Foliar Spray of Salicylic Acid Improved Yield Parameters and Essential Oil Production of Dill Under Water Deficit

Abstract

Drought stress causes physiological disorders and growth restriction, leading to a decrease in crop productivity in the field. Foliar spray of salicylic acid may reduce the adverse effects of this stress on plant performance. Thus, this experiment was laid out as split plot with RCB design in three replicates to assess changes in morpho-physiological traits and essential oil production of dill (Anethum graveolens L.) seeds in response to irrigation intervals (water supply after 70, 100, 130, 160 mm evaporation) and foliar spray of water (control) and salicylic acid (0.6, 1.2 mM). The results showed that, plant height, plant biomass, seeds per umbel and plant were diminished due to water deficit, leading to a decline in seed yield. 1000-seed weight was slightly increased under stress, indicating the extent of drought tolerance of dill plants. Application of salicylic acid improved plant height, branches per plant, leaves per plant, umbels per plant, 1000-seed weight, plant biomass and finally seed yield under different irrigation intervals, especially under water limitation. Essential oil content and yield of seeds were increased with decreasing water supply up to moderate stress. The percentage and yield of essential oil were enhanced up to 54 days after flowering, and thereafter were slightly reduced. In general, application of 1.2 mM salicylic acid on non-stressed and drought-stressed plants was the superior treatment to improve field performance and essential oil production of dill. Therefore, drought tolerance and performance of plants can be promoted by salicylic acid treatment.