Plant origin determines seed mass, seed nutrients and germination behavior of a dominant grass species

Abstract

Although number of studies exploring effects of climate change on plants is increasing, only few studies pay attention to germination. Understanding of germination behaviour is complicated by impact of climate on seed mass and possibly also seed nutrients, which play irreplaceable role in nourishing the sprout. The germination behaviour of species may also depend on trade-off between generative and vegetative reproduction. We studied Festuca rubra originating from localities situated along a natural climatic grid. Seeds of different origin were germinated in two temperature and two moisture regimes, simulating the extremes of the grid. To study relationship between generative and vegetative reproduction we used data on vegetative traits originating from the same study system. Seed mass and nutrient concentrations (nitrogen and phosphorus) were significantly affected by original climate, while carbohydrates not. Higher seed mass and warm temperature of origin caused higher and faster germination. Warm and dry condition during germination caused the lowest germination but the highest seed viability. Total germination and proportion of viable seeds negatively correlated with plant performance variables contributing to vegetative reproduction. Despite this, the patterns detected using datasets of germination and plant performance, did not provide fully comparable results. Simulated changes in climatic condition can modify seed mass and seed nutrients and these changes translate into changes in species germination behavior. After accounting for seed mass, both original and target conditions determine species germination indicating that both genetic differentiation as well as actual conditions drive the germination patterns. As the patterns detected at the level of seed germination do not fully match those detected for the vegetative traits, we urge that future studies should focus on multiple stages of plant life to understand species responses to future climates.