The effect of water deficiency and salinity on the growth and quality of fresh dill (Anethum graveolens L.) during autumn and spring cultivation

Abstract

The aim of this experiment was to determine the response of dill (Anethum graveolens L.) towater deficiency and salinity. In spring, dill biomass decreased with increasing water deficiencydue to a reduction in the number and mean weight of leaves per plant. The concentrations ofchlorophyll, carotenoids, vitamin C and total phenolics within the leaves were unaffected bywater stress, but the Cl, Na and K content decreased. Salinity had no effect on plant growth inthe spring, except at the highest level (8 dS/m-1), where a decrease in biomass occurred. Thechlorophyll and total phenolics content of leaves rose in the autumn with increasing salinity,whereas vitamin C and carotenoids were unaffected. In spring, increasing salinity causedfluctuations in the chlorophyll and vitamin C content of the leaves and a decrease in totalphenolics. The concentrations of chlorophyll and antioxidants were higher in spring than inautumn at all levels of salinity. The essential oil content was also higher in the spring than in theautumn, irrespective of salinity. A relative decrease in dill ether within the herb oil underincreasing salinity was compensated for by an increase in α-phellandrene. In the flower oil,increasing salinity caused a decrease in the relative concentrations of both α-phellandrene anddill ether, which was compensated for by an increase in carvone. Overall, dill appears moreresistant to salinity than to water stress, but the season of cultivation has the most importanteffect on both yield and quality.