Artigo
A reliable methodology for assessing the in vitro photosynthetic competence of two brazilian savanna species: Hyptis marrubioides and Hancornia speciosa
Autor
Otoni, Wagner Campos
Pereira, Flávia Dionisio
Costa, Alan Carlos
Rosa, Márcio
Megguer, Clarice Aparecida
Silva, Fabiano Guimarães
Institución
Resumen
Evaluation of photosynthetic efficiency is critical for studies on plant responses to environmental conditions as well as for genotype selection; however, there is a lack of reliable and functional protocols for such assessments of plants cultured in vitro. In this study, we aimed to adapt the conventional methodology for measuring gas exchange of plants grown in vitro to analyze the effects of irradiance, flow rate, and air humidity on the photosynthetic rate in cultured plantlets of two ‘Cerrado’ species, namely Hyptis marrubioides and Hancornia speciosa plantlets. Chlorophyll (chl) a fluorescence and chloroplastidic pigment content were also assessed. The highest photosynthetic rates were observed at a photon flux density of 600 μmol m^−2 s^−1, with tube inlet airflow rates between 100 and 300 mL min^−1 and 80 % relative humidity in the inlet air. The electron transport rate curve, by means of chl a fluorescence, was similar to the photosynthetic rate response curve obtained with the infrared gas analyzer. These results demonstrate that both H. marrubioides and H. speciosa seedlings grown in vitro have a functional photosynthetic apparatus and respond to variations in measurement conditions, exhibiting substantial rates of CO2 assimilation under saturating irradiance conditions. The methodology proposed here can be adapted and applied to other species growing in vitro.