Growth, leaf gas exchange and mycorrhizal colonization of three medicinal species submitted to different irradiance levels

Viviane Maria Barazetti,George Andrade Sodré,Larissa Corrêa Do Bomfim Costa,Eduardo Gross,Ândrea Carla Dalmolin,Miguel Antônio Quinteiro Ribeiro

doi:10.1590/0103-8478cr20200633

Abstract

ABSTRACT: This study o evaluated growth, leaf gas exchange and arbuscular mycorrhizal fungi root colonization in three medicinal plant species under different irradiance intensities. Fridericia chica (Bonpl.) L.G.Lohmann, Mikania laevigata Sch.Bip. ex Baker and Varronia curassavica Jacq. were propagated by cutting and cultivated for 120 days in artificially shaded environments using black shade-type screens, obtaining four irradiance levels: 100%, 70%, 50% and 30%. The experimental design was completely randomized in a 3 x 4 factorial scheme (three plant species and four irradiation levels) with seven replicates. The three medicinal species showed higher liquid assimilation, mass growth and arbuscular mycorrhizal fungi root colonization rates when exposed to environments with 70% light availability. In relation to physiological responses, V. curassavica presented higher photosynthetic rate, stomatal conductance and transpiration when submitted to 70% irradiance, being able to be cultivated in more open environments with higher irradiation levels. Conversely F. chica and M. laevigata presented shade tolerance characteristics. At the initial growth phase, the results obtained can be used as indicators to recommend the ideal cultivation environment for these species in agroforestry systems.

Highlights

Fridericia chica (Bignoniaceae), Mikania laevigata (Asteraceae) and Varronia curassavica (Boraginaceae) are medicinal plants native to Brazil, with economic importance due to their active ingredients (LIMA et al 2020)
F. chica, M. laevigata and V. curassavica plants obtained by cutting were transplanted into plastic pots with capacity of 10 L containing a mixture of soil and sand at proportion of 2:1 (v/v)
RGRh, RGRd, as well NAR, LMR, RMR, specific leaf area (SLA), ISPAD, and variables related to mycorrhizal colonization (COL, HI, HE, and VES) were influenced by the species x light interaction (Table 1)

Summary

Introduction

Fridericia chica (Bignoniaceae), Mikania laevigata (Asteraceae) and Varronia curassavica (Boraginaceae) are medicinal plants native to Brazil, with economic importance due to their active ingredients (LIMA et al 2020). V. curassavica, known as ‘erva-baleeira’, has anti-inflammatory activity (OLIVEIRA et al, 2020a) and is used as raw material for the first herbal medicine fully developed in Brazil, Acheflan ©, which is based on the essential oil from this species (LIMA et al 2020). The quality of the raw material of medicinal plants is determined by the content of bioactive compounds, mainly resulting from the influence of the environment in which plants are grown. For V. curassavica, changes in the content of bioactive compounds were observed due to changes in the light availability (SILVA et al 2017), depending on the time of year (MARQUES, et al (2019) and the access used for collection (OLIVEIRA et al (2020b). Studies carried out with the species have shown that in protected environments with 50% solar radiation incidence, it is possible to obtain higher levels of bioactive compounds such as transcaryophyllene, α-humulene, germacrene D and α-zingiberene (SILVA, 2017)

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