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光照和水分胁迫对槲树和栓皮栎幼苗形态和化学计量特征的影响
The Effects of Light and Water Stress on the Morphological and Chemical Stoichiometric Traits of Quercus dentata Thunb and Quercus variabilis Blum Seedlings
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摘要: 采用4种光照梯度(100%、75%、50%、25%自然光照)和3种土壤水分梯度(75%~85%, 45%~55%,15%~25%田间持水量)的完全交互试验设计,分析2种幼苗8种形态性状和12种化学计量特征的变化。结果表明:随着光照强度和水分含量减少,槲树和栓皮栎都显著增加了比叶面积;槲树叶片厚度在50%自然光中最大,栓皮栎叶片厚度随光照强度减少而显著减小;槲树和栓皮栎在光照和水分受限的条件下倾向于增加根干物质含量以增强结构。栓皮栎叶片碳含量在50%自然光中随水分减少而显著降低;槲树和栓皮栎的根氮含量随光照强度减小而降低。幼苗叶片和根系性状间存在显著地两两相关,栓皮栎比叶面积与叶干物质含量、叶组织密度显著负相关;槲树比叶面积和叶片氮含量显著正相关;栓皮栎叶片氮含量和叶碳氮比显著负相关;槲树根比表面积与根组织密度显著负相关;2个树种比根长与比表面积显著正相关,且根氮含量与磷含量和氮磷比呈显著正相关,与碳氮比和碳磷比显著负相关。因此,栎属幼苗通过形态和化学计量特征的可调节性来适应异质性环境,为深入研究木本植物对环境胁迫的适应机制提供参考依据。Abstract: To explore the variations in leaf morphological traits and chemical stoichiometry of Quercus dentata Thunb. and Quercus variabilis Blume seedlings under different light intensities and soil moisture contents. A fully factorial experimental design was adopted, with four light gradients(100%, 75%, 50%, 25% natural light) and three soil water gradients(75%~85%, 45%~55%, 15%~25% field capacity). The study systematically analyzed the variations in 8 morphological traits and 12 chemical stoichiometric traits of the two species. The results showed that as light intensities and soil moisture contents decreased, both Q. dentata and Q. variabilis significantly increased their Specific Leaf Area(P < 0.05). The maximum leaf thickness of Q. dentata was observed at 50% natural light availability, and Q. variabilis exhibited a significant reduction in leaf thickness with decreasing light(P < 0.05). Under light and water limitation, both species tended to enhance root dry mass content to strengthen structural support. The leaf carbon content of Q. variabilis significantly decreased with decreasing water availability under 50% natural light(P < 0.05). Additionally, both species showed a reduction in root nitrogen content with decreasing light. Significant pairwise correlations were found among the leaf and root traits: specific leaf area of Q. variabilis was significantly negatively correlated with leaf dry mass content and leaf tissue density(P < 0.05); specific leaf area of Q. dentata was significantly positively correlated with leaf nitrogen content(P < 0.05); and leaf nitrogen content of Q. variabilis was significantly negatively correlated with the leaf carbon-nitrogen ratio(P < 0.05); The specific root area of Q. dentata showed a significant negative correlation with root tissue density. For both species, specific root length was significantly positively correlated with specific surface area. Additionally, root nitrogen content exhibited significant positive correlations with phosphorus ratio and nitrogen-phosphorus ratio, while showing significant negative correlations with carbon-nitrogen ratio and carbon-phosphorus ratio. In conclusion, oak seedlings adapt to heterogeneous environments through the adjustability of their morphological and chemical traits, providing valuable theoretical insights into the adaptive mechanisms of woody plants to environmental stress.
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