Effects of shading on photosynthetic characteristics and chlorophyll fluorescence parameters of four Corydalis species

Abstract

We examined the effects of five shading treatments (0, 20%, 40%, 60% and 80% shading) on chlorophyll content, photosynthetic characteristics, and chlorophyll fluorescence chara-cteristics of four Corydalis species (C. incisa, C. decumbens, C. edulis and C. pallida) in a pot experiment. The results showed that the contents of chlorophyll a, chlorophyll b and chlorophyll (a+b) increased with the increment of shading, with that of C. incisa reaching the maximum under 80% shading treatment and that of C. decumbens, C. edulis and C. pallida reaching a maximum under 60% shading treatment. In contrast, chlorophyll a/b, light saturation point, light compensation point and dark respiration rate decreased with increasing shading. Among the four Corydalis species, C. incisa reached up to the maximum chlorophyll fluorescence parameters under 80% shading treatment, and C. decumbens, C. edulis and C. pallida reached the maximum at 60% shading treatment. The shade tolerance of four species was as follows: C. incisa ＞ C. decumbens ＞ C. edulis ＞ C. pallida. C. incisa under 80% shading treatment and C. decumbens, C. edulis, C. pallida at 60% shading treatment had the highest light energy utilization and photosynthetic capacity, which would facilitate their growth.