Foliar Application Of Salicylic Acid Research Articles

Synergistic Effects of Seed Inoculation with Piriformospora indica and Foliar Hormonal Application on Early Flowering in Rice Bean (Vigna umbellata) Variety Surabhi

This study aimed to evaluate the effectiveness of seed inoculation with Piriformospora indica and various foliar hormonal treatments in promoting early flowering in fodder rice bean (Vigna umbellata Thunb.), variety Surabhi, conducted at the College of Agriculture, Vellayani. The experiment was laid out in randomized block design with ten treatments and three replications. The plot size of 3 m2 was followed in the field experiment. The experiment assessed the impact of different treatments on flowering and other biometric traits in the leguminous crop. The treatments included untreated control, seed inoculation with Piriformospora indica before sowing and foliar applications of salicylic acid (100 ppm,150 ppm), GA₃ (200 ppm,300 ppm), Paclobutrazol (10 ppm,20 ppm) and KNO₃ (1%,1.5%) at 30 days after sowing (DAS). The results revealed that significant differences were observed among treatments for all thirteen biometric traits measured. Early flowering was recorded in plants treated with salicylic acid @ 100 ppm(65.35 days), followed by GA₃ @ 300 ppm (67.72 days), salicylic acid @ 150 ppm (67.81 days), and Paclobutrazol @ 10 ppm (69.87 days), whereas the control flowered last (80.96 days. The findings suggest that the application of specific concentrations of growth regulators and seed inoculation with P.indica can effectively reduce the time to flowering, enhancing the potential for improved seed production in fodder rice bean.

Investigating the positive effects of salicylic acid on peppermint (Mentha piperita l.) under different soil salinity conditions: comprehensive morphological, mineral, and biochemical analyses

This study explored the effects of salicylic acid on the growth and biochemical responses of peppermint (Mentha piperita L.) under different soil salinity levels, a major challenge in agricultural productivity. The experiment was conducted using a factorial design with salicylic acid applied at concentrations of 0, 5, 10, and 50 ppm, combined with sodium chloride-induced salinity at 0, 1,000, 2,000, and 3,000 mg kg–1 soil. Results demonstrated that increasing soil salinity negatively impacted plant growth, reducing plant height, leaf number, and the dry weight of aerial parts. Salinity stress also led to reduced nutrient uptake, particularly for essential elements like calcium and potassium, while increasing sodium levels in plant tissues. However, the foliar application of salicylic acid, especially at 50 ppm, significantly improved growth parameters and mitigated the detrimental effects of salinity. Notably, at the highest salinity level (3,000 mg kg–1), salicylic acid enhanced plant height by 11.1% and leaf number by 30.9% compared to untreated plants. Salicylic acid also boosted biochemical responses, such as increasing total phenolic and flavonoid content, which are critical for stress tolerance. This study underscores the potential of salicylic acid as a stress mitigator, promoting better growth and physiological resilience in peppermint under saline conditions, offering valuable insights for improving crop performance in salinity-affected regions.

Agronomic Interventions for Alleviating Water Stress and Optimizing Productivity of Field Crops: A Review

Water scarcity is the most significant concern facing agriculture today. Agriculture currently utilizes more than 70% of the world's freshwater, with much of it lost through evaporation, leaching and runoff. Drought escape and drought tolerance are the two significant mechanisms for plant growth under water-stressed conditions. Drought, a primary abiotic factor, limits crop productivity. It is a climatic phenomenon characterized by a prolonged lack of rainfall, resulting in moisture loss from the soil and a lack of water potential in plant tissues. It prevents the crop from obtaining its potential yield and substantially reduces crop production. Field crop rely on rainfall and are vulnerable to unpredictable drought stress throughout their vegetative and reproductive growth cycle. Drought stress is typical during the flowering stage in mostly crops, resulting in lower yield when cultivated with scarce rainfall. It can be reduced through agronomic means, such as mulching, tillage, intercropping and nutrient management, as well as chemical measures, such as the use of soil additives herbal hydrogel (Gond katira), foliar spray of salicylic acid and potassium nitrate. Herbal hydrgel helps in reducing the effect of drought stress on plants while also promoting increased plant growth and opverall performance. Foliar application of salicylic acid boosted bioactive chemical synthesis in the presence of water deficiency. Potassium nitrate to enhance water uptake, promote longer pod length and improve drought tolerance in plants.

Comprehensive Effect of Zinc Boron with NPK and Salicylic Acid Foliar Application Treatments on Rice Yield and Grain Quality Under Salty Soil Conditions

Comprehensive Effect of Zinc Boron with NPK and Salicylic Acid Foliar Application Treatments on Rice Yield and Grain Quality Under Salty Soil Conditions

Foliar application of salicylic acid improved morpho-anatomical features of potato by irrigating with wastewater

BackgroundThis study aimed to evaluate the suitability of using drain water as a source of irrigation and its effects along with salicylic acid on morphological, anatomical, physico-chemical as well as yield attributes of potato. For this study, potato tubers were grown in pots and irrigated with different concentrations of drain water. Salicylic acid treatments vis. 0, 0.5 and 1.0 mM were applied foliarly. Pre- and post-harvest analysis was carried out to determine different attributes of soil, water and plants after 60 days.ResultsThe growth of potato plant was increased as the concentration of SA increased through increasing shoot length, fresh/dry weight and tuber number/plant. In this research work, plant respond to overcome metal stresses by up regulating antioxidant defense system such as, peroxidase, catalase and superoxide dismutase) by application of highest treatment of SA when irrigated with 6% drain water. Plants accumulated the highest concentrations of Cd, Cr, and Pb in the leaves when treated with 1 mM of SA, compared to other plant parts. It was observed that photosynthetic pigment enhanced in 6% drain water treated plants when applied with 1mM SA as compared to control. An increase in epidermis and cortical cell thickness, as well as stomatal closure, was observed, helping to maintain water loss under stress conditions.ConclusionsAccording to these results, it can be suggested that SA is potent signaling molecule can play an essential role in maintaining potato growth when irrigated with drain water containing heavy metals through stimulating metal up take and up regulation of antioxidant enzymes.

A Study to Evaluate the Effectiveness of Foliar Application of Salicylic Acid against Mosaic Virus Disease in Capsicum annum

A Study to Evaluate the Effectiveness of Foliar Application of Salicylic Acid against Mosaic Virus Disease in Capsicum annum

Effect of Multi-Walled Carbon Nanotubes, Salicylic Acid, and Drought Stress on Mazut Biodegradation Efficiency in a Pb- and Zn-Polluted Soil Under Cultivation of the Pinto Bean Inoculated with Piriformospora indica

Abstract Aims: Today, remediation of soils contaminated with heavy metals and petroleum compounds is one of the major environmental problems. This research was done to investigate the effect of multiwall carbon nanotubes (MWCNs) and foliar application of salicylic acid (SA) on biodegradation of mazut in the Pb- and Zn-polluted soil under cultivation of the pinto bean inoculated with Piriformospora indica (P.indica). Methods: Treatments included applying MWCNs (0 and 2 % (W/W)) in the soil that was naturally polluted with Pb and Zn, foliar application of salicylic acid at the rate of 0 and 1.5 mmol/lit on the plants inoculated with P.indica under drought stress. In addition, the studied soil was polluted with mazut at the rate of 0% and 6% (w/w). After 3 months, plants were harvested and the plant Pb and Zn, the soil Pb and Zn, and the biodegradation of mazut in the soil were also measured. Results: Addition of MWCNS and foliar application of salicylic acid at the rate of 1.5 mmo/lit significantly decreased the soil Pb by 14.3 and 13.3%, respectively. Plant inoculation with P. indica significantly increased the biodegradation of mazut in the Pb- and Zn-polluted soil by 15.9%. However, drought stress had a negative effect on degradation of mazut in the soil. Conclusion: Regardless of plant expose to drought stress, using MWCNs and foliar application of SA has a positive effect on biodegradation of petroleum hydrocarbon in the soil.

Alleviating salinity stress in canola (Brassica napus L.) through exogenous application of salicylic acid

Canola, a vital oilseed crop, is grown globally for food and biodiesel. With the enormous demand for growing various crops, the utilization of agriculturally marginal lands is emerging as an attractive alternative, including brackish-saline transitional lands. Salinity is a major abiotic stress limiting growth and productivity of most crops, and causing food insecurity. Salicylic acid (SA), a small-molecule phenolic compound, is an essential plant defense phytohormone that promotes immunity against pathogens. Recently, several studies have reported that SA was able to improve plant resilience to withstand high salinity. For this purpose, a pot experiment was carried out to ameliorate the negative effects of sodium chloride (NaCl) on canola plants through foliar application of SA. Two canola varieties Faisal (V1) and Super (V2) were assessed for their growth performance during exposure to high salinity i.e. 0 mM NaCl (control) and 200 mM NaCl. Three levels of SA (0, 10, and 20 mM) were applied through foliar spray. The experimental design used for this study was completely randomized design (CRD) with three replicates. The salt stress reduced the shoot and root fresh weights up to 50.3% and 47% respectively. In addition, foliar chlorophyll a and b contents decreased up to 61–65%. Meanwhile, SA treatment diminished the negative effects of salinity and enhanced the shoot fresh weight (49.5%), root dry weight (70%), chl. a (36%) and chl. b (67%). Plants treated with SA showed an increased levels of both enzymatic i.e. (superoxide dismutase (27%), peroxidase (16%) and catalase (34%)) and non-enzymatic antioxidants i.e. total soluble protein (20%), total soluble sugar (17%), total phenolic (22%) flavonoids (19%), anthocyanin (23%), and endogenous ascorbic acid (23%). Application of SA also increased the levels of osmolytes i.e. glycine betaine (31%) and total free proline (24%). Salinity increased the concentration of Na+ ions and concomitantly decreased the K+ and Ca2+ absorption in canola plants. Overall, the foliar treatments of SA were quite effective in reducing the negative effects of salinity. By comparing both varieties of canola, it was observed that variety V2 (Super) grew better than variety V1 (Faisal). Interestingly, 20 mM foliar application of SA proved to be effective in ameliorating the negative effects of high salinity in canola plants.

Effects of Foliar Application of Salicylic Acid On Morphological, Biochemical and Yield Attributes of Maize (Zea Mays L.) Under Rainfed Condition

An experiment was performed in the kharif- 2022 focusing on the impact of foliar applications of Salicylic acid on various morphological, biochemical, and yield attributes in maize, using the CP-858 variety. The study involved four concentrations of salicylic acid: T1-50ppm, T2-100ppm, T3-150ppm, and T4-175ppm. Notable differences emerged in morphological and yield attributes such as sink size, test weight and yield per plot, revealing a marked increase in plant physiological efficiency treated with Salicylic acid when compared to the control. This trend was also evident in key biochemical parameters like chlorophyll 'a', 'b', and total chlorophyll content, and protein content in leaves, showing a positive response to exogenously applied Salicylic acid. Similar outcomes were recorded in terms of yield and yield-related indicators. These outcomes underscore the significance of Salicylic acid as a potent growth regulator for crop plants, particularly those cultivated under dryland conditions. Bangladesh J. Bot. 53(2): 273-278, 2024 (June)

Physiological and biochemical characteristics of milk thistle (Silybum marianum (L.) Gaertn) as affected by some plant growth regulators.

Milk thistle (Silybum marianum (L.) Gaertn) is a globally and widely used medicinal plant that contains silymarin. This plant has antioxidant, antimicrobial, anticancer, hepatoprotective, cardiovascular-protective, and neuroprotective effects. Plant quality, yield, and phytochemicals, especially silymarin content, change under various conditions like drought stress. Therefore, this research studied plant growth regulators (PGRs) like salicylic acid, spermidine, and brassinosteroid to increase plant tolerance to drought stress. Experimental treatments include different levels of irrigation (25%, 50%, 75%, and 90% field capacity), and foliar spraying including salicylic acid (75 and 150 mg/L), spermine (70 and 140 mg/L), and brassinosteroid (1 and 1.2 μM), separately, and water as a control and a secondary factor. The results revealed that the highest amount of leaf phenolic compounds was observed in the highest drought stress level (25%) and 75 mg/L salicylic acid application. Furthermore, brassinosteroid at different concentrations and salicylic acid (75 mg/L) increased leaf flavonoid content compared to other treatments. In 50% field capacity, foliar application of salicylic acid (150 mg/L) significantly increased seed yield by approximately 75% compared to control under the same stress level. Brassinosteroid application (1 μM) under 75% field capacity significantly increased the seed's taxifolin amount by 159%. Additionally, salicylic acid noticeably increased the silychristin concentration. The concentration of silydianin in the seed has also been increased under drought stress and foliar spraying with PGRs. Compared to the control, using spermidine below 75% field capacity caused an increase in its concentrations by over seven times. The highest silybin A amount was obtained in 50% field capacity and foliar150 mg/L salicylic acid. Taxifolin, silychristin, silydianin, silybinin B, iso-silybinin A, and iso-silybinin B compounds were identified in the seed extract. Generally, foliar spraying using plant growth regulators increased the number of silymarin compounds under drought stress conditions and field cultivation conditions.

Alleviation of Different Climatic Conditions by Foliar Application of Salicylic Acid and Sodium Nitroprusside and Their Interactive Effects on Pigments and Sugar Content of Maize Under Different Sowing Dates

The agricultural sector is seriously impacted by climate change, leading to potential risks to food security. In terms of global food production, maize ranks third. As a result, crop production and food security depend critically on assessing the effects of climate change and developing measures to adapt maize. Regarding adaptability, changing planting dates and using different agrochemicals are more effective than other management. Crop models are part of a global decision support system to help farmers maximize yields despite unpredictable weather patterns. To mitigate yield loss and protect the ecosystem, it is essential to use efficient maize-sowing practices in the field. This experiment was carried out to identify the most favorable sowing dates that maximize yield while ensuring the crop’s productivity and the integrity of the surrounding ecosystem remain intact. The main aim of this experiment was to mitigate the different climatic conditions by exogenous application of salicylic acid (SA) and sodium nitroprusside (SNP) on pigments and sugar content in maize under different sowing dates. A field experiment was carried out in the School of Agriculture, Lovely Professional University, Punjab, India, during the spring season of 2022. The experiment dealt with various maize crops, PMH-10, sourced from the Punjab Agricultural University (PAU), Punjab. The experiment was conducted in an open-air environment. The experimental setup was laid out in a split-plot design. The results stated that foliar application of salicylic acid and sodium nitroprusside successfully influenced high-temperature tolerance and low temperature at the reproductive phase and initial vegetative stages with other growing climatic conditions of maize in early and late sowings when controlled by increasing the chlorophyll index, carotenoids content, and sugar content of maize.

Salicylic acid foliar application meliorates Portulaca oleraceae L. growth responses under Pb and Ni over-availability while keeping reliable phytoremediation potential

The efficacy of SA foliar use on Pb and Ni-induced stress tolerance and phytoremediation potential by Portulaca oleraceae L. were assayed as a factorial trial based on a completely randomized design with four repetitions. The factors included; SA foliar application (0 and 100 µM) and HMs application of Pb [0, 150, and 225 mg kg−1 soil Lead (II) nitrate] and Ni [0, 220, and 330 mg kg−1 soil Nickel (II) nitrate]. Plant height, stem diameter, shoot and root fresh and dry weight, photosynthetic pigments, total soluble proteins, palmitic acid, stearic acid, arachidic acid, and some macro- and micro-elements contents were reduced facing the HMs stress, but SA foliar application ameliorated these traits. HMs stress increased malondialdehyde content, total antioxidant activity, total flavonoids, phenolics, and linolenic acid content, while SA foliar application declined the mentioned parameters. Moreover, shoot and root Pb and Ni content enhanced in the purslane plants supplemented by SA under the HMs stress. The results propose SA foliar application as a reliable methodology to recover purslane growth characters and fatty acid profiles in the soil contaminated with the HMs. The idea is that SA would be potentially effective in alleviating HMs contamination while keeping reasonable phytoremediation potential.

Enhancing Wheat Growth, Physiology, Yield, and Water Use Efficiency under Deficit Irrigation by Integrating Foliar Application of Salicylic Acid and Nutrients at Critical Growth Stages.

Transitioning from full to deficit irrigation (DI) has become a key strategy in arid regions to combat water scarcity and enhance irrigation water use efficiency (IWUE). However, implementing DI requires additional approaches to counter its negative effects on wheat production. One effective approach is the foliar application of salicylic acid (SA), micronutrients (Mic; zinc and manganese), and macronutrients (Mac; nitrogen, phosphorus, and potassium). However, there is a lack of knowledge on the optimal combinations and timing of foliar application for these components to maximize their benefits under arid conditions, which is the primary focus of this study. A two-year field study was conducted to assess the impact of the foliar application of SA alone and in combination with Mic (SA + Mic) or Mic and Mac (SA + Mic + Mac) at various critical growth stages on wheat growth, physiology, productivity, and IWUE under DI conditions. Our result demonstrated that the foliar application of different components, the timing of application, and their interaction had significant effects on all investigated wheat parameters with few exceptions. Applying different components through foliar application at multiple growth stages, such as tillering and heading or tillering, heading, and grain filling, led to significant enhancements in various wheat parameters. The improvements ranged from 7.7% to 23.2% for growth parameters, 8.7% to 24.0% for physiological traits, 1.4% to 21.0% for yield and yield components, and 14.8% to 19.0% for IWUE compared to applying the components only at the tillering stage. Plants treated with different components (SA, Mic, Mac) exhibited enhanced growth, production, and IWUE in wheat compared to untreated plants. The most effective treatment was SA + Mic, followed by SA alone and SA + Mic + Mac. The foliar application of SA, SA + Mic, and SA + Mic + Mac improved growth parameters by 1.2-50.8%, 2.7-54.6%, and 2.5-43.9%, respectively. Yield parameters were also enhanced by 1.3-33.0%, 2.4-37.2%, and 3.0-26.6% while IWUE increased by 28.6%, 33.0%, and 18.5% compared to untreated plants. A heatmap analysis revealed that the foliar application of SA + Mic at multiple growth stages resulted in the highest values for all parameters, followed by SA alone and SA + Mic + Mac applications at multiple growth stages. The lowest values were observed in untreated plants and with the foliar application of different components only at the tillering stage. Thus, this study suggested that the foliar application of SA + Mic at various growth stages can help sustain wheat production in arid regions with limited water resources.

Seed priming with mepiquat chloride and foliar applications of salicylic acid and proline improve the adverse effects of water deficit in cotton (Gossypium hirsutum L.)

Seed priming with mepiquat chloride and foliar applications of salicylic acid and proline improve the adverse effects of water deficit in cotton (Gossypium hirsutum L.)

Ácido salicílico reduz os efeitos prejudiciais do estresse salino em Tropaeolum majus

ABSTRACT Salt stress hampers the growth and physiology of nasturtium (Tropaeolum majus), due to biochemical, physiological, and anatomical disruptions. The application of salicylic acid stands as an alternative to alleviate the detrimental effects of salt stress, but studies on nasturtium are scarce. Thus, the aim of present study was to assess the effects of foliar application of salicylic acid on nasturtium cultivated under salt stress. The experiment followed a completely randomized design in a 3 x 3 factorial scheme, with 0 (no stress), 50 (moderate salt stress), and 100 (severe salt stress) mM of NaCl, and application of 0, 0.5, and 1 mM of salicylic acid, each with six replications. Growth (plant height, stem diameter, and number of leaves), gas exchange (stomatal conductance, photosynthesis, transpiration, internal CO2 concentration, intrinsic water use efficiency, instantaneous water use efficiency, and intrinsic carboxylation efficiency), as well as chlorophyll indices and chlorophyll a fluorescence were evaluated. Salt stress affected the variables analyzed in this study. The application of salicylic acid had a positive effect on mitigating the effects of severe salt stress, resulting in a significant increase in the number of leaves. The most effective dose was 1 mM, also leading to notable improvements in water use efficiency and photochemical efficiency. However, other combinations of salinity and salicylic acid reduced growth and gas exchange in nasturtium plants.

Influence of Drought Stress and Foliar Application of Salicylic Acid on Early Vegetative Stage of Cacao

Cacao (Theobroma cacao L.) is noted to have a low tolerance to drought and is, therefore, not resilient to prolonged dry periods. The study sought to evaluate the morpho-anatomical and physiological responses of two clonal seedlings of cacao BR25 and K9 under drought stress and to explore the potential alleviating effects of salicylic acid (SA) at concentrations of 0.5 and 1.0 mM on the early vegetative stage. Eleven-month-old BR25 and K9 cacao were pre-treated with foliar application of 0.5 and 1.0-mM SA for 2 wk before the onset of drought conditions. Well-watered and drought seedlings with no pre-treatments served as the control. Water was withheld for 20 d, after which rewatering resumed for 3 mo. Results revealed that after 20 d of drought, both clonal varieties experienced a significant decline in relative water content (RWC) and increased ascorbate peroxidase (APX) and catalase activity. Changes in stem diameter were observed after a rewatering period of 3 mo. K9 exhibited a noticeable reduction in root and shoot dry weight and stomatal aperture after 20 d of drought, whereas BR25 showed a decrease in total chlorophyll content and chlorophylls a and b. Furthermore, the results of the study suggest that 0.5-mM SA has the potential to mitigate the drastic effects during drought in BR25 and K9 cacao by improving RWC, stomatal length, and width. On the other hand, 1.0- mM SA has the potential to alleviate the effects of drought experienced earlier on by improving root dry weight and APX activities of the seedlings.

Efficacy of Various Chemical Sprays on Plant Growth of Chickpea (Cicer arietinum L.) in Terminal Heat Stress Conditions

Heat stress is now widely accepted as an important ecological factor influencing growth of plants and production. Rising temperatures as a result of global warming cause heat stress, reducing plant development and potential output throughout the entire globe. A field experiment was carried out at Chandra Shekhar Azad University of Agriculture & Technology, Kanpur, to minimize the heat stress induced-losses in chickpea plants with the foliar spray of chemicals during two consecutive years 2021-22 and 2022-23 at Rabi season (November-April). Experimental treatments comprise two chickpea varieties (RVG-202 and RVG-203) sown on same day (15th November). foliar spray of seven chemicals at at vegetative, anthesis and at both stages. The chemcials include Salicylic acid @ 800 ppm, Salicylic acid @ 400 ppm, Ascorbic acid @ 10 ppm, Potassium chloride @ 1%, Thiourea @ 400 ppm, Cycocel @ 400 ppm and Control (no spray). Results suggested that heat stress severely reduced the chickpea growth and productivity. However, foliar application of salicylic acid and thiourea positively affected the plant growth attributes which ultimately increased the final productivity. Concisely, the foliar spray of chemicals particularly, salicylic acid and thiourea modulated the heat stress induced losses in chickpea cultivars, RVG-202 and RVG-203 by improving their antioxidant defense mechanism and enhanced the productivity.

Maximizing productivity, profitability and water use efficiency in Indian mustard (Brassica juncea) through hydrogel and salicylic acid

Addressing water scarcity in the arid and semi-arid regions of Rajasthan presents a substantial challenge to improve the productivity of Indian mustard [Brassica juncea (L.) Czern.]. The limited availability of water in these areas results in reduced yields of Indian mustard. Therefore, a field experiment was conducted during rabi (winter) seasons of 2018–19, 2019–20 and 2020–21 at the research farm of Sri Karan Narendra Agriculture University, Jobner, Rajasthan, to evaluate the impact of hydrogel and foliar application of salicylic acid on the growth, yield, economic returns and water use efficiency of Indian mustard. The results revealed that the application of hydrogel at a rate of 5.0 kg/ha, in combination with salicylic acid at a concentration of 200 ppm during the flowering and siliqua formation stages through foliar spray, had a significant and highly effective impact. This treatment displayed superior performance across a range of parameters, including growth characteristics, yield attributes, seed yield (1840 kg/ha), stover yield (3847 kg/ha), water use efficiency (8.53 kg/ha-mm), protein content (18.6%), oil content (39.13%), net returns (₹51,710/ha) and benefit-cost ratio (2.03). Furthermore, treatments involved 5.0 kg/ha of hydrogel in conjunction with 100 ppm of salicylic acid, as well as 2.5 kg/ha of hydrogel with 200 ppm of salicylic acid, produced similar results. The combined findings of this experiment endorse the application of hydrogel and salicylic acid as a sustainable and effective strategy for enhancing the productivity, profitability and water use efficiency of Indian mustard in the arid and semi-arid regions of Rajasthan.

Salicylic acid alleviates the effects of cadmium and drought stress by regulating water status, ions, and antioxidant defense in Pterocarya fraxinifolia.

Pterocarya fraxinifolia (Poiret) Spach (Caucasian wingnut, Juglandaceae) is a relict tree species, and little is known about its tolerance to abiotic stress factors, including drought stress and heavy metal toxicity. In addition, salicylic acid (SA) has been shown to have a pivotal role in plant responses to biotic and abiotic stresses. The current study is focused on evaluating the impact of foliar application of SA in mediating Caucasian wingnut physiological and biochemical responses, including growth, relative water content (RWC), osmotic potential (Ψs), quantum yield (Fv/Fm), electrolyte leakage, lipid peroxidation, hydrogen peroxide, and antioxidant enzymes, to cadmium (Cd; 100 µM) and drought stress, as well as their interaction. Moreover, the antioxidant activity (e.g., ascorbate peroxidase, catalase, glutathione reductase, peroxidase, and superoxide dismutase activities) of the stressed trees was investigated. The study was conducted on 6-month-old seedlings under controlled environmental conditions in a greenhouse for 3 weeks. Leaf length, RWC, Ψs, and Fv/Fm were decreased under all treatments, although the effect of drought stress was the most pronounced. An efficient antioxidant defense mechanism was detected in Caucasian wingnut. Moreover, SA-treated Caucasian wingnut plants had lower lipid peroxidation, as one of the indicators of oxidative stress, when compared to non-SA-treated groups, suggesting the tolerance of this plant to Cd stress, drought stress, and their combination. Cadmium and drought stress also changed the ion concentrations in Caucasian wingnut, causing excessive accumulation of Cd in leaves. These results highlight the beneficial function of SA in reducing the negative effects of Cd and drought stress on Caucasian wingnut plants.

Effect of Salicylic Acid Foliar Application on Bioactive Compounds and Antioxidant Activity in Holy Basil (Ocimum sanctum L.)

Holy basil (Ocimum sanctum L.) has been used extensively in Thai traditional medicine, where it is commonly utilized as a part of herbal remedies for treating various ailments. Cultivation methods using exogenous salicylic acid (SA) to induce secondary metabolites have been documented in various plant species. Nevertheless, there is no reported information available on holy basil. Thus, the present study aimed to investigate the impact of SA foliar application on the bioactive compounds and antioxidant activity of holy basil. SA at concentrations of 0.1, 0.5, 1.0, 1.5, 2.0, and 2.5 mM was foliar sprayed 30 days after transplanting (DAT) compared to spraying with tap water as the control. The plants were harvested at 33 DAT. Exogenous SA at 0.1–1.5 mM enhanced the contents of bioactive compounds and improved antioxidant activity. The highest contents of eugenol (17,829.53 ± 243.11 μg/g dry extract), total phenolics (444.10 ± 2.80 mg GAE/g dry extract), and total flavonoids (382.69 ± 6.49 mg QE/g dry extract) were achieved at 1.0 mM SA foliar application, which was 282.96, 1.76, and 2.14 times, respectively, over control. Furthermore, the greatest antioxidant activity was observed in the 1.0 mM SA treatment. In contrast, the 2.0 and 2.5 mM SA treatments had lower levels of antioxidant activity and bioactive compounds than the control. The results of this study suggest that exogenous 1.0 mM SA foliar application is an effective method to produce enriched bioactivity in holy basil.