关键词: 时空尺度, 沙漠化, 景观结构, 主成分分析

Abstract: UV-B radiation is one of the factors that lead to the decrease of wheat photosynthetic activity. From May 2 to June 5, 2007, an experiment was conducted in Xinxiang of Henan Province to study the effects of foliar-spraying the anthraquinones from aloe at grain-filling stage of winter wheat on the leaf photosynthetic rate, photorespiration rate, chlorophyll content, and MDA content, aimed to explore new approaches to prevent or alleviate the UV harm. The results showed that after spraying 1 and 5 mg·L^-1 of anthraquinones, the photosynthetic rate raised by 38.03% and 39.73%, chlorophyll content increased by 3.53% and 3.83%, and MDA content decreased by 11% and 23%, respectively. The anthraquinones could absorb solar UV radiation, and convert the harmful UV into blue or yellow light which can promote plant photosynthesis. It was suggested that foliar-spraying appropriate concentrations of aloe’s anthraquinones could promote wheat photosynthetic activity, alleviate UV harm, and thus, increase wheat yield.

Key words: Temporal-spatial scale, Desertification, Landscape structure, Principal component analysis