Salicornia ramosissima population dynamics and tolerance of salinity

Abstract

Field and greenhouse studies have been conducted to clarify aspects of population dynamics and NaCl tolerance of Salicornia ramosissima J. Woods. Two populations, Varela and Verdemilho, were monitored in the field during two consecutive life cycles and aspects of their morphology and density were recorded monthly. In the laboratory seedlings were exposed to different salinity for 10 weeks and growth and mortality rate were recorded weekly. The growth of the populations differed significantly, possibly because of the different salinities of the two sampling sites and/or genetic adaptations of the two populations to the environmental conditions. The absence of a significant correlation between sediment salinity and stem elongation suggested, however, that salinity, alone was not responsible for the differences observed and was possibly associated with other factors, because of nutritional, edaphic, and microclimatic conditions. S. ramosissima did not develop well in conditions of elevated or moderate salinity; its growth was optimum at low salinity. Optimum development of S. ramosissima may, nevertheless, depend on the total number of large seeds in a population seed bank, because of their greater success in germination and germinability under stress conditions than small seeds.

The influence of cadmium contamination and salinity on the survival, growth and phytoremediation capacity of the saltmarsh plant Salicornia ramosissima

“…concentrations of 0, and 100 µg.l -1 . Therefore, 9 different treatments where tested: salinities (0, and 10) x 3 cadmium concentrations (0, and 100 µg.l -1 ) (table 1), with the treatments without cadmium (S0Cd0, S5Cd0 and S10Cd0) as the controls since, according to Silva et al (2007), the optimum salinity for the development of S. ramosissima is between 0 and 11.7. The cadmium concentrations were selected considering the Portuguese legislation (Decree Law 236/98), that states Cd 50 µg.l -1 as the Maximum Allowed Concentration (MAC) for irrigation waters, Cd 200 µg.l -1 as the Emission Limit Value (ELV) for residual water discharges, and that some plants are affected when submitted to Cd 100 µg.l -1 .…”

“…It usually occupies the higher reaches of the salt marsh, where the salinity is lower, and is a pioneer species in the colonization of the intertidal zones of such habitats (Davy et al, 2001). The optimum growth is at low salinity (Silva et al, 2007), but it can also tolerate high salinity and water potentials (Rubio-Casal et al, 2003). These features, coupled with the geographic distribution and the potential for bioremediation of the genus Salicornia (see for instance Ozawa et al, 2009 andSharma et al, 2010), make Salicornia ramosissima an excellent candidate for phytoremediation.…”

“…Although the life cycle and the population biology of S. ramosissima are well known (e.g. Rubio-Casal et al, 2003;Silva et al, 2007), the trace metal accumulation ability of this plant under distinct salinities has not yet been studied. Experimental essays with the aim of understanding the effects of the interaction between salinity and trace metal contamination on the plants' survival, development and bioaccumulation ability are needed.…”

Is the salt marsh vegetation a determining factor in the sedimentation processes?

“…At the sampling stations (superficial horizon 0-5 cm), the mean values of organic matter are about 9% at Barra and 6% at Verdemilho. The Barra salt marsh has a great amount of clay in the sediment and Verdemilho has a great amount of silt (Silva, 2000;Silva et al, 2007).…”

Modular response to salinity in the annual halophyte, Salicornia ramosissima

“…Woods responds uniformly to salinity. This species is a succulent halophyte characterized by articular stems with carnose segments (internodes), reduced and stem-united leaves, which can tolerate high salinity levels (Silva et al 2007). We hypothesize that internodes of this species may respond as more-or-less independent units or modules.…”