Plants are amazing organisms and plant growth is varied with many different forms and adaptations to different environmental niches.
However, whatever adaptations a plant has made to cope with heat, drought, water, ice, poor soils or contamination, there are certain factors which affect growth.
Temperature – this affects growth because the temperature affects the rate of chemical reactions. Most plant processes are due to the reaction between chemicals, whether this is photosynthesis, flowering, giving scent or producing fruit. A rise in temperature will increase the speed of the chemical reactions and a reduction will slow them down. This has led to many plant adaptations and some plants like alpines even have evolved a different chemical mechanism for respiration to enable them to respire even when temperatures become too low for the normal respiratory equation to occur.
Water availability- water is essential for plants to make their own food in photosynthesis. It also provides support in plant tissues, as the cell cytoplasm if full of water when the plant is turgid or held upright. A lack of water can lead to wilting, slow photosynthesis and eventually poor growth and even death. It is not only the water available from the soil which affects growth , the humidity of the air has an affect as well. Humid air means transpiration is slower and so photosynthesis is reduced leading to, in some cases, poorer growth. In other cases, such as lush tropcial areas with high humidity, plants adapt to humid conditions and grow vigorously.
LIght – light is required by plants to photosynthesise which is how they make their food form sunlight. Most plants use light in all the wavelengths except green (which they reflect and appear green to us as we see the green wavelength) but many will adapt to use other wavelengths of light including green and reflect blue, red or brown light wavelengths, which is why some seaweed, algae and water plants have different color appearance to us. LIght excites electrons in chlorophyll or xanthins, depending on which wavelength the plant uses and this provides energy for photosynthetic processes to occur. Temperature will affect this process as well so many factors are linked.
Temperature, water and light are all very important in the growth of plants. Along with the availability of nutrients, pH and lack of competition, plants are affected by these factors to a high degree but you cannot take one on its own as they all have an interlinked effect because the process which allows plants to grow in the first place-photosynthesis- is affected by light, temperature and the availability of water.