Efeito do CO2 na eficiência quântica do eucalipto e sua utilização na modelagem de seu crescimento pelo 3-PG

• Autor(a) principal: Baesso, Raquel Couto Evangelista
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1504
• topic: Eucalipto; Modelagem; Agrometeorologia; Ecofisiologia; Eucalyptus; Modeling; Agrometeorology; Ecophysiology; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::AGROMETEOROLOGIA

The world concern regarding to climate changes due to global emission of greenhouse-effect gases, especially carbon dioxide (CO2) has increased in the last few decades. It is known, through experimentation, that plants react to increases in CO2 concentration by growing more and requiring less water. Similarly, it is also known that climate changes will be environment conditions resulting from modification in frequency and intensity of climate process, and therefore of time processes. By facing a potential new climate system with aggravation of extreme events, the objective of this study was to analyze the behavior of variations of gas exchanges in young and adult eucalyptus clonal plantations under high concentrations of CO2 (570 and 760 μmol mol-1); to estimate Quantum efficiency of the canopy; and to simulate eucalyptus production by 3-PG growth mode, based in climate scenarios of predicted changes. The highest photosynthetic rates were recorded in young eucalyptus plantation, when concentrations of CO2 increased in the winter, with a difference of up to 30% in comparison to adult plantation. Stomatal conductance and transpiration were reduced at high CO2 concentrations. Stomatal response (reduction) to the increase of CO2intercellular concentration (Ci) followed by increase of photosynthesis and reduction of transpiration (E),favored transpiration instantaneous efficiency. Results of α presented an increase of 17% in the young plantation and 27% in the adult plantation under high CO2 concentration, compared to control-concentration (~380 μmol mol-1). Quantum efficiency presented a relatively small variation from winter to summer. In the simulation of respiration reduction in the forest plantation, annual average increment (AAI, m3 ha-1 year-1) presented an increase trend, that is why AAI presented a reduction trend. Concerning transpiration, variation in the carbon efficient use did not cause great differences. Transpiration was kept below control- transpiration in most scenarios, which was expected, in which the increase in intercellular concentration of CO2 reduced transpiration. The model of forest growth was in agreement with estimation of eucalyptus plantation productivity in scenarios of climate changes.