Co-Application of TiO2 Nanoparticles and Arbuscular Mycorrhizal Fungi Improves Essential Oil Quantity and Quality of Sage (Salvia officinalis L.) in Drought Stress Conditions

Abstract

Drought stress is known as a major yield-limiting factor in crop production that threatens food security worldwide. Arbuscular mycorrhizal fungi (AMF) and titanium dioxide (TiO2) have shown to alleviate the effects of drought stress on plants, but information regarding their co-addition to minimize the effects of drought stress on plants is scant. Here, a two-year field experiment was conducted in 2019 and 2020 to evaluate the influence of different irrigation regimes and fertilizer sources on the EO quantity and quality of sage (Salvia officinalis L.). The experiment was laid out as a split plot arranged in a randomized complete block design with three replicates. The irrigation treatments were 25, 50, and 75% maximum allowable depletion (MAD) percentage of the soil available water as non-stress (MAD25), moderate (MAD50), and severe (MAD75) water stress, respectively. Subplots were four fertilizer sources including no-fertilizer control, TiO2 nanoparticles (100 mg L−1), AMF inoculation, and co-addition of TiO2 and AMF (TiO2 + AMF). Moderate and severe drought stress decreased sage dry matter yield (DMY) by 30 and 65%, respectively. In contrast, application of TiO2 + AMF increased DMY and water use efficiency (WUE) by 35 and 35%, respectively, compared to the unfertilized treatment. The highest EO content (1.483%), yield (2.52 g m−2), and cis-thujone (35.84%, main EO constituent of sage) was obtained in MAD50 fertilized with TiO2 + AMF. In addition, the net income index increased by 44, 47, and 76% with application of TiO2 nanoparticles, AMF, and co-addition of TiO2 +AMF, respectively. Overall, the integrative application of the biofertilizer and nanoparticles (TiO2 + AMF) can be recommended as a sustainable strategy for increasing net income and improving EO productivity and quality of sage plants in drought stress conditions. Future policy discussions should focus on incentivizing growers for replacing synthetic fertilizers with proven nano and biofertilizers to reduce environmental footprints and enhance the sustainability of sage production, especially in drought conditions.

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

“…Water stress causes a metabolic reaction in plants, such as closure of the stomata and also reduction of CO 2 uptake, which leads to decreasing consumption of NADPH+H + for CO 2 fixation via the Calvin cycle. Eventually, metabolic processes are shifted towards the production of secondary metabolites, which increase the synthesis of regenerative compounds such as EOs and phenolic and alkaloid compounds [13]. Additionally, the co-application of Cs-NPs+ Myco-Root improved EO quantity and quality through an increase in the main EO constituents such as germacrene D and (E)-caryophyllene.…”

“…In this study, the integrative application of Cs-NPs+ Myco-Root significantly enhanced the chlorophyll content and chlorophyll fluorescence indices. It seems that the co-application of Cs-NPs+ Myco-Root improves the photosynthetic rate, along with the nutrient accessibility, which have an important role in the production of carbohydrates and also in the development of glandular trichomes, EO channels and secretory ducts [13]. In this situation, the higher photosynthetic rate enhances the concentration of primary metabolites such as pyruvate, erythrose-4-phosphate, phosphoenolpyruvate and glyceraldehyde-3-phosphate, which are used as precursors in the synthesis of EO constituents [52].…”

“…In addition to the negative impacts of drought stress on plant productivity, the nutrient use efficiency of chemical fertilizers reduces in water deficit conditions due to the decrease of mass flow and nutrient diffusion, which leads to an increase in production costs [13]. It is worth noting that, in intensive agricultural systems, the application of chemical fertilizers plays a noteworthy role in plant growth and yield.…”

“…The massive application of chemical inputs in these farming systems, in addition to creating human health hazards, is causing negative impacts on the environmental ecosystems [14]. Moreover, the excessive usage of chemical fertilizer decreases the yield of bioactive compounds in medicinal and aromatic plants [13,15]. Therefore, new, sustainable and eco-friendly strategies are required for improving the EO quantity and quality of medicinal and aromatic plants, especially in arid and semi-arid regions.…”

“…The inoculation of mycorrhizal fungi (Funneliformis mosseae) in thyme plants under drought stress conditions enhanced the EO content and quality by increasing the main EO constituents, such as thymol, p-cymene and γ-terpinen, [14]. The co-application of mycorrhizal fungi and TiO 2 nanoparticles enhanced the main EO constituents of sage (Salvia officinalis L.), including cis-thujone, trans-thujone and 1,8-cineole [13]. Another study by Pirzad and Mohammadzadeh [32] showed that mycorrhizal fungi reduce the effects of unfavorable water deficit stress in three Lamiaceae species, including lavender (Lavandula angustifolia Mill.…”