Effects of temperature on the relationships between seed size and germination characteristics of seventeen alpine grassland plant species

Seed size is an important component in plant growth, and temperature is an important factor affecting seed germination. In this study, 17 plant species seeds harvested on the eastern edge of the Qinghai-Tibet Plateau were used as the study materials; through setting different temperature conditions (10, 15, 20, 25 ℃) laboratory germination experiments, we explored the effect of temperature on the relationships between seed size and seed germination characteristics (germination percentage, germination potential, germination index, mean germination time, and mortality and fungal infection rates). Our results showed that: 1) overall, seed size had a significant positive relationship with seed germination percentage and fungal infection (P < 0.05), whereas there were no significant relationships between seed size and germination potential, germination index, mean germination time and mortality (P > 0.05). 2) At 10 ℃, there was no significant relationship between seed size with seed germination percentage (P > 0.05), whereas there was a significant positive relationship between seed size and germination percentage at 15, 20 and 25 ℃ (P < 0.05); the relationship between seed size and germination was positively correlated with temperature. 3) Seed size showed a significant positive relationship with fungal infection rates at each temperature (P < 0.05), and the relationship was strongest at 25 ℃. Our study provides evidence that an increase in temperature will increase both the germination rates of large seeds as well as the risk of infection by pathogenic fungi. This study provides a theoretical basis for seed germination and survival in the Qinghai-Tibet Plateau under climate change.