The Effect of Drought on Phytochemical active Compounds Content in Chamomile and Yarrow
German chamomile and yarrow are two main medicinal plants belonging to the Asteracea family [1] Both plants contain some active substances which are known as natural products, bioactive compounds or secondary metabolites which are affected by environmental conditions such as drought [2] Drought stress or availability of water is considered to be an important abiotic factor that influences plant growth, development and biochemical processes such as the production of secondary metabolites and aromatic compounds [3 6] In the controlling and management of agriculture production, drought stress is one of the most important environmental factors that determines plant growth worldwide. Medicinal plant phytochemical compounds content including total phenols, flavonoids and essential oil constituents such as limonene, terpinolene, myrcene, quercetin and sabinene are mainly influenced by drought stress [4,7,8] In general, drought stress among cultivars caused a clear decrease in fresh weight, stem length, carotenoid and chlorophyll photosynthetic pigments, total soluble sugars, total flavonoids and total phenolic compounds [9] Moreover, stress factors can damage plant mechanisms for example, an abnormal plant metabolism may occur and cause reduced growth and development and subsequently influence crop yield, or can lead to complete plant/crop death [10] It has been reported that drought stress affects plant growth and the production of secondary products when grown under greenhouse conditions, for example plant vegetative growth has been reduced under stress [6]