摘 要
干旱是影响植物生长发育的重要非生物胁迫因素之一，对林业生产具有显著制约作用。本研究以桉树幼苗为试验材料，旨在探讨不同干旱胁迫程度对其生理特性的影响，从而为提高桉树抗旱能力提供理论依据。通过设置对照组和轻度、中度、重度干旱胁迫处理，并结合土壤水分含量的动态监测，系统分析了叶片相对含水量、渗透调节物质积累、抗氧化酶活性及光合生理参数的变化规律。结果表明，随着干旱胁迫强度的增加，叶片相对含水量显著下降，脯氨酸和可溶性糖等渗透调节物质含量逐渐升高，超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性呈现先升后降的趋势，而净光合速率和气孔导度则持续降低。此外，中度干旱胁迫下，幼苗表现出一定的自我调节能力，但重度胁迫导致其生理功能严重受损。本研究揭示了桉树幼苗在干旱条件下的生理响应机制，首次明确了中度干旱胁迫作为关键临界点的作用，为优化桉树栽培管理策略提供了重要参考。
关键词：干旱胁迫; 桉树幼苗; 生理响应; 中度干旱; 渗透调节物质
Abstract
Drought is one of the major abiotic stress factors affecting plant growth and development, imposing significant constraints on forestry production. This study used Eucalyptus seedlings as experimental materials to investigate the effects of different levels of drought stress on their physiological characteristics, thereby providing a theoretical basis for enhancing the drought resistance of Eucalyptus. By establishing control groups and mild, moderate, and severe drought stress treatments, combined with dynamic monitoring of soil moisture content, we systematically analyzed the changes in leaf relative water content, osmoregulatory substance accumulation, antioxidant enzyme activity, and photosynthetic physiological parameters. The results showed that as the intensity of drought stress increased, the leaf relative water content significantly decreased, while the contents of osmoregulatory substances such as proline and soluble sugars gradually increased. The activities of superoxide dismutase (SOD) and catalase (CAT) exhibited an initial increase followed by a decline, whereas the net photosynthetic rate and stomatal conductance continuously decreased. Additionally, under moderate drought stress, the seedlings demonstrated a certain degree of self-regulatory capacity; however, severe stress caused significant damage to their physiological functions. This study elucidated the physiological response mechanisms of Eucalyptus seedlings under drought conditions and, for the first time, clarified the critical role of moderate drought stress as a key threshold, offering important references for optimizing Eucalyptus cultivation and management strategies.
Key words:Drought Stress; Eucalyptus Seedlings; Physiological Response; Moderate Drought; Osmotic Regulators
目 录
中文摘要 I
英文摘要 II
引 言 1
第1章、干旱胁迫与桉树幼苗生长 3
1.1、干旱胁迫对幼苗生长的影响机制 3
1.2、桉树幼苗生长指标的变化特征 3
1.3、生长特性与干旱适应能力的关系 4
第2章、光合作用的响应与变化 5
2.1、干旱胁迫下光合速率的动态变化 5
2.2、叶绿素含量与光合作用的关系 5
2.3、光合生理对干旱胁迫的适应策略 6
第3章、水分代谢与渗透调节 7
3.1、桉树幼苗水分代谢的变化规律 7
3.2、渗透调节物质的积累与作用 7
3.3、干旱胁迫下水分利用效率的提升 8
第4章、抗氧化系统与逆境适应 9
4.1、干旱胁迫诱导的活性氧积累 9
4.2、抗氧化酶系统的变化特征 9
4.3、非酶抗氧化物质的作用机制 10
结 论 11
参考文献 12
