ABSTRACT: Salinity is an abiotic stressor that greatly influences crop growth and yield. Scientists are always exploring diverse methods to combat salinity depression. Here, we conducted a greenhouse experiment to study the effects of NaCl salinity (0, 50, and 100 mM) under the foliar spray with zinc-oxide, nano zinc-oxide, iron-chelate, magnetized-Fe, and graphene-oxide on tarragon. The results revealed that the treatment with foliar spray of graphene showed the highest K+/Na+. Salinity of 50 and 100 mM × all foliar applications increased superoxide dismutase activity, whereas 100 mM NaCl raised the malondialdehyde content to its highest level. All salinity levels × Zn foliar spray improved the catalase activity. The foliar spray and salinity experiment exposed to Zn-treated plants attained the highest contents of essential oils. Proline and total phenolics showed the greatest amounts with 50 and 100 mM of NaCl, respectively. The GC/MS analysis revealed 38 compounds in the oil of Artemisia dracunculus L. as estragole (81-91.8 %) was the most dominant constituent. The highest amounts of estragole were found at 50 and 100 mM NaCl foliar sprayed with ZnO. Cis-Ocimene (0.1-6.4 %) was another major constituent with a high variation between the treatments. The highest cis-ocimene content was recorded at 100 mM NaCl × foliar Fe-chelated and in the graphene treatment. Overall, salinity adversely affected the physiological responses of tarragon; however, foliar spray with both forms of Fe and Zn partially ameliorated the adverse salinity effects.

ABSTRACT Echinacea purpurea is cultivated around the world due to its unique pharmacological effects. The aerial parts of the plant, especially its flowers, contain a wide variety of beneficial bioactive substances. The objective of this study was to evaluate the effect of different nutrient applications on the growth parameters, essential oil yield, and compounds of Echinacea purpurea L. Moench in Afyonkarahisar/Turkey. The experiment was conducted over a 3-year period (2016-18), including four experimental treatments (F0: control, F1: 75 kg ha-1 N; F2: 150 kg ha-1 N; and F3: 75 kg ha-1 N + foliar fertilizer). As a general result of five cuttings, F2 and F3 had a positive effect on agronomic yield. F2 and F3 recorded the highest plant height (91 and 90 cm, respectively) and yields for fresh bud (578 and 543 kg ha-1), dry bud (118 and 112 kg ha-1), fresh flower (8,595 and 7,449 kg ha-1), dry flower (2,021 and 1,745 kg ha-1), fresh herb (32,645 and 29,291 kg ha-1), dry herb (8,746 and 7,745 kg ha-1) and essential oil (4.55 and 3.57 L ha-1). Sesquiterpene hydrocarbons were the most abundant chemical group compound of E. purpurea essential oil. Germacrene D (20.4-50.6%) was the predominant constituent, recording its maximum level in F1. Other major compounds were β-pinene, β-myrcene, α-humulene, δ-cadinene, spathulenol, and α-cadinol. The application of 150 kg ha-1 N as well as the combined use of 75 kg ha-1 N and foliar application of macro and micro elements resulted in the highest agronomic yield and essential oil production.