Application of the thermal time model for different Typha domingensis populations

Abstract

BackgroundTypha domingensis Pers. is a perennial emergent plant that in comparison to other Typha species, produces more biomass. This species is used in Green Floating Filters (GFFs), one of the most innovative systems of wastewater treatment to bioremediate eutrophic waters and produce biomass as biofuel feedstocks. The establishment of a GFF depends on the seed germination and plant responses under conditions of a new habitat. This study analysed the germination response of four different populations of T. domingensis through a thermal time model to determine which population would have the fastest germination for establishment in a GFF.ResultsSeeds from the Badajoz (Ba), Cuenca (Cu), Madrid (Ma) and Seville (Se) populations were exposed to different thermal regimes (constant and alternating temperatures between 15 and 30°C) and photoperiods (0, 3, 5, 7,10 and 20 days in darkness) to determine the parameters of the thermal model. Regardless of other parameters, no germination occurred in total darkness (20 days). The mean value of the base temperature (Tb) was 16.4±0.2°C in all treatments. The optimum temperature (To) values in Ma and Ba were 25°C, and those in Cu and Se were 22.5°C. The germination response decreased when the temperature approached Tb and increased when it was close to To. In comparison to temperatures with a ΔT= 5°C or 10°C, those with a ΔT= 15°C or ΔT= 0°C had the highest germination response and lowest thermal time (θT(50)). The photoperiod had a relationship with θT(50), but it was not proportional. The populations also affected germination; Cu had the highest values of To and germination response but had a lower θT(50). which coincides with the lowest mean ambient temperatures.Conclusion According to these results, the germination response of T. domingensis under optimal conditions was high in all populations but was affected to a greater or lesser extent depending on thermal regimes, photoperiods, and population. The thermal time model allowed us to determine that in comparison to other populations, Cu is the best population for establishment in a GFF due to its high germination response under the conditions tested.