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ABSTRACT:

Photosynthetic response of two tropical liana species grown under different irradiances

Journal Article

Sanches M; Valio I

2008

Photosynthetica

46

557-566

We investigated the characteristics of gaseous exchanges and chlorophyll a fluorescence under different irradiances in two liana species Canavalia parviflora Benth. (Fabaceae) and Gouania virgata Reissk (Rhamnaceae) both of a semi-deciduous tropical forest of Southeast Brazil. We used cultivated plants growing under irradiances of 100 40 10 and 1.5 % of the photosynthetic photon flux density (PPFD). Higher net photosynthetic rates (PN) were observed during early morning under full sunlight. After this reduced PN values were recorded due to pronounced stomatal closure. In Canavalia the gas exchange responses diminished concomitant with reduced irradiance. Gouania exhibited a narrower range of response with high PN values even at 10 % PPFD. Marked reduction of the effective photochemical yield (ΔF/Fm\) near midday was observed followed by increases in the non-photochemical quenching for both species under full sunlight. Despite the common occurrence of these species in open areas of the forest both were able to maintain relatively high PN in shaded environments. We suggest that lianas present an intermediate physiological behaviour between shade and non-shade tolerant species.

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Support

The Liana Ecology Project is supported by Marquette University and funded in part by the National Science Foundation.