Drought stress
Alireza Mehrinfar; Mohammad Rezaei Moradali; Tooraj Mir Mahmoodi; Saman Yazdan Seta; Suran Sharafi
Abstract
IntroductionAbsorption of nutrients from the soil depends on soil moisture, fertilizer application, soil nutrients and other factors. Foliar application of nutrients under water stress is one of the ways to reduce the effect of stress on the quantity and quality of agricultural products. Today, in many ...
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IntroductionAbsorption of nutrients from the soil depends on soil moisture, fertilizer application, soil nutrients and other factors. Foliar application of nutrients under water stress is one of the ways to reduce the effect of stress on the quantity and quality of agricultural products. Today, in many countries, a variety of organic acids such as humus fertilizers are used to improve the quantity and quality of crops and orchards. These fertilizers can be used with irrigation, foliar application, hydroponic cultivation, soil application and seed inoculation. One of the objectives of this project was to identify new wheat cultivars tolerant to water stress condition and use micro elements to introduce suitable cultivars and the effect of these elements in increasing grain yield.Materials and methodsIn order to study the effect of foliar application of nutrients on grain yield and grain quality of bread wheat cultivars in conditions of water stress, the field studies were carried out during 2017-2018 and 2018-2019 at the Agricultural Research Station of Miandoab, in West Azerbaijan province, Iran (46º 3´ E, 36º 58´ N, altitude 1142 m). The experiment was performed as a factorial split plot in a randomized complete block design with three replications. Irrigation treatments in the main plots were included stopping irrigation at flowering stage until maturity and full irrigation until seed maturity. Sub-plots were foliar application treatments with zinc, potassium, phosphorus, magnesium and humic acid with four cultivars of wheat included Orum, Zare, Mihan and Heidari Each plot was planted in six rows with a length of four meters and a width of 1.2 meters at row intervals of 20 cm. Foliar application of micro elements was at the time of spike emergence and before flowering. Grain yield in the final harvest stage and removal of half a meter from the beginning and end of each plot was performed by a combine of grain experiments. After final sampling, 30 g of seeds per plot after digestion was used to measure micro elements in the grain using an atomic absorption. Combined analysis of variance of data from two years of study and drawing graphs was performed using MSTATC, SPSS and Excel software.Results and discussionIn this study, foliar application of zinc, increased 1000-grain weight, grain yield, harvest index, iron, manganese, zinc, and copper content in grin under normal irrigation by 9.30, 15.99, 18.30, 35.35, 102.10, 18.34, and 20.45 percent respectively under normal conditions and by 9.73, 4.36, 9.00, 41.81, 65.51, 43.24 and 29.78 percent respectively under drought conditions, Under normal irrigation conditions, foliar application of zinc in Mihan cultivar had the highest 1000-grain weight, grain yield, harvest index, manganese, zinc, and copper content in grain. Under drought stress conditions, the highest 1000-grain weight, grain yield, harvest index, manganese, and zinc content were allocated to foliar application of zinc in the Mihan cultivar. In this study, foliar application with zinc, potassium, phosphorus, and humic acid treatments in Mihan cultivar had equal grin yield and more than the control foliar application under normal irrigation conditions and was able to replace some of the water requirement of plant, Therefore, foliar application of these treatments along with selecting the appropriate cultivar can be a solution to improve the quantitative and qualitative yield of wheat in areas where the plant experiences periods of water deficit stress with different intensities.ConclusionsConsidering the favorable effect of foliar application of nutrients, especially zinc and humic acid on the quality and quantity of wheat grains, it is suggested that extension projects be carried out to transfer these results to farmers. Also, due to higher grain yield and high grain quality of Mihan cultivar, it is suggested that this cultivar gradually replace the previous cultivars.
Drought stress
Danial Pashang; Weria Weisany; Faridon Ghasem-Khan Ghajar
Abstract
IntroductionSevere climate changes and rapid population growth have influenced global food security. Oilseeds are the second main source of human food after cereals. Increases in the demand for vegetable oil at global markets and thus increases in the price of these oils, an economic pressure has been ...
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IntroductionSevere climate changes and rapid population growth have influenced global food security. Oilseeds are the second main source of human food after cereals. Increases in the demand for vegetable oil at global markets and thus increases in the price of these oils, an economic pressure has been imposed on the oil-importing countries. So, concerning population growth and increases in per capita food consumption, it is necessary to increase the area under oilseeds' cultivation and crop yield. Safflower is an oilseed crop of the family Asteraceae with favorable and unique characteristics that make it a valuable oilseed crop. Safflower due to having long roots and the high ability for absorbing water from deep soil layers, is considered as a low water-tolerant plant; but after the rosette stage, it becomes more sensitive to water stress such that since the first signs of inflorescence emergence up to the middle of the grain-filling period, it shows more sensitivity to this kind of stress.Materials and methodsThis study was performed during the 2018-2019 cultivation year in a 400-ha farm located in the Seed and Plant Improvement Institute, Karaj, Iran. The geographical location of the study area is 35° 49' N, 51° 6' E, and its elevation is 1321 m AMSL. According to climate data and ambrothermic curve, this area, due to having 150- 180 dry days, is considered as hot and dry Mediterranean climate. Because of having cold and humid winters but hot and dry summers, it has a dry moisture regime. Based on the average of 30-years of climate data, the mean temperature is 13.5 °C, the soil temperature is 14.5 °C, and in terms of soil temperature regime classification, it is considered as thermic areas. Table 1 represents the mean monthly temperature and precipitation during 2018-2019 and 2019-2020 cultivation years in Karaj. The main factor of this experiment was drought stress in two levels, i.e. normal irrigation (control) and irrigation cut-off at flowering stage, and two sub-factors include safflower cultivars (Golmehr and Goldasht) and foliar application of auxin in two levels, i.e. zero-application and applying 4 gL-1 auxin.Results and discussionResults of the present study illustrated that compared with Golmehr cultivar, Goldasht had higher number of grains per head, grain yield and biological yield. On the other hand, Golmehr cultivar had a higher plant height, percentages of oil, linolenic acid, and oleic acid, compared to Goldasht cultivar. Under drought stress, the activities of antioxidant enzymes and proline were not significantly different between the two cultivars; however, the Goldasht cultivar by accumulating the activities of catalase, peroxidase enzymes, and proline content showed higher resistance to drought condition than the Golmehr cultivar. Irrigation cut-off at flowering stage led to decreases in bush height, number of grains per head, number of plant heads, 1000-grain weight, grain yield, biological yield, harvest index, SPAD index, percentages of oil, palmitic acid, linoleic acid, oleic acid and increases in proline content, activities of antioxidant enzymes, i.e., catalase and peroxidase. In comparison with the no-auxin situation, applying auxin increased SPAD index, proline content and, activities of catalase and peroxidase so, it could alleviate the side effects of drought stress. Therefore, in addition to the reduction of production costs and saving water, especially in arid and semi-arid areas, which results from the foliar application of auxin and cutting of irrigation at flowering stage, also crop yield and oil percentage could be gained same as the ones gained under normal condition. Furthermore, concerning the evaluated characteristics and the reaction of studied cultivars to drought, Goldasht cultivar can be introduced as the preferable cultivar under drought stress conditions.
Breeding plants for stress conditions
Payam Pezeshkpour; Reza Amiri; Amin Namdari
Abstract
IntroductionLentil is grown for its biological nitrogen fixation ability and high proteins as well as human and animal nutrition capacity. Terminal drought, lack of suitable varieties and quality seeds have challenged the efforts of breeders to increase its productivity. Assessment of genetic diversity ...
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IntroductionLentil is grown for its biological nitrogen fixation ability and high proteins as well as human and animal nutrition capacity. Terminal drought, lack of suitable varieties and quality seeds have challenged the efforts of breeders to increase its productivity. Assessment of genetic diversity for desired traits in germplasm collections plays a critical role in formulating crop enhancement strategies. The aim of this study was to investigate the agronomic, phenological and morphological traits of advanced lentil lines received from the International Center for Agricultural Research in the Dry Areas (ICARDA) and to identify the relationships between important and effective traits using different statistical methods.Materials and methodsThis experiment was conducted on 15 promising lentil lines received from ICARDA along with two check cultivars (Gachsaran and Sepehr) in a randomized complete block design with three replicates under rain-fed conditions at Sarab-Changai Research Station, Lorestan Agricultural and Natural Resources Research and Education Centre, Khorramabad during 2019-2020 cropping year. Sowing was done by hand at four row plots, 4 m length, and 0.25 m row spacing as 200 seeds per square meter density. Fertilization with chemical fertilizers was performed based on soil test. The weeds control was manually performed twice. The total rainfall received was 542 millimeters in the cropping year. Different traits were measured according to standard guidelines for lentil during each stage.Results and discussionAccording to the results, the “number of two-seeded pods per plant” followed by number of empty pods per plant, number of one-seeded pods per plant, seed yield per plant, weight of pods per plant and number of fertile pods per plant had the highest coefficient of variation (78.78%) and phenological traits had the least variability. The results of analysis of variance showed a significant genetic diversity between the studied genotypes in terms of most traits. The mean of seed yield per plant was 2.66 g plant-1. Genotypes 6, 14 and 17 (Sepehr) by 6.02, 5.06 and 4.15 g plant-1, respectively had the highest amount. The correlation between grain yield per plant and most of the traits, especially yield components, was positive and significant. The genotypes were classified in three clusters. According to cluster analysis using Ward method, the genotypes of third cluster had high yield and yield components in compare with other clusters. Based on the SIIG index, the genotypes 6, 11, 14 and 17 with the highest SIIG values (0.727, 0.584, 0.569 and 0.537, respectively) were known as the best genotypes. On the other hand, genotypes 15, 2, 9, 10 and 5 with the least amount of SIIG value (0.185, 0.284, 0.323, 0.324, 0.357 and 0.362 respectively) were known as the weakest genotypes under rain-fed conditions. The highest direct positive effect on “seed yield per plant” belonged to the “number of fertile pods per plant” and therefore this trait can be applied as selection criteria. Fifteen agronomic traits have been classified into five groups which expressed 90.82% diversity of the total variation according to the factor analysis.ConclusionsIn this study, the studied genotypes were significantly different for most of the studied traits. Genotypes 6, 14 and 17 (Sepehr) were known as the best genotypes based on the results of various statistical methods including mean comparisons, cluster analysis and SIIG index. Therefore, they have the potential to be used in the future breeding and subsequent agronomic research programs. The number of fertile pods per plant had the most direct positive effect on seed yield. Therefore, it can be considered as a criterion for selecting superior genotypes.
Drought stress
Zhila Nazari; Raouf Seyed Sharifi; Mohammad Sedghi; Hamed Narimani
Abstract
IntroductionDrought stress is one of the most important abiotic factors that can limit plant growth and yield. The response of plants to water limitation has been evaluated based on genetic, biochemical and morpho-physiological traits. Several strategies have been developed in order to decrease the toxic ...
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IntroductionDrought stress is one of the most important abiotic factors that can limit plant growth and yield. The response of plants to water limitation has been evaluated based on genetic, biochemical and morpho-physiological traits. Several strategies have been developed in order to decrease the toxic effects caused by severe water limitation on plant growth. Among them the use of bio-fertilizers (such as mycorrhizae and vermicompost) and nano-silicon play a key role in yield improvement. The aim of this study was to investigate the effects of irrigation withholding in reproductive stages and nano-silicon and bio-fertilizers application on grain filling period, chlorophyll content and grain yield of triticale.Materials and methodsIn order to study the effect of vermicompost, mycorrhizae and nano-silicon on yield and chlorophyll content of triticale under water limitation conditions, an experiment was conducted as factorial based on randomized complete block design with three replications in greenhouse research of faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili in 2020. Experimental factors were included irrigation limitation at three levels (full irrigation as control, irrigation withholding in 50 percent of heading and booting stages as moderate and severe water limitation, respectively), bio-fertilizers application at four levels (no application of bio-fertilizers as control, application of vermicompost, mycorrhizae, and both application of vermicompost and mycorrhizae) and foliar application of nano-silicon (2 g.L-1 of nano-silicon and water-sprayed as control). Sanabad cultivar was used in the experiment with plant density of 400 seed m-2. Chlorophyll and carotenoids content were obtained according to Arnon (1949).To study the grain filling parameters in each sampling, two plants in each pot were taken. The first sampling was taken on day 8 after heading, and other samplings were taken in 4-days intervals to determine the accumulation of grain weight. At each sampling, grains were removed from spikes manually and were dried at 75°C for 48 h. A two-part linear model was used to quantifying the grain filling parameters. Total duration of grain filling was determined for each treatment combination by fitting a bilinear model:GW = [a + gfr(daa), ... ... if ... daa<Pm; a + gfr(Pm), ... ... if ... daa≥Pm]Where GW is the grain dry weight; a, the GW-intercept; gfr, the slope of grain weight indicating grain filling rate; daa, the days after earring; and Pm, physiological maturity. Borrás et al. (2004) determined grain filling using a bilinear model. Effective grain filling period (EGFD) was calculated from the following equation:EGFD = HGW/GFRWhere EGFD, HGW and RGF are effective grain filling period, the highest grain weight (g) and grain filling rate (g day-1), respectively.Conversely, an increase in grain weight in filling period was calculated using the above-cited equation in statistical software SAS 9.1 via NLIN DUD procedure. At plant maturity, grain yield in each pot were harvested by five plants per pot.Analysis of variance and mean comparisons were performed using SAS 9.1 computer software packages. The main effects and interactions were tested using the least significant difference (LSD) test at the 0.05 probability level.Results and discussionThe results showed that application of vermicompost, mycorrhizae and foliar application of nano-silicon under normal irrigation condition significantly increased chlorophyll a (61.02 percent), chlorophyll b (43.17 percent), total chlorophyll (55.97 percent) and carotenoid (55.8 percent) content, maximum of grain weight (54.78 percent), grain filling period (16.26 percent) and effective grain filling period (46.16 percent) in comparison with no application of bio-fertilizers and nano-silicon under irrigation withholding in booting stage condition. Also, there were a significant increase about 36.78, 45.83, 61.8, 44.11 and 59.52 percent in plant height, ear length, the number of grain per spike, 100 grains weight and grain yield per plant in application of vermicompost, mycorrhizae and foliar application of nano-silicon under full irrigation in comparison with no application of vermicompost, mycorrhizae and foliar application of nano-silicon under irrigation withholding in booting stage condition.ConclusionsIt seems that the application of bio-fertilizers and nano-silicon can increase grain yield of triticale under water limitation conditions due to improving chlorophyll content and grain filling components.
Salinity stress
Mojdeh Akbarzadeh Lelekami; Mohammad Hadi Pahlevani; Khalil Zaynali Nezhad; Keyvan Mahdavi Mashaki; Andreas P.M. Weber; Dominik Brilhaus
Abstract
IntroductionSalinity as one of the major abiotic stresses influences plant growth and development. Rice with a salt tolerance threshold of 3 ds/m is regarded as a very sensitive crop, especially at seedling stage. Metabolite profiling is conducted by instruments such as GC-MS (Gas chromatography–mass ...
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IntroductionSalinity as one of the major abiotic stresses influences plant growth and development. Rice with a salt tolerance threshold of 3 ds/m is regarded as a very sensitive crop, especially at seedling stage. Metabolite profiling is conducted by instruments such as GC-MS (Gas chromatography–mass spectrometry) and permits the study of plant responses to environmental stresses at the molecular level. The present study assessed the primary metabolite profiles related to high salinity stress in sensitive (IR28) and tolerant (CSR28) genotypes of rice seedlings in shoots and roots after 6h and 54 h salinity exposure.Material and methodsThe seeds of two rice (Oryza sativa L. ssp. Indica) genotypes with different salinity tolerance were obtained from International Rice Research Institute (IRRI) in Philippines. The plants were grown hydroponically in the greenhouse of Heinrich-Heine-University (HHU), Düsseldorf, Germany. The two-week old seedlings were exposed to 150 mM (15 ds/m) NaCl salinity. The topmost parts of the plants were harvested (in five replications of 10 seedlings each) at 6h and 54h post-treatment. Metabolite extraction was performed by GC-MS method. The experiment was conducted as factorial in a completely randomized design (CRD) and significance level was tested using ANOVA in SAS v9.2 software. R software was used for Principal Component Analysis (PCA) using metabolite z-score data Results and discussionGC-MS analysis identified 37 primary metabolites including 18 amino acids (AAs), five sugars and sugar alcohols and 14 organic acids (OAs) in roots and shoots of the CSR28 and IR28 genotypes at 6h and 54h post-salt exposure. In response to salinity, amino acids and sugars accumulated and organic acids depleted in both genotypes. Long-term stress revealed pronounced differences between the two genotypes. The major osmolyte proline indicated maximum response to salinity in CSR28 shoots, while the stress marker GABA accumulated more in IR28 shoots. Under high salinity the osmoprotectants raffinose and myo-inositol increased in CSR28 roots. Principal Component Analysis (PCA) revealed amino acid accumulations in the long-term exposure of salt stress in roots are main contributors to differentiate the genotypes for salt tolerance.ConclusionsBased on GC-MS analysis, 83.3% increase in amino acids and 61.8% decrease in organic acids were observed in response to salinity, indicating an increase in osmotic adjustment mechanisms and a decrease in photosynthetic reactions in the genotypes, respectively. The PCA demonstrated that amino acids play the most important role in separating the samples under salinity stress and control conditions in both organs. Further, the genotypes were differentiated due to metabolic changes in roots in response to salinity particularly in the long-term stress. Proline which is one of the most important osmolytes involved in abiotic stresses was significantly higher in the shoots of CSR28 under the long-term salinity compared to that of IR28. On the other hand, GABA which is a stress marker accumulated more in the shoots of the sensitive genotype. Some metabolites such as aspartate myo-inositol, citrate, glycerate, isocitrate and shikimate were specifically accumulated in roots. Finally, proline, GABA, etc. can be used as biomarkers for selecting salt tolerant lines. The present study highlights the contribution of metabolic adaptation to salinity tolerance.AcknowledgementsWe appreciate the International Rice Research Institute (IRRI) for providing the seeds. We also acknowledge the excellent technical assistance of Gorgan University of Agricultural Sciences and Natural Resources (GAU), Gorgan, Iran and Heinrich-Heine-University (HHU), Düsseldorf, Germany.
Drought stress
Fatemeh Aghaei; Raouf Seyed Sharifi; Hamed Narimani
Abstract
IntroductionIn arid and semi-arid regions, drought stress as the main factor and salinity stress as a secondary factor reduces plant growth and yield. Water limitation can damage pigments and plastids, reduce chlorophyll a, b, rate and grain filling period. One of the important strategies for increasing ...
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IntroductionIn arid and semi-arid regions, drought stress as the main factor and salinity stress as a secondary factor reduces plant growth and yield. Water limitation can damage pigments and plastids, reduce chlorophyll a, b, rate and grain filling period. One of the important strategies for increasing carbon dioxide concentration in plants is using chemicals such as methanol that can increase the concentration of CO2 in a plant and improves photosynthesis rate and growth under water deficit conditions. Methanol is considered as quasi-essential for plant growth and development, and alleviates toxic effects caused by various environmental stresses in plants. The aim of this study was to investigate the effects of methanol on the agro –physiological traits (i.e., chlorophyll content and grain filling period) and yield of wheat under water limitation conditionMaterial and method A factorial experiment was conducted based on randomized complete block design with three replications at the research farm of Faculty of Agriculture and Natural Resources of University of Mohaghegh Ardabili, during 2015-2016. Factors experiment were included irrigation levels (full irrigation as control, irrigation withholding in 50% of booting and heading stages as severe and moderate water limitation respectively, according with 43 and 55 BBCH code) and methanol foliar application at four levels (foliar application with water as control and foliar application 10, 20 and 30% volume of methanol). Foliar application with methanol was done in two stage of period growth (Stem elongation and Flag leaf development).Results and discussionResults showed that the maximum contribution of dry matter remobilization from air parts (20.52%) and contribution of stem reserves in grain yield (16.42%) were obtained with irrigation withholding at booting stage and no foliar application. The maximum grain filling period and effective grain filling period (33.62 and 29.33 days respectively) were obtained in full irrigation and foliar application of 30% volume of methanol and its minimum was obtained at no foliar application under irrigation withholding in booting stage. Also, results showed that there were an increase about 46.98%, 194.17%, 37.54%, 69.82% and 15.96% in grain yield, leaf area index, chlorophyll index, current photosynthesis and contribution of current photosynthesis in grain yield respectively in full irrigation and foliar application of 30% volume of methanol in comparison with no foliar application of methanol under irrigation withholding in booting stage. Based on the results this study, foliar application of 30% volume of methanol can be applied as a proper method to increase grain yield under water limitation conditions.
Drought stress
Shocofeh Gholami; Majid Amini Dehaghi; Amir Mohammad Naji
Abstract
IntroductionPlants often encounter unfavorable conditions, which interrupts their growth and productivity. Among the various abiotic stresses, drought is the major factor that limits crop productivity worldwide. Shortage of water causes drought that is the most dangerous hazard to food security all over ...
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IntroductionPlants often encounter unfavorable conditions, which interrupts their growth and productivity. Among the various abiotic stresses, drought is the major factor that limits crop productivity worldwide. Shortage of water causes drought that is the most dangerous hazard to food security all over the world. Because water supply is limited all over the world, food demand becomes a major problem. Priming of plant seeds is an easy, low-cost, low-risk, and effective approach to improve plant tolerance under stressful environment. . Priming of plant seeds is an easy, low-cost, low-risk, and effective approach to improve plant tolerance under stressful environments. In nutrient priming, seeds are pretreated (primed) in solutions containing the limiting nutrients instead of being soaked just in water. The physico-chemical and anti-oxidative properties of selenium (Se) have raised the curiosity of biologists in recent past. Research shows that selenium promotes the plant growth and may act as heavy metal opponent as it is a necessary micronutrient with some physiological and anti oxidative properties. However, for plants, studies has shown that although low concentrations of selenium can effectively promote plant growth, high concentrations of selenium have a significant toxic effect on plants.Materials and MethodsThus in order to investigate different concentrations of selenium (Na2Seo4) on antioxidant properties and photosynthetic pigments of quinoa under experimental drought stress conditions with 5 levels of selenium priming with sodium selenate source (0.5, 1.5, 3, 4.5 and 6 mg l-1), and two levels of hydropriming without priming and three levels of drought stress using polyethylene glycol (PEG) (0.4, 0.8 and 1.2 MPa) with three replications in Seed Technology Laboratory of Shahed University of Agricultural Sciences was conducted in 1398. Measured traits include antioxidant enzymes including catalase, superoxide dismutase, ascorbate peroxidase, and photosynthetic pigments, proline, and protein. Statistical analysis of the data included analysis of variance using AS 9.1 software and comparison of mean of traits evaluated by LSD test at 5% probability level.Results and discussion The results showed that the application of drought and prime stress with sodium selenate had a positive and significant effect on antioxidant enzymes, photosynthetic pigments, proline and protein content. Seed priming with sodium selenate increased the activity of antioxidant enzymes including catalase, superoxide dismutase and ascorbate peroxidase under drought stress. Based on the results under stress conditions, protein content and photosynthetic pigments showed a decreasing trend and prime with sodium selenate slowed down this decreasing trend. The highest amount of proline in stress of 1.2 MPa and prime with sodium selenate with a concentration of 4.5 mg l-1 showed a 66% increase compared to drought stress of 0.4 MPa and no priming.
Breeding plants for stress conditions
Zeinab Pirsalami; Asad Masoumiasl; Hosein Shahsavand Hasani
Abstract
IntroductionTritipyrum lines are obtained from a cross between durum wheat and Thinopyrum bessarabicum (2n=2x=EbEb) and its tolerance to salinity has been reported. Tritipyrum (2n=6x=42, AABBEbEb) is the third new man-made grain after triticale and tritordium, and needs further studies until release ...
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IntroductionTritipyrum lines are obtained from a cross between durum wheat and Thinopyrum bessarabicum (2n=2x=EbEb) and its tolerance to salinity has been reported. Tritipyrum (2n=6x=42, AABBEbEb) is the third new man-made grain after triticale and tritordium, and needs further studies until release as a commercial cultivar. Therefore, this study was designed to investigate the effect of salinity stress on the amount of sodium and potassium in roots and leaves, the ratio of potassium to sodium in roots and leaves, the amount of soluble protein, soluble sugar and proline in a number of primary and combined tritipyrum lines.Materials and MethodsIn this study, 13 promising of primary and combined tritipyrum lines were tested in a factorial experiment based on completely randomized design with 3 replications. The first factor includes salinity levels (0, 80, 160 and 240 mM of sodium chloride salt) and the second factor includes 13 promising of primary and combined tritipyrum lines and 2 bread wheat varieties of Alvand and Qods (tolerant and sensitive to salinity, respectively). Measurement of sodium and potassium elements of leaves and roots was performed one month after salinity stress and the amount of proline, leaf soluble protein and leaf soluble sugars were also measured.Results and DiscussionThe results showed that with increasing salinity stress, root potassium decreased but root and leaf sodium increased. Levels of proline and soluble sugars also increased with increasing salt concentration. At 240 mM salinity stress, the highest amount of leaf potassium belonged to Ka/b and La(4B/4D)*b lines and the lowest amount of it belonged to Az/b, (Cr/b)(Ka/b)F3 lines and the Qods variety. The highest ratio of leaf potassium to sodium was belonged to (Cr/b)(Ma/b)F3, La(4B/4D)*b and St/b lines and therefore these lines are more tolerant to salinity stress. At 240 mM salinity stress, the highest leaf protein belongs to the Az/b line and the lowest value belongs to the (Cr/b)(Ma/b)F3 line. In both stress and non-stress conditions, the highest genetic variance belonged to leaf protein and the amount of this variance in stress conditions was much higher than non-stress conditions. The environmental variance of root and leaf sodium and leaf potassium traits was higher in salinity stress conditions than in non-stress conditions, which indicates that it will be more difficult to evaluate genotypes for stress traits under stress conditions. Phenotypic variance of root and leaf sodium and leaf potassium as well as leaf protein in salinity stress conditions was higher than non-stress conditions, i.e. the above traits are not suitable for selection. The highest general heritability in normal conditions belonged to proline and in stress conditions belonged to leaf soluble sugar. Under normal conditions, the most significant negative correlation was between root sodium and leaf sodium. There is also a significant positive correlation between leaf protein and soluble sugar. Under stress conditions, there is a significant correlation between leaf sodium and root sodium and also between leaf potassium and proline. There is a significant negative correlation between leaf proline and sodium and the root and leaf potassium to sodium ratio has a significant positive correlation with the amount of proline. The studied genotypes categorized in 3 groups under stress conditions and 4 groups under stress conditions using cluster analysis.ConclusionBased on the ratio of potassium to sodium in plant tissues, which is one of the important index for the identification of salinity-tolerant species, we can introduced (Cr/b)(Ma/b)F3 and La(4B/4D)*b and St/b lines as salinity tolerant lines. On the other hand, according to the results, the crossing of genotypes with maximum genetic distances can be used to hybridization and produce more tolerant hybrids in breeding programs.
Heat stress
Abdollah Bahrani; Mehran Mombeini
Abstract
IntroductionRice (Oryza sativa.L) is one of the most important grains in the world, which as one of the major food sources, provides food to more than three billion people in the world. In the near future, there are several challenges to achieve higher yields in rice plants, and one of the most basic ...
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IntroductionRice (Oryza sativa.L) is one of the most important grains in the world, which as one of the major food sources, provides food to more than three billion people in the world. In the near future, there are several challenges to achieve higher yields in rice plants, and one of the most basic of these challenges is increasing the average temperature of the earth's surface. Increasing the temperature indirectly reduces production by increasing water demand in areas with limited water and reducing the area under cultivation. Therefore, plant physiologists' understanding of plant physiological responses to high temperatures, as well as the selection of adaptation strategies, is an effective and very important role in rice research. In line with international research, research on introducing a diverse range of heat-tolerant rice cultivars on the one hand and finding effective physiological traits and mechanisms in tolerance or resistance of common rice cultivars in the province to this stress can play a valuable role in inactivation, modulation of negative effects or greater efficiency of the heat and light stress situation arising in the coming years. In other words, making management decisions regarding the production and use of improved cultivars, introducing native tolerant or heat-resistant cultivars and possible required changes in the temporal and spatial patterns of cultivation of cultivars, can be a significant help in combating heat stress. Therefore, this experiment was conducted to evaluate heat stress on grain yield and to study stress tolerance indices in studied cultivars in the Khuzestan region.Materials and methods In order to evaluate the stress tolerance and susceptibility indices of rice plant (Oryza sativa L.) in response to heat stress, an experiment with two factors of planting date and cultivar on the basis of split plots in a randomized complete blocks design with three replications in two years 2017 and 2018 were carried out in the south of Khuzestan province. In order to apply high temperature stress (heat stress) in field conditions, three planting dates of May 15, June 5 and June 25 were selected as the main plots. At each planting date, seven rice cultivars including Anbouri, Champa, Daniel, Pollen, Hamr, and Hoveyzeh (native cultivars) and N22 (International cultivar) were cultivated as sub-plots. Stress tolerance indices included GWHSI SSI, STI, TOL. Results and discussion The results showed that at the level of planting date, the highest grain yield was on 5 June with a yield of 5737 kg.ha-1, which was 41.7 more than the first planting date. The highest grain yield was obtained among the cultivars related to Hoveyzeh with an average of 5606 kg.ha-1, which was 34.3% and 29.6% higher than Champa and Anbori, respectively. In evaluating stress tolerance indices, N22 and Hoveyzeh cultivars had the highest SSI and STI, Hammer and Hoveyzeh cultivars showed the highest STI and N22 and Hammer cultivars showed the lowest TOL. The lowest (SSI) was obtained in Hoveyzeh cultivar and then in Hamr and N22 cultivars. The lowest heat stress tolerance was also observed in Champa cultivar. Also, the highest STI index and the lowest TOL index were obtained in Hamr, N22 and Hoveyzeh cultivars. The lowest GDD in all three planting dates was in Hoveyzeh cultivar and the highest one was in sensitive cultivars to heat stress (Anburi and Champa).Conclusions In general, heat-tolerant cultivar N22, Daniel and local cultivars Hoveyzeh and Hamr were heat-tolerant cultivar and Geredeh Ramhormoz cultivar and Anbouri and Champa (native cultivars) were identified as heat-sensitive.
Flooding stress
Zahra Behzadi; Hamid Najafi Zarini; GholamAli Ranjbar; Ali Pakdin
Abstract
IntroductionFlax is a herbaceous plant with the scientific name of Linum usitatissimum L. The origin of this plant is reported to be the western Mediterranean. Flax is one of the most important oily and medicinal plants with wide compatibility and multiple uses. Waterlogging stress is one of the abiotic ...
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IntroductionFlax is a herbaceous plant with the scientific name of Linum usitatissimum L. The origin of this plant is reported to be the western Mediterranean. Flax is one of the most important oily and medicinal plants with wide compatibility and multiple uses. Waterlogging stress is one of the abiotic stresses that has received little attention despite the fact that it causes a lot of damage to the crop.Materials and methodsIn this study, 100 flax cultivars were studied. The mentioned cultivars were planted in a greenhouse as a factorial experiment in a randomized complete block design to investigate genetic diversity and select the best cultivars in terms of yield and other morphological traits. First, flax seeds were planted in drainage pots containing field soil and aerated sand in a ratio of 2:1. Soil-related measurements including field capacity (FC) and soil electrical conductivity (EC) were performed. Waterlogging stress was applied in four-leaf stage. For two weeks, the pots that were in normal condition were irrigated according to the field capacity of the soil and the pots that were under stress were irrigated more than the field capacity of the soil. The main purpose of this study was to identify Waterlogging-resistant flax genotypes using all indices simultaneously and also to identify high-yield genotypes under Waterlogging stress and non-stress conditions. MP, STI, GMP, YI, DRI, YSI, SSI, TOL and β indices were calculated and finally tolerant and sensitive genotypes were identified by stress tolerance score (STS) index. STS equation for the raw data is not accurate. All indices in STS equation were standardized according to equation 10. All calculations were performed using SPSS software version 22 and Excel.Results and discussionThere was a significant correlation between Ys and Yp. TOL, STI, MP and GMP indices with positive and significant correlation with performance under normal conditions and STI, MP, GMP, YI and DRI with performance under normal conditions. Dendrogram was drawn based on stress tolerance score. Flax genotypes were divided into 4 groups: resistant, semi-resistant, semi-susceptible and susceptible. Analysis of variance was performed to determine the accuracy of grouping between groups and there was a significant difference between the groups. According to the stress tolerance score index, genotypes 364, 352, 286, 370 and 172 were identified as waterlogging tolerant genotypes in this study and genotypes 263, 269, 295, 325 and 108 were the most sensitive genotypes. According to the stress tolerance score index, genotypes 364, 352, 286, 370 and 172 were submerged as stress tolerant genotypes. These genotypes are predicted to be used as donors of waterlogging tolerance genes. Research findings also indicate that tolerant genotypes ultimately lead to higher production and yields than other genotypes in conditions of heavy rainfall and prolonged waterlogging. These genotypes can also be used in breeding programs based on hybridization and identification of QTLs associated with waterlogging tolerance.ConclusionsThey were overwhelmed by tension. According to the stress tolerance score, genotypes 364, 352, 286, 370 and 172 were identified as flood tolerant genotypes in this study and genotypes 263, 269, 295, 325 and 108 were the most sensitive genotypes.
Breeding plants for stress conditions
Sima Abyar; Saeid Navabpour; Rahmatollah Karimizadeh; Amir Gholizadeh; Ali Asghar Nasrollahnejad Ghomi; Ghaffar Kiani
Abstract
IntroductionWheat bread is one of the most important food products in the world. In terms of area under cultivation and production it ranks second among different products. Therefore, Genetic advances in sustainable wheat production can play a large role in global food security. The average wheat production ...
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IntroductionWheat bread is one of the most important food products in the world. In terms of area under cultivation and production it ranks second among different products. Therefore, Genetic advances in sustainable wheat production can play a large role in global food security. The average wheat production in the world is reported Nearly 3.425 and its average production in Iran is 2.164 tons per hectare. Given the importance of wheat, Production of this product should be increased by cultivating modified genotypes with high grain yield. Wheat grain yield is affected by environmental conditions, genetic potential and its interaction. Identifying genotypes that have good performance and stability in different environmental conditions seems to be complex due to the strong interaction of genotype and environment. The change that occurs in the relative performance of genotypes in different environments is called genotype × environment interaction.Genotype × environment interaction is one of the most important issues in plant breeding which is of great importance in introducing and releasing modified varieties. Cultivation of genotypes in test environments during different years and places it has determined the stability of performance. And genotypes with less genotype × environment interaction are selected. Usually in breeding programs, Genotypes are known as compatible that the variance of their interaction with the environment is small. Among the multivariate methods, GGE biplot method is one of the most important methods for investigating the interaction of genotype × environment and determining stable genotypes.Water scarcity is the most essential limiting element of agricultural production, particulary in arid and semi-arid areas throughout the world. Evaluation of the bread wheat genotypes under different environmental conditions would be useful to identify stable and high yield potential genotypes.Materials and methods15 new bread wheat lines along with Aftab cultivar were evaluated in a randomized complete block design with three replications in four experimental field stations (Gachsaran Khoramabad, Moghan and Gonbad) during three crop seasons (2017-2020). GGE biplot statistical method (genotype effect + genotype × environment interaction) was used to study stability of genotypes in the studied environments.Results and discussionResults of combined analysis of variance indicated that the effects of environments, genotypes and genotype × environment interaction were significant. The results indicated that 91.49, 1.54 and 5.03 percent of total variation were related to the environment, genotype and genotype × environment interaction effects, respectively. The polygon-view of GGE biplot recognized five superior genotypes and four mega-environments so that the best genotypes within each environment were determined. Based on the hypothetical ideal genotype biplot, the line G7 with 3818 Kg ha-1 grain yield was the better genotype than other genotypes. Also this genotype showed the most stability and had the high general adaptation to all environments. Biplot of correlation among environments revealed that environmental vectors of Gachsaran and Gonbad were near to 90◦ so, these locations were different environments. The results showed that all environments had high discriminating ability so that could able to show differences between genotypes.ConclusionGenerally, the results indicated that the line G7 with suitable mean seed yield and high broad adaptability was selected as superior line for further investigation to introduce the new commercial wheat cultivar under dryland conditions. Also, the Moghan environment was the nearest environment to ideal environment that had the highest discriminating ability and representativeness.
Drought stress
Younes Mir; Hamed Khosravi; Mashalah Daneshvar; ismaili Ahmad
Abstract
Introductioncanola (Brassica napus L.) is one of the most important oilseed plants that has been ranked third in the oil production after soybeans and oil palm. Drought is seriously the most important factor limiting the growth and production of canola in Iran. By foliar application of micronutrients, ...
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Introductioncanola (Brassica napus L.) is one of the most important oilseed plants that has been ranked third in the oil production after soybeans and oil palm. Drought is seriously the most important factor limiting the growth and production of canola in Iran. By foliar application of micronutrients, plant growth condition can be improved under stress. Salicylic(SA) acid plays an important role in abiotic stress tolerance, and more interests have been focused on SA due to its ability to induce a protective effect on plants under adverse environmental conditions. It is necessary to know the traits related to drought tolerance and their relationship with seed yield. due to the important role of roots in the absorption and conduction of water and nutrients, recognition the root system and how it is distributed in the soil is special importance. therefore, the purpose of the present study was to investigate the Effect of foliar application of some micronutrients and salicylic acid on root characteristics and seed yield of canola (Brassica napus L.) under water deficit stress.Materials and methodsthe experiment was conducted as split factorial in a randomized complete block design with three replications in Lorestan University, Iran, in two cropping seasons (2016-2018). water deficit was considered as the main factor in levels irrigation at 80 (control) and 30% of field capacity, and the combination of foliar application of micronutrient fertilizer (non-consumption and spraying at a concentration of 0.2%) and salicylic acid concentration of 0, 0.5, 1 and 1.5 mM were considered in sub-plots. the time of water deficit stress coincided with the stage of the beginning of regrowth (BBCH32). foliar application of micronutrient fertilizer in rosette stage (BBCH29) and foliar application of salicylic acid in two stage of flowering beginning (BBCH60) and pod filling (BBCH72). the measured traits included root dry weight, root volume, root area, seed yield, oil percentage, and water use efficiency. the data was analyzed by statistical analysis system (SAS version: 9.1). the means were analyzed using the Duncan test at P=0.05.Results and discussionthe results of analysis of variance showed the effect of year on seed yield, effect of salicylic acid on seed yield and oil percentage, double interaction of micronutrient fertilizer in salicylic acid on root volume and triple interaction of stress in micronutrient fertilizer and salicylic acid on root weight, root volume and water use efficiency were significant. the results of comparative analysis of the mean data showed that the highest percentage of oil was obtained from concentration of 1 to 1.5 mM of salicylic acid.the highest root volume (49.90 cm3) was obtained from the treatment composition (foliar application of 1.5 mM salicylic acid and concentration of 2 per thousand micronutrient fertilizers). the highest root dry weight (28.95 gr), root area (4360 cm2) and water use efficiency (1.26 kg m-3) from the treatment composition (no stress + 1.5 mM salicylic acid spraying and concentration of 2 per thousand fertilizers Micronutrients) was obtained. the highest seed yield (4955.7 kg ha-1) was obtained from foliar application 1.5 mM of salicylic acid, In the first year, the highest seed yield (4427.7 kg ha-1) from the combination (no stress + foliar spraying of 1.5 mM salicylic acid and a concentration of 2 per thousand micronutrient fertilizers) and in the second year of the combination (no stress + foliar spraying of 1 mM salicylic acid) and a concentration of 2 per thousand micronutrient fertilizers with an average (4955.7 kg ha-1) was obtained.Conclusiontherefore, a triple micronutrient fertilizer (iron+zinc+ manganese) with a concentration of 0.2% is recommended along with a concentration of 1.5 mM of salicylic acid to reduce the negative effects of water deficit stress and achieving acceptable seed yield.
Drought stress
Zohreh Hajibarat; Abbas Saidi; Ahmad Mousapour Gorji; Mohammad Reza Ghaffari; Mehrshad Zeinalabedini
Abstract
IntroductionWater deficit poses severe limitation to potato cultivation as a drought-sensitive crop plant. Selection of tolerant genotypes based on a combination of tolerance indices can provide useful criteria for breeding drought tolerant potato varieties. Water deficit affects plants at various levels ...
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IntroductionWater deficit poses severe limitation to potato cultivation as a drought-sensitive crop plant. Selection of tolerant genotypes based on a combination of tolerance indices can provide useful criteria for breeding drought tolerant potato varieties. Water deficit affects plants at various levels and stages of their life cycle. This abiotic stress not only affects plant–water relations through the reduction of leaf water content, turgor, and total water, but it also affects stomata closure, limits gas exchange, reduces transpiration, and disturbs photosynthesis. In potato, tolerance to drought is a very complex trait. Photosynthesis is one of the basic physiological processes of plants with internal and external conditions. Any reduction of the intensity of this process causes a decrease in the amount and quality of crop plants. One of the indicators for early prediction of potato yielding can be the measurement of chlorophyll content. It is an informative tool for studying the effects of different environmental stresses on photosynthesis. Chlorophyll content has an important role in photosynthesis and in understanding plant functions. In any research, measuring of the chlorophyll content is used for assessment of potato genotypes tolerant and/or sensitive to environmental stresses.Materials and methodsIn this study, 20 potato genotypes were evaluated under two water levels; normal and water deficit stress conditions. The experiment was performed as spilt-plot based on randomized complete block design with three replications at the Seed and Plant Improvement Institute, Karaj, Iran in 2018. The correlations among the different traits were measured and estimated by calculating Pearson correlation coefficients using the statistical tool in Minitab 17. Tuber yield, yield components, growth parameters, and morphological traits were measured under both well-watered and water stressed treatments. Morphological and reproductive characteristics such as plant height, leaf dry weight, chlorophyll content, yield tuber, ware yield, seed yield, non-marketable yield, and marketable yield were measured. Result and discussionAnalysis of variance showed that stem number, chlorophyll content, stem thickness, plant height, leaf dry weight (LDW), total yield, ware yield (yield>55 mm), seed yield (yield 35-55 mm), non-marketable yield (yield<35 mm), and marketable yield (ware and seed yield) were significantly affected by genotype and drough and their interaction. Analysis of variance showed that the simple effect of genotype treatment on all studied traits including yield, ware yield, seed yield and marketable yield, LDW, stem thickness, plant height, chlorophyll content, and stem number were significant at 1% level. Correlation of stem number and plant height was highly positive and significant at the 0.01 level. Principal component analysis (PCA) and measured traits showed that genotypes 2, 5, 7 and 13 had high performance in the studied stress environment. To fully reflect the various factors that played a principal role in the comprehensive indicators, PCA was carried out on quantitative traits. The accumulative contribution rate accounted for 99% of the total variation for PC3. Analysis of PCA by the correlation matrix and the biplot analysis methods used in this study revealed that these parameters could be used for evaluating the responses of potato genotypes to water deficit in different environments. The associations among traits related to yield and genotypes are graphically revealed in a biplot of PC1 and PC2. The PC1 and PC2 axes mainly distinguish the morphological traits and yield-related traits in three different groups. ConclusionParameters related to yield and leaf photosynthetic pigment content (chlorophyll content) were used to rank the clones and cultivars tested for comparative analysis. Based on our results, genotype 7 performed well under normal and water stress conditions. Water deficit is an important constraint limiting the crop productivity worldwide. Plants show a wide range of responses to water deficit which are mostly expressed by a variety of alterations in the growth and morphology of plants. Field experiments revealed that water deficit affects all evaluated morphological and yield related traits.
Drought stress
Reza Rahimi; Farzad Paknejad; Mehdi Sadeghi-Shoae; Mohammad Nabi Ilkaee; Mehdi Rezaee
Abstract
IntroductionWater is one of the most important needs of plants and drought stress is one of the most important stresses for plant growth. Given the global water shortage, provide solutions to save water consumption in agriculture, such as choosing the appropriate irrigation method, irrigation time management, ...
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IntroductionWater is one of the most important needs of plants and drought stress is one of the most important stresses for plant growth. Given the global water shortage, provide solutions to save water consumption in agriculture, such as choosing the appropriate irrigation method, irrigation time management, providing methods to reduce and control the negative effects of water shortage on plants and the use of more resistant varieties to water shortage and The use of different techniques to reduce the effects of water scarcity is important and should be a priority for research. Paclobutrazole is a group of plant growth regulators of triazole that prevents the production of a wide range of gibberellic acid and has many applications in agriculture. Paclobutrazole reduces the negative effects of abiotic stress on plant growth by regulating the levels of hormones, enzymatic and non-enzymatic antioxidants and osmolytes. A group of beneficial soil bacteria that increase plant growth are called plant growth promoting bacteria and are among the most important types of biofertilizers. PGPRs by lat out of volatile organic compounds (VOC) increase biomass, plant tolerance to abiotic stresses and disease resistance.Materials and MethodsThis research was conducted as a factorial split plot in the form of a randomized complete block design with three replications in Qom and Hamedan regions (Hamedan is a cold and mountainous region with mild summer and Qom is a dry and desert region with hot and dry summers). Experimental factors include irrigation regime with three levels 1- (irrigation at 40% of available plant moisture discharge during the growing season (optimal irrigation), 2- optimal irrigation up to pollination stage and irrigation at 60% of available plant moisture discharge until the end of the growing season 3- Irrigation in 40% of available plant moisture discharge up to pollination stage and cessation of irrigation until the end of growing season), foliar application of paclobutrazole at three levels (zero, 50 and 100 ppm in two stages of stem and spike) and invoice The third included five levels of growth-promoting bacteria (non-consumption, Mycobacterium, Azotobacter, Azospirillium, and a combination of three bacteria). Irrigation regimen factors and paclobutrazol in the main plots and growth-promoting bacteria in the subplots. The traits evaluated in this experiment included parameters related to leaf chlorophyll fluorescence and Rubisco activity. Results and DiscussionThe results showed that the interaction effect of irrigation regime on paclobutrazol was significant for biological yield and grain yield, so that at the third irrigation level, the use of paclobutrazol at a concentration of 100 ppm increased grain yield and biological yield. Also, according to the analysis of variance table, the interaction effect of irrigation regime in bacteria for biological yield and grain yield was significant, so that in the third level of irrigation regime, two levels of combination of three bacteria and Azotobacter with 19.05 and 17.95 tons, respectively. Hectares had the highest biological yield.ConclusionsIn general, the results showed that in more difficult conditions of irrigation regime, the use of paclobutrazol can cause less decline and improve grain yield and biological yield. It can also be inferred that the use of growth-promoting bacteria increases grain yield and biological yield and improves morphological traits, and the combination treatment of Mycobacterium, Azotobacter and Azospirillium had the highest yield.
Physiology of crops under stress conditions
Saeedeh Alipour; Elias Soltani; Iraj Alahdadi; Majid Ghorbani Javid; Gholam Abbas Akbari
Abstract
IntroductionSoil erosion causes storms and the release of fine dust. This has a significant impact on climate change and creates global problems. The first effect of dust on agriculture is in the field of reduced production, reduced diversity and reduced vegetation density because fine dust is a factor ...
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IntroductionSoil erosion causes storms and the release of fine dust. This has a significant impact on climate change and creates global problems. The first effect of dust on agriculture is in the field of reduced production, reduced diversity and reduced vegetation density because fine dust is a factor that causes negative effects on plant physiology. geomorphological features, soil type and vegetation are the most influential factors in desertification and dust production. Strengthening natural ecological cycles and rehabilitating forests and plantation pastures is the best basic solution to control wind erosion. The main widely used plant species in arid and saline areas are halophyte rangeland species. Among these, two plant species of Salsola imbricata and Salicornia iranica grow well in the desert pastures of Iran. These two species of halophyte due to their unique characteristics, such as drought resistance, salinity, deep root system, high efficiency in water use, etc. as an important forage plant in soils It is considered dry and is important for planting in saline lands where other crops are not producing well or in areas where irrigation with saline water is possible. But on the other hand, determining the most appropriate planting date means determining the time when vegetative and reproductive growth of the plant is most in harmony with climatic factors and the plant is less exposed to adverse environmental conditions. , Plant development and production during the growing season and is one of the most important management factors in the production of all crops in order to reduce the negative effects of environmental stresses. Therefore, the main purpose of this study was to investigate the effect of planting date on biostability of these two plant species against stress. It was fine.Materials and methodsThis experiment was performed as a split in a randomized complete block design with three replications in the crop year 2020 in Pakdasht city. Factors tested include: three planting dates:, 20 March, 3 April and 19 April as the main plots, dust factor at three levels: (control (without dust), dust spread on the plant for 5 days and 10 days) to The sub-plots and species factor (Salicornia iranica, Salsola imbricata) were considered as sub-plots. In order to spray dust on the space plants, a cubic of transparent plastic was made to the dimensions of each plot and was placed on each plot during the application of stress. The time of application of fine dust stress was on the second of July, 1399. The traits of the studied plant species were measured at the flowering stage. For calculation, chlorophyll content (Arnon.1949), membrane lipid peroxidation assay (Yidirim and et al. 2009), measurement of relative leaf water content (Ritchie et al. 1990), protein content assay (Bremner. 1996), carbohydrate assay Soluble (Hasid and Neufield. 1964) 2 plants were selected from each plot and traits were measured. To measure forage yield, 5 plants from each subplot were calculated and weighed.Results and discussionAmong the agronomic factors, planting time is one of the most important factors determining plant yield. Planting date for each species in a specific area should be considered according to the ambient temperature and soil at the time of planting and also based on the non-interference of flowering plant to high temperature. Both species are more suitable, so to achieve the desired forage yield, it is necessary to plant both plants when the average temperature is 25-25 ° C and to avoid planting delays. On the other hand, the storage capacity of more dust in the plant is one of the determining factors in selecting species compatible with fine dust and reducing air pollution. Salsola also showed more dust holding capacity than Salicornia due to waxy leaf cover, slightly wrinkled margins. Therefore, according to the obtained results, Salsola plant can be a better choice for cultivation in the center of fine dust and control of fine dust.
Drought stress
Sanaz Pourali; Fayaz Aghayari; Mohammad Reza Ardakani; Farzad Paknejad; Farid Golzardi
Abstract
IntroductionAccording to studies, the agricultural sector is the largest consumer of water and in this sector, paying attention to optimal water consumption is very important. On the other hand, climate change and the spread of environmental stresses in recent years have reduced crop yields; therefore, ...
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IntroductionAccording to studies, the agricultural sector is the largest consumer of water and in this sector, paying attention to optimal water consumption is very important. On the other hand, climate change and the spread of environmental stresses in recent years have reduced crop yields; therefore, the need to identify appropriate solutions to deal with such situations is fully felt. Restoring diversity to agricultural ecosystems and its effective management is recognized as one of the important strategies in sustainable agriculture. Mixed cropping as a sample of sustainable systems in agriculture pursues goals such as creating ecological balance, greater utilization of resources, and increasing crop yields. The most important benefit of intercropping systems compared to monoculture systems is the increase in production per unit of area, which of course has not always been achievable and this advantage is achieved only when the plants that make up the mixture are completely different in terms of how and how much to use growth factors (water, light, and nutrients). Therefore, when plants with different morphological characteristics are grown in a mixture next to each other, they can make optimal use of environmental factors and as a result, their total yield increases per unit of area. The present study aimed to evaluate the forage production potential in the replacement and additive intercropping systems of sorghum and red clover under different irrigation regimes.Materials and methodsThis experiment was conducted as split plots based on a randomized complete block design with three repetitions during the 2017 and 2018 cropping seasons at the Research Farm of Damavand Natural Resources Department. The main factor was the irrigation regime at three levels including irrigation with 100% field capacity (full irrigation as control), irrigation with 75% field capacity (moderate stress), and irrigation with 50% field capacity (severe stress). Different cropping systems were considered as sub-factors, including 75% sorghum + 25% clover, 50% sorghum + 50% clover, and 25% sorghum + 75% clover as replacement intercropping systems; 100% sorghum + 50% clover, 50% sorghum + 100% clover, and 100% sorghum + 100% clover as additive intercropping systems, and the monocultures of sorghum and red clover as control. Each experimental plot consisted of six planting rows with a length of six meters with a distance between the lines of 60 cm. In order to prevent water leakage to adjacent plots, the distance between the main plots was four planting lines. In this experiment, forage sorghum of the Speedfeed cultivar and red clover of the Nassim cultivar were used. For planting sorghum and clover in monoculture treatments, 15 and 25 kg of seeds per hectare were used respectively. Also, for planting intercropping treatments based on mixing ratios of 25, 50, and 75%, 3.75, 7.50, and 11.25 kg of sorghum seeds and 6.25, 12.50, and 18.75 kg of clover seeds per hectare were consumed respectively. Experimental treatments were irrigated by the furrow method. The irrigation cycle was adjusted based on draining 40% of available water in the root zone under full irrigation conditions. Irrigation water depth in full irrigation treatment was determined based on the soil moisture deficiency (relative to the point of field capacity) at the time of irrigation through sampling. Irrigation water depths in moderate and severe stress treatments were considered based on 75% and 50% of full irrigation water depth, respectively. It should be noted that after the establishment of sorghum plants, thinning operations were performed and its density was adjusted based on 20 plants per square meter. In this experiment, the planting pattern was in rows and the change of mixing ratios was applied based on the change in the number of planting rows of sorghum and clover. In monocultures and replacement intercropping systems, planting operations were performed in the middle of the ridges, while in additive intercropping treatments, a two-row pattern was used and each species was planted on one side of the ridges.Results and discussionThe results of variance analysis showed that the effect of year, irrigation regime, and cropping system and the interaction of irrigation regime × cropping system on fresh and dry forage yield of clover, sorghum, and total yield were significant. The highest fresh and dry forage yields (65.169 and 14.059 ton ha-1, respectively) were obtained in the additive intercropping system of 100% sorghum + 100% clover under the full irrigation regime, whereas the minimum fresh and dry forage yields (4.191 and 0.920 ton ha-1, respectively) were recorded in clover monoculture under severe drought stress. Under moderate and severe drought stress, the maximum fresh and dry forage yields were obtained in sorghum monoculture and then in the additive intercropping system of 100% sorghum + 100% clover. Furthermore, the effect of the cropping system and the interaction of irrigation regime × cropping system on the land equivalent ratio (LER) for fresh and dry forage production were significant. The highest land equivalent ratio for fresh and dry forage production (1.719 and 1.723, respectively) was obtained in the additive intercropping system of 100% sorghum + 100% clover under full irrigation, whereas the lowest land equivalent ratio for fresh and dry forage production (1.024 and 1.022, respectively) was recorded in replacement intercropping system of 25% clover + 75% sorghum under full irrigation.ConclusionAccording to the results of this study, the additive intercropping system of 100% sorghum + 100% clover can be recommended as the superior treatment in all irrigation regimes, whereas sorghum monoculture was suitable only in moderate and severe drought stress regimes.
Salinity stress
Lamia Vojodi Mehrabani
Abstract
IntroductionSalinity is one of the major environmental stressors limiting the growth and development of plant in the agricultural system. Salinity affects the plants from the physiological, biological and molecular point of view. Emphasizely, salinity influence the plants growth and productivity by the ...
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IntroductionSalinity is one of the major environmental stressors limiting the growth and development of plant in the agricultural system. Salinity affects the plants from the physiological, biological and molecular point of view. Emphasizely, salinity influence the plants growth and productivity by the induction of water stress, ionic toxicity (Na+, Cl-) and nutrients imbalances. With stress goings on, ROS molecules is produced leading to membranes oxidation damage and hence deteriorate the membranes and adversely impact the plant growth and physiological response. Na high accumulation in the soil medium interferes the nutrient balance in the soil and plant cells, leading to disturbances in nutrients uptake deficiency symptoms, oxidative damage, growth reduction and eventually death of plants. In the saline soils, Na+/K+ and Na+/Ca2+ ratios, high above the standard levels and hence the absorption and essential amounts of K+ and Ca2+ is inhibited; membranes deteriorate and the enzymatic dynamics inside cells is interrupted which is called the induced secondary stress. ROS radicals influenced the activity of chloroplast and mitochondria and eventually the plant survival is affected. Considering the main idea with the present study was to assess the effects of salinity stress on the growth and some physiological traits of Lavandula treated with foliar application in hope that the possible promising data could be advisable to the extension section.Materials and MethodsTwo separate experiments were concluded to evaluate the effects of foliar application of nano-cerium oxide and nano-Iron (0, 2.5 and 5 mg.L-1) on Lavandula officinalis L. under saline (0, 50 and 100 mM) conditions as factorial based on Completely Randomized Design in the greenhouse. In the first experiment, the effects of magnetized Iron and in the second experiment, the effect of cerium oxide were assayed on Lavandula officinalis growth and some physiological traits under salinity stress.Results and DiscussionThe results obtained from the first experiment showed that, the plant dry weight, catalase activity and Fe content were independently affected by the salinity and Fe foliar treatment. H2O2 content (4.6 µmol. g-1FW), total phenolic content (36% increases compared to the control) and oil percent (41% increases compared to the control) were influenced by interaction effects of salinity and nano Fe foliar application. The top amounts of Na (8.9 g.Kg-1), proline (94 µg.g-1FW), malondialdehyde (82 nmol.g-1 FW) and H2O2 were recorded at 100 mM salinity stress. At the second experiment, plant dry weight (25% increases compared to the control) and total phenolic content (29% increases compared to the control) were influenced by interaction effects of cerium oxide foliar application and salinity stress. Catalase activity, H2O2 and K content were influenced by sole effects of salinity and cerium oxide foliar application. 2.5 and 5 mg L-1 cerium oxide treatment increased K content (43% compared to the control) and K/Na ratio. GC/MS analysis revealed that Linalool (10.3-27.1%) and 1-8-Cineol were the major constituent of oil at NaCl50 and 100 mM × 5 mg.L-1 cerium spray.ConclusionOur results revealed that cerium oxide and nano-Fe foliar application improved the plants physiological response under no-saline condition. Salinity adversely imposed the yield, some physiological traits and elemental content of plants. Under 50 and 100 mM salinity foliar treatment were not able to mitigate salinity adverse effects except for phenolic content (both experiment), essential oil content (first experiment) and plant dry weight (the second experiment). In total, lavender is a salt sensitive plant and the idea is that to overcome salinity depression, have to experience more concentration of foliar treatment.Acknowledgementshis study was supported and funded by Azarbaijan shahid Madani University, Iran
Breeding plants for stress conditions
Mohammad Reza Karim; Hossein Sabouri; Mohammad Ali Ebrahimi; Somayyeh Sanchouli
Abstract
IntroductionRice is an important crop that is considered a staple meal for 2.7 billion people worldwide. Therefore, the demand for it will increase with the increase of population. Environmental constraints always pose a serious threat to crop production, including rice. Drought is one of the most important ...
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IntroductionRice is an important crop that is considered a staple meal for 2.7 billion people worldwide. Therefore, the demand for it will increase with the increase of population. Environmental constraints always pose a serious threat to crop production, including rice. Drought is one of the most important challenges that limits the production of high-yielding cultivars in arid and rainfed areas. Global warming has also become a factor in limiting rice production in rain-dependent areas. Therefore, researchers are looking for a way to stabilize rice production in arid regions. In this study, informative markers related to the desired agronomic traits were identified in 59 rice genotypes using microsatellite marking system.Materials and methodsIn order to evaluate the tolerance of rice genotypes to drought stress and to identify tolerant and sensitive genotypes, 59 genotypes received from the National Rice Research Institute and the International Rice Research Institute in a randomized complete block design with three replications in two separate conditions, without Stress (flood) and drought stress were performed in a research farm located in Aliabad Katoul city in 2013. In both conditions (normal and drought stress), the genotypes were planted in five rows of 25 × 25 cm in rows one meter long. Thirty days after planting in the nursery, healthy and strong seedlings were transferred to the main land. The required agronomic operations were carried out equally during the growth and development period of the plants under stress and normal conditions and only in terms of irrigation of the experimental field in both flood and stress environments, until the tillering stage of the cultivars were equally flooded. Then, to create stress, irrigation was done from 40 days after transplanting (maximum tillering stage) to the end of the growing season at 25-day intervals. Phenotypic values of grain yield and 1000-grain weight were measured under two conditions according to standard guidelines for evaluation of traits in rice. In order to investigate the relationship between agronomic traits and microsatellite markers with 59 rice genotypes out of 36 microsatellite molecular markers were performed in the Plant Breeding and Genetics Laboratory of Gonbad Kavous University, Faculty of Agriculture and Natural Resources. Young leaves of 21-day-old seedlings were extracted in four-leaf stage using CTAB method. Touchdown PCR reaction was studied and evaluated randomly using 36 microsatellite primers for 3 markers from each chromosome. To separate PCR products, 6% polyacrylamide gel electrophoresis was used and to reveal the banding pattern, silver nitrate staining method was used. The content of polymorphic information was calculated. The relationship between molecular data and traits of studied rice genotypes was investigated using multiple regression. Thus, each quantitative trait was considered as a dependent variable and microsatellite markers were considered as independent variables.Results and discussionThe average content of polymorphic corrections (PIC) was estimated to be 0.58, which showed RM 5647 with 0.81 the highest and RM 6022 with 0.32 the lowest polymorphism (PIC). The results of stepwise regression analysis showed that a total of 90 markers for normal conditions and 69 markers for drought stress conditions for morphological traits were identified. Under normal conditions, the number of spikes and the number of days to flowering with 9 markers and under drought stress, the weight of the cluster with 9 markers showed the most positive markers. The most explanation for variation in normal conditions is related to the total number of grains (0.83) by gene loci RM6324-E, RM5652-E, RM5761-D, RM6179-F, RM549-B, RM462-B, RM7420-D Explained. In drought stress conditions, the most explanation for variation related to panicle weight (0.70) by gene loci RM519-D, RM7545-A, RM6179-E, RM7118-G, RM3525-B, RM5761-B, RM38-C, RM7091-A, RM5647-B explained.ConclusionThe results showed that some markers are associated with more than one trait, which indicates that these traits are very closely related to each other or may be influenced by multi-effect genes. To understand this, it is necessary to develop transgressive generations and linkage.
