Vesela, A. | bioRxiv Science

bioRxiv2020

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

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.

ecology↗

bioRxiv2019

Seed mass and plant origin interact to determine species germination patterns

Ongoing changes in temperature and precipitation regime may have strong impact on vulnerable life-history stages such as germination. Differences in germination patterns among species and populations may reflect their adaptation to conditions of their origin or may be determined by the phylogenetic constrains. These two effects are, however, rarely separated. All the germination patterns may also be modified by seed mass. We studied 40 populations of 14 species of Impatiens coming from Himalayas. Germination of seeds of different origin was tested in four target temperatures, three simulating original conditions plus a warmer climate change scenario. We also studied effect of shorter stratification and warmer temperature in combination as another possible effect of climate change. Original and target climate interacted and had strong impact on total germination, but not on germination speed and seed dormancy. Interaction between seed mass and original climate indicated different germination strategies in light and heavy seeds. Only seed mass was affected by phylogenetic relationships among the species, while germination response (with exception of T50) was driven primarily by climate of origin. This study is the first to show that the effect of seed mass interacts with original climate in determining species germination patterns under changing climate. The differences in seed mass are thus likely crucial for species ability to adapt to novel conditions as seed mass, unlike seed germination patterns, is strongly phylogenetically constrained. Further studies exploring how seed mass modifies species germination under changing climate are needed to confirm generality of these findings.

ecology↗