جستجوی مقالات مرتبط با کلیدواژه « Proline » در نشریات گروه « منابع طبیعی »

Watermelon (Citrullus lanatus) belongs to the Cucurbitaceae family. All plants of this family are sensitive to chilling and their planting is done in the warm season. Plants that are always in a wide range of abiotic stresses that have adverse effects on the survival, growth, quality and quantity of agricultural products. In most plants, chilling stress occurs below 10 to 15 °C, and the cucurbitaceae family, including watermelon, shows chilling symptoms at temperatures below 10 °C. Watermelon is one of the most popular tropical products of this family, and the late spring chilling in temperate and cold regions always threatens its seedlings with chilling. γ-aminobutyric acid (GABA) is a non-protein amino acid that can reduce stress in various plants. Therefore, in present research, the effect of GABA treatments as seed priming and foliar spraying was studied on reducing the amount of chilling index and maintaining the quality of watermelon seedlings under cold stress.

The present study was designed and implemented in the research greenhouse of Ilam University in 2018 as a factorial experiment based on a completely randomized design with three repetitions and each repetition including five pots. The first factor included 0, 5 and 10 mM GABA and the second factor was the application method of GABA treatments including seed priming and foliar spraying. The seed priming treatment was applied before planting and the foliar spraying treatment was applied at the seedlings to the stage of four true leaves. At 48 h after foliar spraying, all the seedlings were subjected to cold stress at a temperature of 3 °C for 6 days by 6 h at night. They were placed inside the incubator at night (24:00 to 06:00). 48 h after the end of the cold stress, the seedlings were examined for different traits. The studied traits included chilling index, relative water content, fresh and dry weight of shoot and root, total chlorophyll and carotenoid, malondialdehyde, proline, ion leakage and activity of ascorbate peroxidase and catalase enzymes.

The results showed that the exogenous application of GABA effectively reduced the complications and chilling index, the amount of ion leakage, malondialdehyde and proline in watermelon seedlings, and the RWC, fresh and dry weight of the shoots and roots, total chlorophyll, carotenoids. Also, GABA increased the activity of ascorbate peroxidase and catalase enzymes in watermelon seedlings. This was despite the fact that foliar spraying treatments are more effective than the use of seed priming treatments. Also, in both application methods, the effect of GABA 10 mM in reducing chilling capital and biochemical changes of watermelon seedlings was more than 5 mM. Probably, the exogenous application of GABA has moderated the increase in cell osmolality with the intensity of cold stress by strengthening the antioxidant system and thus reduced the amount of chilling in watermelon seedlings. GABA has been reported as an osmolyte compatible with osmotic stress. As a result, the accumulation of this osmolyte compound in plant cells is used to maintain cell turgor and also to protect the cell membrane, nutrition and metabolism of the plant by preventing the loss of cell water.

The present study showed that keeping watermelon seedlings under cold stress causes symptoms of chilling and reducing the quality of the seedlings, but the exogenous application of GABA moderated the chilling and improved the quality of the seedlings compared to the control samples. In this study, the foliar application of GABA was more effective than seed priming and 10 mM concentration maintained the quality of seedlings better than 5 mM in both application methods. Therefore, based on the present results, the use of GABA 10 mM is recommended as a practical solution to prevent damage in "Orangeglo" watermelon seedlings under cold stress.

Zinc (Zn) plays an important role in plant growth and tolerance to stress and increasing their yield, but it has been reported that zinc nanoparticles have a better role on improving the growth of plants under water stress conditions. One of the factors limiting the growth of sorghum forage plant is water stress. Studies have shown that zinc nanoparticles have a positive impact on plants response to water shortage conditions through improving photosynthesis and enzymaticactivity. Therefore, this study was conducted to investigate the effect of foliar application of nanosized and non-nano zinc oxide on some physiological and forage yield of three sorghum (Sorghum bicolor L.) cultivars under water deficit condition.

This study was performed at the research farm of Shahrood University of Technology in the growing season of 2018-19. The experiment was arranged as split plot factorial based on randomized complete block design with three replications. Water deficit stress treatment in two levels of 10 and 20 days irrigation interval were assigned as main plots and sub plots were the combination of the two factors; sorghum cultivars at three levels: Eresk, Speedfeed and Pegah, and foliar application of zinc in three levels of control, micro and nano-particles forms at concentration of 2 gr l.-1. Foliage spraying of Zinc was performed before flowering stage of sorghum. Sampling and measuring of sorghum pigments, leaf protein, leaf zinc contents and proline were done at flowering stage. Wet and dry forage yield of sorghum was measured at the end of growing season on the 2 squares meter in each plot. All data collected were subjected of analysis of variance (ANOVA) using MSTATC software. Significant differences between means refer to the probability level of 0.05 by LSD test.

The results showed that by increasing the irrigation interval from 10 to 20 days, chlorophyll a, chlorophyll b, carotenoids, leaf protein, leaf zinc content, fresh and dry forage yield decreased significantly. The results indicated that the minimum fresh forage yield (61.48 ton/ha) and dry forage yield (12.03 ton/ha) was observed with non-application of zinc in irrigation interval of 20 days. Water deficit stress causes damage to photosynthesis pigments, stomatal conductance and finally the growth and yield of plants. The results showed that application of zinc in nano or conventional form causes a significant increase in chlorophyll a, chlorophyll b, carotenoids, proline, leaf protein, zinc content, fresh and dry forage yield under stress conditions. The highest fresh and dry forage yield were observed at the rate of 97.4 and 18.8 ton.ha-1 respectively in irrigation interval of 10 days treatment by application of ZnO nano particles. Also, the results showed that, foliar application of zinc in nano and conventional form increased fresh forage yield of sorghum by 37.58 and 32.49 percent compared with control in water deficit stress condition respectively. This can be due to the role of ZnO nano particles that can enhance the rate of photosynthesis by improving gas exchange, chlorophyll fluorescence, carbonic anhydrase activity, and enhanced proline content in plants. Results also showed that in the most of physiological and yield traits and forage yield the local Ersek cultivar was better significantly than Speed ​​Feed and Pegah cultivars.

The foliar application of ZnO conventional and nano particles significantly mitigated water deficit stress and enhanced photosynthesis pigments, proline, leaf protein and zinc contents as well as improved the fresh and dry yield of sorghum.

Summer savory (Satureja hortensis) is an annual herbaceous plant. The leaves of the plant are spear-shaped, opposite, with a short petiole. The leaves and flowering branches of summer savory are used in traditional medicine with known anti-flatulent, anti-heartache, anti-parasitic, stomach tonic, stimulant and expectorant effects. Spraying or foliar feeding is a method to reduce the stabilization of chemical fertilizers in the soil and as a result reduce environmental risks, including reducing soil and water pollution. With this feeding method, elements can be provided to the plant as quickly as possible. Silicon is the second mineral element in the soil after oxygen, and in higher plants, it usually causes the physical strength of the organs by penetrating the stem and leaves, and also improves physiological and metabolic processes, gas exchanges and strengthens the antioxidant system. Also, this element has beneficial effects on the growth, performance and tolerance of some plants against biotic and abiotic stresses. The form of silicon solution in soil is silicic acid Si (OH)4. The amount of silicon in plants is 0.1 to 10% of the dry weight of the plant. The use of fertilizers containing silicon in the soil affects growth and development in two ways. First, the improvement of silicon nutrition strengthens the plant's protection system against adverse environmental conditions. On the other hand, treating soil with compounds containing geochemically active silicon improves the chemical and physical properties of soil and increases the availability of nutrients for plants. The objective of this research was to investigate the influence of silicon application on some physiological and morphological characteristics of summer savory under drought stress conditions.           

In order to investigate the effect of silicon foliar application on the summer savory characteristics under deficit irrigation conditions, a factorial experiment was conducted based on randomized complete blocks design with four replications. The experiment was carried out at the vegetable production farm of Ardabil municipality during the years 2021-2022. The investigated factors included the first, drought stress at three levels (40, 60, and 80% field capacity (FC)) and the second, silicon foliar spraying at four levels (0 (control), 0.5, 1, and 1.5 mM L-1). Drought stress was induced at the stage of 4 to 6 sub-branches and silicon solutions were foliar applied at two stages including a week before the induction of drought stress, and a week after that. Distilled water was also used as control treatment. In the present study, pots with a diameter of 20 cm, a height of 30 cm, a capacity of 3 kg with 3 holes at the bottom were used to cultivate savory plants. Before the induction of drought stress, the savory plants were regularly irrigated up to the field capacity. Drought stress was applied at the stage of 4 to 6 sub-branches based on crop capacity and after the stress induction, sampling was done.

The obtained results showed that drought stress negatively affected plant fresh weight, dry weight, height, soluble sugar content, chlorophyll a, b and total and carotenoid content, but proline content increased by 61.03% under highest level of drought stress comparing to control. The highest soluble sugar content was recorded in savory plants sprayed with silicon 1 mM L-1 and grown under drought level of 40% FC (4.76 mg g-1 FW). On the other hand, the lowest value of this trait was obtained in plants treated with silicon 0.5 mM L-1, and grown under drought level of 80% FC (3.16 mg g-1 FW). In the present study, the decrease in chlorophyll of the savory plant under drought stress could be probably related to the increase in the production of oxygen free radicals, peroxidase and phenolic compounds, because the absorption of excess energy by the photosynthetic system often stimulates the production of reactive oxygen species. Silicon foliar application had a positive and significant effect on the examined traits, so the negative effects of drought stress were alleviated by increasing silicon concentration.

In general, it could be stated that silicon could be used as a useful element to increase the performance of agricultural-garden plants, as well as to increase plants tolerance rate against environmental stresses (including drought stress). On the other hand, the application of silicon up to a concentration of 1.5 mM L-1 had a positive effect on alleviation of the adverse effects of deficit irrigation on savory plant characteristics.

Savory plant (Satureja hortensis ) belongs to mints family (Lamiaceae). Environmental and abiotic stresses affect the agricultural plants growth and yield in many regions of the world. Salinity is one of the most limiting factors for growth and production of crops in arid and semiarid regions. Soil salinity is a dominant issue for the sustainability of agricultural production. Reduction of vegetative growth, dry weight and cells mass are some of most common adverse effects of salinity. Salinity increases energy consumption to remove excess sodium ions accumulated in the root cells leading to significant reduction in plant growth rate. Nowadays, effective microorganisms (EM) is one of the biological fertilizers which has attracted a lot of attention as a useful tool to increase plant productivity and stress tolerance rate. The micro-organisms existed in EM improve the health and yield performance of agricultural plants by increasing photosynthesis rate, producing biologically active compounds such as hormones and enzymes, controlling soil diseases and accelerating the decomposition of organic matter in the soil. Therefore, the use of EM bio-fertilizer under conditions of environmental limiting factors such as salinity could be highly important to develop horticultural plant cultivation in regions with saline soli or saline water resources. The purpose of the current study was to investigate the morphological and bio-chemical responses of the savory plant to salt stress, and using EM bio-fertilizer to reduce the adverse effects of salt stress.           

In order to investigate the effect of EM bio-fertilizer on the morphological and bio-chemical characteristics of the savory plant under salinity conditions, a factorial experiment was conducted based on randomized complete blocks design with 4 replications at the Faculty of Agriculture, University of Mohaghegh Ardabili, during 2021. In this study, Em treatments were applied at three levels including 0 (control), 1 and 2 %, and salinity was induced at three levels including 0 (control), 6 and 12 dS/m NaCl. Fresh and dry yield of plants and fresh and dry weight of the roots were measured with a digital scale. The content of chlorophyll a and b, and total chlorophyll were measured by a spectrophotometric method. Proline, soluble sugars and total protein were measured as physiological characteristics.

The results showed that the highest height (30.66 cm) was recorded in plants treated with EM 2 % and grown under control condition. The height of plants decreased with increasing salinity level. Also, the highest fresh and dry yield, and fresh and dry weight of root were obtained by applying EM 2 % under control level of salinity. The highest number of leaves was counted in plants treated with EM 2 %, and grown under control level of salinity. The lowest leaf number was related to non-treated plants grown under salinity level of 12 dS/m. The highest recorded contents of chlorophyll a, b and total were 3.11, 1.85 and 4.96 mg/g FW, respectively. The lowest value of these traits (1.14, 0.65, and 1.79 mg/g FW) was recorded in non-treated plants grown under highest level of salinity. Generally, the amount of chlorophyll a, b and total decreased with increasing salinity level, while EM increased the values of these traits. The results showed that the highest amount of soluble proteins was obtained at control level of salinity and application of EM 2 %, with an average of 38.03 mg/g FW, while the lowest value (15.30 mg/g FW) was obtained in non-treated plants under salinity level of 12 dS/m. The amount of soluble sugars increased with increasing stress level. The highest amount of proline (35.4 μmol/g FW) was obtained under salinity level of 12 dS/m. EM increased the content of photosynthetic pigment under salinity conditions which led to increase photosynthetic performance of treated plants. Also, accumulation of proline as osmoprotectant agent in cells of treated plant, definitely led to decrease the activity of reactive oxygen species resulting in lower damages to cells membrane.

In conclusion, results showed that savory plants fed with EM bio-fertilizer had better growth and yield under salinity conditions than the unfed plants. These plants showed more tolerance rate against salt stress due to better absorption rate and physiological responses. So that the highest values of vegetative traits were recorded in plants treated with EM 2 %. Therefore, this treatment could be recommendable to overcome adverse effects of salinity on savory plants characteristics.

Potato (Solanum tuberosum) is one of the most important food products in the world, which is rich in carbohydrates, proteins, vitamins and other nutrients. Choosing the suitable planting date and cultivars is one of the most important and effective ways to reduce the negative effects of environmental stresses on potato characteristics. Cold stress is one of the limiting factors for production of agricultural crops. One of the adverse effects of this stress is increasing the biosynthesis rate of reactive oxygen species that causes oxidative stress. Plants have enzymatic and non-enzymatic mechanisms to overcome oxidative stress. The enzymatic antioxidant defense system includes different enzymes such as superoxide dismutase, catalase, polyphenol oxidase, guaiacol peroxidases and ascorbate peroxidase, and the non-enzymatic antioxidants include the soluble sugars, proline, carotenoids and other compounds such as flavonoids, and polyphenols. Nowadays, application of antifreeze compounds in agriculture is widely used technique to overcome chilling injuries. These substances are quickly absorbed by plants and increase the metabolic activity rate of plants. As a result, the amount of antifreeze proteins, amino acids, carbohydrates, lipids, vitamins and minerals increases in the plant organs leading to more resistance rate of plant cells against freezing. Potassium is one of the elements that reduces the effects of environmental stresses such as drought, salinity, high temperatures, cold, etc. through the accumulation of soluble carbohydrates and osmotic regulation. Also, potassium plays a role in regulating the activity of enzymes related to the detoxification of reactive oxygen species. The aim of the current study was to investigate the influence of cultivar, planting date and foliar application of antifreeze compounds on some of most important morpho-physiological characteristics of potato crop.           

The current study was conducted as a split-factorial experiment based on randomized complete blocks design with three replications at Ardabil Agricultural and Natural Resources Research Station during two cultivation seasons (2018-2019 and 2019-2020). The investigated factors included planting date in two levels (August 1st and 11th), foliar application of antifreeze compound at two levels (foliar application with a mixture of Frezzebon amino acid + potassium, and water as a control) and potato cultivars at 10 levels (901375, 901475, 902375, 8708-7, 8709-106, 7009-3, 905675, 8707-26, Agria and Savalan). Foliar applications were performed at the end of the growth season as same time as the increased likelihood of cold weather (considering the weather forecasts and the measured temperatures in the field and their correlation, one week before the possibility of temperatures below 7 ºC). Furthermore, before the spraying treatments, samples were taken from the experimental treatments and frozen using liquid nitrogen and stored in a freezer. After 24 h of freezing, the samples were again collected from the experimental treatments and rapidly frozen using liquid nitrogen before being transferred to the laboratory for measurement of the desired characteristics. After collecting the samples, laboratory experiments were conducted at the Faculty of Agriculture of Ardabil University of Medical Sciences and the Agricultural and Natural Resources Research Station in Ardabil.

Based on the obtained results, it was found that the foliar application of the amino acid Freezbon combined with potassium increased the yield, number of tuber per plant, leaf relative water content, proline and the activity of antioxidant enzymes. Also, the planting date of August 1st has the highest yield, number of tuber per plant, leaf relative water content, potassium and proline content, and the activity of catalase, superoxide dismutase and polyphenol oxidase enzymes. In terms of yield, 901475 cultivar had the highest yield (43.02 ton ha-1) and Agria cultivar had the lowest yield (26.35 ton ha-1). Among the cultivars studied, 8708-26 cultivar had the highest leaf relative water content, potassium and sodium content. The maximum content of proline and antioxidant enzymes activity were related to 7009-3 and 8707-26 cultivars. Based on these results, it seems that the planting date of August 1st and the foliar application of Freezbon with potassium can enhance the cold tolerance threshold, growth, and performance of potato cultivars in regions with cold weather by regulating physiological and biochemical responses. The results of the current study in line with the observations of the other conducted researches on different horticultural crops demonstrated that choosing appropriate planting date and application of antifreeze compounds positively influence the accumulation rate of osmoprotectants, cells antioxidant capacity and plant water and nutrient status resulting in a significant increase in cold resistance rate of plant cells.

Foliar application of antifreeze compounds Frezzebon amino acid + potassium, and planting date on August 1st can positively influence potato cultivars yield and physiological characteristics under cold conditions, therefore this foliar treatment and planting date are recommendable to overcome negative effects of cold stress on potato characteristics in cultivation reigns with cold weather.

Wheat (Triticum aestivum L.) is one of the most strategic crops for food, feed, and biofuel security worldwide. Drought stress is one of the most destructive environmental stresses that limit crop productivity worldwide. Drought stress causes a wide range of physiological changes and disturbances in metabolic processes. Environmental problems caused by the use of chemical fertilizers, production costs, and consumption costs are significant issues that require methods to increase crop production and improve sufficient food for the world's population. Today, the economic damage and destructive effects of the environment due to the excessive use of chemical fertilizers in agriculture are known worldwide, and it is obvious that a suitable alternative must be found for these fertilizers. Currently, biofertilizers are used as an alternative to chemical fertilizers based on the principles of sustainable agriculture and the stress tolerance of plants. Salicylic acid is a plant growth regulator that plays an important role in the plant protection system against biotic and abiotic stresses and can affect many physiological and biochemical processes.

In order to investigate the effect of biological and chemical fertilizers and foliar application of salicylic acid on wheat tolerance to drought stress experiment, a factorial split plot in the form of a randomized complete block design in the 2019-2020 crop year in the research farm of the Faculty of Agriculture of Lorestan University in three replications was performed. The Main plot includes irrigation levels in two levels: A1: without stress (100% of water requirement) and A2: drought stress (50% of water requirement) and sub-plots including fertilizer in five levels, including B0: use of 50% chemical fertilizer, nitrogen and phosphorus fertilizer (B1: use of 100% chemical fertilizer), B2: use of nitroxin biofertilizer with 50% chemical fertilizer, B3: use of mycorrhizal with 50% chemical fertilizer, B4: use of biological fertilizers nitroxin and mycorrhiza with 50% chemical fertilizer, and foliar application treatment at two levels (C1: foliar application with water and C2: foliar application with a concentration of 1 mM salicylic acid).

The results showed that drought stress caused a decrease in grain yield, leaf chlorophyll index (SPAD), and relative water content, as well as an increase in peroxidase, proline, and electrolyte leakage. Combined treatment of biofertilizer nitroxin and mycorrhiza with 50% chemical fertilizer caused an increase of 40.53%, 5.18%, 5.89%, 13.85%, 8.46%, and 8.90%, respectively, in grain yield, leaf chlorophyll index, grain zinc concentration, peroxidase, proline, relative water content of the leaf, and 6.29 % reduction of electrolyte leakage compared to the use of 50% chemical fertilizer. Also, salicylic acid foliar spray treatment caused an increase of 11.45%, 2.82%, 4.32%, 7.46%, 9.19%, and 8.02 % in grain yield, leaf chlorophyll index, grain zinc concentration, peroxidase, proline, relative water content of the leaf, and 18.11 % reduction of electrolyte leakage compared to no foliar spraying of salicylic acid. Combined fertilizer treatments of nitroxin and mycorrhiza with 50% chemical fertilizer and salicylic acid could reduce the effect of drought stress on the traits evaluated in this research.

Fertilizer application of nitroxin and mycorrhiza with 50% chemical fertilizer and salicylic acid foliar spraying could provide favorable conditions for the growth and better performance of the plant by improving the biochemical characteristics of the plant while increasing its resistance to drought stress conditions. In general, it can be concluded that the application of biological fertilizers nitroxin and mycorrhiza with 50% of chemical fertilizers and foliar spraying of salicylic acid can be an effective and alternative fertilizer to reduce the consumption of chemical fertilizers in the conditions of drought stress in Khorram Abad in the direction of sustainable agriculture. As a result, this treatment can be recommended to farmers in order to reduce the consumption of chemical fertilizers in wheat under drought -stress conditions.

Water shortage is an integral part of our current agriculture, and water stress is one of the most destructive environmental factors which adversely affects agricultural production worldwide. According to several studies, water deficit causes reduction of vegetative growth, leaf area, plant height, dry weight, photosynthesis rate, chlorophyll content, stomatal conductance, enzymatic activities, protein biosynthesis and amino acids accumulation in horticultural plants. Increasing reactive oxygen species (ROS) rate and activity is the one of most damaging effects of drought stress. Cucumber is a tropical crop with high water requirement. Wide leaves and shallow roots have made it a drought-sensitive crop. Based on reports, water deficit and drought stress can seriously affect yield performance and qualitative characteristics of cucumber. Measurements are needed in different aspects to overcome challenges associated with water deficit and water stress in cropping systems. So, in this study glycine amino acid were applied for its possible role under mild water shortage effects on cucumber growth characteristics.

In order to investigate the influence of glycine amino acid application on alleviation of negative effects of deficit irrigation, a greenhouse experiment was conducted based on completely randomized design with four replications. Treatments were assessed at six levels including 60 % FC, 70 % FC, 80 % FC, 60 % FC + glycine 500 mg plant-1, 70 % FC + glycine 500 mg plant-1 and 80 % FC + glycine 500 mg plant-1. Some of most important morphophysiological and biochemical characteristics of cucumber plants such as stem length, stem dry weight, leaf number, leaf area, internode length, growth period duration, fruit number, fruit set, vitamin C, chlorophyll index, total antioxidant, proline, catalase, peroxidase and polyphenol oxidase enzymes content were evaluated.

Result showed that deficit irrigation and glycine amino acid application significantly influenced morphophysiological and biochemical characteristics of cucumber plant. It was observed that vegetative traits including leaf number, leaf area index, stem length and dry weight, length of internode, growth period duration, chlorophyll index, and fruit characteristics including vitamin C content and fruit set were significantly reduced by deficit irrigation levels particularly at 60 % FC. The highest fruit number (86.5) was recorded under 70 % FC and application of glycine. In contrast, antioxidant capacity, proline, catalase, polyphenol oxidase and peroxidase enzymes content increased under 60 % FC. Glycine application could properly alleviate the negative effects of deficit irrigation on plant growth and yield. Studies have shown that glycine application maintains chlorophyll content and photosynthesis rate of plants under stress condition, which is mostly related to increasing stomatal conductance and carboxylation efficiency. Generally, water deficit reduces the yield performance of crops. And, this reduction could be correlated with decreasing leaf area and disruption of nutrients absorption. According to results of this study, maintaining the photosynthetic pigments caused by glycine application resulted in enhanced photosynthesis rate leading to higher yield comparing to control under deficit irrigation conditions.

Generally, the results of the current study demonstrated that deficit irrigation at level of 60 % FC caused induction of drought stress conditions. Induction of water deficit and drought stress higher than 70 % FC led to sever physiological and biochemical changes in cucumber plants resulting in considerable reduction of yield performance and qualitative characteristics. Water deficit increased proline content and antioxidant capacity (increasing the activity rate of antioxidant enzymes including catalase and peroxidase) of cucumber plants. Soil application of glycine amino acid alleviated the adverse effects of deficit irrigation. Because the highest fruit number was counted in 70 % FC + glycine 500 mg plant-1 treatment (with no significant difference with the control (80 % FC)), this treatment could be recommended to growers to save water consumption with no significant changes in yield performance comparing to control level.

Water scarcity due to limited rainfall, high temperatures, and high evapotranspiration is one of the important factors in reducing crops and reducing the efficiency of using dry areas. Iran is one of the arid regions of the world, with an average annual rainfall of 220 mm. wheat cultivation is at serious risk of drought stress. Mycorrhizal fungi, by creating a symbiotic relationship with the roots of most crops, increase the absorption of nutrients such as phosphorus, zinc, and copper, increase water absorption, reduce the negative impact of environmental stresses, and improve the growth and yield of host plants. Therefore, considering the importance of mycorrhiza inoculation in reducing the negative effects of drought stress and improving crop yield, as well as the need to optimize the use of chemical fertilizers for sustainable agriculture, the purpose of this study was to investigate the root growth characteristics and physiological traits of different durum wheat cultivars affected by the combined application of phosphorus fertilizer and mycorrhiza under dryland conditions.

In order to evaluate the effect of mycorrhizal fungi and phosphorous fertilizer on some of the root growth characteristics and physiological traits of durum wheat in rainfed conditions, an experiment was carried out as a factorial based on a randomized complete block design with three replications at Sarableh Agricultural Research station during the growing season 2018–2019. Experiment factors consisted of four cultivars of durum wheat (Dehdasht, Zahab, Saverz, and Saji) and five levels of fertilizer source (control, 25 and 50 kgha-1 P, mycorrhizal fungi, and 25 kgha-1 P). The seeds were sown in rows four meters long and at intervals of 20 cm. The dimensions of each experimental plot were eight square meters, in which eight rows were considered, and the distance between the experimental blocks was considered one meter. Also, the amount of seed used was 120 kg/ha. To measure root-related traits in the field after pollination from a metal cylinder that was manually designed and patterned Was used. To measure the amount of photosynthetic pigment, the leaves of the five-plant flag were randomly sampled. The Analysis of variance and comparison of mean data were performed by a Duncan multi-range test using SAS 9.1 software and the drawing of figures by Excel software.

The results indicated that the application of fertilizer sources significantly improved the traits. The results also showed that the interaction of cultivars and fertilizer sources on root growth characteristics and physiological traits was significant. So that, the highest root area (61.7% increased to control treatment), root special volume (91% increased to control treatment), root tissue density (47.5% increased to control treatment), root volume density (87.1% increased to control treatment), chlorophyll a and b (86.7 and 89.04% increased to control treatment, respectively), and proline (81.9% increased to control treatment) were obtained at Saji cultivar along with application of mycorrhizal fungi + 25 kgha-1 P. The relative water content of leaves also increased in different cultivars with fertilizer application. The application of treatment mycorrhizal fungi + 25 kgha-1 P in Saverz and Saji cultivars increased the relative water content by 84% and 71%, respectively, compared to the control treatment.

According to the results, it was found that the combined application of mycorrhizal fungi with 25 kgha-1 phosphorus fertilizer compared to the control treatment had the most effect on improving and increasing the studied traits. Mycorrhizal fungi seem to increase the root system of crops, and the secretion of phosphorus-soluble organic acids causes more phosphorus uptake, which together increases the surface area and root volume and consequently increases the uptake of water and elements, Which ultimately leads to improved relative leaf water content and photosynthetic pigments. The findings of this study also showed that Saji cultivars showed a better response to mycorrhizal fungi compared to other cultivars. Therefore, according to the obtained results, the Saji cultivar with Mycorrhizal fungi + 25 kgha-1 can be recommended for cultivation under dry land conditions.

Water stress is the most prominent abiotic stress limiting agricultural crop growth and productivity. Deficit irrigation stress as a consequence of the progressive decrease in water availability has been a hot topic regarding food security during the last two decades. Growth and development of plants are influenced by reduction in turgor that results in decreased nutrient acquisition from dry soil. Due to the threat of climate change, there is a need to limit the use of water resources in arid and semi-arid climates. It is therefore important to find new approaches to avoid crop productivity losses in ‘limited fresh-water’ areas. Eggplant (Solanum melongena) is an important non-climacteric fruit grown in tropical and subtropical regions. The estimated total world production for eggplants in 2019 was 51287210 tons. Foliar application of agro-chemicals has widely been used in agriculture as a rapid, low-cost and effective way for enhancing growth and productivity of many vegetable crops under water deficit conditions. Ca is an essential macronutrient for plant growth and development, and is considered as an important intracellular messenger, mediating responses to hormones, stress signals and a variety of developmental processes. Amino acids are important bio-regulators which have promotive effects on plant growth and productivity. Cysteine is the precursor molecule of glutathione, the predominant non-protein thiol, which plays an important role in plant stress responses.

The field experiment was carried out at the Research Farm of Agriculture Faculty, University of Zanjan, Iran, during 2021. The experiment was performed using a split plot based on a randomized complete blocks design with three irrigation regimes (60, 80 and 100 %ETc) as the main plot and foliar spray of two levels of calcium lactate (CaL) (1 and 2 g L-1) and L-cystein (Cys) (0.15 and 0.5 %) as the sub-plot in three replicates. Distilled water was used as a control. Eggplant (cv. Greta RZ) seedlings were transplanted at the 4-5 leaf stage with 35 cm spacing within row and 100 cm spacing between rows. After plant establishment, eggplants were sprayed with different concentrations of CaL and Cys at 6-7 leaf stage. Second and third times of foliar application were performed at 10 and 20 days after the first spraying. Irrigation treatments were applied one week after the first spraying. Number of branch per plant, plant height and leaf area were measured as growth parameters in harvest stage. Total chlorophyll and carotenoid contents, proline, leaf relative water content, stomatal conductance and electrolyte leakage were measured as physiological characteristics. Also plant fruit yield and water use efficiency (WUE) were evaluated.

As the results showed, plant growth, physiological indices and WUE significantly affected by deficit irrigation. Water deficit stress significantly reduced plant length, leaf area and chlorophyll content, and increased carotenoid content. Decreased plant growth may be due to limited cell division, cell enlargement due to turgor loss, and inhibition of various growth metabolites. Foliar spray of CaL and Cys improved plant growth, fruit yield and physiological indices. Leaf relative water content (LRWC) is among the main physiological criteria affecting plant water relations and have been used for assessing drought tolerance. Based on the findings, deficit irrigation caused a significant reduction in LRWC and stomatal conductance, which is due to the reduction of leaf water potential and the decrease of root water absorption rate under drought conditions. The highest value of LRWC and stomatal conductance were obtained in plants sprayed with CaL 2 g L-1 under irrigation 100 %ETc. Free proline is one of the most important osmolytes whose accumulation is a common physiological response to drought stress in higher plants and is probably associated with osmotic regulation and membrane stability under stress condition. WUE, the physiological parameter of crop, describes the relationship between plant water consumption and dry matter production. The proline content and WUE increased under deficit irrigation treatments; in particular with sever deficit irrigation (60 %ETc). The maximum proline content and WUE were observed in plants treated with CaL 2 g L-1 and Cys 0.5 % under deficit irrigation of 60 %ETc. The results showed that deficit irrigation led to a significant increase in electrolyte leakage compared to control, and foliar application of CaL and Cys decreased electrolyte leakage under normal and deficit irrigation conditions. Water deficit stress caused significant reductions in yield. The highest fruit yield was obtained under irrigation of 100 %ETc along with application of CaL 2 g L-1 and Cys 0.5 %.

Water deficit has been shown to adversely affect plant growth and fruit yield. Foliar application of CaL and Cys positively improved plant growth, physiological traits and fruit yield, as well as WUE. According to the results, application of CaL 2 g L-1 or Cys 0.5 % can be proposed to improve growth, fruit yield and WUE of eggplant.

Plants survive in salinity stress by different mechanisms (Mustafa et al., 2020). Melon is grown in arid and semi-arid regions worldwide especially in where the salinity is a threat. Iran is known as one of major centers of diversity for melon in the world (Pitrat, 2008). There is a wide genetic variation among Iranian native melon landraces. This wide range of diversity can be exploited for increasing drought tolerance in breeding programs. Iran ranks fifth in global melon production (FAOSTAT, 2019). Cultivation of native melons in Iran is offten implemented in the margins of desert areas which have degrees of drought and salinity. Therefore salinity tolerance is known as important factor in melon cropping in Iran. Melon is known as a semi-salt-tolerant plant. Salinity stress causes numerous damages such as irregular growth and developement, metabolic disorders, yield loss and poor flesh quality of Melon. Tolerance of melon genotypes to salinity stress depends on the genetic tolerance of genotypes, environmental factoers like of salinity, and plant growth stage. The most marketable Iranian Melon genotypes are produced in warm and dry weather. According to the classification, Iranian Melon, is one of the plants adapted for semi-saline area (Sobhani & Hamidi, 2014).

This study was carried out in 2019 cropping season in Vegetable Research Center (VRC) of Horticulture Science Research Institute of Iran (HSRI) in factorial were administered in three replications design based on completely randomized block design with six melon genotypes including Durango, Shadegani, Shahabadi, Dargzi, Atashi and Khatouni and five salinity levels including 0, 30, 60, 90 and 120 mmol Sodium Chloride. Melon genotypes was planted in the sand in the greenhouse. The sand was washed three times with tap water and sterilized in 120 °C and 1 bar for 30 minutes. Seeds were sown in about 10 L of sterilized sand in plastic pots. Wet weight of oots and shoots were measured and then placed in the oven at 70 °C for 48 hours to measure the dry weight. Genotypes tolerance to salinity was evaluated by the Van-Hoffman index (Mangal & Hooda, 1988). Germination percentage and relative growth in traits in both wet and dry plant organs were analyzed in factorial statistical method using SAS 9.4. Comparing means of the traits were laied out with Duncan’s Multiple Range Test. All graphs were drawn using Excel 2013 software.

In 30 mmol of salinity, Dorango, Shadegani, Shahabadi, Dargzi, Atashi and Khatouni genotypes, respectively, and in 60, 90 and 120 mmol salinity Dorango, Shahabadi, Shadegani, Dargzi, Atashi and Khatuni genotypes, have the highest germination percentage respectively. Compared to the control (No salinity). Studying salinity tolerance of studied genotypes in vegetative growth stage showed that in 30 mmol salinity Shadegani, Dorango, Shahabadi, Khatouni, Atashi, Dargzi genotypes, respectively, in 60 mmol salinity Shadegani, Durango, Shahabadi, Khatouni, Dargazi genotypes, respectively. Atashi, at 90 mmol salinity, Shadegani, Durango, Khatouni, Dargzi, Shahabadi, Atashi genotypes, respectively, and at 120 mmol salinity, Shadegani, Durango, Shahabadi, Khatouni, Dargzi, and Atashi genotyopes, respectively. Germination was significantly different in the studied genotypes and decreased with increasing salinity level.

This result confirms the results of the similar researchs. Therefore, it is suggested that the salinity level and the proper genotype for that salinity level must be determined for a high yielding marketable fruit production.

in this study, the effect of silver nanoparticles and humic acid on some morphological characteristics of quinoa seedlings under drought stress was investigated. The experiment was performed as a factorial experiment in a completely randomized design with three replications. The experiment consisted of three levels of silver nanoparticles (0, 10 and 20 mg L-1 AgNPs), three levels of humic acid (0, 100 and 300 mg L-1) and three levels of drought stress (0, -6 and -12 bar). In this study, Titicaca cultivar was used. The highest amount of seed vigor and seed germination rate were observed in the highest level of AgNPs and humic acid, which indicates the positive effect of AgNPs and humic acid on germination percentage, germination rate and quinoa seed vigor. According to the obtained results, drought stress led to a decrease in germination percentage and growth characteristics of quinoa seeds. AgNPs and humic acid had a positive effect on germination and growth characteristics of quinoa seedlings under drought stress conditions compared to control treatment. With increasing the concentration of AgNPs and humic acid, the amount of proline, soluble sugars, total phenol, flavonoids and catalase activity under drought stress increased, indicating the positive role of AgNPs and humic acid to increase drought tolerance in quinoa. Therefore, the use of humic acid at a concentration of 300 mg L-1 along with 20 mg L-1 AgNPs is recommended to improve germination and seed growth of quinoa under drought stress conditions

Echinacea (Echinacea purpurea L.) is a herbaceous, perennial plant in the sunflower family; its essential oil and extract are widely used in the pharmaceutical, food, health, and cosmetic industries; and it has antimicrobial, anti-oxidant, and radical -neutralizing properties. Anti-allergy, anti-tumor, and anti-inflammatory properties have been ascribed to them. In arid and semiarid regions, a lack of water and inefficient irrigation techniques are the primary factors limiting the development of the agricultural sector. Drought is one of the most influential stresses on crop performance, and it is well known that it affects a number of physiological processes in plants. This investigation sought to determine the impact of biochar and salicylic acid on the physiological traits and yield of echinacea (Echinacea purpurea L.) under non-stress and drought -stress conditions.  In order to examine the effect of biochar (in three levels without biochar as control, 20 t×ha-1 and 40 t×ha-1) and salicylic acid (in three levels of zero, 0.5 mM and 1 mM) in two humid environments (no stress and drought stress), a factorial experiment in split plot experiment was carried out in Ilam province (two locations) in a randomized complete block design with three replicates in 2020. The evaluated traits included chlorophyll a, chlorophyll b, carotenoids, soluble carbohydrates, total protein, proline activity, and biological yield. The results indicate that the highest increase in biological yield was 45.97% and 45.42%, respectively, in the treatment combination of 40 tons of biochar and no salicylic acid foliar spray and the treatment combination of 20 t ha-1 of biochar and 0.5% salicylic acid foliar spray in the condition of 75% drought stress.  Proline content decreased in all treatment compounds; except in the combination of non-drought stress treatment and use of 40 t ha-1 of biochar and 0.5% salicylic acid which increased by 25.71%. The highest increase in carotenoids (36.66%) was obtained if 40 t ha-1 of biochar were used and salicylic acid was not sprayed under 50% drought stress. Also, the results show that by using 20 t ha-1 of biochar and spraying 1% salicylic acid under 50% drought stress, the amount of carotenoids increased by 33.33% compared to the control. As one of the growth regulators, salicylic acid was used to increase plant tolerance to stresses such as drought. In addition, biochar had a positive impact on the enhancement of several physiological characteristics and echinacea yield. Echinacea purpurea L. appears to benefit from the use of biochar and salicylic acid to mitigate the negative effects of drought stress.

One of the most common environmental stresses that affect plant growth and development is drought stress. This stress directly impacts plant morphology, physiology, and biochemistry of plants. Salicylic acid (SA) is a signaling molecule and hormone-like substance that plays an important role in growth and physiological processes, as well as in the regulation of plant growth and development. The purpose of this research was to determine the effects of SA foliar application on morphological, physiological, and biochemical traits of two mung bean genotypes under drought stress.

This experiment was conducted in 2020 at Shandel village, 13 Km away of Zabol. A split plot design within a randomized complete block design with three replications was used. The main-plots were included irrigation after 70 (as normal conditions), 120, and 180 mm evaporation (as stress conditions) from Class A Evaporation Pan, and the sub-plots include two local cultivars of Sistan and Parto mung bean, and sub-sub-plots included the foliar application of distilled water (control), foliar application of 0.5 and 1 mM SA. Drought stress was applied in the middle of the vegetative growth stage. The foliar application of SA was done in three stages: the vegetative growth stage (20 days after planting), beginning of flowering stage and end of flowering stage. After full plant maturity, plant height, biomass, grain yield and yield components, photosynthetic pigments (chlorophyll and carotenoid), Relative Water Content (RWC), and proline of mung bean were measured.

Analysis of variance of yield traits and yield components revealed significant differences between drought stress levels, cultivar, and application of SA for all traits. The interaction effects of drought stress in cultivar on plant height and grain yield at 1% probability level and on fresh and dry plant weight at 5% probability level were significant and non-significant, respectively, while the interaction effects on other traits were not significant. The interaction effect of stress and SA was significant for the number of pods per plant, thousand seed weight, fresh and dry weight of the plant, grain yield, and the number of pods per m2. The interaction effect between SA and cultivar were not significant on 1000-seed weight, fresh and dry weight of the plant. The interaction of stress × cultivars, and SA was significant on all traits except grain yield and the number of pods per square meter.Drought stress has a profound effect on photosynthesis and water potentials of plant. Grain Yield and yield components were better in Parto cultivar than local Sistan cultivar. It is possible that the presence of superior stress resistance genes in Parto cultivars has caused higher yield and yield components than the local cultivar. Application of SA increased pod production per plant. Foliar application of SA probably reduces flower loss by reducing the adverse effects of stress and increases the number of pods per plant and consequently the number of pods per square meter. Foliar application of SA increases photosynthesis by improving photosynthetic pigments. In addition, foliar application of SA enhances photosynthesis, resulting in an increase in 1000-seed weight. SA, as an important signaling molecule, promotes plant growth and induced abiotic stress tolerance. Likely SA increases growth and yield by increasing potassium, phosphorus, nitrogen, and calcium concentrations. The effect of this hormone on other plant hormones that increase vegetative growth and increase cell division in meristematic regions, and cell growth may also contribute to the growth enhancement.

Based on the present study findings, drought stress had a negative effect on all traits examined. The effect of SA at a concentration of 1 mM was the highest in non-stress conditions and in the Parto cultivar. The Parto cultivar was better compared to another cultivar. Foliar application of SA improved drought resistance in both cultivars. This improvement was greater in Parto cultivar than local Sistan cultivar. Based on the results of this experiment, it is recommended to improve the yield and growth characteristics of mung bean during stress conditions. It also seems that Parto cultivar performs better in Sistan's conditions than the local cultivar of Sistan.

In order to evaluate mycorrhizal fungi on physiological characteristics and drought resistance in current almond (Prunus amygdalus) rootstock, a factorial experiment was conducted as a randomized complete block design in three replications in agricultural and natural research center of Shahrekoard. The treatments consist of two level of mycorrhizal fungi (M0: without and M1 with using of mycorrhizal fungi), four kinds of rootstock (bitter, local Shorab 2, GF and GN) and four levels of water deficit stress (I1: without stress as a control, I2: 20, I3: 40 and I4: 60 percent of depletion of plant available water). The results revealed that the maximum amounts of the studied characteristics except leaf proline were obtained from GF rootstock. The studied characteristics were increased from I1 to I4 treatment. Using of mycorrhizae fungi in deficit treatments caused to significantly increase in root and leaf proline, root soluble sugars and the activity of catalase and peroxidase enzymes. The maximum amount of root soluble sugars and leaf proline were obtained from GF+M1 and GN+M0 treatments respectively. The highest and lowest levels of catalase and peroxidase enzymes activity were obtained from I4+M1 and GF+I4 treatments. The maximum and minimum amounts of leaf soluble sugars were obtained from GN+I4+M0 and GN+I1+M1 treatments respectively. Inoculums with mycorrhizal fungi caused to increase rootstocks resistance to water deficit stress. Based on these experiment results the highest resistance to water deficit stress was obtained from GF rootstock.

One of the most important climate changes today is the decrease in precipitation. The present study was conducted to investigate the effect of drought stress on some physiological and biochemical characteristics of some promising grape cultivars. Experimental treatments included 5 Russian grape cultivars (Qazagiski Ramphi, Supran Bulgar, Muscat Yamtazini, Kishmish Hisrao, Besmiamphi Ramphi) and two Iranian cultivars (Chafteh and Soltan) and 3 drought levels (100 (control), 70 and 40% field capacity). A factorial completely randomized design with three replications was conducted in the greenhouse of Takestan Grape Research Station. After stress application, catalase, peroxidase, guaiacol peroxidase, ascorbic peroxidase, and hydrogen peroxidase enzymes activity, soluble sugar, total proteins, proline, chlorophyll and leaf relative water content, leakage rate and membrane stability index were measured. Reducing the amount of irrigation water to 70 and 40% of relative field capacity significantly improved the activity of peroxidase, ascorbic peroxidase, hydrogen peroxidase, and guiocol peroxidase activity, and soluble sugar and proline concentrations. Water shortage significantly reduced ion leakage, chlorophyll content, leaf relative water and the stability of grape leaf cell membrane. There were differences among different grape cultivars in response to stress. In general, Qazagiski Ramphi cultivar was more resistant to drought stress than other cultivars. Bidaneh Sefid and Besmiamphi Ramphi were the second and third cultivars in drought tolerance capacity, respectively.

Almonds are considered as saline sensitive fruit trees. The effect of four types of saline soils with different salinities (2, 4, 8 and 16 dS m-1) along with inoculation with two sterile bacterial and control isolates from three groups of saline, alkaline and saline alkaline bacteria isolated from rhizosphere of Khorasan Razavi almond orchards on induction of resistance against salinity in almond grafted on GN rootstocks was evaluated under salinity and soil alkalinity conditions. The highest 3- Indole acetic acid content, dissolution of mineral phosphates and exopolysaccharide were observed in alkaline, saline and saline isolates, respectively. Soil salinity significantly reduced plant height, leaf area, fresh and dry weight of shoots and roots, soluble, insoluble and total sugars. The highest plant height (61.2 cm) and was observed in the halophilic group and the lowest was recorded in alkaliphilic group. Halophilic bacteria caused the highest increase in fresh weight of shoots. However, the fresh weight of the roots was the highest in the group of haloalkaliphilic bacteria. The ratio of fresh weight of shoots to roots was 0.86, 0.87 and 0.74 for the halophilic, alkaliphilic and haloalkaliphilic, respectively, indicating that the effects of haloalkaliphilic bacteria on root growth were greater than shoot growth. Inoculation of haloalkaliphilic bacteria increased root and shoot water content in high salinity soils (16 and 8 dS m-1, respectively). In general, the use of haloalkaliphilic bacteria had the highest effect in improving the growth of roots, alkalis and saline-like plants by increasing the morphological and biochemical properties of almonds, respectively.

Mentha spicata is one of the most widely consumed vegetables that is grown commercially worldwide. The essential oil and extracts of Mentha spicata are used in the cosmetics, food, and pharmaceutical industries. Salinity is one of the most important abiotic stresses that endanger plant growth and productivity. Salinity stress reduces the plant's capacity to absorb water, creates ion imbalances and induces oxidative stress in the plant due to the accumulation of ions such as sodium and chlorine at toxic levels in cells and tissues. Salicylic acid plays an important role in improving physiological activities and increasing plant resistance to biotic and abiotic stress factors. Chitosan as a biostimulant can improve plant growth and yield. Furthermore, the combined application of salicylic acid and chitosan is believed to ameliorate the salinity defects more efficiently. This study aimed to investigate the application of chitosan-salicylic acid nanocomposite under salinity stress on the growth and some physiological traits of Mentha spicata in hydroponic culture.

To investigate the effects of different levels of salinity stress and application of chitosan-salicylic acid nanocomposite on the morphological and physiological traits of M. spicata, a factorial pot experiment based on a completely randomized design with four replications was performed. Treatments used in this experiment included salicylic acid (1 mM), chitosan (10 mg L-1), an aqueous mixture of chitosan and salicylic acid (1 mM and 10 mg L-1), and 1% w/v chitosan-salicylic acid nanocomposite.

Salinity reduced the height of M. spicata compared to the control plants. However, foliar application of chitosan-salicylic acid nanocomposite improved plant growth and increased plant height under non-salinity conditions and different salinity levels compared to the controls. Salinity stress significantly reduced the fresh and dry weight of the M. spicata. The highest leaf chlorophyll index (56.9) was related to the treatment of 1% w/v of the chitosan-salicylic acid nanocomposite. The highest amount of proline (20.6 µmol g-1.fresh weight) was related to the treatment of an aqueous mixture of chitosan and salicylic acid at a salinity level of 100 mM sodium chloride. The highest content of malondialdehyde (2.93 nmol g-1.fresh weight) was obtained in the treatment without foliar application and a salinity level of 100 mM. The highest protein content (1.81 mg g-1) was related to the treatment with 1% chitosan-salicylic acid nanocomposite and the treatment without salinity stress. Otherwise, the lowest amount (0.858 mg g-1) for protein content belonged to the control and salinity of 100 mM. With increasing salinity levels, H2O2 content in the plant tissues increased. So that, the highest content for H2O2 was observed in the treatment without foliar application and salinity level of 100 mmol and, the lowest H2O2 content was recorded in the control treatment (without foliar application and salinity).

The overall results revealed that salinity stress had a detrimental effect on the growth and some physiological traits of the Mentha spicata L., but the foliar application of salicylic acid and chitosan alone or in combination had a promising role in reducing the effects of salinity stress on the M. spicata, due to the progressive salinity stress incidence in many parts of the world and Iran, it seems that the results of the present study can be proposed to the agricultural extension sections to use the resulting mixture in plant breeding programs under saline areas to possibly reduce the salinity adverse effects

Drought stress is considered to be an important abiotic constraint, limiting plant growth and productivity worldwide. The aim of the present experiment was to investigate the effects of exogenous application of kaolin on growth, yield and physiological responses of sweet pepper plants under drought stress. The experiment was conducted in a factorial experiment based on randomized complete block design in three replicates at the Faculty of Agriculture of Ilam University in 2019. The first factor included three concentrations of kaolin (0, 2.5 and 5%) and the second factor included three irrigation intervals (2, 4 and 6 days).The results showed that total yield, growth parameters and chlorophyll content decreased while proline, Malondialdehyde and antioxidant enzymes activities increased with increasing level of water stress. Kaolin treatment improved growth parameters, total yield and chlorophyll content of pepper plant subjected to drought stress and provided significant protection against drought stress. Moreover, kaolin decreased the malondialdehyde accumulation, which was correlated with the increased activities of antioxidant enzymes. In general, the results indicate that foliar application of kaolin (especially 2.5%), could be effectively used to protect pepper’s plants from the adverse effects of drought stress.

Peppermint, scientifically known as Mentha piperita, is an aromatic and medicinal plant that belongs to the Lamiaceae family. In the Research Greenhouse of University of Zabol, an experiment was conducted in a completely randomized design with three replications to investigate the effect of salicylic acid foliar application on peppermint. Salicylic acid was sprayed in two stages (8 weeks after stolon set-up and 2 weeks after the first foliar application) at levels of 0, 5, 10, 50, and 100 ppm. Phenols, flavonoids, antioxidant activity, total protein, and physiological traits like catalase, carbohydrate, ascorbate oxidase, peroxidase, polyphenol oxidase, and photosynthetic pigments were all measured in this study. The treatment with different levels of salicylic acid had a significant impact on all studied traits (p ≤0.01) and improved all studied traits except carbohydrates, according to analysis of variance. At a dose of 100 ppm, salicylic acid had the greatest additive effect on physiological and biochemical traits. According to the findings of this study, salicylic acid foliar application on peppermint appears to increase antioxidant compounds, osmotic regulators (carbohydrates), and photosynthetic pigments, and is a promising and cost-effective method for increasing secondary metabolites and medicinal properties of this plant.