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.