Self-shading effect in the growth, photosynthesis and anatomy of Typha domingensis Pers.

Abstract

Typha domingensis Pers. (Typhaceae) is found growing naturally at high and low population densities in wetlands and shows remarkable invasive potential worldwide. The objective of this study was to verify the occurrence of changes in the environmental characteristics as well as in the biometry, anatomy, photosynthesis, and nutrient uptake of T. domingensis from natural populations growing at different densities. Plants were sampled from two populations exhibiting high and low densities and were further submitted to biometric, anatomical and physiological analyses. The experimental design was completely randomized with two treatments and 15 replicates. Data were submitted to ANOVA and the Scott-Knott test (P ≤ 0.05). At a high population density, T. domingensis showed close plant spacing, a high number of plants and a large leaf area. In addition, high-density conditions promoted self-shading of the middle and lower parts of the shoots and led to increased whole plant photosynthesis. Soil nutrients were reduced under high-density conditions. In addition, plants from high-density population developed adaptations in their vascular tissues and aerenchyma. Therefore, the high-density population condition of T. domingensis causes and increased vegetative growth of these populations, as well as its invasive potential, may be related to mild self-shading, which promotes a large leaf area and high rate of photosynthesis.