Photosynthetic light-use by three bromeliads originating from shaded sites (Ananas ananassoides, Ananas comosus cv. Panare) and exposed sites (Pitcairnia pruinosa) in the medium Orinoco basin, Venezuela

Abstract

Three Bromeliaceae species of the medium Orinoco basin, Venezuela, were compared in their light-use characteristics. The bromeliads studied were two species of pineapple, i.e. the wild species Ananas ananassoides originating from the floor of covered moist forest, and the primitive cultivar Panare of Ananas comosus mostly cultivated in semi-shaded palm swamps, and Pitcairnia pruinosa, a species abundant in highly sun exposed sites on rock outcrops. Ananas species are Crassulacean acid metabolism (CAM) plants, P. pruinosa is C3 plant. Plants were grown at low daily irradiance (LL = 1.3 mol m-2 d-1 corresponding to an incident irradiance of 30 μmol m -2 s-1) and at high irradiance (HL = 14.7 mol m -2 d-1 or 340 μmol m-2 s-1), and CO2 and H2O-vapour gas exchange and photochemical (q P) and non-photochemical quenching (qNP) of chlorophyll a fluorescence of photosystem 2 (PS2) were measured after transfer to LL, medium irradiance (ML = 4.1 mol m-2 d-1 or 95 μmol m -2 s-1) and HL. All plants showed flexible light-use, and qP was kept high under all conditions. LL-grown plants of Ananas showed particularly high rates of CAM-photosynthesis when transferred to HL and were not photoinhibited.