摘 要

薄壳山核桃(Carya illinoensis)，是一种经济效益、社会效益和生态效益均明显的多用途树种，具有极高的研究价值。但是，国内关于薄壳山核桃抗逆性相关的研究报道不多。本试验采用PEG处理薄壳山核桃幼苗，模拟干旱胁迫，研究其对苗木光合生理特征的影响，分别在24h、48h和72h测定叶片净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)和细胞间CO₂浓度(Ci)等光合生理指标和基础荧光(F₀)、最大荧光(Fm)、可变荧光(Fv)、PSⅡ光化学效率(Fv/Fm)、PSⅡ潜在光化学活性(Fv/F₀)等叶绿体荧光参数，分析了不同浓度梯度下干旱胁迫对薄壳山核桃实生苗的光合生理影响。结果表明：（1）随着PEG胁迫的浓度增加，薄壳山核桃幼苗叶片的Pn、Gs、Tr均显著下降，且随着胁迫浓度增高以及胁迫时间的延长，各指标下降幅度增大；（2）在4%和8% PEG胁迫下，薄壳山核桃幼苗叶片中叶绿素荧光参数无显著差异，但与12% PEG胁迫下各指标间差异均达到显著水平；（3）随着PEG胁迫程度的增加，薄壳山核桃幼苗叶片Pn、Tr、Gs受到抑制，其PSⅡ光能转化效率降低，热能散增加，光化学活性受到抑制，致使光合作用显著降低，影响其生长发育。研究结果为建立理想的综合耐旱评价体系，筛选薄壳山核桃优良抗旱砧木提供理论依据。

关键词：PEG胁迫；薄壳山核桃；光合生理；叶绿素荧光

Effects of PEG Stress on Photosynthetic Characteristics

and Chlorophyll Fluorescence Parameters of Pecan Seedlings

ABSTRACT

Pecan (Carya illinoensis) is a kind of multipurpose tree species with high research value. And it has obvious advantages in economic, social and ecological aspects. However, there were rarely studies about the stress tolerance of pecan in domestic. This study adopted PEG-6000 to deal with pecan seedlings to simulate drought stress and research effects on photosynthetic physiological characteristics, measuring photosynthetic physiological indexes such as the photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs) and intercellular CO₂ concentration (Ci) of chlorophyll fluorescence parameters and chloroplast fluorscence parameters such as the minimal fluorescence (F₀), maximum photochemical efficiency variable fluorencence(Fv), PSⅡphotochemistry efficiency(Fv/Fm), PSⅡpotential photochemistry activity (Fv/F₀) at 24h, 48h and 72h, to study the drought stress on pecan seedlings photosynthetic physiological effect under different concentration gradients. The results showed that: (1) With the increase of the concentration of PEG stress, Pn, Gs and Tr of pecan seedlings leaves were significantly decreased and with increasing the stress of concentration and prolonging time, the indexes decreased significantly. (2)Under the PEG stress concentration of 4% and 8%, chlorophyll fluorescence parameters of pecan seedlings leaves had no significant differences, but they reached significant levels compared with PEG stress concentration of 12%. (3) With the increasing of PEG stress, Pn, Tr and Gs of pecan seedlings leaves were inhibited, and the PSII photochemical efficiency reduced, heat dispersion increased, photochemical activity was inhibited, resulting in photosynthesis decreased significantly and having a worse effect on their growth and development. This experiment compared with the differences and regularities of photosynthetic physiological indexes pecan seedlings under different PEG stress treatments, providing with theoretical and experimental basises to establish the synthesize drought tolerance evaluation system, carry out comparison tests of drought resistance of excellent pecan species at home and abroad as well as screen drought-enduring varieties.

Key words：PEG stress；Carya illinoensis；Photosynthethesis physiology；chlorophyll fluorescence

目 录

1 绪论………………………………………………………………………………………1

1.1 薄壳山核桃概述…………………………………………………………………1

1.2 薄壳山核桃国内外发展现状………………………………………………………2

1.3 国内外干旱胁迫研究进展……………………………………………………………2

1.3.1 干旱胁迫对植物形态指标的影响…………………………………………3

1.3.2 干旱胁迫对植物生理生化的影响…………………………………………3

1.3.3 干旱胁迫对气孔调节的影响……………………………………………3

1.3.4 干旱胁迫对光合作用的影响……………………………………………4

1.3.5 干旱胁迫对渗透调节的影响……………………………………………5

2 材料与方法………………………………………………………………………………6

2.1 试验材料…………………………………………………………………………6

2.2 试验方法…………………………………………………………………………6

2.3 测定项目方法…………………………………………………………………6

2.3.1 单叶光合参数测定………………………………………………………6

2.3.2 叶绿体荧光参数测定……………………………………………………7

2.4 数据分析…………………………………………………………………7

3 结果与分析………………………………………………………………………………7

3.1 PEG胁迫对薄壳山核桃幼苗叶片光合气体交换参数影响……………………7

3.1.1 PEG胁迫对Pn的影响……………………………………………………7

3.1.2 PEG胁迫对Tr的影响……………………………………………………8

3.1.3 PEG胁迫对Gs的影响……………………………………………………8

3.1.4 PEG胁迫对Ci的影响……………………………………………………8

3.2 PEG胁迫对薄壳山核桃幼苗叶绿素荧光参数影响……………………………9

4 结论与讨论……………………………………………………………………………10

4.1 结论……………………………………………………………………………10

4.2 讨论……………………………………………………………………………11

致谢………………………………………………………………………………………13

参考文献…………………………………………………………………………………14

1 绪论

1.1 薄壳山核桃概述