Biometric and physiological aspects of young plants of Mikania glomerata Sprengel and Mikania laevigata Schultz Bip. ex Baker under colored nets

Abstract

Mikania glomerata and Mikania laevigata are commonly called “guaco” and are among the species used to treat fever, rheumatism, flu and respiratory diseases. The understanding of the physiological behavior of these species and their responses to environmental conditions is necessary to improve methods of cultivation. The aim of this study was to assess the effect of the controlling of the light spectrum, using colored nets, on the biometric and physiological characteristics of M. glomerata and M. laevigata during early development. Plants were obtained from cuttings and kept under the treatments for 120 days, using colored nets with 50% shading in red, gray and blue and full sunlight (0%). Total and partitioned (leaf, stem and roots) dry weight, leaf area, leaf area ratio, leaf weight ratio, specific leaf area and photosynthetic pigment contents (chlorophylls and carotenoids) were determined. The results revealed that the blue net allowed the increase in total dry and partitioned matter accumulation in the shoots and increased the height of the plants. The levels of chlorophyll a, b and total, were also increased under the blue net. On the other hand, the plants under red net showed higher allocation of dry matter to roots. No changes in the leaf weight and in chlorophyll a/b ratio were observed.  Shading significantly altered the plant dry weight distribution, while the use of different nets modified the content of photosynthetic pigments in the plant species under study.