Typha domingensis Pers. growth responses to leaf anatomy and photosynthesis as influenced by phosphorus

Abstract Cattail ( Typha domingensis Pers.) can show intense growth depending on phosphorus (P) eutrophication. We verify how P enrichment and deficiency influence T. domingensis growth and the relationship with anatomical and physiological modifications. Vegetative T. domingensis plants were grown for 60 days in a modified nutrient solution in five P levels: 0, 0.20, 0.40, 0.60 and 0.80 mM. Plant growth was evaluated at the end of the experiment. Leaf fragments were collected and fixed in F.A.A.70 and sectioned in bench-top microtome. Sections were stained with safrablau solution, mounted in slides and photographed with an optical microscope. Images were evaluated in UTHSCSA-Imagetool software which was used to measure leaf tissues. Leaf gas exchanges were evaluated 30 and 60 days after the experiment started. The data were submitted to one-way ANOVA and regression analyses or means were compared using the Scott–Knott test. Plants showed more growth in a P-rich nutrient solution. T. domingensis showed different biomass partitioning under P levels, with an increasing leaf biomass allocation for higher P levels and a lower rhizome investment. For higher P levels, plants showed increased photosynthesis, stomatal conductances and transpiratory rates. However, the highest concentration promoted a decrease in these characteristics. The leaves of T. domingensis showed larger stomata, thicker palisade parenchyma and an increased phloem proportion under higher P levels. Our results suggest that the increased growth of T. domingensis in P-rich conditions may be related to increased photosynthesis; this characteristic is limited to anatomical traits such as palisade parenchyma and stomatal modifications.