Variação térmica ambiental para emissão de folhas estoloníferas e eficiência fotossintética em Paspalum sp.

• Ano de defesa: 2017
• Autor(a) principal: Áurea Rodrigues Cordeiro
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; Brasil; ICB - INSTITUTO DE CIÊNCIAS BIOLOGICAS; Programa de Pós-Graduação em Biologia Vegetal; UFMG
• Palavras-chave em Português: Paspalum; Tempo térmico; Temperatura; Emissão foliar; Termotolerância; Fisiologia vegetal
• Link de acesso: http://hdl.handle.net/1843/35337

Among several environmental factors, air temperature is strongly related to plant distribution in different ecosystems once each plant species is conditioned to a given environmental thermal range. The forecast and ongoing increases in global temperature averages make things uncertain when it comes to species adaptation facing climate changes. Pastures are a relevant component of natural landscapes and cattle raising – a significantly important economy sector in Brazil. The Paspalum genus species are highlighted due to the forage potential, and since many species are native from Brazil, they do not represent a threat to Brazilian biomes. In this study, the thermal time for stoloniferous leaf growth and the relations between growth temperature and thermal tolerance in Paspalum sp. were determined. Stolons harvested in UFMG campus were placed to grow in different temperature of 15, 20, 25, 30, 25/15 and 30/20 ºC to stablish base temperature (Tb) maximum temperature (Tc), optimum temperature (To) and thermal time (θg) to grow. Besides that, parameters like leaf final percentages, leaf growth speed, leaf length, dry weight accumulation, leaf area, specific leaf area, potential and effective quantum yield, electron relative excess and thermotolerance were evaluated. The Tb found was 13.5ºC and Tc of 43.5 ºC. The θ50 (θg) was 49.5ºCd. The temperature of 30ºC was the one which induces the highest speed of leaf growth and that is why it was determined as To. There was a higher biomass accumulation for roots grown at 20ºC. The largest leaf area was obtained at 25 and 30 ºC, and the largest specific leaf area at 25 ºC. The greatest effective quantum yield was obtained above 20ºC, and the potential quantum yield at the temperature of 25ºC. The relative electron excess was higher between 20 and 25ºC and there were no differences in thermal tolerance. The thermal time model presented itself as an adequate tool to predict leaf growth and growth of Paspalum sp. Growth temperature did not influence the species thermotolerance.