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There are different climate classes in Iran where about 85% of the agricultural lands are located in arid and semi-arid regions. To mitigate or compensate effects of drought stress and increase crop fitting and yield, effects of micronutrient application have been studied by several researchers. Field experiments were conducted during the 2021–2022 and 2022–2023 crop seasons to investigate the effect of micronutrients on quantitative and qualitative characteristics of canola cultivars under late-season drought stress conditions. The experiments were arranged in a factorial split-plot design, with two irrigation treatments – normal irrigation (control) or restricted irrigation at flowering stage – and four foliar applications of Zn and Mn after rosette stage (F1: Water, F2: ZnSO4, F3: MnSO4 and F4: ZnSO4 + MnSO4) as the main factor. Winter canola cultivars, including Okapy, Hyola401 and Hyola308, as sub-factor. The results showed that limited irrigation at flowering reduced seed yield, oil percentage and fatty acids content in different canola cultivars. Most of the canola oil is composed of unsaturated fatty acids, and the occurrence of drought stress at the reproductive stage reduced oil quality. By contrast, the minimum yield loss was obtained from Hylon401 cultivar, an early mature cultivar. Overall, it is recommended Hylon401 cultivar for normal irrigation and Hylon308 cultivar for a drought environment when considered the acceptable seed yield in canola. In general, it is suggested that a suitable performance of canola seeds is achieved by foliar application of manganese and zinc. [ABSTRACT FROM AUTHOR]

Background: Biodynamic agriculture and the use of plant growth-promoting bacteria (PGPBs) have been demonstrated to offer various benefits for achieving agricultural sustainability. The aim of this study was to evaluate the effects of PGPBs Azotobacter and Azospirillum, compost, and compost with biodynamic preparations (BD) on the essential oil (EO) characteristics of lavender under salinity stress. Research methods: The experiment was carried out in a greenhouse for 2 years and involved three factors: four PGPBs, three types of compost, and three levels of salinity stress. Results: The results indicated that the essential oil (EO) characteristics increased with 50 mM NaCl but decreased with 100 mM NaCl. Salt stress reduced the cell membrane stability (CMS) and auxin content, while increasing proline contents. However, the application of PGPBs, compost, and compost with biodynamic preparations had an opposite effect on CMS, auxin, and proline parameters compared to salt stress. Based on the results, the treatment that combined compost + BD with Azotobacter was found to be the most effective in enhancing the EO characteristics under both mild and severe salinity stress conditions. Conclusions: The results of this study suggest that compost, biodynamic compost preparations, and PGPBs could be useful in enhancing the EO in medicinal plants and alleviating the adverse effects of salt stress on plants. [ABSTRACT FROM AUTHOR]

Background: Water scarcity is responsible for losses in the yield of many plants and this is expected to continue due to climate change. However, cowpea which is known for its drought tolerance, is considered as a plant without limitations to climate change. A two-year experiment was conducted to evaluate the effect of water restriction on phenolic compounds, antioxidant capacity and leaf nutrients concentration of four cultivars of cowpea at different growth stages. At second leaf stage, two irrigation regimes were initiated (Water irrigation was applied after 75% and 55% of field capacity, as well watered and drought stress treatment, respectively).Plants samples were collectedat three stages(immature pod, immature seed and dry seed stage) for total phenol and flavonoids content, ortho-diphenols andantioxidant capacity measurement and leaves sampling for nutrients concentration. Results: The results indicated that polyphenolic compounds and antioxidant capacity increased under drought conditions. However, in both irrigation regimes, immature pods had the higher polyphenolic compounds, antioxidant capacity and leaf nutrients concentration rather than immature seeds and dry seeds. Among the genotypes, ILC482 revealed the highest content of total phenolics and ortho-diphenols (6.9 and 3.57 mg GA g−1dry weight, respectively). In addition, nitrogen, phosphorus and magnesium concentration of leaves were higher in ILC482 genotype. Under drought stress, ILC482 maintained higher ABTS radical scavenging capacity (0.0083 mmol Trolox g−1dry weight) compared to other genotypes. Conclusions: It is suggested that drought stress affect the quality of cowpea productions through polyphenolic compounds, ABTS and DPPH radical scavenging capacity which can be used as a helpful strategy to save water in the regions where water is scare. [ABSTRACT FROM AUTHOR]

Evaluate silica fertilizer's effect on the quantitative and qualitative yield of forage sorghum (Sorghum bicolor L.) under drought stress. A split-plot experiment was implemented in a randomized block design with three replications in two cropping years, 2017-2018, in a farm located in the Varamin - Iran. The treatments included irrigation at three levels of 60, 120 and 180 mm of evaporation from class A's evaporation pan level. The main factor was silica fertilizer as non-consumption (control), foliar application and silica irrigation fertilizer as a secondary factor. Based on the obtained results, the treatment containing total chlorophyll, RWC and stomatal conductance was obtained from the 60 mm evaporation treatment and silica fertilizer use in irrigation water. The use of silica fertilizer as irrigation water reduced the Hydrogen cyanide content by 4%. The highest amount of crude protein was estimated to be 12.60 from 180 mm stress treatment and the use of silica fertilizer in irrigation water, which were 19% higher than the control treatment, respectively. The best sorghum dry forage yield was obtained from 60 mm evaporation irrigation and silica irrigation fertilizer with an average of 82.22 ton ha-1, which was 52% higher than the 180 mm evaporation stress treatment. [ABSTRACT FROM AUTHOR]

Î' two-year field experiment was conducted in Varamin-Pishva Branch, Islamic Azad University, Iran to study the impact of drought stress and foliar application of some hormones on the safflower growth. The drought stress was induced at three levels and considered as main plots. Irrigating after 75% water depletion was considered to be normal irrigation (control), irrigating after 60 and 45% water depletion, defined as mild and severe drought stress, respectively. The foliar application of humic acid (HA), salicylic acid (SA), Gibberellic acid (GA3), ascorbic acid (AA), water, and the non-foliar application was considered as sub-plots. The main effect of irrigation regimes was significant on seed yield, oil yield, palmitic acid, and water use efficiency (WUE). Also, the main effect of foliar applications was significant for seed yield, oil yield, stearic acid, and WUE. Normal irrigation produced the maximum oil yield (2270 kg ha-1) that was decreased by 25.9% and 37.1% under mild and severe stress regimes, respectively. The maximum and minimum oil yields were produced by the application of SA and non-foliar treatment with average values 1970 and 1357 kg ha-1, respectively. Although the palmitic acid content was enhanced under the drought stress conditions, oleic acid content was significantly decreased in such conditions. The current findings suggest that the foliar application of SA can be recommended when optimal water supply was applied to increase the quality and quantity of safflower oilseed. [ABSTRACT FROM AUTHOR]

A 2-year field experiment was conducted in a research farm at Tehran, Iran, to determine the effect of mild and severe drought stress and foliar application of glycine betaine (0, 50, and 100 mM L−1) and gibberellic acid (0, 60, and 120 ppm) on some physiological traits and yield and yield-related traits of cowpea (Vigna unguiculata L. Walp.) genotypes. Drought stress at both mild and severe levels decreased relative water content (RWC), carotenoids, and total chlorophyll contents, while increased ion leakage which finally affected the yield of cowpea plants represented by 100-seed weight, number of pods per plant, and number of seeds per pod. Application of glycine betaine and gibberellic acid at all tested concentrations significantly alleviated the negative effect of drought on cowpea plants. The maximum relative water content, carotenoids, total chlorophyll, and yield were achieved by application of 120 ppm gibberellic acid and 100 mM glycine betaine at the three irrigation regimes. Gibberellic acid and glycine betaine succeeded in increasing cowpea plant tolerance to drought stress by improving vital plant components and preventing ion loss through ion leakage by controlling cell permeability. [ABSTRACT FROM AUTHOR]

A two-year field experiment was conducted at the Islamic Azad University, Iran, in 2018 and 2019 growing season to examine the influence of foliar application of zinc and salicylic acid on chlorophyll, phenolic and flavonoid content, essential oil percentage, oil yield, total dry matter and oil composition of peppermint (Mentha piperita L) under drought stressed conditions. Irrigation regimes (no stress, moderate, and severe drought stress), zinc (0, 2 and 4 mg L−1), and salicylic acid (0 and 1 mM) foliar application were included in the treatment group. Drought stress reduced the chlorophyll content and oil percentage of peppermint, but moderate drought stress increased oil percentage. The application of zinc increased total phenolic compound content. Total phenolic and flavonoid contents increased with increasing stress levels. Comparisons of the drought and zinc treatments showed that the highest DPPH (2,2-diphenyl-1-picrylhydrazyl) was in severe drought stress plus 2 mg L−1 zinc treatment. Drought stress and salicylic acid comparisons showed that the highest oil yield was observed in well-watered plants and salicylic acid. The application of zinc + salicylic acid resulted in higher oil percentage and oil yield compared with the non-treated control. Menthol and menthone concentrations increased significantly in response to moderate drought but were reduced under severe drought. Moderate drought stress increased synthesis of oil compounds while foliar applications of zinc and salicylic acid alleviated its effect. [ABSTRACT FROM AUTHOR]

The effects of presence and absence of arbuscular mycorrhizal (AM+ and AM-) fungus (AMF) Glomus intraradices on agronomic and chemical characteristics of field-grown tobacco (Nicotiana tabacum L.) Virginia type (cv. K-326) plants exposed to varying concentrations of chloride 10, 40, 70 and 100 mg Cl L-1 (C1-C4) were studied over two growing seasons (2012-2013). Mycorrhizal plants had significantly higher uptake of nutrients in shoots and number of leaves regardless of intensities of chloride stress. The cured leaves yields of AM+ plants under C2-C4 chloride stressed conditions were higher than AM-plants. Leaf chloride content increased in line with the increase of chloride level, while AMF colonised plants maintained low Cl content. AM+ plants produced tobacco leaves that contained significantly higher quantities of nicotine than AM-plants. AM inoculation ameliorated the chloride stress to some extent. Antioxidant enzymes like superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase as well as non-enzymatic antioxidants (ascorbic acid and glutathione) also exhibited great variation with chloride treatment. Chloride stress caused great alterations in the endogenous levels of growth hormones with abscisic acid showing increment. AMF inoculated plants maintained higher levels of growth hormones and also allayed the negative impact of chloride. The level of 40 mg L-1 in combination with arbuscular mycorrhizal can be considered as the acceptable threshold to avoid adverse effects on Virginia tobacco. [ABSTRACT FROM AUTHOR]