Background and Aims

Research required to clarify leaf nutrient relations of cycad species has been inadequate. Common garden studies are useful for determining the influence of genetics on leaf traits because of the homogeneous environment among experimental units. To date, there have been no common garden studies which included all ten genera of cycads. The full phylogenetic breadth has, therefore, not been included in this important area of study.

Methods

We examined macronutrient and micronutrient content of leaves from one representative species from each of the ten cycad genera at Nong Nooch Tropical Botanical Garden in Thailand. Nitrogen content was determined by dry combustion, and the remaining nutrients were quantified by spectrometry.

Results

The least variable elements were nitrogen and phosphorus, and the most variable elements were boron and sodium. Nutrient content based on leaflet area was more variable than based on leaflet mass, reflecting species differences in specific leaf area. There were no universal macronutrient or micronutrient signals indicating clear phylogenetic distinctions.

Implications for Conservation: Active management of threatened cycad taxa requires research to develop the knowledge to enable evidence-based decisions. This common garden study inclusive of all 10 cycad genera creates a foundation to determine leaf nutrient sufficiency ranges to inform management decisions.

中文翻译：

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普通园中苏铁的叶片养分关系

背景和目标

澄清苏铁物种叶片养分关系所需的研究还不够充分。由于实验单元之间的同质环境，常见的花园研究可用于确定遗传对叶性状的影响。迄今为止，还没有包括所有 10 个苏铁属的常见园林研究。因此，完整的系统发育广度并未包括在这一重要的研究领域中。

方法

我们检测了泰国 Nong Nooch 热带植物园 10 种苏铁属植物中一种代表性物种的叶子的常量营养素和微量营养素含量。氮含量通过干燃烧法测定，剩余营养物通过光谱法定量。

结果

变化最小的元素是氮和磷，变化最大的元素是硼和钠。基于小叶面积的营养成分比基于小叶质量的营养含量变化更大，反映了特定叶面积的物种差异。没有普遍的常量营养素或微量营养素信号表明明显的系统发育差异。

对保护的影响：对受威胁的苏铁类群的积极管理需要研究以开发知识，以实现基于证据的决策。这项包含所有 10 种苏铁属植物的普通花园研究为确定叶片养分充足范围奠定了基础，从而为管理决策提供信息。