Modificações de trocas gasosas, fluorescência de clorofila, crescimento e anatomia foliar de Typha domingensis Pers. em ambiente enriquecido com ultravioleta

Abstract

Typha domingensis Pers. (cattail) is an aquatic plant presenting high growth capacity and tolerance to a variety of environmental stressors. However, effects of ultraviolet (UV) radiation on growth and development have not yet been explored for T. domingensis. Furthermore, an increase in UV radiation is expected as a consequence of climate change, which may favor T. domingensis in competition with other species. This work aimed to evaluate the effect of UV radiation on the growth, photosynthesis, anatomy, and biochemistry of T. domingensis depending on leaf position. Individuals were collected and propagated to obtain viable clones for the experiment. The clones were subjected to the following UV radiation conditions: unshaded (US), shaded net (SN), greenhouse (GH) and greenhouse plus UV supplementation (GH+UV). We performed a completely randomized two-way Anova to analyze the effects of the interaction between UV radiation x leaf position (leaf apex (LA) and leaf middle part (LM)). Growth, leaf gas exchange, chlorophyll fluorescence, anatomy, and anthocyanins and chlorophyll contents were evaluated. UV radiation compromises both photochemical and biochemical stages of T. domingensis. The highest UV intensity (US) reduces T. domingensis growth but increases its clone production, suggesting an UV-defense mechanism by enhancing population growth and self-shading. Moreover, the leaf apex of T. domingensis presents higher photosynthesis compared to the middle part, and T. domingensis leaves produce anthocyanins as a UV-defense mechanism due to absence of relevant anatomical defense traits. Therefore, our results indicate that T. domingensis is partially an UV-tolerant species.