جستجوی مقالات مرتبط با کلیدواژه "تنش خشکی" در نشریات گروه "اکولوژی"

The present study was conducted with aim of investigating the effect of nanosilicon on yield the performance and reducing the effect caused by water stress in Quinoa plant. The experiment was conducted as split plot based on randomized complete blocks design with three replications in Fars Agricultural and Natural Resources Research and Education Center. The treatments included irrigation regimes in four rounds of 7, 14, 21 and 28 days and nanosilicon spraying at zero, 30 and 60 mg L-1 levels. Application of moderate moisture stress (irrigation cycle of 21 days) and severe (28 days) compared to no stress (7 days) caused a decrease of 5.93 and 24.65% in panicle length, 8.77 and 27.81% in panicle width, 5.14 and 29.44% in panicle number, 23.87 and 12.05% in total aerial organ weight, 24.73 and 54.95% in seed yield, 26.11 and 55.94% in the weight of one thousand seeds and 14.53 and 41.16% in the plant harvest index. The above moisture stresses caused a 125 and 78.84% increase in water consumption efficiency. Also, nanosilicon foliar has a significant effect on Quinoa plant growth, so that the maximum morphological growth, grain yield and water consumption efficiency observed in nanosilicon application with concentration 30 mg L-1 was. Nanosilicon spraying with 30 mg L-1 concentration reduces the negative effects of moisture stress in drought stress conditions (21 and 28 days) on the Quinoa plant.

In order to decreasing the chemical fertilizer application in low-input and sustainable agricultural systems, a field experiment was carried out to evaluate the effects of different irrigation intervals along with separately and integrative application of chemical and biofertilizer on the quantity and quality of camelina (Camelina sativa L.).Material and methodsThe study was carried out as a split plot based on a randomized complete block design (RCBD) with 18 treatments and three replications at the Saqez city, Iran in 2022 growing season. The main factor was three irrigation intervals including without irrigation (rainfed conditions), irrigation after 10 and 20 days. Also, the sub-factor was different fertilizer sources including non-application (control), 100%chemical fertilizer, biofertilizer, biofertilizer+ 25% chmical fertilizer, biofertilizer+ 50% chemical fertilizer and biofertilizer+75% chemical fertilizer.ResultsThe results demonstrated that the highest (457.81 kg ha-1) and lowest (186.29 kg ha-1) seed yield of camelina was obtained in 10 days’ interval irrigation following integrative application of biofertilizer+ 75% chemical fertilizer and rianfed conditions without fertilization. The highest oil content (37.88%) and oil yield (173.65 kg ha-1) was observed in 10 days’ interval irrigation following integrative application of biofertilizer+ 75% chemical fertilizer. The chemical analysis showed that linolenic (30.59-34.58%), linoleic (16.92-19.29%), oleic (14.16-17.36%) and eicosenoic acid (8.93-11.76%) were the main fatty acids compounds of camelina oil. The maximum content of oleic, linoleic and linolenic acids obtained in in 10 days’ interval irrigation following integrative application of biofertilizer+ 75% chemical fertilizer.

Field studies were carried out for two years at the research farm of the Faculty of ‎Agriculture‏ ‏and Natural Resources, University of Mohaghegh Ardabili. Experiment was conducted as a split plot ‎factorial based on randomized complete block design with three replications. The main factor included drought ‎stress at three levels [irrigation at 80% of field capacity (no stress), irrigation at 65% of field capacity (moderate ‎stress) and irrigation at 50% of field capacity (severe stress)]. Sub factor was combination of external ‎phytoprotectants application at five levels [Distilled water as control, Ascorbic acid (1 mM), Tocopherol (1 mM) ‎‎, Silicon (1 mM) and Zinc NPS (1 mM) and inoculation with phosphorus-solubilizing bacteria at two levels (with ‎and without inoculation)]. ‎The severe water limitation (50% field capacity) compared to non-stress conditions (irrigation at 80% ‎field capacity), led to a significant decrease in wheat yield and yield components. However, the application of ‎organic (ascorbic acid and tocopherol) and mineral (silicon and zinc NPS) phytoprotectants, as well as ‎inoculation with phosphorus-solubilizing bacteria were significant on Chl a, Chl b content and also, leaf area ‎index and increment of the effective compounds in plant tolerance under stress conditions such as carotenoieds, ‎prolin and slouble sugars. under the severe water limitation, ‎application of stress modulators increased grain yield 28, 18.2, 17.3 and 9.3% in compared to no application of ‎stress modulators at the same level of irrigation‎

a field experiment performed to evaluate the effects of peppermint and sage intercropping with application of different fertilizer resources on the dry matter yield, essential oil content, and ecological indices under drought stress.A field experiment was carried out as a split split plot based on a randomized complete block design (RCBD) with 36 treatments and three replications . The main factor was three irrigation regimes included 25 (MAD25), 50 (MAD50), and 75% (MAD75) maximum allowable depletion (MAD) percentage of the soil available water (SAW) as normal irrigation, mild and severe water stress, respectively. The sub-factor was different planting patterns included peppermint monoculture, sage monoculture, and intercropping of peppermint + sage and also sub-sub factor were application of different fertilizer sources including no‐fertilizer as control, TiO2 nanoparticles (100 mg L−1), arbuscular mycorrhiza fungi (AMF) inoculation, and integrative application of AMF and TiO2 (AMF + TiO2).The maximum essential oil content of peppermint (1.51%) and sage (1.33%) was observed in intercropping plants with integrative application of AMF + TiO2. The essential oil content of peppermint and sage increased by 13.1 and 41.2% under mild stress in compared with normal irrigation, respectively. Also, the highest LER, K, AYL,, and monetary indices were achived in mild water stress with integrative application of AMF + TiO2. it can be concluded that the application of AMF + TiO2 in intercropping of peppermint/sage could be suggested as a sustainable strategy to increasing the quantity and quality of essential oil of both plants under drought stress conditions.

The lack of fresh water resources in arid and semi-arid regions is the most important factor limiting agricultural activities. On the other hand, one of the challenges that exist in cities is the accumulation of sludge resulting from urban sewage treatment. According to the available sources, the sludge obtained from urban sewage treatment contains large amounts of mineral and organic substances, which can improve soil fertility and water retention and are useful for agricultural products. In this regard, in order to investigate the effect of sewage sludge in reducing the effects of drought stress on the growth characteristics of Hibiscus sabdariffa L., a study was conducted in the form of a completely randomized design in a factorial format and under greenhouse conditions. The test factors included drought stress with four levels (100, 75, 50 and 25% of crop capacity) and sewage sludge with two levels (zero and 10 grams per kilogram of soil) and four replications. During the six-month growth period of the plants in the greenhouse, dry treatments were applied using tap water with a salinity of 700 micro Siemens per meter, based on the weighing of the pots. After the plants reached the stage of flowering and boll production, morphological traits such as plant height, shoot weight, stem diameter, number of bolls, root weight and number of leaves were measured. The results showed that the effect of sewage sludge application on the wet and dry weight of shoot, height, number of bolls, stem diameter and root wet weight at the level of one percent (p<0.01) and the dry weight of the root at the level of five percent (p>0.05) was significant. Using sewage sludge increased plant dry weight by 46%, height by 24%, stem diameter by 14%, and root dry weight by 50% compared to the control treatment.​ The investigation of the interaction effect of drought and sludge on the morphological characteristics of the plant showed that the application of sewage sludge at stress levels of 100, 70 and 50% of the field capacity increased the fresh weight of aerial parts by 118, 90 and 75%, respectively, compared to the control. The interaction effect of drought and sludge on the number of plant bolls showed that the highest amount of this trait was obtained with an average of 25 numbers in the treatment of sewage sludge application and 100% field capacity, and the lowest amount was equal to 1.25 in the treatment of 25% field capacity and no sewage sludge application. The interaction effect of drought and sewage sludge on plant physiological traits such as proline, sugar, chlorophyll a, chlorophyll b and carotenoid levels was not significant. In general, the results of this research show the positive role of sewage sludge on improving the growth and performance of this plant under drought stress conditions.

This research was carried out in order to evaluate the effect of intercropping of replacement and addition series on the yield and yield components of Camelina and Lentil under rainfed and irrigated conditions.

The experiment was carried out in the form of split plots in the form of a basic design of randomized complete blocks with three replications in the research farm of the Faculty of Agriculture of Ilam University in growing season in 2020-2021 and 2021-2022. The main plots include irrigation on two levels (rainfed and irrigated) and the subplots include alternative and incremental mixed cropping patterns in nine levels including (75% Camelina+ 25% lentils, 50% Camelina+ 50% lentils, 25% Camelina+ 75% lentils), 100% Camelina+ 25% lentils, 100% Camelina+ 50% lentils, 100% Camelina+ 75% lentils, 100% Camelina+ 100% lentils, monoculture of Camelina and lentils).

The results showed the highest grain yield (1827 kg ha-1) and biological yield of camelina (7012 kg ha-1) in the series of 100% camelina+ 25% lentil and the highest grain and biological yield of lentil was 750 and 1950, respectively, related to monoculture lentil cultivation. The evaluation of the ratio of land equality showed the superiority of all ratios of camellia and lentil intercropping over their monoculture, and the incremental rows of 100% camellina+ 75% lentils and 100% camellina+ 100% lentils had the highest LER.

The results showed that the intercropping of camelina and lentils under irrigation and rainfed conditions was beneficial and superior compared to their monoculture.

The aim of this study was to evaluate and select bread wheat cultivars by some physiological traits under drought stress conditions. Experiments were conducted in the cropping years from 2018- 2019 and 2019-2020 in the farm of Agricultural and Natural Resources Research Center of Moghan in the form of split plots complete random block design with three repetitions. The Main plot covered the three irrigation regimes including control irrigation (without drought stress), medium drought stress (moderate drought stress) and full drought stress. Sub-plots included bread wheat cultivars and lines (Tirgan, Ehsan, Aftab and lines N-91-17, N-92-9 and N-93-17). The results showed that moderate and full drought stress caused a significant decrease in the number of days to germination, number of fertile tillers per plant, thousand seed weight, seed yield, proline content, catalase, leaf protein and leaf greenness index. Under moderate and full drought treatments, the seed yield declined (12.5 and 31 percent, respectively). Also, the results showed that moderate drought stress and full drought stress increased proline content and catalase enzyme activity and decreased leaf protein content and leaf greenness index. Considering the critical water conditions in the world and Iran, especially in Ardabil (Maghan) province, the introduction of cultivars that can reduce yield at least in low irrigation conditions are of great importance. Therefore, among the studied cultivars, the N-93-17 line and the Aftab variety are recommended for cultivation in the conditions of drought stress at the end of the season and the development of drought-resistant varieties.

In order to evaluate of grain yield, anti-oxidante enzymes activitie and osmolytes accumulation in leaves of peanut as affected by different irrigation levels and Salicylic acid, the present study was done. This experiment carried out as split plat based on randomized complete block design with three replications in experimental field of Agicutural and Natural Resources Research and Education Center of Guilan Province, Astara, Iran, during 2018 and 2019 years. Four level of irrigation regimes including no irrigation (as control), irrigation at initial flowering stage, irrigation at pod formation stage and irrigation at initial flowering + pod formation stages and three levels of salicylic acid such as 100, 200 and 300 µmol/l comprised experimental treatments, as main and sub plot, respectively. Deficit irrigation decreased grain yield, chlorophyll index (SPAD) and leaf relative water content in peanut. Prolne, catalaz, superoxide dismutase, peroxidase, soluble sugar content, soluble protein content and leaf anthocyanin content enhanced in responses to deficit irrigation. In addition, foliar application of salicylic acid caused to improve all measured traits in peanut at different irrigation levels. The greatest grain yield of peanut (3450 kg/ha) was obtained in response to supplementary irrigation at both initial flowering stage + pod formation stage along with salicylic application at the rate of 300 µmol/l. Based on results of this study, supplementary irrigation and foliar application of salicylic acid could be recommendable in direction to increase plant resistance to drought stress and grain yield improvement in peanut .

The present study was performed to evaluate the effect of selenium application on yield, yield components and oil yield of safflower (Carthamus tinctorius L.) cultivars under water deficit irrigation conditions as factorial split plot based on randomized complete block design with three replications in Mahalat province, Arak, Iran during 2013-2014 crop season. The main factor included complete irrigation during growing season, cutting irrigation at flowering stage and cutting irrigation at head forming stage. Sub factor was considered application of selenium (including 0, 20 and 40 k/ha) and safflower cultivars (Sina and Mahaly Esfahan). The results showed that the plant height, leaf area, yield and yield components and oil yield of safflower cultivars decreased under water stress treatments. Discontinuation of irrigation in the pollination stage led to the greatest reduction in grain yield and oil yield by 31.6% and 39.7% compared to full irrigation, respectively. The highest grain yield, biological yield and oil yield with average of 3987, 9514 and 609 k/ha by application of 40 g/ha selenium and complete irrigation obtain, respectively. Application of selenium in discontinuation of irrigation regimes due to decrease negative effect of water stress on yield components, grain yield, biological yield and oil yield. The Mahaly Esfahan cultivar had the highest number capitulum per plant, number grain per capitulum, grain yield, biological yield and oil yield. In general, 40 g/ha application of Mahaly Esfahan safflower cultivar with selenium not only can decrease water stress effect but also increase grain yield and oil yield under optimum conditions.

The aims of this study was to investigate the radiation and nitrogen use efficiency at different irrigation regime and nitrogen rate in Ilam climatic condition.

The experiment was conducted as a split-plot based on randomized complete block design with three replications in Agronomy Research Farm of Ilam University. The experimental factors included 3 irrigation regime (100, 80, and 60 percent of field capacity) and nitrogen rate at three levels (0, 100 and 150 kg.ha-1).

The highest grain and biological yield were obtained with 5275 and 17209 kg/ha in I100 N150 treatment, respectively. Radiation use efficiency of Maize was affected by irrigation regime and nitrogen rate. Radiation use efficiency was in the range of 1.97 (I60N0 treatment) to 2.66 g/MJ (I100 N150 treatment). The highest and lowest of radiation absorbed were obtained in I100 N150 and I60N0 respectively. The highest of nitrogen use efficiency of agronomic (47.5 kg/kg) and uptake (1.6 kg/kg) were observed in I100N0 treatment and the highest of nitrogen use efficiency of physiologic was obtained I80N0. Nitrogen uptake in harvested biomass increased with additional N fertilizer application. The nitrogen uptake increased from ∼65 kg/ha at I60N0 treatment to ∼280 kg/ha for I100N150 treatments.

In this study, an inverse relationship was observed between radiation use efficiency and agronomic nitrogen use efficiency. The results of the experiment showed that the application of higher nitrogen rate was not the appropriate strategy for compensating for the reduced grain yield under low irrigation.

Due to the water limitation in Iran and the widespread use of maize in human and animal feeding, this research was carried out to evaluate the effects of different salicylic acid levels on some morphological traits and grain yield of this crop under drought stress during reproductive stages. A field experiment was conducted as a split-plot based on a randomized complete block design with three replications in 2020 to investigate the effect of salicylic acid (SA) levels (0, 1, 2 and 3 mM) on morphological traits, grain yield and yield components of maize under normal irrigation and irrigation disruptions at reproductive stages. Irrigation and SA levels were assigned to the main and sub plots, respectively. The results revealed that irrigation disruptions from initial flowering up to maturity caused a significant decrease in the mean plant height, ear length, grains per ear and plant, 1000-grain weight, grain yield, plant biomass and harvest index. Foliar spray of salicylic acid, especially with 3 mM concentration increased most of these traits as well as 1000-grain weight, leading to an improvement in grain yield per unit area. The 1000-grain weight, harvest index, plant biomass, ear length, grains per plant and ear had the highest positive correlation with grain yield of maize. Water supply during grain filling stage is necessary to obtain a higher yield in maize. Foliar application of 3 mM salicylic acid was the superior treatment for increasing maize yield under normal and limited irrigation conditions.

This study was conducted to evaluate the effect of biofertilizer application and drought stress on physiological characteristics and forage quality of pea (Pisum sativum L.).

The factorial experiment was conducted based on a randomized complete block design in the lands of Harris County, East Azerbaijan Province Experimental factors include: irrigation treatment at four levels of normal irrigation (control treatment), cessation of irrigation at the stage of seed filling, cessation of irrigation at the stage of flowering and non-irrigation and treatment of biofertilizers at eight levels of seed inoculation (treatment) Control was seed inoculation with Azotobacter, Azospirillium, Mycorrhiza, combined application of Azotobacter and Azospirillium, combined application of Azotobacter and Mycorrhiza, combined application of Azospirillium and Mycorrhiza and combined application of Azotobacter, Azospirillium and Mycorrhiza.

The highest digestibility, ash and insoluble fibers in acidic detergent were obtained in complete irrigation and non-application of biofertilizers and the lowest in non-irrigation and combined application of three types of biofertilizers. The highest yield, soluble carbohydrates and crude protein were obtained in complete irrigation and combined application of three types of biofertilizers and the lowest in non-irrigation and non-application of biofertilizers. Drought stress reduced insoluble fibers in neutral detergent by 3.62% compared to full irrigation treatment.

It is necessary to evaluation of the occurrence of climate change, Inadequate distribution and Stop of rainfall in the final stages of wheat growth in Varamin.

From the output of HadGEM under RCP4.5 and RCP8.5, to simulate the future climate using AgMIP model with long-term baseline data (1980-2009), in the periods of 2025, 2055 and 2085 were used. SSM model was used to simulate the phonological stages of wheat and in order to calibrate and validate the model, an experiment in the form of a randomized complete block design with five treatments including; [No stress, booting stage, Flowering, Milking, and Doughing], with 3 replications, was carried out during the 2020-2019 growth season in Varamin.

The SSM model simulated the occurrence of phonological stages with high accuracy. In 2085 period under RCP8.5, the highest increase of Tmax and Tmin was observed with 6.9 °C and 5.6 °C compared to the baseline period, respectively. While the amount of precipitation decreased in 2025 and 2055 under RCP8.5, but it increased in RCP4.5. The smallest difference between day to Flowering, BSG, TSG and day to was related to the period 2025 under RCP4.5 with 3, 9, 12 and 11 days, respectively. The highest differences were observed in the period 2085 under the RCP8.5 with 90, 77, 47 and 43 days, respectively.

Increasing the temperature and decreasing rainfall have neutralized the beneficial effects of increasing CO2 concentration and these factors have shortened the duration of phonological stages.

Guar (Cyamopsis tetragonoloba) is an annual and tropical plant of the legume family that is suitable for seed production in arid and semi-arid regions due to its resistance to drought.

Methods & Materials: 

Therefore for studying the effects of salicylic acid on morphological, physiological characteristics, yield and yield components of Guar under at three levels of field capacity (drought stress), a split plot experiment based on randomized complete block design with four replicates was conducted in Jiroft in Kerman province, Iran. The experimental treatments were included three levels of irrigation (45, 65 and 85% of field capacity as main factor) and four concentrations of salicylic acid (0, 0.5, 1 and 2 mM as the sub factor). Foliar application of salicylic acid was carried out in three five-leaf, flowering and pod stages.

Results showed that by reducing soil moisture (from 85 to 45% FC) significantly decreased all traits except grain protein. The effect of salicylic acid was also significant on all traits except for 1000-grain weight. Foliar application of 1mM salicylic acid at 85% and 65% of field capacity resulted in the highest grain yield.

There was no statistically significant difference between 2 and 1 mM concentrations in most of the studied traits, so, it can be concluded that foliar application of salicylic acid at a 1 mM concentration can reduce the negative effects of decreasing soil moisture, Finally 65% of field capacity it can be introduced as superior level for irrigation of Guar.

The aim of this study was to investigate the effect of biochar produced from wastes from pruning of pomegranate trees and compare it with vermicompost Oenothera biennis under drought stress.

Treatments included different levels of organic modifier application (seven levels including no modifier application, application of 10, 20 and 30 ton ha-1 vermicompost and application of 10, 20 and 30 ton ha-1 biochar) and three levels of drought stress (irrigation in 80, 60 and 40% of field capacity (FC)).

The results showed that drought stress significantly decreased leaf length, leaf area, stem diameter, plant height, chlorophyll index and relative water content (RWC) while increased the ratio of root dry weight to shoot and ion leakage. Application of 30 ton ha-1 biochar and all application levels of vermicompost decreased root dry weight to shoot ratio under severe drought stress. All application levels of vermicompost were increased the chlorophyll index under severe stress while different levels of biochar had not significant effect. All amendments significantly increased RWC compared to the control under moderate and severe stress conditions. Application of 30 ton ha-1 biochar and vermicompost decreased ion leakage compared to the control.

It seems that organic amendments can help the plant in stressful conditions by affecting the availability of nutrients and increasing the soil moisture holding capacity. In this study the effectiveness of vermicompost was better compared to biochar, which can be attributed to the higher content of nutrients in vermicompost.

In natural environments, plants are continuously exposed to diverse environmental conditions that may affect plant survival, development and production. Water deficiency considers as one of the most ominous abiotic factors that limits the growth and yield of crops and decreases water use efficiency and photosynthesis rate. Nowadays it is suggested to use bio-fertilizers as a tool to adjust adverse effects of water shortage in soil. Bio-fertilizers containing Arbuscular mycorrhizal fungi are supposed to use. Some plant species have the ability to form a symbiosis relationship with the Arbuscular mycorrhizal fungi (AMF). AMF can increase growth and yield of plants under water deficiency, and it is one of the most important bio-inoculant that can be used to adjust adverse effects of water stress in plants. AMF-symbiosis considerably increases root colonization which turns into improving water use efficiency. Also, it establishes a platform to increase phosphorus mobility between soil and roots in the rhizosphere. Lallemantia iberica (Dragon’s head) and Lallemantia royleana (Lady’s mantle) are medicinal plants that belong to the Lamiaceae family. Genus Lallemantia seeds contain mucilage, polysaccharide, fiber, oil, protein, and plenty of valuable secondary metabolites. Limited information is availiable about the ability of these two species to make symbiosis relation with AMF under water deficit condition.  Hence, the current study was aimed to evaluate of Lallemantia iberica and Lallemantia royleana inoculated by mycorrhizal in the different irrigation regimes.

The field trial was conducted at the Research Farm of the Agricultural Faculty of Shahed University, Tehran, during the cropping season of 2018 and 2019. A split-factorial experiment was employed in a randomized complete block design (RCBD) with three replications. The main plot consisted of three-level of irrigation regimes (30% (I30; without stress), 60% (I60; mild stress), and 90% (I90; sever stress) depletion of available water resource). The sub plots were factorial combination mycorrhizae (non-inoculation and inoculation of mycorrhizae) and plant species of Lallemantia (L.iberica and L. royleana). 

Increasing water deficit significantly reduced plant height, grain yield, chlorophyll a and b, water use efficiency, root colonization, seed phosphorus, seed mucilage, and seed oil content However, the highest plant height, grain yield, chlorophyll a and b, water use efficiency, root colonization, seed phosphorus, mucilage, and oil seed content obtained at 60% available water soil of depletion (mild stress). The application of mycorrhizae increased plant height, grain yield, chlorophyll a and b, water use efficiency, root colonization, seed phosphorus, seed mucilage, and oil seed content in cross all irrigation regimes. It has been reported that establishment a relationship of symbiotic AMF with roots of host plant, through spreading the hyphae and developing the root system, improves growth and provides more water for plants, which finally this ability leads to the yield, root colonization and water use efficiency. Inoculated and non-inoculated L .royleana had the greatest resistance to different levels of irrigation regimes and mycorrhizal treatments than L. iberica. It has been reported that L. royleana was more tolerant to water deficit in compared to L. iberica  Also the results showed that the highest root colonization was in L. royleana species which was grown under different levels of irrigation regimes and mycorrhizal treatments.

In general in this research, it can be concluded that under water deficit stress conditions, water deficit stress damages can be reduced in both species of Lallemantia with careful irrigation management (using an irrigation regime of 60% available water soil of depletion) and application of mycorrhizae.

The purpose of this research was to determine the effects of biostimulats application on the yield and yield components of canola (Brassica napus L.) in a semi-arid region based on Amberje classification in Ilam province. The experiment was carried out as split plots arrangement based on randomized complete block design with three replications. The main plots were two irrigation regimes after evaporation of 80 and 140 mm from class-A evaporation pan and soil moisture compensation to the extent of field capacity in silty clay loam soil texture. The sub-plots were as 1- control (application of chemical fertilizers according to soil test), 2- compound 1 and L-amino acid (glycine, betaine and proline) spraying, 3- compound 1 and fertigation of 5 kg per hectare of humic acid in two stages (after the second irrigation and the beginning of shoot elongation) 4-compound 1 and spraying fulvic acid 5-compound 1 and spraying seaweed extract, 6-compound 1 and the co-application of treatments 2, 3 and 5. In all treatments, foliar spraying was done with a concentration of 5 per thousand at the late rosette stage and the beginning of flowering. Quantitative traits measured were seed yield, number of seeds per pod, number of pods per square meter, thousand grain weight and concentration of nutrient elements. Statistical analysis of data was done with SAS software and mean comparison was done with Duncan's test. The results showed that drought stress caused a significant decrease in yield and yield components, but the combined application of growth stimulants caused a significant increase in grain yield compared to the control. The amount of increase of grain yield without drought stress and under drought stress were 16.2% and 21.1%, respectively. These data indicated the greater effect of growth stimulants on increasing grain yield under drought stress than without drought stress. In normal condition, the application of amino acid significantly increased the grain yield by 14.4% compared to the control. In the condition of drought stress, the best results were obtained by combined application of growth stimulants. The application of growth stimulants improved the absorption of nutrient elements under drought stress. So, in the case of potassium, which is an important element in improving plant growth under drought stress, the application of fulvic acid had a significant effect on the increase of potassium concentration compared to the control, and its concentration increased from 2.9% to 3.8%. Also, the combined application of growth stimulants increased potassium concentration up to 3.6%. The results of this research showed the increase of drought tolerance and the improvement of canola growth with the combined application of growth stimulants.

Organic agriculture is an integrated farming system, based on natural principles and laws, where the quality of products is more important than their quantity. Therefore, the present study was conducted in order to investigate the effect of two types of biological and organic fertilizers on the growth and yield of two types of beans under drought stress in the research farm of Shahrekord University. The experiment was carried out in the form of split split plots in the form of a completely randomized block design, and in three replications. The investigated factors include 1- drought stress at three levels of 60, 90 and 120 mm of evaporation from the surface of the class A pan and the second factor at four levels: EM biological fertilizer, Vinas organic fertilizer, a combination of both, and control; and the third factor: species of two levels (Mexican yam beans, red beans of the flower variety). In this experiment, the traits of plant height, number of secondary branches, relative humidity of leaf water, cell membrane stability index, number of pods per plant, biological yield, seed yield and harvest index were measured. The results of variance analysis of the data showed that the effect of the studied factors and their interaction (except for the interaction of stress × fertilizer on the number of pods per plant and cell membrane stability index) was significant on all traits. The results showed that the combined fertilizer treatment (vinas + EM) in red bean plant and stress 60 had the greatest effect on the characteristics of seed yield (8834 kg/ha), harvest index (64.66%), plant height (117 cm), the number of pods per plant was (32.33), and the number of sub-branches (14). In the same fertilizer treatment and in the control stress treatment, the greatest effect was on the trait of cell membrane stability index in red bean plant (57.7%) and relative humidity. Leaf water (91.88%) and biological yield (35710 kg/ha) were in Mexican yam plant. Generaly, it can be said that this experiment showed the superiority of combined fertilizer treatment on red bean plant under drought stress compared to Mexican yam plant.

Water stress is one of the most important factors in reducing the yield of agricultural products worldwide. If the stress is intensive and continuous, plant growth and productivity are severely diminished. Water superabsorbent polymer can absorb and retain extremely large amounts of a liquid relative to its own mass. They have a wide range of applications because of their high water absorbing capacity, biodegradability and low cost.Humic acid is an organic compound that is derived from the decomposition of organic matter and contains carbon, hydrogen, oxygen and nitrogen. This acid plays a key role in increasing the fertility of the soil and feeding the plant when added to the plant, in helps to increase its growth through its effect to photosynthesis, respiration, increase the plants resistance to harsh environmental conditions and stimulates many of the vital interactions within the plant.Salicylic acid, a naturally occurring plant hormone, acts as an important signaling molecule and enhances tolerance of treated plants against biotic stresses. Salicylic acid also has a vital role in plant growth, ion uptake, and nutrient transport within the plant.Factor analysis is a technique that is used to reduce a large number of variables into fewer numbers of factors. This technique extracts maximum common variance from all variables and puts them into a common score.

In order to evaluate the effects of different irrigation levels and nutritional treatments and determining factors affecting water use efficiency of maize (Zea mays L.), a split plots experiment based on RCBD design with three replications was conducted during 2015-16 growing season, at Research Field of Ferdowsi University of Mashhad, Iran. Irrigation levels in two levels (50 and 100% of water requirement) and nutritional treatments in five levels (1- Nitrogen+Superabsorbent, 2- Superabsorbent+Humic acid+Salicylic acid, 3- Humic acid+Salicylic acid+Nitrogen, 4- Humic acid+ Salicylic acid+Nitrogen+Superabsorbent and 5- Control) assigned to main and sub plots, respectively.

The results showed that all of the nutritional treatments affected water use efficiency, but in both conditions of 50 and 100% of water requirement, the highest water use efficiency were obtained in treatment of Humic acid+Salicylic acid+Nitrogen+Superabsorbent. The highest seed yield (17542 kg.ha-1) observed in treatment of nitrogen+superabsorbent+humic acid+Salicylic acid and supply 100% of water requirement and the lowest seed yield (12515 kg.ha-1) obtained in treatment of control and supply 50% of water requirement. Factor analysis results showed that variables analyzed to two factors. First factor included 51% of variables variance, respectively. First factor included variables of seed yield, biological yield, plant height, leaf area index, crop growth rate and soil nitrogen, phosphorous and pH and variables of seed weight per plant, soil EC and water use efficiency were in second factor. In first factor, important variables such as soil nitrogen, phosphorous were included, so this factor describe soil conditions and second factor which had the highest impact on water use efficiency was called as water use efficiency factor. In a research reported that application of water superabsorbent increased seed yield of maize compared to control. In another research, the highest seed yield of maize obtained in treatment of simultaneous application of 120 kg.ha-1 water superabsorbent and 8 kg.ha-1 humic acid. Application of salicylic acid and humic acid enhanced seed yield of maize 24.5 and 24.2% compared to control, respectively.

In general, based on results of this research, it seems simultaneous application of nitrogen and ecological inputs can improve yield, growth characteristics and water use efficiency. Factor analysis and high correlation among variables in same group showed that with change of variables that are in same group of water use efficiency, can increased water use efficiency and decreased damages of drought stress.

The goals of study were to investigate the inoculation effects of Enterobacter S16-3 on growth characteristics of canola cultivars under drought stress.

This experiment was conducted as factorial-experiment based on randomized complete block design with three replications at hydroponic system of greenhouse, College of Agriculture, University of Tabriz. Inoculated and non-inoculated six canola cultivars were evaluated under two levels of drought stress conditions (0.6 and 1.2 MPa) and control.

Results showed drought stress caused a significant reduction in canola growth parameters such as fresh and dry weights of plant organs, height, root length, leaf relative water content and biological yield. Chlorophyll and proline content were suppressed under stress. Inoculation of canola cultivars with plant growth-promoting rhizobacteria not only improved height and root length, but also increased biological yield by 57.5 %. Bacterial inoculation also increased chlorophyll content and the concentration of proline under different stress conditions. Inoculated canola cultivars have better growth characteristics and biological yield than non-inoculated plants under drought stress conditions. Among canola cultivars inoculated Hyola308 surpassed other cultivars in all parameters under drought stress and the lack of a negative response to increasing drought stress indicated enhanced drought tolerance of Hyola308.

Taken together, these results demonstrated that Enterobacter S16-3bacteria probably has moderated the negative effects of drought stress and reduced the negative response of rapeseed cultivars to increasing drought stress by modifying the plant growth.