Photorespiration and antioxidant metabolism in young rubber plants grown under different nitrogen sources (NO3- and NH4+)
DOI:
https://doi.org/10.5039/agraria.v10i1a4941Keywords:
antioxidant enzymes, nitrogen sources, chlorophyll fluorescence, Hevea brasiliensis, gas exchangeAbstract
In this study, the effects of nitrate (NO3-), ammonium (NH4+) and of the absence of nitrogen (N) in photosynthesis, photorespiration and antioxidant metabolism of young rubber plants were evaluated. Plants were grown in sand irrigated with Bolle-Jones’s nutrient solution, with the nitrogen final concentration (8mM) added in the following NO3-/NH4+ proportions: 8/0, 0/8 and 0/0, respectively. The gas exchange, chlorophyll a fluorescence, photorespiration and antioxidant enzyme activities (SOD, CAT and APX) in leaves were evaluated. The net CO2 assimilation rate (A) and the electron transport rate (ETR) were higher in NO3- treated plants. Lowest ETR and higher photorespiratory activity were observed in plants treated with NH4+. SOD activity was higher in leaves of plants treated with both N sources. Lower CAT and higher APX activities were found in NO3- treated plants. Plants grown in the absence of N showed lowest values of A. We observed that the different N sources significantly affected the photosynthetic process and that NH4+ favored photorespiratory process in rubber plants.
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