Photosynthetic pigments content, photosynthesis rate and chloroplast structure in young plants of Mikania laevigata Schultz Bip. ex Baker grown under colored nets

Abstract

Guaco (Mikania laevigata) is a medicinal plant used to treat fever, rheumatism, flu and respiratory tract diseases. Understanding the physiology of this species and its responses to environmental conditions has become necessary to improving the cultivation methods. In this context, this work aimed to access the effects of shading by using colored nets in on photosynthetic pigment concentration, photosynthetic rate and ultrastructure of chloroplasts of Mikania laevigata. The plants were cultivated during four months under nets with 50% shading in blue, red and gray color nets and under full sunlight (0%). The plants grown under full sunlight had decreased contents of a and b chlorophyll, and of carotenoids, while those grown under blue nets shown higher concentrations of a and b chlorophyll. The lowest density of chloroplasts was found in plants cultivated under full sunlight. Elongated chloroplasts were noticed in treatments with 50% shading. Regarding the potential rate of photosynthesis no significant change was observed among the plants grown under red, blue and gray nets, which leads to the conclusion that the spectrum transmitted by different coloured nets did not affect guaco photosynthetic apparatus.