Optimizing Phytochemical and Physiological Characteristics of Balangu (Lallemantia iberica) by Foliar Application of Chitosan Nanoparticles and Myco-Root Inoculation under Water Supply Restrictions

Balangu is a medicinal plant used in the Iranian traditional medicine to treat nervous, hepatic and renal diseases. To determine the effects of Myco-Root biofertilizer and chitosan nanoparticles (Cs-NPs) on the physiological and biochemical properties of balangu (Lallemantia iberica (M.Bieb.) Fisch. & C.A.Mey.) under different irrigation levels, an experiment was laid out as a factorial based on completely randomized design (CRD) with twelve treatments and three replications. The first factor was represented by different irrigation regimes, including no water deficit (90% FC), mild water deficit (60% FC) and severe water deficit (30% FC); the second factor included control (no Myco-Root and Cs-NPs), inoculation with Myco-Root biofertilizer, foliar application of chitosan nanoparticles (Cs-NPs) and co-application of Cs-NPs along with Myco-Root. The results showed that the highest fresh and dry weight, chlorophyll and carotenoid content, chlorophyll index (SPAD) and fluorescence indices were obtained in 90% FC treated with Cs-NPs+ Myco-Root. In addition, the maximum activity of superoxide dismutase (SOD), ascorbate peroxidase (APX) and peroxidase (POX) was achieved in 60% FC with application of Cs-NPs+ Myco-Root. Moreover, the maximum essential oil content (1.43%) and yield (0.25 g pot−1) were recorded in 60% FC following the application of Cs-NPs+ Myco-Root. Chemical analysis of essential oil showed that germacrene D (31.22–39.77%), (E)-caryophyllene (16.28–19.82%), bicyclogermacrene (7.1–9.22%) and caryophyllene oxide (3.85–6.96%) were the major volatile constituents of balangu. Interestingly, the maximum contents of germacrene D and (E)-caryophyllene were recorded in 60% FC after the application of Cs-NPs+ Myco-Root. Overall, it can be concluded that co-application of Cs-NPs+ Myco-Root could be a sustainable and eco-friendly strategy for improving the essential oil quantity and quality, as well as physiological characteristics, of balangu under water deficit conditions.