Photosynthesis is the process a plant uses to create simple sugars by dividing water and carbon dioxide molecules using light. The amount of each component needed for photosynthesis is directly proportional to the availability of the other components needed and varies greatly among different species. When a plant's sugar production is artificially limited and it shows poor growth, it is lacking a sufficient amount of one of the necessary components in a relationship to the others.
Light is the most essential component of photosynthesis. Plants use light energy to break water molecules and convert them to energy that the plant can use and store. All wavelengths of light are used in photosynthesis except green which is reflected. This is why plants look green to us. Plants also need a period of dark, where they rest. Under continuous light over an extended period of time, many plants will lose their ability to photosynthesize.
Atmospheric carbon dioxide is usually the most limited ingredient available for photosynthesis. During the photosynthetic process, a plant uses the carbon atoms in carbon dioxide as the source of carbon for the glucose molecules it is producing. The extraneous oxygen atoms are release into the air. Increasing the amount of carbon dioxide available for a plant to use increases the growth rate and overall size and quality of the plant. Many horticulturists fertilize with atmospheric carbon dioxide to improve production.
Water is a plant's source of hydrogen atoms when creating glucose. The extra oxygen atoms in the water are released to the atmosphere. How much water is needed for photosynthesis varies greatly among species. Some plants are more efficient with higher levels of moisture content in the air and ground while others prefer lower levels. Some plants increase productivity after it rains, while for others, this limits the plant's ability to absorb carbon dioxide.
Temperature greatly effects photosynthesis. When the temperature is warmer, a plant can use more carbon dioxide than when the temperatures are lower. Very low temperatures will cause freezing which inhibits the water availability to a plant. Some plants, however, such as those in cold and Arctic climates. are able to photosynthesize at temperatures well below freezing.
The pH, or acidity level, is important when it comes to aquatic plants that remain submerged and rely on carbon dioxide that has been dissolved in the water from the atmosphere as their primary source of carbon. Some plants, however, are able to use carbon obtained from the dissolved solids in the water. There is a relationship between the amount of carbon dioxide that can be absorbed into the water and the carbon hardness of the water. pH determines how much usable carbon the water can hold. Acidic water is able to contain more carbon dioxide while alkaline water contains less. How much carbon dioxide, and what acidity and hardness levels an aquatic plant requires varies greatly depending on the species.