Gas exchanges in peach palms as a function of the spad chlorophyll meter readings

Abstract

The close relationship between the chlorophyll-meters readings and the total chlorophyll and nitrogen contents in leaves, has allowed their evaluation both in annual and perennial species. Besides, some physiological events such as the CO2 assimilation have also been estimated by chlorophyll meters. This work was carried out aiming to evaluate the gas exchanges of peach palms as a function of the chlorophyll SPAD-Meter readings. Three year-old peach palms from Yurimaguas, Peru were studied in Ubatuba, SP, Brazil, spaced 2 x 1 m in area under a natural gradient of organic matter which allowed four plots to be considered, according to the peach palms leaves colors, from light yellow to dark green. The SPAD readings and the stomatal frequency of leaflets were evaluated. The photosynthetic photon flux density (PPFD, μmol m-2 s-1), the leaf temperature (Tleaf, ºC), the CO2 assimilation (A, μmol m-2 s-1), the stomatal conductance (g s, mol m-2 s-1), the transpiration (E, mmol m-2 s-1) and the intercellular CO2 concentration (Ci, μmol mol-1) were evaluated with a portable infrared gas analyzer (LCA-4, ADC BioScientific Ltd., Great Amwell, U.K.). A linear increase in the CO2 assimilation as a function of the SPAD readings (y = -0.34 + 0.19x, R² = 0.99), indicates that they can be a rapid and cheap complementary method to evaluate in peach palms some important physiological events, such as CO2 assimilation.

Validação das unidades arbitrárias do teor de clorofilas obtido em folhas intactas de seringueira.

“…A pigmentação foliar pode ser diretamente relacionada com o estresse fisiológico, havendo aumento na concentração de carotenoides e diminuição na de clorofilas nas situações de estresse e durante a senescência foliar (LARCHER, 2004), limitando o potencial fotossintético e a produção primária. Estudos realizados com pupunheira mostraram correlação linear da assimilação de CO 2 em função das leituras com clorofilômetro, indicando que esta monitoração pode ser um meio complementar, rápido e de baixo custo para se estimar importantes eventos fisiológicos nesta espécie (TUCCI et al, 2011).…”