Physiological, biochemical, and yield attributes of fennel, anise, and ajwain in response to saline irrigation water

Saline irrigation water is increasingly becoming an inevitable choice for agricultural production in arid regions. However, its comparative suitability for production of medicinal species is not satisfactorily understood. Physiological and biochemical responses in relation to grain and essential oil yield penalties of three medicinal species, including anise (Pimpinella anisum L.), fennel (Foeniculum vulgare Mill.), and ajwain (Trachyspermum ammi L.) were examined under normal (control) and saline (100 mM NaCl) irrigation water conditions in a 2-year field experiment. Chlorophyll-a and K⁺ concentrations, relative water content (RWC), shoot dry mass, grains plant⁻¹, 1000-grains weight, and grain yield were decreased but H₂O₂, Na⁺, and essential oil concentrations, electrolyte leakage, malondialdehyde concentration, and Na⁺/K⁺ were increased upon exposure to the saline water. Certain F. vulgare and T. ammi genotypes tended to indicate smaller Na⁺ concentrations and Na⁺/K⁺, resulting in an ability to indicate the greatest above-ground dry mass and essential oil concentration, particularly in the presence of saline water, compared to P. anisum genotypes. P. anisum genotypes indicated smaller grain essential oil concentration and above-ground dry mass, particularly upon exposure to the saline water. The data obtained were suggestive of distinct salt-induced physiological and biochemical responses that are important to differential yield penalties of these species and potentiate F. vulgare and T. ammi to being irrigated with saline water. This potency of these species was brought about, in part, through an ability to exclude Na⁺ and hence refrain from ion toxicity and partially through osmoregulation and, therefore, sustaining water status and RWC.