Caracterização fotossintética de três espécies arbóreas da Mata Atlântica submetidas a diferentes intensidades lumínicas
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Data
2017-08-07
Autores
Gomes, Marcos Thiago Gaudio
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Universidade Federal do Espírito Santo
Resumo
The regulation of the photosynthetic process is modified according to the available light and has a direct effect on the plant's ability to live in a given habitat. Three tree species of the Atlantic Forest were evaluated while submitted to three irradiance intensities in order to investigate the effects of light radiation on the photosynthetic behavior and on the slenderness index (SI). The plants were cultivated during seven months at 20, 50 and 100% of the solar radiation. The species used, Schinus terebinthifolius Raddi. and Joannesia princeps Vell, classified as pioneers, and Lecythis pisonis Camb, as secondary, are widely used in environmental recovery programs. It was tested the hypothesis that the three species would present different ecophysiological behaviors in response to light availability. Irrespective of the light regimens, S. terebinthifolius displayed the highest values of net photosynthesis rates on a per mass or area basis, followed by J. princeps. L. pisonis which presented the lowest values of this parameter. S.terebinthifolius also showed higher light saturation point and higher stomatal conductance in the three imposed 10 irradiances. S. terebinthifolius and J. princeps exhibited increased SI value at reduced light availability. However, this value was higher for S. terebinthifolius, with values higher than 50% in plants under full sun compared to those under 20% of light showing a morphological adjustment to the irradiance difference. L. pisonis showed no changes in this parameter by light variations. This species presented more negative values of ?W throughout the day and between the light regimes when compared to the other two species, demonstrating a lower hydraulic conductivity. The results confirmed the hypothesis, insofar it was observed greater acclimatization capacity of S. terebinthifolius to the three light treatments imposed. J. princeps showed an intermediate behavior among the studied species, presenting average values in almost all the parameters analyzed during the experiment. In turn, L.pisonis, exhibited a low acclimatization capacity at high irradiance. These results instigated the development of a second work to evaluate the physiological and biochemical characteristics that could influence the ability of S. terebinthifolius to occupy several territories around the planet as an invasive exotic species, whereas J. princeps, even being a species of Atlantic Forest, pioneer, as S. terebinthifolius does not present records of invasion in other ecosystems. S. terebinthifolius showed higher photosynthetic efficiency when submitted to the three levels of irradiance. This same species demonstrated a greater hydraulic conductivity as deduced from the smaller oscillation of the water potential registered during the day under the imposed treatments. J. princeps exhibited a greater investment in energy dissipation mechanisms to avoid possible damages to the photosynthetic apparatus. S. terebinthifolius showed to be more effective in light capture efficiency, as evidenced by the its higher values of carbon isotopic composition, photochemical quenching and specific leaf area. The results show that although the two species studied belong to the same state of ecological succession, S. terebinthifolius presented a greater plasticity in response to the imposed treatments. In addition, the data recorded partly explains the invasive potential of this species along the continents.
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Acclimatization , Atlantic forest , Ecophysiology , Gas exchange , Trocas gasosas , Irradiance , Irradiância
Citação
GOMES, Marcos Thiago Gaudio. Caracterização fotossintética de três espécies arbóreas da Mata Atlântica submetidas a diferentes intensidades lumínicas. 2017. 81 f. Tese (Doutorado em Biologia Vegetal) - Universidade Federal do Espírito Santo, Centro de Ciências Humanas e Naturais, Vitória, 2017.