RONQUIM, C. C.

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Trocas gasosas em folhas de coffea arábica sob incremento de temperatura e CO².

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AGU Abstract Browser BetaAboutMeetingsSectionsIndex TermsAdvanced Search TROCAS GASOSAS EM FOLHAS DE Coffea arabica SOBINCREMENTO DE TEMPERATURA E CO2DetailsMeeting 2010 Meeting of the AmericasSection Global Environmental ChangeSession Global Environmental Change General Contributions II PostersIdentifier GC13C-02Authors Ronquim, C*, Embrapa, Campinas, BrazilIndex Terms GLOBAL CHANGE [1600]Regional climate change [1637]AbstractCarlos Cesar Ronquim (Presenting) Embrapa Monitoramento por Satélite; Av. Soldado Passarinho, 303; CEP13070-115; Campinas - SP - Brasil ronquim@cnpm.embrapa.br The increase of greenhouse gas emissions(GHG) in the atmosphere is causing wide changes in atmospheric events, influencing climate change andvariability with critical impacts on vegetations. In Latin America, the air temperature is supposed to increase1 °C to 5.8 °C and the rainfall 15% in the tropical areas of Brazil; and agriculture and water resources aremost affected through the impact of extreme temperatures and changes in rainfall. Arabica coffee vegetatesand fructifies very well in the Southeast area of Brazil. It is usually affected in their growth stages by theenvironmental conditions, especially by the meteorological conditions, mainly, the rainfall distribution andair temperature that interfere in the crop phenology, and consequently in the coffee bean productivity andquality. High temperatures are known to disturb plant metabolism. Coffee cultivation in the open is the usualpractice in Brazil, and this provokes leaf exposure to high irradiance and the absorption of much more energythan that usable by photosynthesis. Such conditions may cause an energy overcharge and to an overheatingof leaves, especially if stomata are closed, as occurs on sunny days in unshaded crops. The relationshipsbetween the climatic parameters and the agricultural production are quite complex, because environmentalfactors affect the growth and the development of the plants under different forms during the phenologicalphases of the coffee crop. The optimum mean annual air temperature for arabica coffee range from 18 to 23°C. Above 23 °C, development is accelerated, often leading to loss of quality. Continuous exposure to dailytemperatures as high as 30°C could result in not only depressed growth but also in abnormalities such asyellowing of leaves. In this study, photosynthetic responses of Coffea arabica L. cultivars subjected todifferent thermal treatments during 14 h were analyzed to determine the optimal temperature for maximumcarbon net assimilation (PNmax) and if elevated CO2 concentration modifies responses to temperature stress.The optimal temperature for PNmax measured at 355 ppm CO2 was from 17-23 °C. At temperatures ofabove 23 °C the decline in PNmax was associated with decrease in apparent quantum yield. The difference inoptimal temperature range of PNmax when compared to apparent maximum electron transport rate throughphotosystem II (Jmax) as a function of irradiation (26-29 °C), showing an imbalance betweenphotochemistry and biochemistry phases of photosynthesis, resulting in electron excess. Elevated CO2concentration did not affect the response of PNmax to temperature, despite the variation in optimal rangebetween 23-29 °C for Catuaí Vermelho. At temperature of above 29 °C were measured the higher mesophylllimitations to photosynthesis (Lm), which was greater than stomatal limitations (Ls). Photosynthetic processof C. arabica is strongly inhibited at leaf temperature about 32 °C.Cite as: Author(s) (2010), Title, Eos Trans. AGU, 91(26), Meet. Am. Suppl., Abstract GC13C-022013. American Geophysical Union | All Rights Reserved | Created by Eric Rozell and Tom Narock |Powered by LODSPeaKr

Trocas gasosas em folhas de coffea arábica sob incremento de temperatura e CO².

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