Photosynthetic activity of young Ricinus communis L. plants under conditions of flooded soil

Abstract

Soil flooding is a stress condition that causes changes in hydric relationships and in the metabolism of crops, thereby affecting their productivity. To evaluate the effects of soil flooding on the chlorophyll a fluorescence transient, as well as gas exchange and Ricinus communis growth, young plants of the 'AL Guarany 2002' and 'IAC Guarani' cultivars, grown in a greenhouse, were subjected to flood conditions by maintaining a layer of water 2-3 cm above the soil. The stressed plants showed drastic reduction in net CO2 assimilation and growth variables. There was, however, an increase in performance index (PIABS e PITOTAL) at different moments of stress between the two cultivars. In general, R. communis plants possess mechanisms to protect the electron transport chain during a period of stress, without causing damage and reducing functionality. However, this is not enough to maintain photosynthetic activity owing to the decrease in stomatal conductance and intrinsic carboxylation efficiency, which affects biomass accumulation in stressed plants. In summary, this study found that the 'AL Guarany 2002' was found to be more sensitive to stress than the 'IAC Guarani' was.