Abstract
We grew Amaranthus cruentus L. (NAD-ME subtype) under different light and nitrogen conditions, and investigated how nitrogen partitioning responded to different growth light conditions employing physiological and anatomical techniques.
When grown under low light, chlorophyll contents per leaf area were greater, indicating that C4 leaves, like C3 leaves, increase nitrogen allocation to light harvesting proteins. The leaf δ13C values of high light-grown plants were around -15‰ typical for C4 plants; but when grown under low light, the leaf δ13C values shifted to -19‰ which is intermediate of the typical values for C3 and C4 species. Therefore, it is likely that C4 leaves grown under low light partly perform C3 photosynthesis. In leaves of low light-grown plants, cell size and leaf thickness were greater than those in leaves of high light-grown plants. These differences in leaf structural characteristics might influence efficiency of C4 photosynthesis.
