Theme 1: Grassland Ecology
Description
In the context of climate change, grasslands are considered, similar to forest, as an important sink for atmospheric CO2. However, environmental change seems to go faster than species adaptation to survive on site. Germination and heterotrophic growth are key phases for plant, and consequently, communities’ establishment and structure. They are under genetic control and affected by temperature. The objective of this study was to analyze the intra-specific variability of six accessions of Dactylis glomerata in their responses to eight constant temperatures (5 to 40˚C) during germination and initial heterotrophic growth. The novelty of this work comes from the non-linear modeling of germination and growth velocities and the estimation of cardinal temperatures. High variability within temperatures and significant differences between accessions were observed for germination speed. No germination was observed at 40˚C for any accession. Further, seed germinated at 25˚C died soon after they were transferred to 40˚C for heterotrophic growth. The growth of the axes, whenever it existed, was negligible at 40˚C. The speed of heterotrophic growth of the roots and shoots showed asymmetric bell-shaped response curves to temperature. Base temperature for germination was fixed to 0˚C. After curve-fitting, optimum temperatures for germination were estimated to be between 21.5 and 26.3˚C. Those for heterotrophic growth were, up to 5˚C, higher. Contrariwise, the upper limits, for both processes, appeared between 34 and 40˚C. Overall, this study demonstrates that genetic variability does exist between accessions. For each accession, the response of the germination rate was different from the response of heterotrophic growth rate.
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Germination and Seedlings Heterotrophic Growth of Cocksfoot (Dactylis glomerata L.) in Response to Temperature
In the context of climate change, grasslands are considered, similar to forest, as an important sink for atmospheric CO2. However, environmental change seems to go faster than species adaptation to survive on site. Germination and heterotrophic growth are key phases for plant, and consequently, communities’ establishment and structure. They are under genetic control and affected by temperature. The objective of this study was to analyze the intra-specific variability of six accessions of Dactylis glomerata in their responses to eight constant temperatures (5 to 40˚C) during germination and initial heterotrophic growth. The novelty of this work comes from the non-linear modeling of germination and growth velocities and the estimation of cardinal temperatures. High variability within temperatures and significant differences between accessions were observed for germination speed. No germination was observed at 40˚C for any accession. Further, seed germinated at 25˚C died soon after they were transferred to 40˚C for heterotrophic growth. The growth of the axes, whenever it existed, was negligible at 40˚C. The speed of heterotrophic growth of the roots and shoots showed asymmetric bell-shaped response curves to temperature. Base temperature for germination was fixed to 0˚C. After curve-fitting, optimum temperatures for germination were estimated to be between 21.5 and 26.3˚C. Those for heterotrophic growth were, up to 5˚C, higher. Contrariwise, the upper limits, for both processes, appeared between 34 and 40˚C. Overall, this study demonstrates that genetic variability does exist between accessions. For each accession, the response of the germination rate was different from the response of heterotrophic growth rate.
