Disponibilidade hídrica nas respostas fisiológicas de espécies de chapéu-de-couro

Abstract

Used in association with the treatment of inflammatory processes, the “chapéu-de-couro” is the popular name attributed to species of the genus Echinodorus spp., a plant usually found in flooded areas present in different Brazilian states, including areas of Northern Minas Gerais and Vale do Jequitinhonha. The environment where these species are found is an important factor to determine their water needs and physiological relationships. Also, under the effect of climate change, these areas may undergo changes and modify their availability or water capacity. In this context, the present work had the objective of investigating the physiological and productive behavior of two species of “chapéu-de-couro” plants, E. floribundus and E. subalatus, according to the water availability. The experiment was conducted in a greenhouse at the ICA/UFMG in a percolation lysimeter for 90 days. The design used was randomized blocks in a 2x2 factorial scheme, being two species of Echinodorus, two water availabilities (field capacity – CC and 50% of available water – 50AD) and five repetitions. The growth was measured in: temperature and number of leaves, height, size, leaf area, fresh and dry matter. At 30, 50, 70 and 90 days the chlorophyll content, gas exchange (photosynthetic rate, transpiration and water use efficiency) were determined. At the end of the cultivation, the total phenolic, proline and hydroxycinnamic acid content was determined. The data collected were submitted to analysis of variance followed by mean tests and analysis of canonical correlations using the R software. The variables of leaf area, height and size present interaction between the species and water availability applied and have strong correlation. In the analysis of canonical correlations, the species when submitted to 50AD present the smallest biometric estimates with E. floribundus presenting the most contrasting results with greater height, size and leaf area when cultivated in CC. The fluorescence analysis of chlorophyll indicates that there was no damage in the photosynthetic apparatus of the plants, only with E. floribundus over CC in stress situation. The treatment with lower water availability (50AD), also presents higher leaf temperature. According to the time, the chlorophyll content and transpiration rate were reduced only in the first 30 days. However, the photosynthetic rate and the efficiency of water use are maintained with similar averages, without interaction with water availability. Proline levels remain statistically the same among species and treatments. While total phenolic and hydroxycinnamic acid, a compound preconized by the Brazilian Pharmacopoeia, did not present a distinction between the species in the content found, but rather between the treatments, with a higher content in CC. Thus, it is concluded that the species can be cultivated in non-flooded environments, although the availability of water may alter chemical and biometric characteristics, the functioning of the photosynthetic apparatus was not affected by the environment.