Biofertilizers, such as arbuscular mycorrhiza fungi (AMF) and seaweed extract (SWE), have been effective in environmental and agricultural ecosystems. In this study, the effects of AMF, SWE, and their co-application were assayed on the growth and antioxidant potential of lettuce plants. The experiment was conducted as a factorial based on a completely randomized design with two factors and four replications under greenhouse conditions. The first factor was AMF (Glomus mosseae) at two levels consisting of AMF application (20 g pot⁻¹), and without using AMF; and the second factor was SWE foliar spraying (Ascophyllum nodosum) at 0.5, 1.5 and 3 g L⁻¹ concentration. The results revealed that the highest root colonization (85%) belonged to AMF and SWE (3 g L⁻¹) × AMF; the lowest colonization rate (65%) was observed for AMF × SWE (0.5 g L⁻¹) treatment. The highest growth parameters (leaf number, shoot and root fresh weight, head diameter), biochemical traits (total soluble proteins, carbohydrates content) and TAA, total antioxidant activity by FRAP method and ascorbic acid, total phenolics, and flavonoids content were obtained with the co-applications. Therefore, the best results of the evaluated traits were achieved with AMF × SWE (3 g L⁻¹). The TAA value was increased three-fold compared to the control. Total phenolics and flavonoids content were 2.24 and 6.59 times higher than the control, respectively. On the other hand, leaf dry weight was decreased with the further growth of the plants. Overall, the co-application of AMF with SWE can be recommended to producers as an alternative and environment-friendly strategy to improve the qualitative and quantitative traits of the lettuce crop.

Beneficial plant–microbe interaction for enhancing crop yield and quality is a sustainable way to achieve eco-friendly, desirable agricultural productions. The main objective of this experiment was to evaluate the individual and combined effects of an arbuscular mycorrhizal fungus (AMF) strain (Funneliformis mosseae) and a seaweed extract (SWE) derived from Ascophyllum nodosum, on the growth and physiological responses of lettuce (Lactuca sativa L.). Lettuce plants were inoculated with commercial AMF inoculum (5 g kg⁻¹ soil), and SWE foliar application was done at three levels (0.5, 1.5, and 3 g L⁻¹). The findings revealed that AMF along with SWE generated the greatest impact. In fact, co-application of AMF inoculation and 3 g L⁻¹ SWE considerably enhanced root colonization, chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, and mineral content in the shoots and roots (N, P, K, Ca, Fe, Zn, and Mn content) of lettuce plants. This combination improved initial fluorescence (F₀), photochemical efficiency of PSII (F_V/F_m) and Y(NO) and total antioxidant activity (TAA), whereas the maximum fluorescence, (F_m) and Y(II), showed the highest increase in lettuce plants treated with AMF and 1.5 g L⁻¹ SWE. Furthermore, AMF inoculation along with SWE, at concentrations 1.5 and 3 g L⁻¹, considerably enhanced variable fluorescence (F_V) and the activity of water decomposition in electron donor photosystem II (F_V/F₀). As a result of these findings, it can be stated that the co-application of AMF and SWE positively improves the growth and development of lettuce plants.

Zinc oxide nanoparticles (ZnO-NPs) have been proven to helpfully improve plant tolerance to several abiotic stresses. However, no information has been reported concerning the role of ZnO-NPs on pepper plants under salinity stress. Hence, this research aimed to evaluate the growth and physiological responses of pepper (Capsicum annum L.) plants to ZnO-NP foliar application under salinity. Plants were subjected to 0 (control), 25 (S1), 50 (S2), and 75 mM (S3) NaCl salinity with a foliar spray of 0, 1000, and 2000 ppm ZnO-NPs. Significant reductions were recorded in the chlorophyll index (SPAD) and chlorophyll fluorescence parameters, and in the activity and/or ratios of reduced ascorbate (AsA), reduced ascorbate/dehydroascorbic acid (AsA/DHA), reduced glutathione (GSH), reduced glutathione/oxidized glutathione (GSH/GSSG), and K⁺ content. There was a significant increase in proline content, electrolyte leakage (EL), H₂O₂ content, guaiacol peroxidase (GPX), ascorbate peroxidase (APX), superoxide dismutase (SOD), glutathione reductase (GR), dehydroascorbic acid (DHA), and oxidized glutathione (GSSG) activities, and in Na⁺ content and Na⁺/K⁺ ratio. Foliar treatments improved the salinity tolerance of the pepper plants by fortifying the antioxidant defense system, leaf fluorescence parameters, K⁺, and proline content, and in contrast, by decreasing the EL, Na⁺, and H₂O₂ levels. ZnO-NP foliar treatment efficiently improved the pepper plants’ physiological responses under salinity. Considering the overall results, 1000 ppm of ZnO-NPs would be advisable for the amelioration of salinity depression and to promote growth potential. However, at higher levels, the nanoparticle showed toxicity symptoms that limited its reliable applications.

Background: Heavy metals (HMs) phytoremediation is a well-recognized protocol to remove toxic elements from the soil. As known, arbuscular mycorrhizal fungi (AMF) enhance the plants' growth responses. The idea of the present study was to assay the response of lavender plants to HMs stress under AMF inoculation. We hypothesized that mycorrhiza will enhance the phytoremediation and simultaneously reduce the harmful effects of heavy HMs. So, lavender (Lavandula angustifolia L.) plants were inoculated with AMF (0 and 5 g Kg⁻¹ soil) under Pb [150 and 225 mg kg⁻¹ soil from Pb (NO₃)₂] and Ni [220 and 330 mg kg⁻¹ soil from Ni (NO₃)₂] pollution, in the greenhouse conditions. The control treatment was plants not treated with AMF and HMs. Doing this, the root colonization, HMs uptake, enzymatic and non-enzymatic antioxidants pool, MDA, proline, total phenolics (TPC), flavonoids (TFC), anthocyanins, and essential oil (EO) components were evaluated. Results: According to the findings, the AMF inoculation enhanced shoot and root Pb and Ni content, antioxidant enzymes activity, the total antioxidant activity by DPPH and FRAP methods, TPC, TFC, anthocyanins, and H₂O₂ content in the lavender plants subjected to Pb and Ni stress. Moreover, the highest (28.91%) and the least (15.81%) percentages of borneol were identified in the lavender plants subjected to AMF under 150 mg kg⁻¹ of Pb and the control plants without AMF application, respectively. Furthermore, the top 1,8-cineole (12.75%) content was recorded in AMF-inoculated plants. Conclusions: The overall results verify that AMF inoculation can be a reliable methodology to enhance the phytoremediation of Pb and Ni by lavender plants while maintaining reliable growth potential. The treatments improved the main EO constituents content, especially under moderate HMs stress conditions. With more detailed studies, the results will be advisable for the extension section for the phytoremediation of polluted soils.

Mentha aquatica L. (Lamiaceae) is found in different parts of Iran. Its essential oil and preparations regulate bile function and are used as a stomach tonic and disinfectant. This study investigates the morphological and essential oil diversity of M. aquatica populations from the Hyrcanian hotspot of Iran. Plant samples were collected from Gilan, Golestan, and Mazandaran provinces in the Caspian Region for analysis. The results showed significant differences among the studied ecotypes for the stem diameter, collar diameter, number of inflorescences, length and width of inflorescence, sepal diameter, sepal length, and secondary stem length number. Principal component analysis showed that the first seven principal components explained 90.6% of the total variation. Moreover, essential oil concentration varied widely from 1.13% for a sample from Behshahr-Mazandaran, down to 0.27% for one from Abbas abad-Mazandaran. GC–MS analysis identified 29 constituents that accounted for 91% of the total essential oil. The main components of the essential oil were menthofuran (13.21–52.46%), 1,8-cineole (12.42–25.55%), (E)-caryophyllene (3.18–15.43%), viridiflorol (1.04–11.16%), germacrene D (1.70–8.29%), caryophyllene oxide (0.51–4.96%), neryl acetate (1.11–4.95%), p-cymene (1.55–4.77%), and β-pinene (1.7–3.45%). Overall, meaningful diversity was recorded among the populations; Rahimabad-Gilan and Behshahr-Mazandaran would be reliable selections for the food and pharmaceutical industries due to their higher yields and content of α-pinene, 1, 8-cineole, menthofuran, viridiflorol, and β-caryophyllene. Further evaluation of populations from diverse habitats is needed to guide future breeding programs.

The morphological and essential oil diversity of Stachys lavandulifolia populations from the west and northwest of Iran were evaluated. The results showed a significant difference between the populations for nearly all the evaluated traits. The broadest variation ranges were recorded for the auxiliary shoot length, leaf length in the main branch, and the number of flowers in the inflorescences. Furthermore, cluster analysis divided 13 populations into four separate groups. GC/MS analysis verified the presence of 28 components comprising up to 94/4% of the oils. The dominant constituents were α-pinene (1.07–34.87%), (E)-caryophyllene (0.45–25.99%), germacrene D (3.36–20.61%), Δ-cadinene (2.82–19.90%), bicyclogermacrene (1.72–12.08%) α-terpineol (0–11.86%), α-muurolol (0.31–11.50%), p-cymene (0.67–9.67%), β-elemene (0.63–9.31%), and sabinene (0.32–6.29%). The results revealed that natural habitats and the related geo-climatological cues influenced morphological traits and oil composition. Considering the substantial environmental variations and the broad diversity, there would be a rich selection pool for the traits of interest. The populations are a step forward in the breeding programs for the highlighted essential oil constituents needed by the pharmaceutical and related industries. Furthermore, with the future comparative study of the populations from all Iranian territories and the neighboring countries, we will have a realistic idea of the coming conservational and exploitation programs.