ABSTRACT
Medicinal plants are the source of secondary metabolites which have great significance in the pharmaceutical industries and other disciplines. The production of secondary metabolites in medicinal plants is highly influenced by both abiotic and biotic factors. Ultraviolet (UV) radiation is one of the abiotic factors which affect secondary metabolites concentration and hence the pharmaceutical properties of medicinal plants. Out of three types of UV radiation, UV-C is fully absorbed and scattered by ozone whereas all of UV-A and some of UV-B radiation reaches the Earth’s environment. UV radiation affects the rate of photosynthesis by reducing leaf area and total canopy leaf area, altering loss of water by transpiration, and also leaf thickness in medicinal as well as crop plants. The concentration of secondary metabolites such as terpenoids, alkaloids, and phenolics is usually accelerated by exposure to UV-B. However, it has been noticed that enhancement in secondary metabolites is mainly affected by the duration of radiation, and the dose of radiation at the various plant developmental stages. It has been postulated that exposure to UV-B radiation can be applied to medicinal plants, and used for the commercial production of secondary metabolites, but at the same time this radiation is known to harm plant growth and developmental processes; therefore, the overall risk factors need to be carefully investigated. Chapter 3 aims to discuss the impact of UV radiation on medicinal plant growth, development, secondary metabolites concentration, and reproductive processes.
