Growth and matters production of Typha australis (SCHUM. and THON) subject to different levels of immersion.
Objective: Invasive plants cause a dysfunction of ecosystems particularly in wetlands for agricultural use such as the "Niayes" where the water level fluctuates during the year. The present study aims at assessing the growth and the production of matters of Typha australis when the rhizomes are subject to different levels of immersion in experimental conditions from two hypothesis: 1 - growth plants from rhizomes is affected by the level of immersion; 2 - allocations of materials in different parts of the plant are influenced by the level of immersion. Methodology and Results: The test was carried out under experimental conditions in containers filled with sand, of the "Niayes" area, whose characteristics are defined. Typha plants harvested in the area were transplanted into containers. Three levels of water supply were used: a water-saturated level chosen from the withdrawal curve; two levels of water column to 50 mm and 100 mm. Parameters such as height, relative growth rate, and fresh matter of the aerial parts are even higher than the level of immersion is important with significant differences. The dry matter of the underground parts is distributed preferentially in the upper horizons for the 3 levels of water supply. In saturated environment, it has an even distribution between the two horizons. In the 50 and 100 mm levels of immersion, redistribution of the underground system is established. Ratio PA/PS decrease during the experiment with the immersion level with significant differences between saturated level and the two others levels (p<0.05). Typha australis concentrates more matters in the underground part to maximize its growth. Conclusion and Application: These results show that some morphological parameters and production matters of Typha australis are all higher than the environment is in immersion. This growth is due to the allocation of matters produced in the underground parts that are also particularly important that immersion is strong. This allows Typha australis to maximize growth. This study contributes to the understanding of the growth mechanisms and matter allocation in different parts of Typha australis. This could limit its expansion and possible eradication.