Foliar Application Of Methyl Jasmonate Research Articles

Differential response of roots and leaves to combined heat and salinity stresses in tomato plants

Despite our understanding of plant responses to single stresses, knowledge on how plants respond to combined abiotic factors and the underlying hormonal regulation is still very limited. Here, we aimed to examine the plant response to combined heat and salt stresses in tomato plants, the underlying hormonal response and the effectiveness of methyl jasmonate application in its alleviation. We measured fruit production and various stress markers in both roots and leaves, together with endogenous contents of stress-related phytohormones (including abscisic acid, salicylic acid and jasmonates) in tomato plants (Solanum lycopersicum cv. Micro-Tom), exposed to combined stress. In addition, we evaluated the effectiveness of a methyl jasmonate treatment as a priming agent to alleviate the negative effects of stress, with an emphasis on evaluating the effects of this hormone on triggering antioxidant protection by enhancement of vitamin E contents. Plants responded differently to combined stress treatment than to single stresses, but this differential response was organ-specific, with roots being more sensitive to stress than leaves. Both abscisic acid and jasmonates were involved in the plant response to combined stress but leaves and roots responded differently. Furthermore, abscisic acid and jasmonates correlated with vitamin E accumulation, most particularly in roots. Foliar application of methyl jasmonate at the flowering stage in plants challenged with combined stress did not improve fruit production but resulted in enhanced vitamin E accumulation in leaves. It is concluded that (i) roots and leaves show a differential sensitivity to both single and combined heat and salt stresses, (ii) the response of abscisic acid and jasmonates in plant stress responses seems to be markedly organ dependent, and (iii) foliar methyl jasmonate increased vitamin E accumulation under combined stress in tomato plants.

Effects of foliar application of methyl jasmonate and/or urea, conventional or via nanoparticles, on grape volatile composition.

Viticulture has adapted foliar applications of biostimulants as a tool to improve crop quality. Recently, nanotechnology has been incorporated as a strategy to reduce the loss of biostimulants and treat nutrient deficiencies. Therefore, the present study aimed to investigate the effect of foliar applications of amorphous calcium phosphate nanoparticles (ACP) doped with methyl jasmonate (ACP-MeJA) and urea (ACP-Ur), individually or together (ACP-MeJA+Ur), on the content of volatile compounds in 'Tempranillo' grapes, compared to the conventional application of MeJA and Ur, individually or in combination (MeJA+Ur). The results showed that nanoparticle treatments reduced the total C6 compounds and some carbonyl compounds in the grape musts. This is of novel interest because their presence at high levels is undesirable to quality. In addition, some aroma-positive compounds such as nerol, neral, geranyl acetone, β-cyclocitral, β-ionone, 2-phenylethanal and 2-phenylethanol increased, despite applying MeJA and Ur at a lower dose. Consequently, although few differences in grape volatile composition were detected, nanotechnology could be an option for improving the aromatic quality of grapes, at the same time as reducing the required doses of biostimulants and generating more sustainable agricultural practices. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Influence of Elicitors on Growth and Yield of Black Cumin (Nigella sativa L.) Varieties

Black cumin is a miracle herb, an emerging seed spice and a medicinal plant of great demand. Black cumin has been used since thousands of years as a spice and food preservative as well as a protective and curative remedy for several disorders. A field experiment was conducted at the Department of Plantation, Spices, Medicinal and Aromatic Crops, College of Horticulture, UHS Campus, GKVK, Bengaluru, from November 2018 to March 2019. The experiment followed a randomized complete block design (RCBD) with three replications and included two factors: varieties and elicitors. Among the various treatment combinations, foliar application of methyl jasmonate at 100 ppm resulted in the highest recorded values for plant height (46.7 cm), primary branches (5.43), stem diameter (4.62 mm), dry weight of plants (8.42 g), and plant spread (397 cm2) when applied with nitric oxide (Sodium Nitroprusside (SNP)) at 2 mM on Pant Krishna variety. Conversely, the significantly highest chlorophyll content in leaves was observed in the Azad Kalonji variety sprayed with salicylic acid at 100 ppm. Furthermore, the significantly highest numbers of capsules (22.60), seeds per capsule (84.28), and seed yield per hectare (12.40 q) were recorded in Pant Krishna sprayed with methyl jasmonate at 100 ppm. The present study concludes that all varieties, including Azad Kalonji, AN-20, and Pant Krishna, performed equally well regarding growth and yield attributes in this location. Among the elicitors tested, methyl jasmonate and salicylic acid at 100 ppm show promise for commercial cultivation of black cumin.

Exogenous methyl jasmonate enhanced kenaf (Hibiscus cannabinus) tolerance against lead(Pb) toxicity by improving antioxidant capacity and osmoregulators.

In this study, the effects of exogenous methyl jasmonate (MeJA) on metal uptake and its ability to attenuate metal toxicity in kenaf plants under Pb stress were investigated. The experiment was conducted with five different MeJA concentrations (0, 40, 80, 160, and 320 μM) as a foilar application to kenaf plants exposed to 200 μM Pb stress. The results revealed that pretreatmen of MeJA significantly increased plant dry weight, plant height, and root architecture at all concentrations tested, with the most significant increase at 320 μM. Foliar application of MeJA at 160 μM and 320 μM increased the Pb concentrations in leaves and stems as well as the translocation factor (TF) from root to leaf. However, the bioaccumulation factor in the shoot initially decreased and then increased with increasing MeJA concentration. By increasing enzymatic (SOD, POD, and CAT) and non-enzymatic (AsA and non-protein thiols) antioxidants, MeJA pretreatment decreased lipid peroxidation, O2- and H2O2 accumulation and recovered photosynthetic pigment content under Pb stress. Increased osmolytes (proline, sugar, and starch) and protein content after MeJA pretreatment under Pb stress restore cellular homeostasis and improved kenaf tolerance. Our results suggest that MeJA pretreatment modifies the antioxidant machinery of kenaf and inhibits stress-related processes that cause lipid peroxidation, hence enhancing plant tolerance to Pb stress.

Influence of methyl jasmonate and methyl jasmonate plus urea foliar applications on amino acids composition throughout ‘Tempranillo’ grape ripening over two seasons

This work studies the impact of foliar application of methyl jasmonate (MeJA) and methyl jasmonate plus urea (MeJA + Ur) on the evolution of amino acid content in ‘Tempranillo’ grapes during ripening, across two vintages. To achieve this goal, sample grapes were harvested at five different timing. Fol1: 1 day before first foliar application; Fol2: 1 day before second foliar application; Preharvest: 15 days after second foliar application; Harvest: the day of harvest; and Postharvest: 15 days after harvest. The effect of foliar treatments was season dependent, being effective to improve the amino acids content of grapes only in the first vintage. Among the treatments studied, foliar application of MeJA-Ur showed better results. The evolution of amino acids during ripening also was different among seasons. Overall, in the 2019, amino acids reached their highest content at Preharvest or Harvest samples, whereas in the 2020 season, these highest concentrations were reached at Postharvest. Asparagine might serve as a suitable amino acid for controlling grape ripening, as its content decreased from Fol1 to Postharvest in the two vintages. Moreover, differences on the total amino acids content at Harvest date between vintages were observed, probably due to different climatological conditions. Therefore, this study pioneers the examination of the impact of foliar applications of MeJA and MeJA + Ur on the amino acids evolution in ‘Tempranillo’ grapes during ripening. The need for further research is clear to comprehend the complex interaction between foliar treatments and grape amino acids dynamics for optimizing nitrogen quality of grapes.

Foliar application of methyl jasmonate and methyl jasmonate + urea: effect on nitrogen compounds in Tempranillo grapes over two vintages

The effects of foliar application of methyl jasmonate and methyl jasmonate plus urea on the amino acids content of Tempranillo grapes were evaluated during two seasons (2019 and 2020). In 2019, the foliar treatments favored an increase in ammonium nitrogen (N), amino N and yeast assimilable N when compared to the control grapes; whereas, in 2020, treatments did not affect N parameters in grapes. In 2019, foliar application of both treatments was effective in improving amino acids content in grapes, being significantly higher the effect of methyl jasmonate plus urea treatment than methyl jasmonate treatment. However, in 2020, the effect of both treatments on amino acid content was minor. The different effect among seasons could be explained by environmental conditions and by the differences in N content in grapevines. A multifactorial analysis and discriminant study were carried out, showing that both treatments enhanced amino acid content in grapes. The effect of methyl jasmonate plus urea was stronger than the effect of methyl jasmonate treatment. Also, a great effect of season on amino acids composition was observed.

Different Effects and Application of Methyl Jasmonate on Triticum aestivum L. by aphid Attack

Wheat (Triticum aestivum L.) widely grown in Pakistan during winter season. Aphid is one of the biological factors that inhibits seed germination and plant development. Methyl jasmonate is a plant growth regulator known to take part in defense responses against different types of stresses including Aphid attack. The current study was conducted to improve the growth of the wheat by the foliar application of Methyl jasmonate. Two wheat varieties (Shafaq and Gold) were be sown in plastic pots filled with 6 kg soil in each pot. After germination, wheat plants were treated with different Aphids. After three weeks of treatment data about survival percentage, root attributes, shoot attributes and nutrient analysis was be recorded using standard procedure. The experiment was be conducted under a complete randomized design (CRD) with three replicates and results was be deducted after statistical analysis. Different concentrations of methyl jasmonate (100 micromolar and 1mM) were applied to 20 days old wheat plant. Rhopalosiphum padi was allowed to infest the methyl jasmonate treated plants as well as non-treated plants. Control plants were covered with net and no concentration of methyl jasmonate were applied. Aphids were allowed to infest the plant for 48 hours, after that the plant from all treatments were sampled for all physiological studies. Methyl jasmonate treated plants as well as control plants were used for direct aphid population count after every week. Concluded results depicted that plants exposed to different concentrations of methyl jasmonate affected the root and shoot length, plant height which was further improved through MeJA supplementation.

Effect of Methyl Jasmonate Plus Urea Foliar Application on the Polysaccharide and Monosaccharide Composition of Tempranillo Grapes and Wines and on the Wine’s Quality

Polysaccharides are the main group of macromolecules in wines. Climate change is a major problem for viticulturists as it leads to the production of unbalanced grapes. This is attributed to a mismatch between the technological maturity and phenolic maturity of grapes, which can negatively impact the production of high quality wines. To mitigate this effect, biostimulants can be applied to grapevines. For the first time in the literature, this work studied the foliar application of methyl jasmonate plus urea (MeJ + Ur) on the vineyard and its effect on the monosaccharide and polysaccharide composition of Tempranillo grapes and wines over two consecutive seasons. To achieve this, the extraction and precipitation of polysaccharides was conducted, and the identification and quantitation of monosaccharides was performed via GC–MS. The effect of MeJ + Ur foliar treatment in both the grapes and wines was season-dependent. The MeJ + Ur treatment had a slight impact on the monosaccharide composition of the grapes and also demonstrated a small effect on the wines. Multifactor and discriminant analysis revealed that the season had a greater influence on the monosaccharide and polysaccharide composition of grapes and wines compared to the influence of MeJ + Ur treatment. Interestingly, the MeJ + Ur-treated wines exhibited a higher sensory evaluation than the control wines in the second vintage. To gain further insights into the effect of MeJ + Ur foliar application on the monosaccharide and polysaccharide composition of grapes and wines, further investigations should be conducted.

Inducing the Production of Secondary Metabolites by Foliar Application of Methyl Jasmonate in Peppermint.

Mentha x piperita is a major source of secondary metabolites (SMs), and developing tools to enhance these compounds would be beneficial to meet the increasing demand in the industry. Elicitation by plant hormones became a new strategy to reach this goal. Three experiments in a climatic chamber and two experiments in an open field were conducted with peppermint to explore the effect of methyl jasmonate (MeJa) on the essential oil (EO) content, EO composition, and the total phenolic content (TPC). The treatment was applied for all experiments by spraying the aerial parts of the plants with a dosage of 2 mM MeJa twice. The treatment influenced all the parameters studied in the trials. The volatile content increased by 9-35%; however, in one trial it remained unchanged. The treatment also affected the main compounds of the EO. Menthone increased significantly in two trials while pulegone and menthofuran decreased. In the case of menthol, the change may also be influenced by the phenological and developmental stages of the plants. In the majority of cases, the TPC was also elevated considerably due to the treatments. MeJa treatments may have promising effects in influencing the accumulation of biologically active compounds and the quality of the drug; therefore, further systematic studies are needed to optimize the technology in vivo.

Foliar application of methyl jasmonate affects impatiens walleriana growth and leaf physiology under drought stress

ABSTRACT In this study, the effects of foliar applied methyl jasmonate (MeJA) on drought-stressed Impatiens walleriana growth and leaf physiology parameters: stomatal conductance, chlorophyll, flavonoid, anthocyanin, and nitrogen balance index (NBI), were evaluated. These parameters could serve as indicators of drought tolerance of I. walleriana, a popular horticultural plant worldwide that is very sensitive to drought. The experiment included four treatments: control, drought-stressed plants sprayed with distilled water, drought-stressed plants sprayed with 5 µM MeJA, and drought-stressed plants sprayed with 50 µM MeJA. Foliar spraying with MeJA was performed twice: seven days before and on the day of drought induction. The stressed plant groups were non-irrigated to achieve soil water contents (SWC) of 15 and 5%, while control plants were well-watered throughout the experiment (35–37% SWC). The results of this study showed that drought significantly reduced I. walleriana fresh and dry shoot weight, as well as total leaf area, but did not impact on dry matter content. The foliar application of MeJA improved growth parameters of I. walleriana, depending on the elicitor concentration and drought intensity. Stomatal conductance was slightly reduced at 5% SWC, and foliar applied MeJA at both concentrations. The flavonoid index was slightly reduced at 15 and 5% SWC when 50 µM MeJA was foliar applied, while there were no observed changes in the anthocyanin index in any treatments. The foliar application of 50 µM MeJA increased the chlorophyll index and NBI of I. walleriana at 5% SWC, indicating a contribution of the elicitor to plant drought tolerance at the physiological level.

Using Biochar and Foliar Application of Methyl Jasmonate Mitigates Destructive Effects of Drought Stress Against Some Biochemical Characteristics and Yield of Barley (Hordeum vulgare L.)

Using Biochar and Foliar Application of Methyl Jasmonate Mitigates Destructive Effects of Drought Stress Against Some Biochemical Characteristics and Yield of Barley (Hordeum vulgare L.)

Could foliar applications of methyl jasmonate and methyl jasmonate+urea improve must grape aroma composition?

Grape aromas are formed by a great number of volatile compounds. Methyl jasmonate (MeJ) and urea (Ur) foliar applications have been studied to improve grape quality, but their combined application has never been studied. In both seasons, MeJ application enhanced terpenoids and C6 compounds synthesis, whereas decreased alcohols content. Moreover, MeJ + Ur treatment reduced benzenoids and alcohols and did not affect C13 -norisoprenoids content. However, there was no clear effect of these treatments on the rest of volatile compounds. Multifactorial analysis showed a season effect on all volatile compounds, except terpenoids. Discriminant showed a good separation among samples under treatment criterion. The great effect of MeJ treatment on terpenoids was probably due to this elicitor influences their biosynthesis. Season has a strong influence on grapes aromatic composition since affected to all volatile compounds families but terpenoids. MeJ foliar application enhanced terpenoids, C13 -norisoprenoids and C6 compounds synthesis, whereas decreased alcohols content; however, MeJ + Ur foliar treatment did not affect C13 -norisoprenoids and C6 compounds, and decreased benzenoids and alcohols grape compounds. Therefore, no synergistic effect was observed between Ur and MeJ on grape volatile compounds biosynthesis. Foliar application of MeJ seems to be sufficient to improve the aromatic quality of grapes. This article is protected by copyright. All rights reserved.

Changes on Grape Aroma Composition as a Consequence of Foliar Application of Methyl Jasmonate and Nano-Sized Particles Doped with Methyl Jasmonate

In recent years, foliar application of elicitors to the vineyard has been increasingly used, in particular, elicitation with methyl jasmonate (MeJ). However, due to the high cost of this compound, it is necessary to find a form of application in which the amount to be used is considerably reduced. Therefore, the aim of this work was study for the first time the influence of foliar application of nanoparticles doped with MeJ (ACP-MeJ) and foliar application of methyl jasmonate (MeJ), using a dose of 1 mM versus 10 mM, respectively, on volatile composition of Tempranillo grapes during two consecutive vintages. Grape volatile composition was determined by SPME-GC-MS. The obtained results reveal that MeJ application increased the concentration of terpenoids, and total C6 compounds in 2019 and 2020, and C13 norisoprenoids in 2019. In addition, ACP-MeJ enhanced the amount of terpenoids, and benzenoids in 2020. These are encouraging results considering that the ACP-MeJ dose was 10 times lower than that of MeJ. Therefore, the foliar application of MeJ supported on nanoparticles could be a tool in order to improve grape volatile composition, favoring a more viable and sustainable viticulture.

Methyl jasmonate and type of fertilization affect growth, production and accumulation of sulforaphane in black radish taproot

ABSTRACT Arable areas frequently lack sufficient soil nutrients, necessitating use of fertilizers, whose excessive usage presents a threat to the environment, human health, and food safety. Natural plant-based growth regulators are inexpensive and favorable to the environment. Phytohormone methyl jasmonate (MeJA) is important in improving quality, productivity, and resistance against various pests, diseases, and environmental challenges. The objectives of this study were to compare effects of fertilization and application of MeJA on taproot yield, leaf nutritive value, and accumulation of sulforaphane (SF) in black radish (Raphanus sativus L. var. niger) taproots. Sulforaphane is a potent cytoprotective agent, promoting antioxidant, anti-inflammatory, antiglycative, and antimicrobial effects. The treatments (T) were: T1 = 3 t∙ha−1 of poultry litter (PL); T2 = PL+2.5 ml∙L−1 foliar application of micro-sulfur (S); T3 = PL+S+3 g∙L−1foliar application of sorbitol (SO); T4 = 480 kg∙ha−1 of NPK 20,20,20; T5 = NPK+S; T6 = NPK+S+SO. The second experiment was foliar application of MeJA at 0, 50, or 100 mg∙L−1. Application of treatments and MeJA alone, and in combination, improved growth, leaf nutrient concentrations, taproot yield components, and accumulation of SF in black radish. The T3 treatment produced the highest relative chlorophyll content (SPAD index = 31.56), most leaf area (495.33 dm2), tallest plants and longest taproot (57.95 and 17.68 cm), highest dry matter of leaf and taproot (8.10 and 12.57%), heaviest fresh weight of leaves and taproots (249.15 and 360.40 g) and highest total taproot yield (120.13 t∙ha−1). Treatment T6 produced highest nitrogen (N), phosphorus (P) and potassium (K) content in leaves, 3.57, 0.52 and 3.87 g 100 g, respectively, and highest SF content in taproots (8.5 mg/100 g). The 100 mg∙L−1 MeJA rate produced the largest leaf area (480.10 dm2), highest dry matter of leaf and taproot (7.31 and 11.65%), heaviest fresh weight of taproot (356.23 g), highest N, P, K and S content in leaves (3.45, 0.47, 3.69 and 0.375 g/100 g), most taproot yield (118.74 t∙ha−1) and highest FS content in taproot (9.62 g/100 g). The 100 mg∙L−1 foliar application of MeJA was effective in increasing and improving vegetative growth, taproot productivity, and FS accumulation in black radish.

The application of methyl jasmonate in combination with ascorbic acid on morphological traits and some biochemical parameters in red willow.

Red willow, an economically important ornamental shrub in Iran, is characterized mainly by its red stems, making it a valuable ornamental plant in flower markets. This study aimed to investigate the effect of foliar application of methyl jasmonate (MeJA) and ascorbic acid on the morphological and biochemical characteristics of red willow. The experiment was conducted as a completely randomized design with two factors and three replications. Juvenile willow shrubs (3 to 4-year-old red) were cultivated in Hossein Abad village, Markazi province, Iran. The experimental treatments consisted of MeJA (0, 100 and 200mgL-1) and ascorbic acid (0, 100 and 200mgL-1). Several traits were evaluated such as the longest branch and two nearest heights, total shrub diameter, the longest branch diameter (at lower, middle and upper parts), total anthocyanin content of the longest branch, salicin content, leaf chlorophyll (a, b and a + b) content, and carotenoid content. In addition, the number, length and width of leaves from the longest branch, fresh and dry weight of branches were analyzed. Results revealed that the application of MeJA and ascorbic acid significantly increased growth characteristics (height, leaf number, total shrub diameter, branch diameter, fresh and dry weight and total anthocyanin content) of red willow shrubs. Furthermore, it was found that 200mgL-1 treatments of these two substances produced the best results. Red willow shrub growth parameters and yield were also improved by the interaction of these two factors. Additionally, a significant correlation was found between total anthocyanin content and leaf number of the longest branch, total shrub diameter, the height of nearest branch 2 and the plant fresh weight.

Foliar application of methyl jasmonate and methyl jasmonate supported on nanoparticles: Incidence on grape phenolic composition over two seasons

Tools to address the mismatch between technological and phenolic maturity of grapes are needed. Application of elicitors could be an effective alternative. This work compares the effect of the application of methyl jasmonate (MeJ) in conventional form and, as a novelty, in the form of MeJ-doped nanoparticles (ACP-MeJ) on the phenolic composition of Tempranillo grapes. Results showed that, regardless of season, both treatments increased the grape total phenols content. In 2019, most of the anthocyanins, and to a lesser extent the flavanols, increased with the application of MeJ, and several hydroxycinnamic acids increased in the grapes treated with ACP-MeJ, with dose 10 times lower than those of the MeJ conventional. In 2020, anthocyanins were not affected by the treatments, but total flavanols, flavonols, hydroxybenzoic acid, and stilbenes increased after ACP-MeJ application. Thus, foliar application of ACP-MeJ could serve to increase grape phenolic composition, reducing maturity decoupling and the environmental impact.

CsbZIP2-miR9748-CsNPF4.4 Module Mediates High Temperature Tolerance of Cucumber Through Jasmonic Acid Pathway.

High temperature stress seriously affects the growth of cucumber seedlings, and even leads to a decline in yield and quality. miRNAs have been shown to be involved in regulating the response to stress in plants, but little is known about its effects on cucumber high temperature stress tolerance. Here, we found that high temperature stress induced the expression of miR9748 in cucumber. Overexpression of cucumber miR9748 in Arabidopsis improved high temperature tolerance. Transcriptome analysis revealed that miR9748 might mediate high temperature tolerance through plant hormone signal pathway. 5′ RNA ligase-mediated rapid amplification of cDNA ends (5′ RLM-RACE) and transient transformation technology demonstrated that CsNPF4.4 was the target gene of miR9748. CsNPF4.4 overexpression plants decreased high temperature tolerance accompanied by reducing the content of jasmonic acid (JA), but alleviated by foliar application of methyl jasmonate, indicating that CsNPF4.4 negatively regulated high temperature stress tolerance through inhibition JA signal pathway. Furthermore, high temperature stress also increased the expression level of CsbZIP2. Yeast one-hybrid and dual-luciferase assays showed that CsbZIP2 directly bound to the promoter of MIR9748 to induce its expression. Taken together, our results indicated that CsbZIP2 directly regulated miR9748 expression to cleave CsNPF4.4 to mediate high temperature tolerance through JA pathway.

Using Biochar and Foliar Application of Methyl Jasmonate Mitigates Destructive Effects of Drought Stress Against Some Biochemical Characteristics and Yield of Barley (Hordeum Vulgare L.)

Using Biochar and Foliar Application of Methyl Jasmonate Mitigates Destructive Effects of Drought Stress Against Some Biochemical Characteristics and Yield of Barley (Hordeum Vulgare L.)

Manipulation of Flowering Time to Mitigate High Temperature Stress in Rice (Oryza sativa L.)

Background: High temperature is an important abiotic stress affecting the productivity of rice. Early morning flowering trait is an escape mechanism from heat. This trait is present in wild rice cultivars. Here we tried to induce early morning flowering trait by the application of methyl jasmonate.Methods: A pot culture experiment was conducted during Rabi, 2017 and 2018 to study the effect of foliar application of methyl jasmonate on high temperature stress (more than 35°C) mitigation in rice was conducted in the Department of Plant Physiology, College of Agriculture, Vellayani during 2017-2019. The variety used was Uma (MO 16). Methyl jasmonate was applied as foliar spray to the spikelet in varying concentration with different time. Physiological observations were taken at 50% flowering stage and yield parameters were taken at harvest stage. Conclusion: There was significant variation for physiological and yield components among treatments. 4mM L-1 methyl jasmonate at 7am treatment exhibited increase in pollen viability, spikelet fertility percentage, yield per plant and 1000 grain weight. Hence, it is found that methyl jasmonate can advance anthesis time and thereby plants can escape from the severity of temperature experiencing at the normal flowering time in rice.

Enhancement of freezing tolerance of olive leaves by foliar application of methyl jasmonate and 24–epibrassinolide through changes in some metabolites and antioxidant activity

The olive production is limited by the important factor of winter freezing damage. The purpose of this research was to investigate the probable role of exogenously applied methyl jasmonate (MeJA; 0.02, 0.1, and 0.2 mM) and 24–epibrassinolide (EBR; 0.2, 0.4, and 0.6 μM) to alleviate the adverse effect of freezing stress in olive (Olea europaea L. cv. Koronieki) leaves, which was conducted in a research orchard. Furthermore, some physiological and biochemical changes were studied in olive leaves at six sampling dates, and their relationship with freezing tolerance (expressed as LT50) were investigated. The results indicated that the olives freezing tolerance, soluble carbohydrates, proline, total soluble proteins, antioxidant enzymes, DPPH radical scavenging capacity, as well as total phenolic content were significantly increased using the foliar application of MeJA and EBR. The highest and lowest freezing tolerance in EBR 0.6 μM and control olives was as much as –8.22 °C and–6.87 °C, respectively. The LT50 profile had a significant negative correlation with accumulation of some compounds such as leaf soluble carbohydrates, total soluble protein, total phenolic content, DPPH scavenging capacity, as well as activating the catalase enzyme. Moreover, EBR 0.6 μM and control treatments respectively had the highest and lowest ratio between unsaturated fatty acids and saturated fatty acids (UFA/SFA ratio), especially in January. It can be concluded that the freezing tolerance of olive leaves can be increasing by the foliar application of MeJA and EBR treatments, which can be utilized as a preventive instrument to decrease freezing damage.