辣椒叶片生理特性对光照强度和土壤水分的响应

以辣椒为研究对象，研究了不同光照强度和土壤水分对辣椒叶片相对含水率（RWC）、叶绿素（Chl）含量、保护酶活性以及游离脯氨酸和丙二醛（MDA）含量的影响。结果表明：1）随着遮阴程度和土壤水分的增加，叶片RWC,叶绿素含量均呈上升趋势，土壤水分增加主要有利于叶绿素a含量的增加，遮阴主要有利于叶绿素b含量的增加。类胡萝卜素含量随遮阴程度的增加和土壤水分的降低而下降。MDA含量在干旱胁迫条件下升高，随着遮阴程度的增加呈先降后升的趋势。光照相同，在干旱和高水条件下，保护酶活性和脯氨酸含量均表现出不同程度的上升；水分条件相同，保护酶活性和脯氨酸含量均随遮阴程度的增加而下降，且保护酶对光照强度的敏感性为SOD＞CAT＞POD。2）保护类物质（脯氨酸与保护酶）与伤害类物质（MDA）均达到了极显著正相关，膜保护酶与叶绿素含量达到了极显著负相关。综合以上认为，将遮阴30%和土壤相对含水率为70%～85%作为适宜的遮阴和灌溉指标是科学合理的。

Response of physiological characteristics of pepper leaf to different light intensities and soil moisture contents

This study object was to define the influences of different light intensities and soil moisture contents on the leaf relative water content (RWC), chlorophyll (Chl) content, activity of protective enzymes, free proline and malondialdehyde content (MDA) with hot pepper plants. The results showed that: 1) RWC and Chl content increased gradually with the enhancement of shading and soil moisture. The increased of soil moisture was mainly beneficial to the increase in chlorophyll a, while shading contributed mainly to the increment in chlorophyll b. Carotenoids contents depressed with the increasing of shading and the decline of soil moisture. MDA content increased under drought stress, and existed quadratic trend with the increase of shading levels. In the same light level, protective enzymes activity and proline content showed degrees of increase under drought and high water condition, but decreased with the increased of the shading in the same soil moisture conditions, and the protective enzyme sensitivity to light intensity was: SOD>CAT> POD. 2) There was a significantly positive correlation between protective enzyme and MDA, and a significantly negative correlation between protective enzyme and Chlorophyll content. Conclusively, taking shading 30% and soil relative water content of 70%-85% as the appropriate shading and irrigation indicators are scientific and rational.