Gas Exchange and Production of Photosynthetic Pigments of <i>Piper aduncum</i> L. Grown at Different Irradiances

Abstract

The species Piper aduncum is a plant with great economic potential, because the essential oil has antimicrobial acti v ity and insecticides. Thus, as the light directly affects photosynthesis process, the present study evaluated the gas ex changes ’ variables and photosynthetic pigments ’ production of P . aduncum grown under different irradiances. Treat ments consisted in environments with 100%, 70% and 50% of irradiance and environments with colored nets (red and blue). After 150 days of culture, photosynthetic activity (A), stomatal conductance (gs) transpiration rate (E), internal CO 2 concentration (Ci), deficit vapor pressure (DVP), leaf temperature, concentration of internal/external CO 2 (Ci/Ca), carboxylation efficiency (A/Ci) and efficiency water use (A/E) were evaluated. Pigments chlorophyll a , b , carotenoids, total and chlorophyll a / b ratio were also measured. From the observed data, it can be concluded that the species Piper aduncun developed various mechanisms for adaptation to different irradiance conditions . Moreover, it can be inferred that their photosynthetic process is more efficient and has larger spectral intensities of light, with higher efficiency photosynthetic when grown under 70% and 100% of radiation.