Temperature influences certain chemical reactions such as photosynthesis, respirtation, and germination. Increase in temperature would increase the rates of these reaction, therefore supporting plant growth. However, if the plant experiences extreme temperatures, it could potentially denature proteins (enzymes) and thus distrupting the plant's health. This could possibly lead to the death, or sickness of the plant.
IV: temperature (°C) = 15,20,25,30,35,40,45
DV: as temperature would affect the plant's growth rate more significantly, measuring the length change in the root system or leaves would conduct a more precise experiment.