جستجوی مقالات مرتبط با کلیدواژه "تنش خشکی" در نشریات گروه "منابع طبیعی"

The management of water and nutrients are among the most important factors affecting the quality and quantity of medicinal plants. Among the medicinal plants, isabgol has a particular importance due to its mucilage, which is obtained from the seeds. It is an annual plant, which is mainly distributed in dry regions of the world. Considering that Iran is one of the arid and semi-arid countries and has recently faced with consecutive droughts, the optimal use of water resources should be prioritized. In this regard, it is important to introduce plants with low water requirements, such as isabgol. Since it is a medicinal plant, its fertilization using biological and organic fertilizers is also considered important. Therefore, in this experiment, the effect of different levels of water availability and bio fertilizers was studied on the growth and yield of isbgol. In this experiment, the effect of water availability (irrigation after evaporation of 100, 150, and 200 mm from the evaporation pan) and organic nutritional resources (humic acid, fulvic acid, and seaweed extract along with no fertilization as control treatment) was studied on the growth of and yield of Isabgol, under climatic conditions of Birjand (59 oE, 32 oN, 1410 m above sea), Iran. The experiment was conducted as split plot based on a randomized complete block design with three replications. The levels of water availability were placed in the main plots and nutritional resources in the sub-plots. The measured traits included plant height, number of leaves and number of tiller per plant, fresh and dry weight of plant, number of spikes per plant, number of seeds per spike, weight of 1000 seeds, seed yield, biological yield, percentage and yield of mucilage. Statistical analysis was performed using SAS, version 9.4 and the means were compared using the protected LSD test at the 5% probability level. The results of analysis of variance showed a significant effect of fertilizers application on most growth and yield indices, while the effect of irrigation management (except for number of leaves per plant) and interaction of studied factors was not significant on the evaluated traits. Application of all fertilizes, especially seaweed, improved the vegetative growth of the plant. The highest plant height (21 cm), number of leaves (16 per plant), number of tillers (4.8 No. per plant) and fresh weight of the plant (9.6 g) were gained from the seaweed extract, which were 31.2, 29.2, 39.9 and 78.1%, superior to the control treatment (no fertilizer application), respectively. The highest number of spikes (13.24 No. per plant) was obtained from humic acid application, which was 2.1 times more than the control treatment. Number of seeds per spike in seaweed, humic acid, fulvic acid and control treatments were 45.1, 44.3, 44.9 and 29, respectively, and 1000-seed weight was 1.63, 1.60, 1.62 and 1.55 g, respectively. Fertilizers application improved biological yield and seed yield, but in terms of these two traits, irrigation levels were in a same statistical group. The highest and the lowest biological yield (1942.2 and 1225.7 kg ha-1, respectively) and seed yield (763.4 and 456.1 kg ha-1, respectively) were gained from seaweed and control treatments, respectively. The percentage of mucilage was not affected by irrigation and nutritional managements, but the mucilage yield by the use of algae extract, humic acid and fulvic acid was increased by 56.4, 31.4 and 23.0%, respectively, compared to the control. In general, consumption of all organic fertilizer types improved the growth and quantitative and qualitative yield of Isabgol, while reduced water availability had no negative effect on the plant growth and yield, which indicates that isabgol is well adapted to semi-arid regions.

Sesame (Sesamum indicum L.) is an important oilseed crop belonging to the Pedaliaceae family with high quality yield, which can be said to have originated in some developing countries in the world due to the need for labor, and high rural harvest. Sesame is an edible plant that contains odorless oil. In addition, it is also a good source of protein and fat for humans and pets.Crops are grown underwater in dry and semi-arid regions where water pressure is great. Furthermore, it is sensitive to the dry season, mainly in the vegetative stage in all growing districts, and its production potential is low in semi-arid areas due to water stress. Since much of Iran's land is located in arid and semi-arid areas, this has led breeders to enhance water or drought tolerance traits, which is one of the main goals of the program crop improvement. However, genotype × environment interaction poses a major challenge in studying quantitative traits because it reduces yield stability across different environments and also complicates the interpretation of genetic experiments, and makes prediction difficult. A stable genotype has performance that remains constant or little changed regardless of any changes in environmental conditions. Several stability analyzes have been proposed to determine the linear relationship between genotype and environment performance. Among these, Eberhart and Russell (1966) proposed a method in which the environmental index is the average performance of all inputs in an environment. Therefore, further research into sesame's genetic differences and breeding is needed to progress and stabilize its yield under different environments. These findings may be applicable in detecting how sesame genetic resources may be used to develop novel cultivars suited to dry settings or enhance remaining cultivars. In this regard to analyze genotype × environment interaction and determine the grain yield stability of 104 sesame genotypes in the tropics and subtropical climates of Iran, an alpha lattice design with two replications during 2019 in two stations, including Kerman and Jiroft were evaluated under two conditions, normal irrigation, and drought stress at the end of the season (irrigation interruption in 50% of flowering). Then, the univariate statistics of regression coefficient (bi), mean squares of deviation from regression (Sdi2), Shukla’sstability variance (σi2), Wricke’s ecovalence (Wi2), Environmental variance (Si2), determination coefficient values (R2) and coefficient of variability (C.V) were used to evaluate the stability of the grain yield of genotypes. Combined analysis of variance showed that the effects of genotype, environment × genotype and genotype × environment linear on grain yield were significant, suggesting that genotypes differ in response to changes in environment. In order to study the interactions of genotype × environment more precisely and to determine genotypes with stable and high yields, different stability parameters were calculated for each genotype. Calculating stability parameters showed that genotypes G14, G19, G42, G80, G46, G69, G44, and G43 were recognized as genotypes with stable yield and suitable adaptation, respectively. Different parametric and non-parametric stabilization procedures can be proposed to select drought-tolerant genotypes under different environmental conditions; these procedures can be used to identify the best genotypes under drought conditions. Therefore, yield stability analysis can be used in combination with parametric and non-parametric methods to evaluate and identify drought-tolerant genotypes. In this research, the studied genotypes indicated various environmental responses and proved a high genetic ability to adapt to water-deficient stress conditions. According to the findings of this research, the genotypes Jiroft local cultivar, Dezful local cultivar, TN78-84, SG90154-137, JL18 (82), SG90154-71, TN78-369, and, Halil had the best at adapting to environments with water stress. Therefore, according to the above analysis results, these genotypes can be introduced to low-water areas of Iran.

Sunflower (Helianthus annuus L.) is one of the most valuable agricultural products, mainly cultivated for edible oil. As an oilseed plant, the sunflower has the fifth place in the world after soybeans, rapeseed, cotton and peanut. Due to climatic changes, reduction of water received from rains and incorrect management of water consumption, the crop production experienced severe drought stress during the growth period which causes the fluctuation and decrease of the product. Considering the importance of studying and selecting cultivars tolerant to abiotic stresses such as drought stress, investigating the genetic diversity for adaptive responses in sunflower cultivars and genotypes, as well as identifying QTLs are necessary for breeding programs.  The aim of this study is to investigate genetic diversity and identify markers related to drought tolerance in the inbred lines population of oilseed sunflower using the REAMP (retrotransposon microsatellite amplified polymorphism) markers. In the present research, the genetic diversity of an oilseed sunflower population including 100 inbred lines was evaluated in terms of morpho-physiological traits using a 10x10 simple lattice design with two replications under two normal and limited irrigation conditions during two consecutive years. Different morpho-physiological traits were measured under both conditions. DNA extraction was done from 78 lines out of 100 investigated genotypes by CTAB method. Then, in order to evaluate the quality and quantity of extracted DNA, 1% agarose gel electrophoresis and spectrophotometry were used. The molecular profile of genotypes was prepared using 7 REAMP primers combinations. Based on molecular data and Neighbor Joining algorithm in DARWin 6.0.21 software the studied genotypes were grouped in three groups. Cluster and population structure analyses as well as analysis of molecular variance were performed with GenAlEx and Structure 2.3.3. The number of possible sub-populations (optimal K) was determined based on the delta K (ΔK) method. For optimal K, the Qst matrix was calculated. Using mixed linear model (MLM) related to Q + K matrices (matrix of population structure coefficients + matrix of kinship relations) molecular markers associated with studied morpho-physiological traits were identified. Based on the results of cluster analysis, the genotypes were grouped into 3 groups. Each group included genotypes from different geographical areas. The results of principal component analysis showed that the first three components explain 71.32% of the total changes. Principal coordinate analysis was not able to completely separate the genotypes into separate groups. Molecular analysis of variance showed that 91% of the variation are within group and the rest 9% are between the groups, which indicates high genetic diversity within the groups. According to the mixed linear model, totally 20 molecular markers showed a significant relationship (P≤0.01) with the studied morpho-physiological traits under both normal and limited irrigation conditions. “6181810” marker with oil content and "cf8267" marker with two leaf length and leaf width traits showed a significant relationship (P≤0.01) under limited irrigation conditions. “658268” marker showed a significant relationship with yield and leaf width traits under both normal and limited irrigation conditions. Observing the relationship between one marker and several traits can be derived from the effects of pleiotropy or the linkage of genomic regions involved in the control of these traits. The results obtained from this study present valuable information on the genetic basis of studied traits that can be used for breeding and developing high performance varieties in sunflower. In this research some common markers were identified. Identification of markers that showed linkage with several traits in both conditions, such as “658268” and “cf8267” markers, are more important in the breeding program due to the possibility of simultaneous breeding of several traits

Sesame (Sesamum indicum L.) is an important oilseed crop belonging to the Pedaliaceae family, treasured in different food and cosmetics industries. Sesame as a rich source of protein, carbohydrates, minerals, and various antioxidants, is widely cultivated throughout Africa and Asia. The Sesame plant is well adapted to harsh environments. Adverse environmental conditions, such as drought stress, have severely limited plant growth and reduced plant yield. Some crop management programs have been conducted to develop strategies to mitigate the harmful effects of drought on plant growth, physiology, and yield. To this end, the exogenous application of plant hormones such as abscisic acid (ABA) has been applied to some species. Therefore, this study aimed to investigate the effect of foliar application of different abscisic acid concentrations to improve morphological characteristics, yield components, biomass production, seed yield, and water use efficiency (WUE) of sesame under water-limited conditions. A field experiment with the aim of evaluating the effect of different abscisic acid (ABA) concentrations (0: distilled water application, 10: foliar application of 10 µM ABA; 50: foliar application of 50 µM ABA; 100: foliar application of 100 µM ABA), under different irrigation regimes (normal: 100% field capacity (FC), and water-limited condition: 60% FC) was conducted as at Narju region, Jiroft, Iran, during the growing season of 2022-2023. The experimental design was a randomized block design in a split plot scheme with eight treatments replicated three times. Sesame seeds were prepared from the Agriculture and Natural Resources Research and Education Center of Jiroft and were sown on July 23, 2022. After establishment, the plants were thinned to obtain a final density of 60 plants per 3 m2 plot. The plants were treated with ABA at different concentrations two times. Different concentrations of ABA were applied 50 (first time) and 70 days (second time; at the time of stress imposition) after sowing. At the end of the growing season (November 29, 2022), 10 plants were harvested from each plot and various traits including plant height, number of branches, number of mature, immature, and total capsules per plant, number of seeds per plant, 1000-seed weight, biomass production, and seed yield were measured. Harvest index (HI) and WUE were also calculated. The results showed that under normal irrigation conditions, the application of 10 μM ABA concentration led to producing the highest number of mature capsules per plant, while no application of ABA resulted in the highest number of immature capsules per plant. In the conditions of application of irrigation level of 60% FC, the application of 100 μM ABA concentration with 25 and 8 capsules, respectively led to the production of more mature and immature capsules per plant. As a result, the highest number of capsules per plant (33 capsules) and the number of seeds per plant (2055 seeds) were obtained from the mentioned conditions. On the other hand, the thousand seed weight showed a different trend. In total, such variations observed led to the insignificant response of seed yield to the application of different ABA levels to different irrigation conditions. Applying limited irrigation in this study showed a greater effect on the reduction of seed yield (25.6%) compared to the biological yield (10.6%), which led to a decrease in harvest index by 19%. As a result of increasing the number of seeds per plant and 1000-seed weight, the application of 100 μM ABA concentration resulted in the highest seed yield (1138 kg ha-1) and biomass production (10054 kg ha1). Influenced by such results, increased water use efficiency by 9, 22, and 41% was observed for the 100 μM ABA level compared with the control and 10 and 50 μM ABA concentrations, respectively. In conclusion, the integration of different ABA concentrations with different irrigation management could be considered an effective strategy to improve the growth, yield, and water use efficiency, and alleviates the adverse effects of drought stress on sesame plants.

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.

Wheat is the most important source of carbohydrates in a majority of countries. It provides more nourishment for people than any other food source. Limited rainfall and drought stress occur frequently during the grain filling stage of wheat in many areas. Accumulation of photoasimilates in the stem of wheat and remobilization of theses storages could be considered as important adaptive traits to environmental stresses and are important in breeding cultivars with improved grain yield. Previous published researches on carbohydrates accumulation and remobilization in wheat were studied. The results of these articles were summarized systematically and then critically analyzed. Approaches for future works in terms of carbon accumulation and remobilization were also presented. Water-soluble carbohydrates (glucose, fructose, sucrose, and fructans) accumulate in the stem of wheat plants. The accumulation of reserves in the different internodes started near the end of extension growth. That is to say, the accumulation of reserves in the lower internodes takes place over long periods of time compared to the upper internodes. Accumulation of stem reserves, depend on environmental conditions and cultivars, continues until 10-25 days after anthesis when maximal amounts are reached. Wheat cultivars with optimum stem length and stem specific weight (stem dry weight per unit stem length) have higher potential for stem storages. Under optimal conditions, where photosynthesis takes place over long periods of time, storage of assimilates is high. In contrast, stress conditions such as drought reduce the amount of accumulated carbohydrates. Typically, remobilizations of stem reserves are started at the second half of linear grain growth when the current photosynthesis is declined. Physiological bases for remobilization initiation have not been understood well. It is probable that sucrose level as well as abscisic acid (ABA) concentration in the stem are involved in this process. The amount of remobilization in each cultivar is determined by stem reserves and remobilization efficiency. The later factor is affected, in turn, by grain number and grain weight (sink strength). That is to say, cultivars with higher stem storage do not necessarily show higher carbohydrates remobilization. Abiotic stresses (such as drought, salinity and heat stress) have pronounced effects on the amount and initiation of carbohydrate remobilization. However, wheat cultivars respond to such conditions differently. Researches on 81 Iranian wheat cultivars showed that drought stress increased stem dry matter remobilization from 2 to 45% whereas this trait was decreased from 1 to 72 percent in the remaining cultivars. Interestingly, the response of each stem segment (internode) to imposed stress conditions may be different with respect to remobilization amount. The flow of carbon (carbohydrates) to the grain from stored stem materials has been classified to pre- (All the carbon in the grain which is derived from photosynthesis prior to anthesis) and post-anthesis (All the carbon in the grain which is derived from photosynthesis after anthesis) remobilization. The contribution of stem dry matter to grain growth is not consistent and varies depends on the cultivar, environmental conditions, and grain weight changes. Clear association is not found between grain yield and remobilization. No clear relation was found between stem reserve mobilization and year of cultivar release. Weather conditions have pronounced effects on carbohydrates accumulation and its subsequent remobilization in wheat stem. Therefore, when breeding for these traits are considered, special attention should be paid to the environmental conditions. Typically, the lower internodes of wheat stem have higher potential for carbohydrates accumulation and remobilization when compared with the upper internodes (peduncle and penultimate). Clear relations were not found between grain yield and remobilization. This suggests that manipulating of this trait (remobilization) in wheat breeding program is a challenging task.

The Henbane (Hyoscyamus SPP.) belongs to the potato genus and due to the presence of alkaloids such as atropine, hyoscyamine and scopolamine, it affects the human nervous system. Among the annual and perennial species of this genus, five of them are endemic in Iran. The aim of this study was to determine the cardinal temperatures and evaluate the germination response of five seed ecotypes (Hyoscyamus SPP.) to water temperature and potential. For this purpose, a factorial experiment was conducted in a completely randomized design with four replications. Experimental treatments were run according to eight temperature levels (5, 10, 15, 20, 25, 30, 35, and 40°c) and six water potential levels (0, -0.2, -0.3, -0.4, -0.6 and -0.9 MPa). The results showed that with decreasing water potential, the percentage and germination rate of Ecotypes decreased. Estimation of cardinal temperatures showed that the base temperature and ceiling temperature of the five studied Ecotypes were the same and were equal to 8 and about 40 ° C, respectively. Furthermore, the optimum temperature of these Ecotypes was recorded in the range of 25-35 ° C. The Dashty Ecotype had a wider optimum temperature range. According to R2 and RMSE statistics, the Dent-like model well describes the germination rate response of the studied ecotypes to temperature and water potential.

Fig trees are the most common type of rainfed orchards in Fars province. In droughts, due to rainfall decline, the trees water requirement is not met and supplementary irrigation is necessary. Thereby, to reduce the damage caused by drought stress on fig (Sabz cultivar) under rainfed conditions, the present study was carried out to evaluate the effect of different levels of water stress on quantitative and qualitative characteristics. Experiment was conducted in a randomized complete block design with four replications (one tree per each replication) in Estahban fig research station. The treatments comprised of different water stress index (WSI), 0.0 (no water stress), 0.2, 0.4, 0.6, 0.8 and without supplementary irrigation. WSI was determined by recording leaf temperature, environmental humidity and air temperature and its effect on figs characteristics was measured. Results showed that the 0.4 WSI had the lowest leafy chlorosis disorder (1.4%) with one-time supplementary irrigation annually (1.5 m3 water per tree for each supplementary irrigation), but the difference was not significant with the 0.0 WSI (6 times supplementary irrigation equal to 9 m3 water per tree annually). The value of leaf relative water content in the 0.4 WSI was 53.4%. The 0.4 WSI showed the highest content of chlorophyll, carotenoid, syconium number per shoot and high quality (open ostiole) of dried fruit with the values of 0.05, 3.25 mg. g-1, 3.2 and 3.6%, respectively however the differences were not significant with the 0.0 WSI. In general, the 0.4 WSI was recommended for Sabz cultivar fig to maintain tree health, production of acceptable quality fruits, save groundwater, and sustainable agriculture.

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.

In order to evaluate the drought tolerance of some hybrid apple rootstocks, a factorial experiment was conducted base on randomized complete block design with 11 rootstock genotypes obtained from the apple rootstock breeding program, including AR1 to AR11, with MM111 rootstock as control in two irrigation treatments (40) and 80 (control) percent of usable water in the soil was applied. The water relative content of leaf and enzymes superoxide dismutase, peroxidase, ascorbate peroxidase, catalase and hydrogen peroxide were measured in leaf samples. The results showed that the water relative content of leaf, the activity of superoxide dismutase, peroxidase and ascorbate peroxidase enzymes and hydrogen peroxide were significantly affected by the rootstock genotype and the interaction effect of stress level and rootstock genotype. Drought stress caused a decrease in the relative water content of leaves in all the genotypes, but AR4, AR8, and AR11 genotypes had less differences compared to control irrigation. Drought stress increased the activity of superoxide dismutase, ascorbate peroxidase and peroxidase and hydrogen peroxide in the leaves of rootstock genotypes. The comparison of the activity of enzymes under drought stress compared to control irrigation treatment showed the activity of antioxidant enzymes increased in genotypes AR3, AR4, AR7, AR8, AR11 and hydrogen peroxide accumulation in genotypes AR3, AR6, AR7, AR10. Therefore, the genotypes of AR4, AR8, and AR11 under drought stress conditions, with high relative leaf water content and higher antioxidant enzyme activity, are evaluated as tolerant to drought stress compared to other genotypes.

Cumin (Cuminum cyminum L.) is an important crop for medicinal purposes in Razavi Khorasan province, especially in Sabzevar. With 80% of the country's cultivated land, Khorasan Razavi province is the leading producing province in Iran. In the world's arid and semiarid regions, access to water is a greater constraint on crop production than access to land. Using cultivars or plant species that are adapted to the climatic conditions of these regions is one of the easiest ways to combat drought stress. Despite the fact that cumin is considered a drought-tolerant plant, drought stress, particularly in years with low precipitation, significantly reduces cumin yield. The management of water during cumin's growth and maturation can affect crop yield and quality. Cumin's low productivity is largely attributable to weed infestations. Cumin is especially susceptible to weed competition during its early growth stages. Several characteristics of cumin, including slow plant emergence, short plant height, and cumin morphology, enable weeds to effectively compete. Yield losses ranging from 40 to 90% have been sustained in cumin due to weed competition. To determine the effect of different irrigation cut-off times on cumin yield and yield components under weed interference conditions, a field experiment was conducted in 2018 and 2019 at the Hakmabad Joven Agricultural Service Center (Khorasan Razavi) using a randomized complete block design with three replications. Irrigation cut-off time (full irrigation, irrigation cut-off in flowering stage, irrigation cut-off in seed-filling stage, and rainfed cultivation) was the main plot, while weed interference  was the sub-plot. Land preparation was done with moldboard in the fall of the previous year, the tillage operation included shallow plowing, double disc plow, and full leveling. Each subplot was 5 m long and 1 m wide, with five planting rows, 20 cm between rows, and 5 cm between plants. To prevent water from spreading laterally, plots were surrounded by dikes and separated by 2 m. The local landrace (Sabzevar), which is widespread and suitable for the region, was utilized. The height, number of sub-branches, number of umbrellas per plant, number of umbels per umbrella, and number of seeds per umbel were measured for five plants randomly selected from each plot at the end of the growing season. Before performing combined analysis across years, homogeneity was determined using Bartlett's Chi-square test. Due to the significance of the year effect, separate analyses of variance were conducted for each year using SAS (version 9.4) statistical software, and treatment means were compared using Fisher's least significant difference (FLSD) tests (p < 0.05). The results showed that in the rainy year, the yield and yield components of cumin did not respond to irrigation cut-off times. However, in the dry year, the highest seed and essential oil yield was obtained with full irrigation, and a delay in irrigation cessation had fewer negative effects on yield and yield components.In the first and second years, full irrigation increased the number of lateral branches (45.7% and 38.4%), the number of umbels per plant (46.1% and 12.9%), the number of seeds per umbel (36.4% and 44.7%), and 1000-seed weight (6.4 and 36.4%). All irrigation levels resulted in a lower grain yield under weed interference conditions compared to non-interference. The most detrimental effects of weed interference were observed when irrigation was stopped at the time of flowering (34.8%). In full irrigation conditions, grain yield decreased by 12.8%, but the yield reduction percentage was lower compared to other irrigation levels. Dryland cultivation yielded the highest amount of essential oil in both the first and second year. In the first year, complete irrigation produced the highest yield of essential oil, whereas in the second year, cessation of irrigation at the seed stage produced the highest yield. In the first and second year, weed competition significantly reduced the number of lateral branches (14.7 and 25.6%), the number of umbels per plant (33.1 and 21.2%), the number of seeds per umbel (17.2 and 37.2%), and the weight of 1000 seeds (9.22 and 17.2%). The percentage of essential oil was unaffected by weed interference. Delays in irrigation cessation increased grain and essential oil yield under both interference and non-interference conditions. In conclusion, this experiment revealed that the response of yield and yield components to the irrigation regime depended on weather conditions and precipitation during the growing season. In conditions where the amount and distribution of rainfall was adequate during the growing period, yield and yield components did not react significantly to the irrigation regime, whereas supplementary irrigation produced the optimal grain and essential oil yield in the absence of rainfall. Weed control increased yield in both irrigated and rainfed environments. Weed competition reduces cumin yield, yield components, and the number of umbrellas per plant, but has no effect on the percentage of essential oil produced. Consequently, in wet years, full irrigation is recommended in terms of both interference and non-interference of weeds, and in terms of appropriate irrigation, cessation of irrigation after seeding is recommended to produce optimal economic performance.

Drought is one of the most significant abiotic stresses that reduce crop yield. The primary objective of breeding programs is to increase the yield of plants under drought stress, as these plants are vital to food security. This study was conducted to evaluate the drought tolerance of sugar beet pollinator lines and to identify drought tolerant lines. 20 sugar beet lines were planted in two conditions of normal irrigation and drought stress in the randomized complete block design with three replications in the 2014 crop year in Motahhari Sugar Beet Research Station, Karaj, Alborz, Iran. These lines were produced by crossing a drought tolerant fodder beet (7221) with an O-type monogerm variety over the course of several years in order to produce a pollinator parent for the development of drought tolerant sugar beet hybrids. Sugar yield under normal conditions (Yp) and drought stress (Ys) were estimated.  On the basis of these two yields, tolerance and sustainability indices were subsequently calculated. Results revealed that the effects of environment, genotype, and their interaction were statistically significant. The MP, GMP, STI, HM, YI, REI, and MRP indices of lines S1- 9501116 and S1- 950123, the DI index of line S1- 9501116, the ATI index of line S1- 950123, and the RDI, TOL, SSI, and SSPI line indices S1- 950079 were introduced as drought tolerant lines. Among the lines introduced by the aforementioned indices, the SIIG index designated line S1- 950116 as the most tolerant pollinator line due to its short distance from the ideal line (0.56), its greatest distance from the non-ideal line (1.12), and the highest value of SIIG (0.66),  After the mentioned line, the lines S1- 950123, S1- 950077, and S1- 950119 followed with SIIG values of 0.57, 0.56, and 0.56, respectively. Cluster analysis showed, 20 pollinator lines and three controls were categorized into five main groups, while sugar yield under normal conditions, sugar yield under drought stress conditions, and 16 estimated indices were categorized into four main groups. The S1-950116 line was placed in the first group alone due to its superior sugar yield under both normal irrigation and drought stress conditions, as well as its superior MP, GMP, STI, HM, YI, DI, REI, and MRP indices. So, this pollinator line can be used to produce drought-tolerant hybrids for cultivation in various regions where water scarcity stress is a possibility. In the second group, S1-950077, S1-950118, S1-950074 and S1-950119 pollinator lines and IR7 tolerant control were present. This group exhibited relatively high values in both conditions and stress tolerance indices, indicating that they are drought-tolerant and capable of producing hybrids with a high sugar yield. MP, GMP, HM, STI, YI, DI, REI and MRP indices were found to be the most suitable indices for selecting lines with high sugar yield potential and tolerance to drought stress environment based on the results of correlation analysis of the studied indices. Among 20 pollinator lines, according to these indices, lines S1-9501116 and S1-950123 had the highest tolerance compared to other lines in terms of drought stress. Additionally, the aforementioned lines with SIIG values close to one were identified as tolerant lines. Under both normal and stress conditions, the aforementioned lines had the highest sugar production potential and yield, which may be due to the transfer of drought tolerance genes from their tolerant maternal parent; consequently, these lines can be suggested as the parent for the production of drought-tolerant hybrids.

Cumin (Cuminum cyminum L.)  is one of the most important medicinal plants grown in arid and semiarid environments. Cumin is suitable for rainfed cultivation due to its short growing season, leaf shape, canopy structure, and low water requirement. However, when rainfall falls short of crop requirements, rain-fed agriculture does not produce adequate economic yields. Several agronomic and physiological strategies have been implemented to mitigate the negative effects of drought stress and increase plant tolerance to it. Utilizing plant hormones is one of the realistic and promising strategies for increasing crop yields under stressful conditions. Few studies have examined the use of these substances as stress modulators in medicinal plants. This research was conducted to investigate the effect of stress modulator application on seed and essential oil yield of cumin in dryland and irrigated conditions. The split-plot factorial experiment was done based on a randomized complete block design with 3 replications on a private farm in the city of Jaghtai (Khorasan Razavi) in 2017-18. The cultivation method at two levels (dryland and irrigated conditions) and sources of stress modulators at four levels (control, 1.5 M Glycine Betaine, 10-7 M Brassinosteroids, and 10-3 M Sodium nitroprusside) were studied as the main plot and subplot, respectively. The experimental field underwent wheat and barley cultivations in the previous first and second years. For soil preparation, the land was plowed in autumn. The fertilizers consisted of P2O5 (75 kg.ha-1), K2O (100 kg.ha-1), and N (100 kg.ha-1) represented ammonium diphosphate, potassium sulfate, and a form of urea, and were applied at sowing under irrigated conditions. In the rain-fed condition, nitrogen fertilizer application was reduced to 50 kg.ha-1. At the end of the growing season, 10 plants were randomly selected from each plot and their cumin yield components were measured, including final plant height, number of branches, number of umbels per plant, number of seeds per plant, and 1000-seed weight. To determine grain yield and biological yield, a 2.5 m2 area was harvested from each plot after removing the margins. Using the steam distillation method, the Clevenger apparatus was utilized to measure the essential oil. For this purpose, 50 grams of the seeds in each treatment were selected, crushed with a laboratory mill, and dissolved in 500 mL of water for three hours.The essential oil yield was obtained by multiplying the essential oil percentage by seed yield. ata analysis was performed using SAS software (ver. 9.4) and tables and charts were drawn using Word and Excel software. Mean data was compared with LSD method. Slicing of moderator interaction at the planting method levels revealed that foliar application with brassinosteroids in irrigated and dryland conditions increased number of umbrellas per plant (150 and 137%), number of seeds per plant (85.5% and 41.7%) and seed yield (57.9% and 44.8%) relative to no foliar application. Under irrigated conditions, the type of stress modulators affected the number of lateral branches and essential oil yield, with foliar application of glycine betaine producing the highest number of lateral branches and foliar application of brassinosteroids producing the highest essential oil yield. Foliar application of brassinosteroids decreased the essential oil content of irrigated plants by 8.81%. In general, the results of the experiment indicated that in cumin, in order to obtain proper seed and essential oil yield, cultivation should be done as irrigated and the most suitable modifiers to obtain maximum grain and essential oil yield could be classified as brassinosteroids > glycine betaine > Sodium nitroprusside.

In this research, Sesame (Sesamum indicum L var.shevin) seed germination characteristics under drought stress conditions influenced by different seed priming treatments were investigated. In two separate experiments, germination responses to different temperatures (1, 5, 10, 15, 20, 25, 30, 35 and 40 ° C) and also different drought stresses (water potentials of -9, -11, -13 and -15 bar) were considered. Based on the results, 25 ° C was determined as optimum germination temperature. The -11 bar water potential was also determined as drought stress. Hydropriming and osmopriming of the seeds were performed at three temperatures of 20, 25 and 30 ° C. The duration of priming was determined based on the priming temperature and type. Calcium chloride osmopriming treatment was performed in three concentrations of 1, 2 and 3 mM. The seeds were primed using potassium nitrate in three concentrations of 0.1, 0.2 and 0.3%. After priming using the mentioned treatments, the seeds were dried out to initial seed moisture content and then subjected to drought stress (-11 bar) during germination period to determine the best priming treatments. Priming treatments significantly improved seed germination characteristics under drought stress. Overall, The results of this experiment demonstrated that use of hydropriming for the seeds of sesame had the highest germination features. So this treatment can be presented as an appropriate treatment for this plant as it is cost-effective, safe and eco-friendly.

Research on the effect of salinity and drought stress on germination and growth pattern among pasture grass populations is very important to determine the potential of suitable species for restoration and protection as well as fodder production. For this purpose, a research was carried out to evaluate the salinity and drought stress of the Pennisetum divisum plant in the germination and seedling growth stage of 2019 in the seed laboratory of the Faculty of Agriculture of Tehran-Karaj University in the form of a completely randomized design and in 3 replications. The treatments of this experiment included 4 levels of salinity (100-150-200 and 300 mM sodium chloride), 4 levels of dryness (2-, 4-, 6- and 8-bar polyethylene glycol) and distilled water (control). The evaluated traits included germination percentage, germination speed, stem length and root length. The results showed that the germination percentage, germination speed, root length and shoot length increased with the increase of salinity stress up to 200 mM and then decreased so that practically no seeds germinated. In drought stress, the studied traits increased up to -6 times and then started to decrease. The results showed that the Pennisetum divisum plant is relatively resistant to salt and drought stress.

In order to evaluate the effect of temperature, drought and priming on the percentage and rate germination of corn seeds, a factorial experiment based on a completely randomized design with four replicates was conducted. Treatments included eight temperature (5, 10, 15, 20, 25, 30, 35, 40 and 45 ºC), four drought potential (0, -0.4, -0.8 and -1.2 MPa), and five priming (control, hydroprimin, GA priming, ABA priming and, SA ptiming). Both percentage and rate of germination were inhibited at osmotic potentials ≤−0.8 MPa PEG. At 35 ºC temperature. Germination percentage of unprimed seeds was reduced from 94 to 36% in −1.2 MPa. Under these conditions, gibberellic acid hormone treatment improved seed germination. The effect of temperature on germination can be defined in terms of cardinal temperatures. We compared three non-linear regression models (Dent-like, segmented and beta). The outcome revealed that the Dent-like function was suitable for use in describing seed germination response to temperature. The base, optimum 1, optimum 2 and ceiling temperature were estimated to be 9.51, 24.12, 35 and 44.62 °C, respectively. The response of germination rate to both temperature and water potential can be described as a non-linear function of the hydrothermal model. According to the results of this study, hydropriming, gibberellic acid, and salicylic acid increased the mean deviation of the base temperature compared to non-priming treatment, increasing the standard deviation of the base temperature indicates the ability of seed germination in different osmotic potentials.

In many studies, the medicinal properties and impact of plantago ovata on mechanisms of human physical activities has been proven. So that one of the most useful, effective and harmless herbal laxative. drought is one of the limiting factors and a serious danger for the successful production of crops. An experiment was conducted to study germination characteristics of plantago ovata under water and drought stress conditions at different temperatures. The experiment was conducted at the University of Tehran lab, Karaj, in 2015. Temperatures regimes included 5, 10, 15, 20, 25, 30, and 35 °C). For each temperature, the treatment for drought and water stress was four potentials (zero, -4, -8 and -12 bar) with sodium chloride. The effects of drouth stress on seed germination of plantago ovata at different temperatures showed the highest resistance to drought at 20 º C. drouth stress at different temperatures reduced germination parameters nad in the potential -12 germination stopped. Increased temperatures resulted in better conditions for seed germination and increase the drought stress tolerance. Increased severity of drought causes the reduction of temperature range in which the seed can germinate.

Legume crops as human and animal feed are high in protein and have a positive effect on the yield of other crops when grown in rotation with cereals or as cover crops. However, drought can reduce pulse grain yield by 10 to 100 percent. It has been observed that drought stress has different effects on the yield of various genotypes of lentils; additionally, drought stress reduces grain yield in various cultivars of pinto beans and other genotypes of beans. According to reports, nitrogen can effectively mitigate the damaging effects of drought stress on maize. It has also been reported that the application of fertilizer treatments to various chickpea cultivars increases yield. The creation of stress-resistant plant cultivars has always been regarded as an effective method for mitigating the negative effects of stress. Consequently, the purpose of this study was to examine the impact of irrigation stress and varying nitrogen fertilizer levels on yield and yield components of bean genotypes. In 2020, two separate experiments (normal irrigation and low irrigation) were conducted on the research field of the school of Agriculture and Natural Resources at the University of Tehran in order to evaluate the effect of low irrigation stress and different levels of nitrogen fertilizer on bean plant yield and yield components. The experiment was designed with a factorial layout based on a completely randomized block with three replications. The experimental treatments included two levels of irrigation (normal irrigation and 50% normal), five levels of bean genotype (Pak, Dorsa, Goli, Sadri, D81083), and three levels of nitrogen fertilizer (no nitrogen fertilizer, 50% nitrogen fertilizer, and 100% nitrogen fertilizer). SAS 9.4 and Excel 2016 were utilized for data analysis, combined analysis of variance of both experiments, comparison of means, and graphing. Also, Minitab was utilized to examine the homogeneity of error variance. Prior to the combined analysis of variance, the homogeneity of variance of the experiments was examined, and it was determined that the homogeneity of variance of error in none of the experiments (at the one percent level) was rejected. The results of a combined analysis of variance indicated that irrigation stress and bean genotypes had a significant effect on all investigated traits. In addition, the application of different nitrogen fertilizer levels had a significant effect on all traits except harvest index and number of grains per pod. The dual interaction of treatments and the triple interaction of irrigation, nitrogen, and genotype on the number of seeds per pod. A comparison of the means of different levels of irrigation revealed that the values of all yield traits and yield components of beans decreased when low irrigation stress was applied. Significant reduction in grain yield, biological yield, and harvest index percentage under drought stress conditions were 30.5, 23 and 12 percent, respectively, when compared to the fully irrigated treatment, demonstrating the significance of drought stress effects on bean crop yield. The findings of this study indicate that drought stress and nitrogen fertilizer have a significant effect on yield and yield components for all bean genotypes. In such a way that a 30% reduction in grain yield is observed with low irrigation stress. Nevertheless, application of nitrogen fertilizer caused relative resistance of bean genotypes to low irrigation stress, so that using 100% nitrogen fertilizer treatment, the highest grain yield was obtained for white beans (4481 kg / ha), pinto beans Sadri (4373 kg / ha), and red bean (3936 kg / ha), among the five genotypes. In general, the findings of this study indicated that the destructive effects of low irrigation stress or drought on bean grain yield could be mitigated to some extent by selecting suitable bean genotypes and applying appropriate nitrogen fertilizer levels.