مجله تنشهای محیطی در علوم زراعی
سال پانزدهم شماره 1 (بهار 1401)

It is expected that world wheat production would be about 761.5 million tons in 2020 while world demand would be doubled by 2025. Drought stress is one of the most important factors of yield loss that can decrease wheat production significantly. In the Middle East, drought stress usually happens at the end of the growing season and after the spike appearance. Late-season drought stress can slow down the seed development stage and decrease grain yield. In order to have stable food security one of the ways is to use the genetic diversity of germplasms.

An association panel including 199 Iran bread wheat landraces was sown in Alborz and Zanjan provinces under late-season drought stress and normal irrigation conditions where climate zones are semi-arid. The experiments conducted using two alpha lattice designs with two replications for each of the conditions in each of the locations. The drip irrigation method was used for watering till spike appearance. Then, watering terminated for one of the designs whereas another design was normally irrigated for more three times in each location. Phenotypes measurements included days to heading, days to heading, duration of heading-to-maturity, plant height, grain yield/m2, thousand kernel weight, seed length, seed width, seed number per spike, spike length, spike weight, flag leaf length, flag leaf width, peduncle length, shoot diameter, and awn length.

Agronomic traits varied lower under late-season drought stress conditions compared to normal irrigation conditions (except days to heading). Significant genetic effects observed for all of the traits under both irrigation systems. The genetic by environment effect was only significant for days to heading, days to heading, duration of heading-to-maturity, plant height, and grain yield. Heritability values were increased under normal irrigation conditions. Days to maturity and days to heading had lowest (0.35 and 0.47) and highest (0.85 and 0.86) heritability under both late-season drought stress and normal irrigation conditions, respectively. The highest correlation coefficients were achieved for the traits of days to heading and plant height (0.65) and grain yield/m2 with seed number per spike (0.60) under late-season drought stress conditions and the traits of days to heading and plant height (0.76) and spike weight with seed number per spike (0.64) under normal irrigation conditions. The first two components in principle components analyses were explained 0.40 of phenotypic variations under late-season drought stress conditions and 0.39 of phenotypic variations under normal irrigation conditions. A significant negative correlation was observed between days to heading and duration of heading-to-maturity under both late-season drought stress and normal irrigation conditions (-0.42 and -0.54, respectively). Using path analysis, thousand kernel weight (0.60) and seed number (0.79) under late-season drought stress conditions and days to heading (-0.57), days to maturity (0.40), duration of heading-to-maturity (-0.53), thousand kernel weight (0.52), and seed number per spike (0.81) under normal irrigation conditions had the highest direct effects on grain yield. The indirect effect of seed number through spike weight (0.51) on grain yield was highest under late-season drought stress conditions, and the indirect effect of days to heading through the duration of heading-to-maturity (0.42), as well as seed number through spike weight (0.52) on grain yield, were highest under normal irrigation conditions. The dendrograms obtained for grouping landraces showed a very good match with principal component analyses, while more landraces were placed in higher-yielding groups under normal irrigation conditions. The results showed that additional waterings increase grain yield in Iran bread wheat landraces. The landraces such as 57785, 57733, and 54502 are suggested to be used in applied breeding programs due to high yield performance under both late-season drought stress and normal irrigation conditions.

The results of this study suggest that the available genetic diversity of Iran bread wheat landraces be used in applied breeding programs.

Rye is one of the imoptant cereals that have wide range of adaptation, its ability to grow and produce high yield in poor soil, has made it possible to exploit unfertilized lands. Since rye is a native plant of Iran, its ecotypes are predicted to be valuable genetic resources for adapting to the climatic conditions of this region. Based on the results of previous evaluations on the high adaptability of this plant, this study aims to determine the effects of drought stress on grain and forage yield in winter rye ecotypes.

In the current research project, 9 rye ecotypes, along with cultivar of rye (Danko), were evaluated for drought stress tolerance in a randomized complete block design with three replications in two cropping seasons (2016-17 and 2017-18) in the experimental field of Seed and Plant Improvement Institute. Morphological, phenological and agronomic traits as well as stress tolerance indices were calculated and their relationship was evaluated. Ecotypes were evaluated in plots containing 4 three-meter manually cultivated lines in two separate experiments, including normal and irrigation discontinuation after plant establishment. Growth was irrigated, while drought test ecotypes were irrigated in only two stages of planting and plant establishment. The beginning of the stalking stage (Z30) is considered to be a good time to harvest forage so that the maximum forage is obtained without damaging the spike buds (Kottmann et al., 2013). Fodder and grain yields were taken from one square meter of the middle section of the two middle lines of the plot.

Combined analysis of variance and mean comparision showed that drought stress accelerated phenological stages of the plant growth. Drought stress treatment caused a significant reduction in seed weight and grain yield in the ecotypes studied (83.29 and 29.66% respectively). Principle component analysis indicated that in both years ecotypes with early maturity had higher Stress Tolerance Index. Overall, the results of the components analysis and the evaluation of the position of the trait vectors relative to each other indicated that in both years the stress tolerance index vectors in the quarter are opposite to the phenological traits. Therefore, in both years, ecotypes that had lower values ​​in the trait of day to spike emergence, or in other words, were earlier, had a higher tolerance index. Comparison of meteorological data of stress intensity index (SI) in the first and second years of the experiment and study of the reaction of rye ecotypes to drought stress in these two years showed that in the first year of the experiment when more severe drought stress was applied, Ecotype No. 119 compared to cultivar Danko excelled. While in the second year of the experiment, when the stress intensity was milder, Danko cultivar produced more yield.

In assessing the reaction of plants to stress, the severity of stress is of great importance, and this greatly affects the results of research. In this study, which evaluated the reaction of rye ecotypes to drought stress in two crop years, according to meteorological information, the distribution and different amount of rainfall in these two years were different. This indicates that in the first year, the occurrence of drought stress at the end of the season occurred earlier. A study of the reaction of rye ecotypes to drought stress in these two years also showed that in the first year of the experiment, when the drought stress was more severe, the ecotype No. 119 was superior to the Danko cultivar. While in the second year of the experiment, which was moderately intense, the Danko cultivar produced more performance. This indicates that the potential yield is higher in the Danco cultivar and it makes it superior in mild stress conditions, but in severe drought stress conditions, was less tolerant rather than No. 119 ecotype. This indicates higher adaptability and performance stability in native ecotypes, which is the result of their evolution over the years in the region's climatic conditions. In general, results indicated that ecotypes number 4 (KC13139) and number 119 (TN06-243) and Danko cultivar had higher tolerance to drought stress than other rye ecotypes. Therefore, these ecotypes can be used for further evaluations and application in breeding programs.

Most of the Produced fodder in Iran is provided by alfalfa and corn. These two forage products have a relatively high water requirement. Among cereal forage plants, sorghum is a great plant due to its high production capacity, adaptation to different climatic conditions and different uses. Iran, with an average rainfall of 240 mm per year, is classified as arid and semi-arid regions. One of the most fundamental issues of the country is water and irrigation. Food security concerns are a major threat due to climate change and water scarcity, hence replacing plants with high water use efficiency is essential. this experiment was carried out for 1(investigate the possibility of cultivating sorghum as a substitute for common forage plants in drought stress conditions in the south of Kerman province and 2) also to determine the most suitable sorghum cultivar under the different Irrigation levels in terms of forage characteristics in Jiroft region.

In order to identify the most suitable cultivar resistant to drought sorghum, an experiment was carried out as strip plot design based on randomized completely block design with three replications in 2019-2020. Vertical plots were drought stress levels (irrigation after 90, 130, 180 and 220 mm evaporation from class A evaporation pan). Horizontal factors were sorghum genotypes (Speedfeed, Pegah, KFKFS18 and KFKFS2. Each experimental plot consisted of four planting lines. Plant density was 220,000 plants per hectare. The planting date was April 17th. The first irrigation was done after measuring soil moisture and calculating moisture deficiency. Irrigation was done uniformly every 5-7 days until the 4-leaf stage. The time of application of stress was after 4 to 6 leaf stage and ensuring complete establishment of plants. Early cultivars such as Speedfed were harvested based on the beginning of flowering and late cultivars were harvested based on 150 cm plant height by cutting from 10 to 15 cm above the soil surface. In each row, all plants were harvested from two middle lines of each plot and the fresh weight of leaves and stems was immediately measured. Water use efficiency in kilograms per cubic meter was calculated from the ratio of dry forage yield in kilograms per hectare per water consumption in cubic meters per hectare. Finally, combined analysis of variance of data was performed using SAS statistical software version 9. The means were compared using the LSD test at the level of 5% probability.

Combined analysis of variance showed that the interaction effect of irrigation regimes and cultivars was significant on fresh forage yield, leaf and stem fresh and dry weight, plant height and leaf area. Mean comparison of simple effects were studied only for dry forage yield and water use efficiency. The results showed that Speedfeed cultivar had the highest fresh forage yield (298.42 tons.ha-1) at the 90 mm level irrigation. Lowest forage yield (142.49 tons.ha-1) resulted from the combination of KFS18 and irrigation after 220 mm evaporation. Highest dry forage yield was obtained at 90 mm irrigation level (46.22 tons.ha-1). Lowest dry forage yield (39.70 tons.ha-1) was related to the irrigation after 220 mm evaporation from the surface of evaporation pan. Speedfeed and KFS18 had the highest and lowest dry forage yield (41.69 and 31.17 tons.ha-1), respectively. The highest and lowest water use efficiency were related to Speedfed and KFS18 (4.08 and 3.68 Kg.m-3), respectively. There was no statistically significant difference between 90 mm (4.76 Kg.m-3) and 220 mm (4.49 Kg.m-3) levels of irrigation.

According to the results of the experiment, speedfeed cultivar with irrigation after 130 mm evaporation from the surface of evaporation pan can be suggested for forage production in southern Kerman province.

Coriander is an annual herb of the umbel family and is belonged from North Africa to south-western of Asia. Coriander is one of the important medicinal plant that used in the pharmaceutical industry and it mainly cultivated and widely distributed for the fruits. The dried fruits are widely employed as a condiment, especially for flavoring of sauces, meat products and bakery and confectionery items. Also, coriander fruits are as a source of essential oils and fatty oil. Water deficit stress is one of the most important factors limiting the growth and survival of plants in arid and semi-arid regions of the world. Water is a major component of the fresh produce and significantly effects on weight and quality of plants. Also, water deficit may cause significant changes in the yield and composition of essential oils in aromatic and medicine plants. So that, was reported that water deficit increased essential oil percentage in coriander but decreased essential oil yield. Iran with an average annual rainfall of 240 mm is included among arid and semi-arid regions of the world. Of the million hectares of cultivated region, only five millions are under irrigation because of intense water limitations. However, Iran is one of the world’s commercial coriander producers. Coriander has been cultivated for many years in different parts of Iran. Therefore, development of drought-tolerant cultivars with high essential oil yield is important in coriander. This research was conducted in order to evaluate the effect of drought stress on morphological, physiological and phytochemical characteristics of endemic coriander genotypes.

F2 generations derived from half-diallel crosses of six endemic coriander genotypes including Isfahan, Hamedan, Bushehr, Mazandaran, Markazi and Alborz, together with their parents were evaluated in randomized complete block design with three replications in each experiment during growing season of 2016 in the research field of Tarbiat Modares University. Plants were treated with different levels of water treatment: well watered (WW), moderate water stress (MWS) and severe water stress (SWS). Data were collected on fruit yield, essential oil content and essential oil yield. GGE biplot statistical method (genotype effect + genotype × environment interaction) was used to study stability of genotypes in the studied environments.

Results of Combined analysis of variance indicated that the effects of environments, genotypes and genotype × environment interaction were significant, suggesting that the genotypes responded differently in the studied environment conditions. So, there was the possibility of stability analysis. Results of stability analysis using GGE biplot method indicated that the two first and second principal components of the GGE biplot explained 96.4% of the total essential oil yield variation. Based on a hypothetical ideal genotype biplot, the genotype G17 was better than the other genotypes across environments for essential oil yield and stability and had the high general adaptation in all environments. . Furthermore, the genotype G9 at E1 environment and genotype G18 in E2 and E3 environments were superior genotypes with the high specific adaptation. Too, the results showed that all environments had high discriminating ability so that could able to show differences between genotypes. The moderate stress environment was the nearest environment to ideal environment that had the highest discriminating ability and representativeness.

Generally, the results indicated that all environments had high discriminating ability so that could able to show differences between genotypes. Also, the genotype as stable and drought tolerant genotype can be considered as donor parent which contains drought tolerance genes and could be used to improve coriander high essential oil yield in drought condition.

Drought stress is one of the major risks to wheat production in many parts of the world. Due to its multidimensional effects, drought stress become a known concern for food security. The purpose of this study was to evaluate the effect of drought stress on agronomic traits of wheat using meta-analysis. A large number of studies have been conducted worldwide regarding effect of drought stress on crops as a major risk in cereals production. The multi-dimentional effect of drought on agronomic traits of wheat are too complex to compare using traditional methods. Therefore, meta-analysis was used in the present study to identify general trends among numerous independent drought-related studies and combine the results into one measure known as the effect size. Meta-analysis of field trials data can provides an overall view of variables affecting crop traits and precision of experimental data. The purpose of this study was to evaluate the effect of drought stress on agronomic traits and evaluating reliability of studies using meta-analysis.

Using scientific database of agronomic researches, 120 articles were evaluated to build a database of experimental data. The study synthesized results from 60 papers and published researches on drought effects and the database was built based on keywords such as wheat, drought stress, yield and agronomic traits. All studies that met the following criteria were included in the database: (1) available data of trial and control plots, (2) reported data of drought effect on at least one of five traits(yield, harvest index, biological yield, 1000-grain weight and grain per spike of wheat). The effect size for each datasets was calculated using cohen's index. Cohen's methodology applies differences between trial and control data as a measure of effect size. As a common measure in meta-analysis, Standard Mean Difference(SMD) used to evaluate precision and bias of experimental data of studies. I-squared measure used as estimation of heterogeneity for results of studies. An I-squared of less than 50% is usually viewed as low heterogeneity and over 50% as high heterogeneity.

The results of analysis demonstrated that effect of drought stress on all mentioned agronomical traits is significant and negative. Using Cohen's index, the calculated effect size of drought stress on varies from 1.9248 to 4.4280 among traits. Grain yield had highest effect size and harvest index showed the lowest among all traits. Lower effect size in harvest index shows tolerance of the trait and it's relative sustainability during stress period.
Analysis of experiments showed a medium rate of heterogeneity in studies on grain yield, harvest index and biological yield and a higher heterogeneity in trials on 1000-grain weight and grain per spike.

Using meta-analysis in agronomic researches provides a framework to examine reliability and generalizability of experiments and individual studies. Drought stress affects many agronomic traits of wheat in different way in spite of statistical significance, results of many studies are not reliable and evident degrees of biases. Higher heterogeneity of experimental data shows a higher probability of bias and less trustable results in the examined researches and lower reliability of the sources for field application and generalization of the results.

Legumes contain an average of 18-32% protein and are an important source of protein for low-income people (Majnoun Hussein, 2008). Chickpea (Cicer arietinum L.) Is known for its resistance to moisture changes; this plant shows physiological and morphological changes under conditions of water scarcity (Ghorbanli et al., 2001). Chickpea grows in a wide range of weather conditions from the subtropical to Mediterranean regions of western Asia, northern Africa, and southern and southwestern Europe (Toker et al. 2007). Environmental stresses are the most important factor that limits crop production of chickpea. The most critical environmental stresses that have a negative effect on crop production are water and heat stresses (Rahbarian et al. 2011). By applying the effect of different levels of irrigation and plant density on yield and yield components of chickpea, grain yield, 1000-seed weight, the number of pods per plant and harvest index decreased during drought stress (Raei et al., 2008). Severe drought stress, by reducing the water uptake by the roots, disrupts the transfer of sap in the phloem, which ultimately leads to a decrease in nutrient uptake and the activity of antioxidant enzymes (Armand et al. 2016). Plant density is one of the most important management factors on crops that will affect plant yield. When competition for growth increases, the yield will be decreased. The selection of appropriate plant density should be based on environmental factors such as cultivar, cultivation target, weed competition, seed size, soil moisture content, and plant characteristics including plant height, plant density, leaf angle, and production capacity of the growing environment (Khajehpour, 2008). According to the above, this study was conducted to investigate the effects of different levels of irrigation and planting density on some agronomic traits of white chickpea in Karaj.

To investigate the effect of water regime and plant density on some agronomical traits of chickpea (Cicer arietinum), a split-plot experiment based on randomized complete block design with three replications conducted at the College of Agriculture and Natural Resources of Karaj, Iran in 2015. The water levels included eight levels (I1 =full irrigation at all growth stages, I2 = irrigation to grain filling and then stop, I3 = irrigation to podding and then stop, I4 = irrigation to flowering and then cut, I5 = 50% of full irrigation at all growth stages, I6 = 50% of full irrigation to grain filling and then stop, I7 = 50% of full irrigation to podding and then stop, I8 = 50% of full irrigation to flowering and then stop, considered as the main factor and plant density at three levels (30, 40 and 50 plants.m-1) as subplots. Geographical characteristics of this farm include 1321 meters above sea level, longitude 51 degrees east, latitude 35 degrees and 48 minutes north. This region has a hot and dry climate with an average rainfall of 33 years, about 248 mm.

The results showed that increasing water deficit stress reduced the growth traits and ultimately the grain yield of chickpea cultivar ILC 482. Increasing plant density increased the growth traits of yield components and grain yield. The highest grain yield (2892 kg. ha-1) was obtained in full irrigation (I1), and the lowest (1075 kg. ha-1) gained from I4. The highest grain yield (2068 kg. ha-1) was acquired at 40 plants m-1.

The results of this study showed that low water stress reduced the yield of chickpeas, but since Iran has low average rainfall, it is possible to achieve a good yield by using 50% irrigation at all stages of growth.

Water deficit stress occurs when a combination of physical and environmental factors reduces the availability of water in the root environment and the structure of the plant, thereby reducing crop yield. One of the most important stresses is WDS, which may occur under low rainfall conditions, high temperatures and winds. The response of the plant to WDS depends on the stage of growth in which the drought occurs at that stage. WDS limits photosynthesis by stomata to close and, thus alter the physiological traits and productivity of plants such as synthesis of photosynthetic pigments, antioxidant enzyme activities, proline, anthocyanin, and etc. Tolerant crops cultivation is a quick and low-cost methods that could be used to increase the yield of crops and economically productive under stress conditions. Thus, the aims of this experiment was to study the effect of WDS on seed germination indices, seedling physiological traits, yield and physiological and biochemical responses of sesame, hemp, and purslane under laboratory and field conditions.

Field experiment was performed as a split-plot based on a randomized complete block design with three replications. Irrigation levels based on the potential for evapotranspiration at three levels (40%, 70% and 100%) and three plant species (sesame, purslane and hemp) were as main plots and sub plot, respectively. Germination test was conducted as a factorial based on a completely randomized design with three replications to evaluate the effect of drought stress (at four levels of zero, -3, -6 and -9 bar) and sodium silicate (at three levels of zero, 1.5, and 3 mM) on germination characteristics of these three plants. After checking the normality of data distribution assumption, the studied traits were statistically analyzed by the Statistical Analysis System software (SAS) for germination and field experiments. The differences among means were using the least significant difference (LSD) test at 0.05 level of significance.

The highest GP (86%) was achieved purslane seed under the non-stress condition and lowest GP (39.33%) was in hemp seed under -9 bars. Increasing the WDS severity, GR showed a significant decrease in the three crops. Although, in all three crops, GP and GR showed significantly reducing compared to the non-stress condition, the rate of GP reduction were different. These reductions in sesame, hemp, and purslane seeds compared to the control treatment were 15.3, 24.6, and 48.06%, respectively and rate of GR reduction was 37.1, 28.7, and 59.8%, respectively Seed priming with sodium silicate at the level of 1.5 mM in drought levels increased the mean weight of seedling vigor index. The effect of WDS on total chlorophyll of sesame, hemp, and purslane seedlings was significant. Among the osmotic potential levels, -3 bars treatment had the highest total chlorophyll content (37.1 µg/g FW). The interaction effects of year × WDS × crops on seed yield were significant. Mean comparison of triple interaction showed that the purslane plant in both years and sesame plant in the first year under non-stressed conditions (100% PET) had the highest seed yield (1389.8, 1355.7, and 1352.4 kg/ha, respectively). The lowest this trait was related to hemp plant under severe stress conditions (40% PET) in both years of experiments. The average seed yield of two years was high in purslane crop but the mean seed yield loss under WDS was lowest in sesame and highest in hemp crops. These results indicate the superiority of two purslane and sesame crops compared to hemp under WDS. Among the plants tested, purslane had the highest total chlorophyll content. In conclusion, although purslane had the highest grain yield, the reduction in grain yield under severe stress conditions was the lowest in sesame and the highest in hemp. Overall, the results of the germination and field experiments showed that purslane was more tolerant of drought stress due to its morpho-physiological characteristics.

Drought is one of the most important environmental stresses and occurs for several reasons, including low rainfall, salinity, high and low temperatures, and high intensity of light. Drought stress causes changes in the physiological, morphological, biochemical, and molecular traits in plants. In Iran, many regions suffer from water stress. Moreover, rapeseed is one of the best crops for rotation with wheat. So, and the culture of rapeseed has been increasing recently in Iran. However, rapeseed often suffers from many stresses, such as salinity, cold and drought, which cause great yield loss every year. Since the rapeseed is an economical crop in Iran and drought stress is a limiting factor for crop production, this study was performed to compare some drought resistance mechanisms in sensitive and tolerent cultivars of rapeseed.

This research was designed to identify some drought resistance mechanisms in two cultivars of rapeseed. (Sensitive and tolerant) in germination (with five drought levels) and vegetative stages (zero, low, moderate and severe levels). Polyethylene glycol 6000 (PEG) was used to induced drought. Finally, pigment photosynthesis, proline content, and activity of guaiacol peroxidase was determined. The data obtained undergone a two-way analysis of variance and the mean differences were compared and tested by Duncan test using SPSS v. 2016 software from three replications. Differences at P≤0.05 were considered significant.

In the low level of drought stress, the significant difference was not observed between cultivars at the germination stage. However, the results showed that with increasing drought, germination percentage and shoot length decreased so that it reached zero at the lowest water potential, while root length increased at -0.14 MPa osmotic potential and then decreased at the lower water potential. In the second stage of experiments, the amount of photosynthetic pigments enhanced with reduction of water potential and it was more under moderate and severe stress in sensitive and tolerant cultivar, respectively. Also, the proline content increased to the level of moderate drought stress, which was significantly higher in the tolerant cultivar than the sensitive cultivar. Except for severe drought, the activity of guaiacol peroxidase enzyme was not statistically significant between other treatments and it was more in the roots of tolerant plants compared to sensitive plants. In general, due to the high amount of photosynthetic pigments and proline and guaiacol peroxidase activity in resistant cultivars, it can be suggested that increased efficiency of photosynthesis under stress as a result of more photosynthetic pigments, effective removal of ROS due to high activity of guaiacol peroxidase enzyme and higher compatibility as a result of osmotic regulation by proline accumulation, are part of the mechanisms of coping with dehydration in tolerant canola cultivars.

The results of this study showed that just germination factors could not confirm the sensitivity and resistance of rapeseed cultivars, and more experiments in the hydroponic culture medium is a better way to identify resistant cultivar.

Fertilizer use is cost-effective until the higher yield supply the cost of consuming more fertilizer. In other words, like any other investment, fertilizer use should have a reasonable return because the law of diminishing returns also applies to fertilizers (Khajehpour, 2008). Application of nitrogen increased Seed yield and Protein percentage but nitrogen agronomic efficiency decreased (Doaei, 2018). In many crops, topping reduces vegetative growth and transfers more and better photosynthetic materials to specific organs, especially seeds. This increases the penetration of light into the canopy and the lower leaves of the plant can use more light. Therefore, increases the photosynthesis of the lower leaves, transfers more photosynthetic materials to growing organs and as a result, productivity will increases. It seems that earlier topping will reduce the number of pods per plant and will improve the conditions for photosynthetic material to be transferred to the pods. Thus, more seeds per pod will be produced. Furthermore, the flowers that will be set in late, have no opportunity to form a large pod and consequently, the fewer seeds will be set in the pod. Delay in topping will reduce the number of seeds per pod of faba bean (Nakhzari Moghaddam, 2013).

In order to study the effect of topping, nitrogen and supplemental irrigation on green pod yield, protein percentage, proline rate and agronomic efficiency of nitrogen in faba bean, a factorial experiment based on Randomized Complete Block Design was conducted with three replications at research farm of Gonbad Kavous University during growing season of 2016-2017. Planting date was 11.13.2016 and harvest date was 5.6.2017. Topping factor was in three levels of non- topping, topping at beginning of flowering and topping at beginning of seed filling, nitrogen in three levels including 0, 50 and 100 kg nitrogen per hectare and supplementary irrigation in two levels of non irrigation and irrigation at the filling stage. Each plot had four rows with 50 cm width and four meter length. Seed planted in depth of three cm. one third of nitrogen were used in sowing date, one third in branching and other one third in seed filling stage. Supplemental irrigation was done in 5.24.2017, first topping in 4.30.2017 and second in 5.13.2017.

The results showed that the effect of topping on green pod yield, proline rate and agronomic efficiency of nitrogen was significant but on protein percentage was not significant. Effect of nitrogen and supplementary irrigation on green pod yield, proline rate, protein percentage and agronomic efficiency of nitrogen were significant. Green pod yield in none topping treatment, topping at the beginning of flowering and seed filling stages was 21523, 29118 and 27737 kg.ha-1, respectively. The highest yield of green pod with 29118 kg.ha-1 was related to consumption of 100 kg N.ha-1 and the least was related to treatment of non application of nitrogen with 22149 kg ha-1. Although application of nitrogen increased green pod yield but agronomic efficiency of nitrogen was decreased. Reducing of nitrogen use efficiency was due to increasing nitrogen loss through leaching and sublimation and the lack of effective absorption by the plant. Supplemental irrigation increased green pod yield 5143 kg ha-1 (21.83%). Topping by reducing top dominance transfered more nutrients into pods and therefore pod yield increased. Agronomic efficiency of nitrogen in treatment of topping at beginning of seed filling was 89.85 and at beginning of flowering was 55.96 seed grain/kg nitrogen. Nitrogen consumption increased protein percentage of the seed so that in treatment of 100 kg Nha-1 protein percentage was 22.65 (7.65% more d the protein cont than non consumption). Proline rate and protein percentage in none irrigation treatment was greater than irrigation treatment but green pod yield and agronomic efficiency of nitrogen was lower.

Topping, nitrogen consumption and irrigation increased green pod yield. Therefore, for obtaining more yield of faba bean it is nessesary to remove head of plant, use enough nitrogen and irrigate plans at least one time in reproductive stage.

Potato is an important food crop with high yields. However, when exposed to drought it suffers major yield losses. Considering its global importance and the increasing incidence of drought due to climate change, research toward drought tolerance in potatoes remains imperative. In vertebrates, estrogen, and androgen steroidal hormones have important functions in development and reproduction. Estrogens and estrogen-like compounds (xenoestrogens) from livestock manure, animal waste, and human waste (especially pharmaceutical waste), are being disposed of and excreted at high rates into the agricultural soil and groundwater all over the world. The aim of this study was to investigate the effect of the β-estradiol application on the tolerance of different potato genotypes to water deficit stress.

To study the effect of β-estradiol application in enhancement of drought tolerance in different potato genotypes, an experiment was conducted as a factorial split-plot arrangement with three replications in the greenhouse of Zare Gostar Arta Technology Company in Ardabil. Treatment of drought stress was reducing the amount of irrigation water (100, 60, and 40% of available water) and β-estradiol hormone at three levels of zero (control), 10-6 and 10-12 molar both in the main plots and 10 potato genotypes were placed in sub-plots. In the present study plant height, leaf relative water content, number of tubers per plant, tubers weight per plant, mean tubers weight, reducing sugar percentage, dry matter percent, protein tubers percent, starch percent, proline content, superoxide dismutase, catalase activity, and polyphenol oxidase were measured. Data were analyzed by using SAS software, 9.2, and also the mean of the studied traits were compared by LSD test at 5% probability level.

The results of the analysis of variance showed that there was a significant difference among the drought levels in terms of all studied traits. Difference between β-estradiol levels in terms of plant height, number of tubers per plant, the weight of tubers per plant, mean tuber weight, the relative water content of leaves, tuber dry matter percent, protein tuber percent, percentage of starch, and catalase, polyphenol oxidase and superoxide dismutase contents was significant. Interaction effect of drought and hormone on plant height, tuber weight per plant, mean tuber weight, number of tubers per plant, tuber dry matter percent, the relative water content of leaves, reducing sugar percent, starch percent, catalase and polyphenol oxidase was significant. There was a significant difference between the studied genotypes in terms of all studied traits. Interaction effect of genotype × drought on plant height, the relative leaf water content, number of tubers per plant, tuber weight per plant, mean tuber weight, tuber dry matter percentage, protein percent, starch percent, proline content, catalase, and superoxide dismutase was also significant. Finally, the interaction of genotype × hormone on plant height, relative leaf water content, number of tubers per plant, tuber weight per plant, tuber weight mean, dry matter percent, protein percent and catalase content was significant. In all three drought levels, the highest number of tubers per plant allocated to two genotypes of G3 and G6. The highest relative water content was assigned to the G6 genotype, the highest percentage of regenerating sugar and the percentage of the dry matter assigned to the G3 genotype and the highest plant height, the percentage of starch and the percentage of protein assigned to the G4 genotype.The results showed that under normal conditions, G6, G4, and G3 genotypes (with an average of 96.90, 93.77, and 92.04 g/plant respectively) had the highest tuber weight per plant. In drought treatment of 60% of usable water supply, although the highest tuber weight was assigned to G1 genotype, there was no significant differences between the mentioned genotype and G2, G3, G5, and G6 genotypes. Also, in drought treatment of 40% of usable water supply, there was only significantly difference between G6 and G9 genotypes. In this study, the use of β-estradiol (especially the level of 10-12 molar) in all three water deficit treatments significantly increased the plant height, mean tuber weight, relative water content, dry matter percentage, starch percentage, proline, catalase and polyphenol oxidase contents as compared with the control. Finally, the highest plant height, number of tubers per plant, tubers weight per plant, dry matter percentage, and protein content were assigned to the G4 genotype with 10-12 molar of β-estradiol. Finally, among the studied genotypes, G4 at the level of 10-12 (with an average of 62.21 g/plant) had the highest tuber weight per plant.
 

 Based on the results of the present study, it can be stated that both G3 and G6 genotypes can be promising genotypes for cultivation under normal conditions and mild drought stress in the study area. In the drought treatment of 40% of usable water supply, only a significant difference was seen between G6 and G9 genotypes. It can be concluded that the response of the 10 genotypes to severe drought stress conditions was almost similar. Also, the genetic potential of G4 and G6 genotypes for uptake and use of β-estradiol was higher compared to other genotypes. Furthermore, the use of β-estradiol hormone can improve the quantitative and qualitative characteristics of potato genotypes under water deficit conditions.

Water shortage is the most important non-biological limiting factor for achieving the potential of crop yield. The millet is one of the drought-tolerant species that the study of its specific traits can help to identify the effective mechanisms of drought coping. Humic acid contains abundant elements that improve soil fertility and increase the availability of nutrients to plants, thus affect their growth and yield, but in the millet, humic acid function on increasing tolerance to drought is unclear.

To evaluate the effect of humic acid foliar application on yield and yield components of millet under drought stress conditions, the experiment conducted in 2015 using a split-plot based on randomized complete block design (RCBD) with three replications. Irrigation regime considered as the main factor including two levels of normal irrigation and drought stress (irrigation cut off) at 50% flowering stage and sub-factors also included the foliar application of humic acid at five levels (1, 3, 5, 7% humic acid and pure water as control) in the Ramjeard region of Fars province.

The results of this study showed that drought stress caused a significant decrease in the most morphological and physiological traits such as leaves chlorophyll content, the number of grain per spikes, 1000-grain weight, grain yield and harvest index but also humic acid has greatly controlled the effects of drought stress, then, ultimately the performance of treatments with humic acid was more than the control treatment. The remarkable point in this study was the process of changes in biochemical traits, that by increasing the percentage of humic acid, biochemical traits such as proline, superoxide dismutase and peroxidase enzyme decreased, these changes showing a positive effect of humic acid in reducing the effects of drought stress. As a result, the use of humic acid foliar application increased the leaves chlorophyll content, the number of spikes m-2, 1000-grain weight as well as grain yield, so that changes in 7% humic acid treatment were higher compared to the other treatments. The highest proline content was related to foliar application with water (control) under drought stress conditions, while the lowest proline content observed in 7% humic acid foliar application under normal irrigation conditions. The amount of superoxide dismutase under normal irrigation conditions was significantly lower than all drought stress treatments. Under drought stress conditions the highest rate was observed in foliar application with water (control), which could be confirmed by reducing the amount of superoxide dismutase as a result of using humic acid under stress conditions. The highest amount of peroxidase enzyme was observed in foliar application with water (control) under drought stress conditions. Generally, peroxidase content was significantly higher in drought stress treatments than in normal irrigation conditions. Under drought stress conditions, the highest chlorophyll a content was observed in the foliar application of 7% humic acid, similarly, the highest amount of chlorophyll b was observed in the foliar application of 7% humic acid, while there was no significant difference with foliar application of 5%. In this experiment, the number of grain per spikes affected by humic acid application and the interaction of drought stress and humic acid. Humic acid compensated for the negative effect of drought stress on the number of grain per spikes. Among drought stress treatments, using 7% humic acid increased the number of grain per spikes by 12% compared to control treatment. The comparison of two irrigation regimes showed the highest and lowest yield observation under normal irrigation and drought stress conditions, respectively. The yield under drought stress decreased by 56% compared to normal irrigation. Generally, we can conclude that even though drought stress significantly decreased the number of grains per spikes, 1000-grain weight and yield, but the variation trend of biochemical traits in drought stress treatments was significantly decreased proline, superoxide dismutase and peroxidase with increasing of the humic acid percentage, while the amount of chlorophyll a and chlorophyll b increased.

It seems that humic acid can improve the morphological and physiological characteristics of the conventional millet in drought stress conditions. It seems that humic acid can play a role in improving biochemical and physiological characteristics of conventional millet under drought stress conditions, so that by reducing the effects of drought stress increased chlorophyll and ultimately improved the photosynthesis rate. Therefore, the yield and yield components of humic acid treatments were higher than foliar application with water (control).

Sesame (Sesamum indicum L.) is one of the important oil crops that get attentions due to its relatively high oil content and tolerance to drought. Drought is one of the most important causes of crop products reduction and can affect plant phenology, growth and yield depending on the severity, time and stage of plant development. Superabsorbent polymers are suitable materials for increasing soil water retention capacity that can provide better conditions for crop growth, especially under water deficit conditions. The importance of useing chemical fertilizers in addition to their nutritional role, is to support the crop in tolerating environmental stresses such as drought and preventing yield loss which potassium has such role in plant life and survival under stress conditions. Potassium fertilizers, especially potassium sulfate, can play an important role in reducing the negative effects of water stress. Potassium is the third main nutrient for plant growth and plays a special role in the survival of plants under environmental stress and increasing their resistance to drought, high temperatures, cold, disease, salinity, weeds and maintaining osmotic potential.

In order to investigate the effect of superabsorbent polymer, potassium sulfate and water deficit on growth, yield and yield components of sesame (Sesamum indicum L.), an experiment was conducted out on factorial arrangment based on randomized complete block design with three replications in Research Field of Agricultural College, at Birjand University in 2018. Experimental factors included three levels of irrigation (full irrigation in the whole growing season, irrigation up to 50% flowering stage and cutoff irrigation until maturity, and irrigation up to 50% capsules appearance and cutoff irrigation until maturity), potassium fertilization at three levels (No potassium application, fertilizing at optimum recommendation using 100 kg.ha-1 potassium fertilizer and fertilizing 50% higher than optimum recommendation using 150 kg.ha-1 potassium fertilizer) and superabsorbent at two levels, including no application and 100 kg.ha-1 application. The studied traits were plant height, number of lateral branches, seeds per capsule, capsule per plant, 1000-grain weight, grain yield and days to maturity.

Results showed that irrigation levels had a significant effect on measured traits except for number of lateral branches. The highest grain yield (2316.61 kg.ha-1) was obtained under full irrigation conditions and the lowest seed yield (667.89 kg.ha-1) was observed at 50% flowering cutoff irrigation. The effect of superabsorbent on all traits was significant. The results showed that superabsorbent moderated the effects of drought and improved sesame growth indices. Interaction effect of potassium and irrigation on grain yield was also significant. Although, under water deficit conditions, grain yield was significantly reduced, but potassium sulfate application under these conditions partially prevented the yield loss. Due to the role of potassium in the plant, the presence of this element in water deficit conditions can be effective in tolerance and crop yield increment. The highest number of days to maturity (124.77 day) in interaction effect of water deficit and superabsorbent was obtained from full irrigation and 100 kg/ha superabsorbent treatment and the least amount (109.55 day) was obtained from50% flowering cutoff irrigation and non-superabsorbent treatment.The increase in soil moisture caused by the use of soil moisture absorbers can increase the duration of the day to maturity.

The results showed that irrigation levels decreased sesame growth and yield. Water deficit at flowering and encapsulation stages reduced grain yield compared to full irrigation treatment. Therefore, it is necessary to irrigate the crop according to water requirement during these stages. Due to the necessity of conserving available water resources as well as optimum consumption of water, the use of superabsorbent and potassium can be effective in increasing crop yield and drought resistance. Obviously, it is necessary to provide sufficient water requirement in order to achieve higher grain yield. Therefore, it seems that hydrogels reduce the negative effects of drought by absorbing water and making it available for the crop. Potassium application in environments with different levels of drought can be considered as a practical method to reduce drought damage and prevent yield loss.

Proper management and the use of advanced methods to preserve and store soil moisture and increase water containment capacity are among the most effective measures to increase water use efficiency and thus improve the utilization of water resources of the country. Considering the importance of chickpea as a source of protein and, on the other hand, the irreparable damage of drought stress to chickpea performance, it is very important to adopt methods that can increase the plant tolerance to drought stress. Considering the importance of chickpea as a source of protein and, on the other hand, the irreparable damage of drought stress to chickpea performance, it is very important to adopt methods that can increase the plant tolerance to drought stress. Recently, the use of superabsorbent has increased due to the ability to absorb and maintain water and consequently increase water use efficiency in the soil. Therefore, the aim of this study was to determine the proper amount of diatomite to obtain maximum chickpea yield under drought stress conditions.

In order to investigate the effect of diatomite on some of the morphological and physiological characteristics of chickpea under different irrigation regimes, a test was conducted in Khaf in the year 1397-1396. This research was conducted as split plot based on randomized complete block design with three replications. The main factor of irrigation regimes was five levels (full irrigation, rainfed, one irrigation only in vegetative stage, one irrigation interval only at reproductive stage, two irrigation intervals, one vegetative stage and one reproductive stage) and factor The subdivisions of Diatomite were in three levels (0, 3.5 t/ha and 7 t/ha). Each plot had 6 planting lines at a distance of 30 cm from each other and 3 m long. In this experiment, diatomite was placed under the seeds next to the ridges at a depth of 20 cm (maximum root density area). Cultivation was done manually on the 15th of Esfand month with a density of 45 plants per square meter and a depth of 5 cm. In this experiment, native chickpea mass of Khaf region was used.

The results showed that changing the irrigation regime from full to dry farming irrigation reduced Height stem, stem diameter, Number of primary branches, Number of secondary branches, relative water content, seed yield and increased relative electrolyte leakage. Application of diatomite under different irrigation regimes increased all evaluated traits and seed yield. The application of 7 t/ha of diatomite compared to the non-application of diatomite increased 29, 29, 77 and 39 percent of seed yield in irrigation regimes, including dry farming, one irrigation in the vegetative stage, one irrigation in the reproductive stage, two irrigations included vegetative and reproductive stages. The results of interactions showed that the application of 7 t/ha of diatomite under irrigation treatment in the vegetative and reproductive stages in stem diameter, Number of secondary branches, relative water content and relative electrolyte leakage was significantly different from the application of 3.5 t/ha of diatomite. Only in seed yield under irrigation treatment in vegetative and reproductive stages, application of 7 t/ha of diatomite in the joint statistical group with application of 3.5 t/ha of diatomite was included, although it had a higher numerical value.

In general, using diatomite as a superabsorbent while saving the cost of production in arid areas, by maintaining and storing soil moisture and improving soil water permeability can be an effective step towards exploiting limited water resources. And increase grain yield in the harvest. It is also recommended to further study and use different amounts of diatomite in a certain range of moisture stress and also the effect of its use on the amount of nutrients in soil and water.

Iran is one of the arid and semi-arid regions of the world with an average rainfall of 240 mm per year. Water scarcity is one of the most important abiotic stresses that adversely affects the yield of garden plants. However, the use of new technologies such as nanoparticles can be effective in improving plant performance. Metal nanoparticles such as nano-titanium, zinc, iron, aluminum and silver can be effective in increasing the supply of elements in the roots and shoots of plants. Recently, the use of titanium nanoparticles has been highly regarded by plant physiologists due to its outstanding properties.

For this purpose, a factorial experiment based on a completely randomized design with four replications on tarragon (Artemisia dracunculus) was designed and conducted at Ferdowsi University of Mashhad. Experimental treatments included three levels of drought stress (90, 70 and 50% of field capacity) and three levels of nano titanium dioxide (0, 10 and 20 ppm). The method of applying titanium dioxide nano treatments was foliar spraying. In this way, the above treatments were sprayed on tarragon leaves in four stages every seven days (two stages before stress and two stages after drought stress). At the end of the experiment, the following traits were measured. Plant height, number of lateral stems and number of leaves per plant were recorded. Dry weight of shoot, root and total dry weight after drying in an oven at 70 ° C for 48 hours were measured with a digital scale with an accuracy of 0.001. Stem diameter, root length and root diameter were calculated with a digital caliper and leaf area with a leaf area meter. Relative water content, electrolyte leakage, chlorophyll a, chlorophyll b, total chlorophyll and carotenoids, total carbohydrates and percentage of antioxidant activity were measured

According to the results, the highest shoot and root dry weight of tarragon were in 90% of irrigation and foliar application with 10 and 20 ppm titanium dioxide and also the lowest percentage of antioxidant activity (49%) and the percentage of total carbohydrate solution (14%) was seen in 90% FC and in the absence of foliar application with nano titanium dioxide. Root diameter, height and stem diameter increased by 41.8%, 39.5%, and 42.2% in 90% FC and 10 ppm nano titanium dioxide compare to 0 ppm nano titanium dioxide at the same drought levels (90% FC). By increasing the concentration of nanoparticles from 0 to 20 ppm these traits increased by 16.4, 8.8 and 16.5% respectively, at 50% FC. As the results show, the dry weight of the plant decreased under drought stress. In fact, plant dry weight is affected by plant growth and photosynthesis process and decreases with decreasing photosynthesis under stress conditions. On the other hand, the condition of plants in drought stress conditions is improved by the use of nano titanium and the dry weight of the shoot is increased. Studies have also shown that drought stress significantly reduces the content of chlorophyll a, b, total chlorophyll and carotenoids. On the other hand, an increase in chlorophyll content under stress conditions has been reported due to the use of nano-titanium

In general, although drought stress reduced morphological traits and photosynthetic pigments in tarragon, foliar application of titanium dioxide at concentrations of 10 and 20 ppm was effective in improving these traits. It has been reported that titanium nanoparticles may increase photosynthesis and efficiency by increasing light reception and increase the plant's carbohydrate production potential. Studies by Soltani et al. Have shown that titanium nano dioxide has an effect on the activity of antioxidant enzymes such as catalase, peroxidase and ascorbic peroxidase.

Origanum is a plant of the Lamiaceae family that is considered one of the most important and best-selling medicinal plants in the world. The aerial parts, especially the leaves of different species of Origanum, have always been used as one of the most popular spices and flavorings in the food, perfume and cosmetics industries. Drought is one of the most important abiotic stresses may cause deleterious damage to plants. Lack of access to adequate amount of water or increase in transpiration can induce drought stress in plants and alter the production of metabolites. Drought stress reduces the water and turgor potentials, thereby negatively affecting various physiological processes. Chitosan is a natural biodegradable substance derived from crustacean shells such as crabs and shrimp. Having unique biological and physiological properties, it has found several applications in various industries such as pharmaceuticals, medicine and agriculture. As a bio-elicitor, chitosan prevents severe damage to plants under stress conditions by increasing the plant's defense activity.

This experiment was performed in 2019 in the research greenhouse of Azarbaijan Shahid Madani University, Iran as a factorial experiment in the complete randomized block design with three replications. The experiment treatments included three different concentrations of chitosan as foliar application (0, 250, 500 mg/l), and drought stress treatment at two levels (no stress and water deficit stress) in two species of Origanum (Origanum vulgare, Origanum majorana). The Origanum seeds were obtained from the Forest and Rangeland Research Organization and planted inside the seedling trays. Then, as the plants reached the desired growth of 4- and 5-leaves stages, each of the plant seedlings was transferred to plastic pots with the opening diameter of 15 cm, height of 25 cm, and capacity of 4 kg. The soil transferred to the pots had a loamy texture and a mixture of 33.32% sand, 40% silt, and 26.48% clay. Also, the soil inside the pots had a pH equal to 7.96, electrical conductivity of 2.8, organic matter of 2.415%, organic carbon of 1.401%, and calcium carbonate of 12.5%. The pots were kept in the greenhouse for 16 hours in light at 24 °C and 8 hours in dark at 18 °C. The application of water deficit stress treatment and foliar application of chitosan was performed in three stages three weeks before the complete flowering. In this experiment, a TDR moisture meter was used to measure the soil moisture of each pot for applying the water deficit treatment.

The results of the present study show that the water deficit stress reduces total shoot dry weight. This reduces the yield when regarding the yield of aerial part of the plant. It should be noted in this study that the foliar application of chitosan under the water deficit conditions improved this trait. In this study, the foliar application of chitosan at the concentration of 500mg/l under the water deficit stress conditions increased the shoot dry weight. The results showed that the water deficit stress reduced relative water content, chlorophyll a, chlorophyll b, total chlorophyll and carotenoids, while increasing the hydrogen peroxide (H2O2), malondialdehyde (MDA) and proline contents. The foliar application of chitosan under water deficit stress conditions increased RWC, chlorophyll a, carotenoids, total chlorophyll, and proline contents.

According to the results of this study, by conducting extensive research, the use of chitosan as a bio-elicitor to reduce the water deficit stress in the medicinal plant of Origanium can be suggested and the positive aspects of chitosan to be used for improving the physiological parameters in Origanium and other medicinal plants. In the end, it is suggested to perform this research in the areas with different climates, especially arid and semi-arid climates, with different concentrations of chitosan on different plants.

Drip irrigation delivers moisture to the soil surrounding the plant root, leaving the uncultivated ridges mostly dry. The dynamics of dryness and moisture can help adjust the soil salinity and redistribute moisture and salinity (Li et al., 2013; Wang et al., 2011). Further, the distribution of soil salinity in arid regions is affected by a multitude of factors, including the water table (Ming et al., 2016), groundwater salinity, (Abliz et al., 2016), irrigation system (Lie et al.,2013;Zhang et al.,2017), and soil texture (Hu et al., 2011; Zhang et al., 2014). Given the complexity of investigating moisture and salinity distribution in the soil and their uptake by plant roots, the subject has been addressed by several studies around the world. The present study attempts to investigate and evaluate the effects of different irrigation regimes (two-, three-, and four-day) using a tape drip irrigation system on the diffusion and distribution of salinity and moisture around the root of summer maize over two crop years (2018–19) in the South Khuzestan region, where a heavy soil texture is predominant.

Located between the 29°57’ N and 33°0’ N relative to the equator, and between 47°40’ E and 50°33’ E relative to the prime meridian, Khuzestan Province occupies 64,057 square kilometers in Southwest Iran. The present study was carried out in a research farm at the Center for Agriculture and Natural Resources Research and Training, Ahwaz, Khuzestan Province, in summers 2018 and 2019. With clay and silty clay soil textures, shallow and saline groundwater (1.5 m depth), and its particular climate, this research farm can be representative of the farmlands of Central and Southern Khuzestan. The required volume of water during each irrigation by the drip tape irrigation system under different irrigation regimes (two-, three-, and four-day) was calculated for different plant development stages and treatments, thus enabling control over the different irrigation hours in different regimes. the farm soil was sampled at four stages, namely before planting, upon germination, during the middle development stage, and after planting), for physical and chemical characterization and monitoring salt levels from three depths (0–25, 25–50, and 50–75 cm) at a 20 cm distance from the tape by manual excavation using an auger (10 cm in diameter and 20 cm in length). Soil salinity and other quality criteria were measured in the lab. Further, the SMC was measured by the weight percent method, which involves weighing and drying the samples.

The present study addressed moisture and salinity distribution in the soil profile around the plant root under different irrigation regimes. The moisture distribution results showed that all irrigation regimes (two-, three-, and four-day) could maintain the moisture around the FC, slowing down the vertical flow and minimizing penetration into depths. The soil salinity results showed that, considering the soil salinity conditions at the start of the growing season, using the drip tape irrigation first reduced and then increased salinity in the first year of cropping. In contrast, in the second growing season, soil salinity at the end of the growing season using two-, three-, and four-day irrigation regimes was cut to a fourth and a third of its initial level. This shift in the behavior was, however, due to the differences in the quality of irrigation water. This outcome shows the susceptibility of using the drip tape irrigation system in soils that are prone to sodicization and salinity, which requires preparing the conditions to ensure the sustainable function of the irrigation system. The final set of samples showed that, under all irrigation regimes, the emitter output effectively reduced soil salinity, and that this reduction is more effective with frequent irrigations, washing the salts further away from the source. Further, the 0–25 cm deep layer was found to have the least salinity among the studied layers. All irrigation regimes (two-, three-, and four-day) were successful in controlling salinity in the root zone, but the two-day treatment, with a shallower irrigation depth and shorter irrigation intervals, offered the best leaching. The results of performance analysis in two years showed that the year did not have a significant effect on grain and dry matter yield. The results also showed that irrigation regimes did not have a significant effect on dry matter yield but significant on grain yield at 5%.

Low yield and instability, is one of the most important issues in chickpea cultivation. The adverse environmental conditions have affected the crop yield; in this regard, one of the most important factors is salinity stress that reduces crop yield. Meanwhile, microorganisms have a high ability to mitigation the adverse effects of salinity. In addition, the coexistence of beneficial bacteria and fungi creates a potential for a decrease of salinity stress impacts on plants. Mycorrhizal fungi belonging to the branch Glomeromycota, one of the oldest living organisms introduced to coexist with plants on land and in salinity. These fungi are widely found in saline soils. Research has shown that mycorrhizal arbuscular fungi increase salinity tolerance and prevent yield loss. Studies have shown that the coexistence of mycorrhizal arbuscular fungi with crop roots increases the activity of antioxidant enzymes and this expansion of activity to the plant helps to reduce the effects of salinity stress. With regard to the beneficial effects of mycorrhizal fungi on reducing salinity effects in crops, this study aimed to evaluate salt tolerance in chickpea using native mycorrhizal fungi to improve soil properties and its sustainable production under saline conditions.

This study was performed in 2016 as factorial based on completely randomized block design with three replications in the research glasshouse of the College of Agriculture, Ferdowsi University of Mashhad. Salinity stress treatments included four levels (tap water [control], 6, 6 and 9 dS.m-1 sodium chloride) and mycorrhiza species at three levels (native mass, Piriformospora indica as endophyte, and Gigospera margareta). Four weeks after applying salt stress, maximum quantum efficiency of PSII photochemistry (F'v/F'm) II, stomatal conductance, SPAD index, relative water content (RWC) of leaves, and membrane stability index in the youngest fully expanded leaf were measured. In addition, morphological traits, including plant height, lowest branch height, number of branch number, and number of leaves per plant were measured. At the end of the experiment, the shoot fresh and dry weight, length, volume and dry weight of root were measured, finally root colonization was assessed.

The maximum quantum efficiency of PSII photochemistry (F'v/F'm) affected by different levels of salinity and mycorrhiza application. The highest and lowest maximum quantum efficiency of PSII photochemistry (F'v/F'm) levels were related to 9 dS.m-1 salinity treatment with mycorrhiza Piriformospora indica and control treatment with Gigospera margareta species, the difference between which was 4.5 times. In addition, the highest amount of gas exchange was observed in the Piriformospora indica species. The highest SPAD index was related to treatment with Piriformospora indica fungi in non-stress conditions and the highest salinity stress level. Moreover, application of Piriformospora indica fungal species increased RWC by 4.54% and 9.20%, compared to the use of mycorrhiza native mass and Gigospera margareta species, respectively. Application of Piriformospora indica showed superiority in membrane stability index relative to Gigaspora margareta in all treatments of salinity stress, with the exception of 9 dS.m-1 treatment. However, no significant difference was observed between mycorrhiza treatments in 9 dS.m-1 of salinity stress. Root inoculation with Piriformospora indica increased plant height by 12.7%, compared to mycorrhiza native mass. At all levels of salinity stress, Piriformospora indica increased shoot fresh weight, compared to native mass and Gigospera margareta treatments. Furthermore, the least and highest decrease in root length was observed in Piriformospora indica and Gigospera margareta treatments, respectively. Among mycorrhiza fungi treatments, Piriformospora indica produced the highest root volume, compared to native mass and Gigospera margareta treatments with a difference of 10.9% and 36.4% between them. In addition, in non saline treatment with Piriformospora indica had the highest percentage of root colonization (54.66).

According to the results of the study, most traits evaluated in the study were affected by increased intensity of salinity stress. In addition, increased salinity had a negative impact on root development due to increased soil osmotic potential and toxicity, which ultimately reduced plant growth. Moreover, mycorrhiza inoculation had a significant, positive effect on the photosynthetic system of photosystem II, shoot and root dry weight, ratio of shoot to root, root length and percentage of colonization, root volume, root fresh weight, RWC and membrane stability index. Inoculation of commercial species of mycorrhiza under salt stress increased plant salinity tolerance.

Salicornia is one of the most important industrial plants of the Chenopodiaceae family, which is grown as oilseed, fodder, or vegetable crop around the world. All Salicornia species produce succulent shoots suitable for leafy vegetable production, but they differ in germination charactristics, seedling growth and physiological parameters. Germination and seedling emergence depend on the specific genotype requirements of each species and the environmental factors such as salinity stress. Salinity stress is one of the major abiotic stresses which negatively limit crop productivity. The aim of the present study was to test biochemical and physiological responses of Salicornia species to salinity stress.

In order to investigate the seed germination and seedling growth properties of Salicornia, two separate factorial experiments were conducted based on a completely randomized design with four replications and four destructive examples for each replication during 2019. The first experiment (seed investigation) was carried on in the petri dish culture and second experiment (seedling investigation) was conducted using pots in the green house condition. Experimental treatments were six levels of salinity stresses (control, 10, 20, 30, 40 and 50 dS/m) arranged as the fist factor and in the second factor was three Salicornia species S. persica Golestan, S. biglovii and S. europaea.

Results of analysis of variance revealed that there was significant effect of salinity stress, genotype and interaction effects of both treatment on all measured germination and seedling growth characteristics (p<0.01). In all studied Salicornia species, the maximum value of traits obtain at control condition and the minimum value was observed in 50 dS/m salinity except for germination uniformity, seedling water content and total phenol content. The highest seedling water content (89.44%) was obtained from S. persica at 40 dS/m. The maximum flavonoid (0.156 mg/g.fw) and total phenol content (0.031 mg/g.fw) was observed in S. persica at 20 dS/m. Based on the output of Gompertz function (R2adj≥0.95 and RMSE≤3.25), salinity increase from 0 to 50 dS/m, the time to reach 50% of total seed germination was increased from 5.73 to 16.20 days in S. percia, 4.42 to 17.07 days in S.biglovii and 5.75 to 11.95 days, respectively.

Seed germination traits and seedling growth of Salicornia genotypes exhibited some level of sensitivity to salinity stress. All Salicornia species were germinated successfully at a salinity of 10 dS/m while seed germination was inhibited at 50 dS/m of salinity stress. It was revealed that the Salicornia sp. originated from Iran (S. persica) exhibited higher salinity tolerance than the species originated from Europe (i.e., S. biglovii and S. europaea). In conclusion, all Salicornia spp. exhibited reasonable salinity tolerance in the range of (10 to 30 dS/m) without compromising the high quality of the final yield. Therefore, it could be a promising alternative crop in saline-prone areas of Iran. Now, after understanding the behavior of different Salicoenia species above 10 dS/m salinity and increae of seed germination from 0 to 10 dS/m in, scrutiny of plants reaction between 0 to 10 dS/m in, it is possible to use this finding for a better breeding program of Salicornia species.

Soil salinity causes major losses in crop production, especially in arid and semi-arid regions where 110 million out of 270 million ha of irrigated lands are located. Salinity is becoming more extensive as a result of land clearing and unsustainable irrigation and salinity management practices, as well as increasingly by bringing marginal lands into production. Priming is one of the effective methods to improve seed germination and seedling establishment in stressful environmental conditions such as salinity. Safflower (Carthamus tinctorius L.) is the most important oil seed crop from Asteraceae family. These plants are usually preferred in arid and semi-arid regions under rain-fed conditions, where low rainfall and high evapotranspiration during vegetation periods restricts the growth of crop plants. Under these conditions, drought and salinity are the major abiotic stresses that severely inhibit germination, seedling establishment and plant growth; consequently, seed yield decreases. The purpose of this experiment was to investigate the effect of salicylic acid and potassium nitrate pretreatments on germination components, growth characteristics, photosynthetic pigments and proline of two safflower cultivars under salinity stress.

In order to investigate the effect of salicylic acid and potassium nitrate on germination and photosynthetic indices of two safflower cultivars under salinity stress, a factorial experiment was conducted in a completely randomized design with three replications in the Seed Technology Laboratory of Shahed University of Agricultural Sciences in 2018. Experimental factors include safflower cultivars of Sofeh Isfahan and Goldasht cultivars, priming at three levels of control (distilled water), salicylic acid 0.5 mM and potassium nitrate 0.3% and salinity stress caused by Qom Lake salt at four levels of 0, 5, 10 and 15 dS/m, respectively.

The results showed that increasing the salinity of salt (sodium chloride) decreased the seed germination characteristics, relative water content and photosynthetic pigments and increased proline content. In Sefeh cultivar, the highest amount of germination components such as germination percentage (90%), germination rate (9.16 seeds per day), root length (25 mm), stem length (49.5 mm) Seedling fresh weight (1.25 g) and seedling dry weight (0.14 g) were obtained in the absence of salinity stress and application of salicylic acid. Also, under stress conditions of 15 dS/m and salicylic acid treatment, Sefeh cultivar had significant germination and growth. Salicylic acid pretreatment under salinity stress reduces the negative effects of salinity stress, thus increasing the germination percentage and seedling growth indices. Pretreatment of potassium nitrate increased photosynthetic pigments in Sefeh cultivar of Isfahan under salinity stress. Using cost-effective seed priming can improve seed germination components for growth in salinity conditions.

The results showed that salinity stress reduced the percentage and rate of germination, root and shoot length, fresh and dry weight of seedlings in both safflower cultivars. Negative effects of salinity stress on physiological parameters included reduction of photosynthetic pigments. Also, salinity stress affected the amount of proline in the contract and increased the amount of this trait. Sefeh cultivar under salinity stress with salicylic acid application had better tolerance than Goldasht cultivar. It is suggested that the quantitative and qualitative traits of safflower cultivars be evaluated under field conditions under salinity and priming to yield stages and yield components. To be able to more confidently recommend suitable cultivars in areas with saline soils.

The scientifically named potato (Solanum tuberosum L.) is one of the most important agricultural products in the world that belongs to the Solanaceae family, an autotetraploid plant (2n=4x=48), with complex inheritance patterns and in terms of nutritional importance, it ranks fourth after wheat, rice and maize and plays an important role in the nutrition and food basket of the global population. This research aims of this study was to investigate the effect of planting date and planting depth on some quality traits, glandular function and water use efficiency of potato cultivars in autumn and spring cultivation of temperate cold region in Araloo Agricultural Research and Natural Resources Station farm in Ardabil region for 2 years (2017-2018).

Split-factorial experiment based on complete randomized block design in three replications of planting date at three levels (10 Novomber, 10 December and 10 May)  as the main factor and factor combination of four potato cultivars (Sprite, Marfona, Savalan and Agria) And four planting planting depths (10, 15, 20 and 25 cm) were considered as a secondary factor. After performing the normality of the data and the experimental error uniformity of the compound analysis based on the statistical factor design and comparing the mean based on the LSD test at 5% probability level by SAS9.1 software and correlation between traits using Minitab.16 software. And the graphs were drawn with Excel software.

The results of analysis of variance of the evaluated traits showed that the simple effect of planting date (gland function and water use efficiency) and simple effect of planting depth (nitrogen content, fiber percentage and soluble sugars) had a statistically significant difference between 5 and 1% probability. In terms of the quadrilateral effect A×B×C×D, the traits (percentage of dry matter and soluble sugars) had a significant difference. Water Use efficiency was higher in November and December planting at depths of 10, 15 and 25 with the number of sprays with water efficiency of 6 (kg/m3).The average yield of the tuber in Marfona cultivar was 30 tons per hectare in May and 24 tons per hectare in November cultivation and 20 tons per hectare in December cultivation.The difference in glandular function between spring and autumn planting was on average 8 tons per hectare. Meanwhile, in the autumn cultivation, about 4551 cubic meters per hectare (4 irrigations) and in the spring, about 14214 cubic meters per hectare (12 irrigations) were done. In this study, the number of irrigation times in autumn and spring planting was reduced from 12 irrigations to 4 irrigations and the difference in water consumption was 9663 cubic meters per hectare.The gland with the traits of the percentage of glandular starch and the percentage of fiber of the gland was negative and significant and with the percentage of dry matter of the gland was positive and significant.
 

Finally, it can be concluded that autumn cultivation of potato is suitable, especially in areas with water shortages. The highest water use efficiency in autumn cultivation at depths of 10, 15 and 25 cm was related to the Esprit cultivar.

Autumn sowing leads to production improvement and yield stability of Plantago major due to the longer growing season, avoid late summer heat stress, and effective use of rainfall. However, in order to succeed in autumn sowing, cold tolerance is essential. It is crucial to carry out plant selection to evaluate and identify top traits for adaptation to environmental factors and ultimately higher production of valuable plants such as broadleaf plantain. Therefore, evaluation of the characteristics of important plants such as broadleaf plantain plays a fundamental role in the selection of top ecotypes for different purposes of selection and increase of yield in different climatic conditions of each region.

This experiment was conducted as split-plot based on randomized complete block design with three replications at Research Farm of Agriculture Faculty of Ferdowsi University of Mashhad (36°15’ N, 56°28’ E, 985 m altitude) during the growing season 2013-14. The experimental factors included six ecotypes of Plantago major (Bojnord, Kalat, Mashhad, Ghaen, Torbat Heydarieh, and Birjand) and four sowing dates (late September, late October, late March, and late April). Irrigation was done immediately after planting and during the growing season according to the need of the farm by furrow method. Survival percentage, spike length, peduncle length, number of capsules, seed in capsule, 1000 grain weight, grain yield, biomass, and harvest index were evaluated. Data analysis was performed in SAS v9.4, and the means were compared by Duncan test at a 95% confidence interval.

The results showed that delay in autumn sowing from September to October reduced the survival percentage in all ecotypes. While, the delay in spring sowing from March to April improved the survival percentage in Birjand, Ghaen, Mashhad and Kalat ecotypes by 12, 8.9, 7.3 and 5%, respectively. The highest percentage of survival in April sowing belonged to Mashhad, Birjand, Ghaen, and Kalat ecotypes and in March sowing belonged to Bojnord ecotype. The highest grain yield (796.9 g m-2) was observed in Ghaen ecotype and the lowest was obtained in Torbat Heydariyeh, Mashhad, and Kalat ecotypes. So that grain yield in Ghaen ecotype was 48, 46, and 59% higher than the mentioned ecotypes, respectively. The highest biomass was observed in September sowing in Bojnord ecotype (2768 g m-2) and the lowest was obtained in April sowing in Kalat ecotype (622 g m-2). Ghaen ecotype had the highest harvest index in all sowing dates. Autumn planting of Plantago major L. leads to reduce in survival percentage compared with the survival percentage of spring planting. Lack of significant difference in grain yield of Plantago major ecotypes in autumn and spring sowing dates indicates the high flexibility of this plant to the date of sowing.

Despite the effectiveness of other factors in the improvement of a plant’s growth, it could be predicted that the Plantago major L. ecotypes that have the ability for establishment in cold conditions are more likely to be in a better position than other ecotypes at other stages of development. Due to the occurrence of heat and drought stresses during the spring growing season and production of suitable biomass for most ecotypes in autumn sowing, the continuation of field and controlled experiments is necessary to evaluate the success of autumn sowing of this plant seems necessary.