Estudo bioquimico e da estrutura foliar de plantulas do jatoba da mata (Hymenaea courbaril L.) e do cerrado (Hymenaea stigonocarpa Mart.) expostas a concentração elevada de C O IND. 2 / Structural and biochemical study of leaves of jatobas Hymenaea coutbaril L. and H. stigonocarpa Mart. exposed to elevated concentrations of carbon dioxide atmosphere

AUTOR(ES)

Marcelo Rubens Machado

DATA DE PUBLICAÇÃO

2007

RESUMO

The atmospheric concentration of carbon dioxide (CO2) increased from 280 ppm, during the Industrial Revolution period, to about 370 ppm in the nowadays. It is continuing to increase about 1.8 ppm per year. The effect of this rise in CO2, which is leading to global warming have attracted considerable attention, generating reports on how these changes can affect vegetables, in particular tropical trees species. There are few reports on the consequences of the rise in atmospheric CO2 on plant structure, even considering its relevance for the competitive and physiological success of plants. In this study we present the data about structural, ultrastructural and biochemical analyses of seedlings from two tropical species – the jatobá Hymenaea courbaril and H. stigonocarpa – both exposed to high CO2 concentration. After one hundred days of exposure to elevated CO2 (720 ppm) in open top chambers, the species demonstrated to be reactive, in particular the H. stigonocarpa. This atmospheric alteration resulted in slightly higher plant growth, with significant reduction of the number of stomata and increase of the photosynthetically active tissues, especially of the palissadic layer of the leaves. The quantitative analysis of the epicuticular wax indicated no variation in the species. Gas chromatography and mass spectrometry analyses have shown that the epicuticular wax of the two species is constituted mainly of nonacosans and triterpenoids of probable alcoholic function. The ultrastructural studies revealed alterations in the morphology of the epicuticular wax, and of the chloroplasts the later due to the increase in starch deposition, in the samples submitted to increased CO2 concentration. However, there were no evidences that these changes affect plant development as a whole. The microscopical and biochemical techniques used were useful in determining the responses of tropical plants to the increase of CO2 concentrations, being therefore valuable tools in studies of climatic change.

ASSUNTO(S)

dioxido de carbono dioxido de carbono hymenaea stomata estomato plant morphology morfologia vegetal

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