N content.ConclusionOur data suggest that the threshold of N deposition is about 80 kg N ha−1year−1forF. mandshuricaseedlings in this region. Excessive N input decreased performance on the seedling growth and photosynthesis.