ABSTRACT
Solar radiation is the sole energy source that can be used in metabolic activity by green plants. The efficiency with which plants harvest energy is the efficiency with which energy is transformed into the 6-carbon sugar, glucose, by photosynthesis. Numerous measurements have been made to measure the actual efficiency with which plants convert solar radiation into potential energy. One of the main reasons why plants rarely achieve their photosynthetic capacity is the variation in the intensity of radiation. Plants exist in a world where radiation varies throughout the day and the year, and where the radiation received may be modified by external factors. The major strategic difference between plant species in their reaction to the intensity of radiation is that which has evolved between plant species that are characteristic of sunny, open habitats and those that are characteristic of shaded habitats. The rate at which a leaf photosynthesizes is also dependent on the demands required by other parts of the plant.
