The Rate of Photosynthesis
Plants are an essential part of the food chain required by all living things to survive. The growing world population and subsequent alteration to the natural environment has placed increased pressure on available plant resources. This is particularly evident in the area of agriculture, where optimum crop productivity is important to meet the increased demand for food by the growing world population.
Plants are autotrophic, which means they make their own food, sustaining life without needing to consume other organisms1. They do this through the process of photosynthesis. This is where light energy from the sun (or other radiant source) is trapped by green plants and transformed into chemical energy.
All photosynthetic organisms contain chlorophyll, a green pigment found in plant chloroplasts. There are three types of chlorophyll pigment – a, b and carotenoids. Chlorophyll a is the pigment primarily responsible for the process of photosynthesis. It is green as a result of reflecting green light rays. Light energy is captured by chlorophyll and used to form ATP molecules, which are in turn used as an energy source by plants in a chemical reaction with combines carbon dioxide and water to produce glucose and oxygen.2 The equation which describes the process of photosynthesis is:
Carbon dioxide + water light energy ► glucose + water + oxygen Chlorophyll
Light energy is essential for photosynthesis to occur and this is usually provided in the form of sunlight. All light, including sunlight, is a collection of wavelengths. The visible light spectrum contains wavelengths which vary in intensity from around 350nm (nanometres) to 750nm (Figure 1). Chlorophyll reflects green light (so leaves appear green) and absorb more blue and red light 4 .
Figure 1: Wavelengths on the Visible Light Spectrum