Drought stress
Alireza Mohseni Mohammadjanlou; Raouf Seyed Sharifi; Saeid Khomari
Abstract
IntroductionWater limitation is one of the most important environmental factors in reducing the growth and yield of wheat due to producing reactive oxygen species and reducing membrane stability (El-Tayeb, 2006). Several strategies have been suggested in order to improve grain yield of wheat under water ...
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IntroductionWater limitation is one of the most important environmental factors in reducing the growth and yield of wheat due to producing reactive oxygen species and reducing membrane stability (El-Tayeb, 2006). Several strategies have been suggested in order to improve grain yield of wheat under water limitation condition, among them use of bio fertilizers and putrescine play a key role in yield improvement. PGPR and Mycorrhiza fungi have the potential to modulate and regulate the physiological and biochemical responses of plants against drought stress, and for this reason, they increase plant survival under environmental conditions (Marasco et al., 2012). Polyamines are another compound that play a significant protective role in plants when environmental stress occurs (Hadi et al., 2016). Foliar of putrescine is able to improve the resistance of plants in oxidative stress and by increasing the activity of antioxidant enzymes, it increases the resistance of plants against oxidative stress (Groppa et al., 2001). A better understanding of physiological responses under water limitation condition may help in programs which the objective is to improve yield of wheat. During the course of these stresses, active solute accumulation of compatible solutes such as proline and the activities CAT, POD and PPO enzymes are claimed to be an effective stress tolerance mechanism. Therefore, the aim of this study was to evaluate the effects of bio fertilizers and putrescine on some the physiological and biochemical responses (i.e., antioxidant enzyme activity, soluble sugars, proline, malondialdehyde (MDA) and hydrogen peroxide (H2O2) content) of wheat under water limitation.Materials and methodsA factorial experiment was conducted based on randomized complete block design with three replications at the research farm, faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili during 2018-2019. Factors experiment were included irrigation at three levels (full irrigation as control, irrigation withholding in 50% of heading stage and irrigation withholding in 50% booting stage as moderate and severe water limitation respectively) and bio fertilizers at four levels [no bio fertilizer, both application of Psedomunas Putida Strain 186 and Flavobacterim Spp, both application of Mycorrhiza with Psedomunas and Flavobacterim, application of Mycorrhiza], and putrescine foliar application in three levels (foliar application with water as control and foliar application 0.5 and 1 mM of putrescine). Psedomunas putida strain 186 and Flavobacterim spp were isolated from the rhizospheres of wheat by Research Institute of Soil and Water, Tehran, Iran. For inoculation seeds were coated with gum Arabic as an adhesive and rolled into the suspension of bacteria until uniformly coated. The strains and cell densities of microorganisms used as PGPR in this experiment were 1×107 colony forming units (CFU). Mycorrhiza fungi (Glomus intraradices) was purchased from the Zist Fanavar Turan institute. The activity of antioxidant enzymes (catalase, peroxidase and polyphenol oxidase) was measured by Sudhakar et al. (2001) method, soluble sugar content by Dubios et al. (1956) method, measurement of malondialdehyde (MDA) by Stewart and Bewley, (1980) and method of Alexieva et al, (2001) was used to measure the hydrogen peroxide. Proline content was measured by Bates et al. (1973) method. Analysis of variance and mean comparisons were performed using SAS9.1 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 discussionApplication of both Mycorrhiza with Pseudomonas and Flavobacterium and putrescine foliar application under severe water limitation conditions (irrigation withholding in booting) increased the activity of polyphenol oxidase, peroxidase and catalase enzymes. The highest activity of these enzymes were obtained in irrigation withholding in booting stage with application of both Mycorrhiza with Pseudomonas and Flavobacterium and foliar application of 1 mM putrescine and the lowest of values were obtained in full irrigation and no application of bio fertilizers and no putrescine foliar application. The highest rates of proline and soluble sugar were observed under irrigation withholding in heading with the both application of biofertilizers and putrescine and the lowest of them were observed in full irrigation, no application of biofertilizers and no foliar putrescine. Water limitation increased electrical conductivity (EC), malondialdehyde (MDA) and hydrogen peroxide (H2O2) content, while application of bio fertilizers and putrescine under water limitation conditions decreased electrical conductivity, malondialdehyde and hydrogen peroxide content. Application of Mycorrhiza with Pseudomonas and Flavobacterium and foliar of 1 mM putrescine under severe water limitation decreased malondialdehyde and hydrogen peroxide content about 51 and 31.72% respectively compared to no application biofertilizers and putrescine under same water limitation level. In general, water limitation (irrigation withholding in booting and heading) decreased grain yield compared to full irrigation. application Pseudomonas and Flavobacterium (23.1%) and both application of Mycorrhiza with Pseudomonas and Flavobacterium (16.6%) increased grain yield in comparison with no application of biofertilizers under conditions of irrigation withholding in booting. Foliar application 1 mM of putrescine increased grain yield about 8.5% in comparison with no application putrescine.ConclusionIt seems that application of bio fertilizers and putrescine can increase grain yield of wheat under water limitation conditions due to improving physiological and biochemical trait.
Drought stress
Mina Shafiei; Ali Behpouri; Ehsan Bijanzadeh; Maryam Mirdoraghi
Abstract
IntroductionDue to the increase in world population and the need for food using traditional agricultural methods does not meet the needs of society. The Food and Agriculture Organization (FAO) predicts that by 2050, 60 percent more food production will be needed to feed the world's 9 billion population. ...
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IntroductionDue to the increase in world population and the need for food using traditional agricultural methods does not meet the needs of society. The Food and Agriculture Organization (FAO) predicts that by 2050, 60 percent more food production will be needed to feed the world's 9 billion population. This has concerned agroecologists to sustainable agriculture and encouraged them to do more research and design new sustainable agricultural systems. Therefore, the aim of this study was to examine different mixed cropping systems of cereals and evaluation of different drought tolerance indices using a mixture of winter cereals, wheat, barley and triticale and their response to end-of-season water stress in hot and dry ecological conditions.Materials and methodsIn order to investigate the grain yield and drought tolerance indices of mixed culture of different cereal genotypes to water stress in hot and dry ecological conditions, an experiment was conducted as split plot design based on a randomized complete block design with three replicates during 2017-2018 cropping year in College of Agriculture and Natural Resources of Darab, Shiraz University. In this experiment, the first factor was irrigation regime in two levels of normal irrigation and water stress and the second factor was ten cropping systems of genotypes (tall barley line EB-95-97, dwarf barley line EB-95-97, dwarf bread wheat line S-92-19, tall bread wheat cultivar Khalil and a cultivar of Triticale called Juanilo) which were grown as double and pure row culture. Double mixed crops included of: dwarf barley- tall barley (one row of dwarf barley + one row of tall barley), dwarf barley - triticale (one row of dwarf barley + one row of triticale), tall barley - triticale (one row of tall barley + one row of triticale), dwarf wheat - triticale (one row of dwarf wheat + one row of triticale) and tall wheat - triticale (one row of tall wheat + one row of triticale) in a 50:50 planting ratio and their pure cultivation.Results and discussionThe results of this experiment showed that the highest grain yield was obtained in tall wheat-triticale mixed culture with 9472 kg ha-1 under normal irrigation and the lowest grain yield was achieved in pure dwarf barley with 3934 kg ha-1 under water stress condition. The results of correlation analysis of drought indices showed that positive and significant correlations were observed between STI (r=0.858**), GMP (r=0.747*) and MP(r=0.801**) with grain yield under water stress conditions. Alos, positive correlation coefficients were observed between STI (r=0.884**), GMP (r=0.922*) and MP (r=0.932**) with grain yield under normal irrigation conditions. The highest SIIG index in this investigation was observed for dwarf barley-tall barley cropping system which had the minimum yield difference in normal and water stress conditions. 3D-graph of cropping systems using SIIG index indicated that cropping systems of pure tall wheat, pure dwarf wheat and tall barley+triticale mixture demonestraed the highest grain yield both in normal and water stress conditions.ConclusionTall wheat+Triticale mixed culture wheat cultivation system under normal irrigation conditions showed a 16% increase in yield compared to the tall wheat pure cultivation system, while it did not show a significant difference with the Triticale pure cultivation system. Some of the mixed cropping systems such as tall wheat + triticale mixed cropping systems produced higher yields that their pure cultivation systems. Alos, it was concluded that STI, GMP, MP and SIIG were the best drought stress indices to evaluate different cropping systems.
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.
Salinity stress
Peyman Varjavand; Sayed Bahram Andarzian; Ali Mokhtaran; Abdolnour Mosadeghi
Abstract
IntroductionAccording to the growing human need for food production, using of unconventional water is defined as one of the strategies for overcoming the water crisis in the world. Drainage water recirculation for producing economic sustainable agricultural products can be very useful to management of ...
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IntroductionAccording to the growing human need for food production, using of unconventional water is defined as one of the strategies for overcoming the water crisis in the world. Drainage water recirculation for producing economic sustainable agricultural products can be very useful to management of drainage water environmental impact and adapt with water crisis in the world. For this purpose, overcoming on salinity stresses and preservation of soil quality during cultivation are so important. Studying on salinity effect of irrigation water on wheat yield and soil salts has a long history in the world but genotype and climatic conditions are very influential on the results, so do this research can be very useful. This research has been conducted to determination the best genotype of wheat and analysis of soil behavior in the study of solutes in it.Materials and methodsThis research was conducted in 2018-2019 in an experimental farm of AmirKabir Agro-Industry Sugarcane Company using split plot design with randomized complete block with three replications, yield reaction of 20 genotypes of wheat to irrigation with sugarcane drainage water farms was investigated. Also applied water volume, farm water requirement and drainage water effect on soil salts were analyzed. Main plots was irrigation water quality with two quality: 1- fresh water with EC=1.3 dS m-1 and 2- sugarcane drainage water with EC=7.0 dS m-1. Sub plots were 20 genotypes of bread and durum wheat which is cultivated in 8 lines and 20 cm distance. Water requirement was determined by 10-years climate data and wheat crop coefficient and calculated using FAO Penman-Monteith method. Field irrigation management was performed based on water requirement information and considering soil physics, leaching requirements and effective rainfall. Extracted information included volume of applied water, salt and moisture soil samples, water and drainage water quality samples, physical soil specifications, grain yield, biological yield, spike per square meter, grain per spike, 1000-grain weight and flowering date. Results and discussionResults showed that using sugarcane drainage water reduced the mean yield by 9.7% and decreased irrigation water productivity from 1.08 to 0.97 kg m-3. There is no significant difference between Bow, Shoele, Narin, Bloudan, Sarang, Irna, Spn and Pishtaz varities for using Karun River and drainage water in terms of grain yield, biological yield, spike per square meter, grain per spike, 1000-grain weight and flowering date, so it can be concluded that these genotypes are stable in different environmental conditions. Stress tolerance index varied from 0.57 to 1.22 among different genotypes. 1-63-31 and Narin genotypes had the highest and the lowest tolerance indices, respectively. Bam and Shoele genotypes were in the mean group with 0.92 and 0.89, respectively. Overall, Sistan, 1-63-31, Bow, Shoele, Sirvan, Sarang, Irna, Khalil, Barat, and Pishtaz with an index above the mean index (0.90) are among the most tolerant and it can be concluded that they can be considered as the most tolerant figures. Also Barat genotype had maximum applied water and total water productivity with fresh water irrigation which were 1.35 and 1.14 kg m-3 and Sistan had maximum water productivity for drainage water in these parameters which were 1.16 and 0.98 kg m-3. Soil results showed that using agricultural drainage water for irrigation not only led to changing farm soil from non-saline to saline condition, it closes to become sodic. Under drainage water cultivation conditions, soil quality will be compromised, which will require new development of irrigation management, leaching and cropping patterns. In these conditions, accurate knowledge of the time and amount of water required for wheat, irrigation with high efficiency and application of appropriate amount of leaching water with proper field drainage, can be effective.ConclusionsThis research was conducted to reaction investigation of various genotypes of wheat in condition of using sugarcane drainage water. Due to the fact that in the middle of autumn and late winter, the drainage of sugarcane fields is low and in this period, most of wheat water requirement is supplied by rainfall and the most important irrigation events start after winter in Khuzestan, so wheat had been chosen for this research. Results showed that yield decrease in drainage water farm for 20 studied genotypes was about 9.8% which is varies between 30.6% for ChamranII to 8.6% for Sistan genotypes. Applying drainage water as irrigation water can cause negative effects on farm soil quality in short term and studying of this behavior by using simulating models can be very useful. For reduction of negative effect of drainage water on soil quality, it is necessary to pay enough attention to the amount and time of irrigation at the last 2 or 3 irrigation events.
Heat stress
Sabrieh Seimrizade; Ali Moshatati; Abd-AlMahdi Bakhshandeh; Aydin Khodaei Joghan; Ahmad Koochekzadeh
Abstract
IntroductionTerminal heat stress in Khuzestan province, decrease growth, yield and yield components of wheat. The vermicompost fertilizer improve water reserve and physical and chemical properties of soil. One of the important ways to reduce the negative effect of terminal heat stress on plant is using ...
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IntroductionTerminal heat stress in Khuzestan province, decrease growth, yield and yield components of wheat. The vermicompost fertilizer improve water reserve and physical and chemical properties of soil. One of the important ways to reduce the negative effect of terminal heat stress on plant is using vermicompost fertilizer in the soil. Using vermicompost fertilizer in agricultural soils lead to increase nutrient elements and conserving the soil water and decrease the negative impacts of drought stress on plant. Generally, vermicompost fertilizer contribute to preserving the moisture storage of the soil and to supply the nutrients required by the plant. In this study, the most important aim is to study the effect of vermicompost fertilizer on bread wheat yield and yield components under terminal heat stress in Ahwaz climatic condition. Materials and methodsIn order to evaluate the effect of vermicompost fertilizer on growth and yield of wheat in terminal heat stress of Ahwaz, a field experiment using split-plot design based on randomized complete block design with four replicates was conducted in research farm of Agricultural Sciences and Natural Resources University of Khuzestan during (in 31º N, 48º E, 35 Km north-east of Ahwaz, and 20 m above the sea level) 2017-2018 growing season. Experimental factors were three sowing dates (22 Nov., 11 Dec. and 31 Dec.) in main plots and five vermicompost rates (0 (control), 5, 10, 15 and 20 t.ha-1) in sub plots. Results and discussionAnalysis of variance showed that the effect of sowing date and vermicompost were significant on measured traits. Mean comparison revealed that the highest grain yield (2356 kg.h-1) was at the first sowing date and the lowest grain yield (1732 kg.h-1) was at the last sowing date. Also, in vermicompost levels, the maximum grain yield (2593 kg.ha-1) was in 20 t.ha-1 of vermicompost application and the minimum grain yield (1566 kg.ha-1) was in control of vermicompost. ConclusionsGenerally, the results showed that with delay in sowing date and occurrence of terminal heat stress, decreased growth and grain yield of wheat. But, using vermicompost fertilizer decreased the negative impact of drought stress. So that, with increase vermicompost application, increased measured traits. Also, in areas with terminal heat stress after flowering stage, using 20 tons per hectare of vermicompost fertilizer is recommended for maintaining grain yield.
Heavy metals
Zahra Vatanpour; Rouhollah Motafakker Azad; Soodabe Jahanbakhsh; Ali Movafeghi; Mohsen Sabzie Nojah Deh
Abstract
IntroductionHeavy metal pollution is one of the major problems of human societies in the production of agricultural products and is considered as a major threat to human health. Wheat is a strategic crop in human nutrition and the growing global population requires more agricultural production. To achieve ...
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IntroductionHeavy metal pollution is one of the major problems of human societies in the production of agricultural products and is considered as a major threat to human health. Wheat is a strategic crop in human nutrition and the growing global population requires more agricultural production. To achieve high yields of crops, especially in developing countries, chemical fertilizers and pesticides are widely used, which causes excessive accumulation of heavy metals in agricultural soils and has detrimental effects on human health and other living organisms. Increasing the concentration of heavy metals in the soil on the other hand affects the toxicity and growth and yield of crops. Considering the mentioned cases and the importance of wheat as a major human food, the present study aimed to investigate the effect of plant growth-promoting rhizobacteria (GPR) in reducing the effects of cadmium in two wheat cultivars and their effect on plant pigments. It was done by examining the change in the content of plant pigments. Materials and methodsThe experiment was carried out as a factorial experiment in a completely randomized design with three replications in Research Greenhouse of Agricultural Faculty of Mohaghegh Ardabili University in 2018. Experimental treatments included cadmium chloride stress (CdCl2H2O 0, 75, 150 and 300 μM) and the effect of growth promoting bacteria (Azotobacter and Pseudomonas). The studied traits included content of photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll and chlorophyll a/b ratio), adjuvant pigments (carotenoids, flavonoids), quantum yield, SPAD, stem dry weight, yield, seed weight and number of seeds. Results and discussionsThe results of analysis of variance of the main photosynthetic pigments (chlorophyll a, chlorophyll b and total chlorophyll) at 24, 48 and 72 hours after cadmium treatment and shoot showed that the interactions of the cultivar in bacteria at 72 hours on chlorophyll a (5% level) and was significant on chlorophyll b and total chlorophyll (1% level) . Comparison of means showed that the highest amount of chlorophyll b (without change compared to control) and total chlorophyll (4.63% compared to control) of Karim and chlorophyll a (95.3% compared to control) in Gonbad cultivar in the range 72 hours were observed. The highest amount of chlorophyll a was 6.31 mg / g and total chlorophyll (7 mg / g) was observed from Gonbad cultivar and inoculation with Azotobacter, which was not significantly different from the control. In the case of chlorophyll b, the lowest amount (0.57 mg / g) was obtained from the use of Pseudomonas in Gonbad cultivar and bacterial inoculation in Karim cultivar had no significant effect. The superiority of Karim cultivar over Gonbad cultivar is probably due to the genetically precocious of Karim cultivar and faster maturation process. In addition, different wheat cultivars have significant differences in cadmium accumulation in their organs because plants absorb more cadmium in stress conditions by secreting siderophore to compensate for nutrient deficiencies. Gonbad cultivar is probably more sensitive due to the absorption of heavy metals, which in turn produces more reactive oxygen, and consequently oxidative stress and degradation of photosynthetic proteins and a decrease in chlorophyll content. Among bacteria, genus pseudomonas increases plant phosphorus uptake due to its high ability to dissolve insoluble mineral phosphate. Phosphorus, as an energy carrier, increases the uptake and transport of nitrogen to the leaves, as a result in the production of higher amounts of chlorophyll. Pseudomonas may have produced more chlorophyll by increasing the uptake of trace elements by stimulating the activity of the ATPase protein pump and converting insoluble phosphate into a plant-usable form. The interaction of cultivar in bacteria was significant for carotenoids at 24 hours, flavonoids at 24, 72 and shoot stage at 1% level and for carotenoids at 72 hours and quantum yield at 48 hours at 5% level showed significance. Comparison of the mean interaction of cultivar in bacteria also showed that the highest amount of carotenoids (0.67 mg / g) was obtained in 24 hours from Gonbad cultivar and inoculation with Azotobacter, while in 72 hours of control treatment in Karim cultivar the highest carotenoids (0.61 mg / g) and did not differ significantly from Pseudomonas treatment. The decrease in carotenoids is probably due to their role in the non-photochemical suppression of excited chlorophylls, which disrupts the structure of these pigments and ultimately reduces the amount of these pigments. Cadmium appears to act as a degradation agent for pigments and other macromolecules by increasing ROS accumulation and degrading photosystem II. Non-photochemical suppression of excited chlorophylls can be another cause of degradation and reduction of auxiliary pigments. Among the main stressful effects on stem dry weight, yield, seed weight and number of seeds, the effect of cadmium on these traits (except number of seeds) was significant at the level of one percent. The interaction effect of cultivar on bacteria on stem dry weight (at 1% level) number of seeds (at 5% level) was significant and in other cases no significant. Regarding stem dry weight, Azotobacter was more effective than Pseudomonas on Karim cultivar and the number of seeds of Karim cultivar increased more in the presence of bacteria than the control. This is probably due to the higher resistance of Karim cultivar to cadmium toxicity and also due to the higher efficiency of carbon cycle enzymes in this cultivar. ConclusionsThe results showed that cadmium decreased photosynthetic pigments, increased auxiliary pigments (such as carotenoids) and decreased dry weight, yield, grain weight and number of grains in wheat plants studied. The presence of plant growth stimulating bacteria improved the photosynthetic system, dry weight, seed weight, number of seeds and yield. Application of Azotobacter growth promoting bacterium had the best results, so that in most of the studied traits, it improved the stress effects of cadmium; Therefore, Azotobacter can be used as a bacterium that reduces the stress effects of cadmium in Karim wheat.
Zahra Zinati; Abbas Alemzadeh; Ali Niazi; Esmaeil Ebrahimie
Abstract
Introduction Salinity stress is one of the most important factors causing yield loss in crop worldwide. In order to improve salt tolerance in crop, it is important to understand salt-tolerance mechanism. Ongoing researches have been directed toward understanding the effects of salt stress, with the eventual ...
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Introduction Salinity stress is one of the most important factors causing yield loss in crop worldwide. In order to improve salt tolerance in crop, it is important to understand salt-tolerance mechanism. Ongoing researches have been directed toward understanding the effects of salt stress, with the eventual goal of discovering molecular and cellular mechanisms used by stress-tolerant species and the elements that might contribute to enhanced salt tolerance to sensitive plants. An active process of cellular suicide termed programmed cell death (PCD) is crucial for development and immune responses in eukaryotes. In plants, PCD is involved in plant development and survival. Recent studies have revealed that diverse environmental stresses, such as salt stress, nutrient starvation and drought, are able to induce PCD in plant root tips. This findings indicate that this active process is highly conserved and has vital roles in development and response to external stimuli. PCD plays an important role in adapting to environmental stress. Understanding the molecular basis of PCD mechanism makes possible genetically manipulation of plants to improve environmental stress tolerance. BAX inhibitor-1 (BI-1) located in the Endoplasmic reticulum(ER) was found to be a key cell death attenuator in eukaryotes. Materials and methods In this study, the potential role of a gene which encodes BAX Inhibitor 1-like protein (BI_85) in salt tolerance was evaluated using bioinformatics and experimental approaches such as promoter and gene regulatory network analysis, as well as Real-Time PCR. Two salt-tolerant (Arg) and salt-sensitive (Alamut) cultivated wheat genotypes and Aegilops crassa, as a wild wheat relative, were materials used in this experiment. Seeds imbibing in the dark for 24h at 4°c germinated for 3d at 25°C and were grown hydroponically in half-strength Hoagland solution circulated by air pumps in a stabilized greenhouse at 25oC, with a 16h light/8h dark photoperiod. To distinguish salt stress response from developmental changes in gene expression, an experiment was designed to monitor changes in transcripts in the absence of stress. Three-week-old seedlings were treated with a 0 and 150-mM NaCl solutions in combination with Hoagland solution. Sampling was carried out after treatment at 0h, 12h, and 3w. RNA extraction (Denazist, Mashhad, Iran, S-1020-1) and cDNA synthesis (Fermentas, Ontario, Canada, EP0441) were carried out for real-time RT-PCR according to the manufacturer’s instruction. Normalization of the target gene (BI_85) was carried out based on Actin reference gene. The Pfaffl formula (ratio=2-ΔΔCt) was used to calculate relative expression. Building a network using Pathway studio software was carried to discover another components that have relationships with differentially expression gene (BI-1), which probably are involved in stress-related responses. Results and discussion BAX Inhibitor was shown to be part of an interaction network that included 26 relationships. For example TED4 which has a relationship with BAX Inhibitor like-1 is implicated in salt acclimation signaling. Some evidence has been offered for the hypothesis that BI-1 probably can be used as a pore or ion channel in the endoplasmic reticulum for calcium handling. The Salt Overly Sensitive (SOS) signaling pathway is a well-recognized signaling pathway known to be essential for acquisition of ion homeostasis. In response to salt stress, a calcium signal activates the SOS pathway by binding to the calcium binding proteins, SOS3 and SCaBP8/CBL10, which in turn activate the protein kinase protein kinase SOS2 to regulate the plasma membrane Na+/H+ antiporter SOS1. According to the regulatory network, this gene may act upstream of the SOS signaling pathway. Promoter analysis were applied using plantcare database to shed light on underlying regulatory mechanism of the BI_85 expression. According to promoter analysis, the presence of stress-responsive regulatory elements such as ABRE (abscisic acid responsive element), LTR (low-temperature responsive element), MBS (MYB binding site involved in drought-inducibility), CGTCA-motif (MeJA- responsive element), TGACG-motif (MeJA- responsive element), ERE (ethylene-responsive element), and GT-1 motif (salt responsive element) in the promoter confirms the role of this gene in environmental stresses tolerance including salinity. It was also figured out that the expression patterns of BI_85 was significantly different between susceptible and salt resistant cultivars in response to salt stress. In more details, after 12h, salt stress induced BI-1 expression in the shoots of Arg and roots of Ae. crassa and reduced it in shoots of Alamut. After 3 weeks, salt stress induced BI-1 expression in the shoots of Arg and reduced it in shoots of Alamut and Ae. crassa. Conclusion According to bioinformatics and experimental results, it can be concluded that BI_85 can contribute to salt tolerance in wheat and can be used for genetic manipulation to improve tolerance to stress.
Hoorie Najafi; Saeed Navabpour; Khalil Zainli Nezhad
Abstract
Introduction Mercury, as a heavy metal element, plays an important role in contaminating the environment and causing toxicity and stress in living organisms. . Heavy metals are defined as metals having an atomic number greater than 20 densities greater than 5 grams per cubic centimeter.Non-toxic stresses, ...
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Introduction Mercury, as a heavy metal element, plays an important role in contaminating the environment and causing toxicity and stress in living organisms. . Heavy metals are defined as metals having an atomic number greater than 20 densities greater than 5 grams per cubic centimeter.Non-toxic stresses, including heavy metals, cause much damage to wheat. The industrialization of societies is releasing many toxic compounds on the biosphere. Among heavy metals, mercury is considered to be the most toxic metal in the environment. This metal is considered as the major environmental pollutant. Its toxicity is a big problem for ecological, evolutionary, nutritional and environmental reasons. In fact, heavy metals do not excrete the body after entering the body and accumulate in the tissues of the body. Despite the contamination of resources used in heavy metals, while reducing the quantity and quality of agricultural products, sustainable production and human health are also at risk. The same causes many diseases and complications in the body, the pollution of the environment with heavy elements will transfer them to crops, which is now spreading as a global problem.Mercury ions produce oxidative stress that produces reactive oxygen species in plants. This pro cess damages the structure of the membranes and disrupts the cytoplasm of the cell. To reduce and eliminate various active oxygen species and avoid oxidative damage in plants, the activity of antioxidant enzymes such as catalase increases. One of the other mechanisms of coping with heavy metal stresses in living cultures is the production of intracellular, rich in cysteine amino acids such as metallothionein. The high number and special makeup of cysteine amino acids in these proteins has made it possible to connect them to metals. Materials and methods A split plot experiment was conducted in a completely randomized design with hydroponic culture. The treatments consisted of chloride ivy with concentrations (0, control, 5, 10 and 15 μm) as the main factor and bread wheat genotypes (morvared, gonbad and N9108) as a sub factor. Results and discussion Results showed that the expression of catalase and metallothionein gene was increased in morvared and N9108 genotypes by mercury chloride and the highest expression of these genes was obtained by treatment with 15 mM mercuric chloride (9.2 and 2.7 times more than control) Was. In Gonbad cultivar, the amount of gene expression was increased by treatment with mercury chloride compared to control, but this increase was lower than the other two genotypes. By increasing the concentration of mercury chloride, there was a significant decrease in the chlorophyll content of different genotypes, as well as chloride ivy significantly increased the oxidative cell index in the treated seedlings compared with the control It can be concluded that the morvared cultivar and the promising line of N9108 under heavy metal stress showed a better response than the gonbad. Used to deal with heavy metal stresses. According to the results of this experiment, it seems that the antioxidant defense system plays an important role in the defense strategy of the wheat plant against the tension of mercury metal and this defense system is induced and activated at the transcriptional level to help the plant.
Saied Ghavam saeidi Noghbi; Mostafa Yaghoobzadeh; Ali Shahidi; Hossein Hammami
Abstract
Introduction Due to the presence of Iran in the arid and semi-arid regions of the world, drought and salinity are environmental stresses known as main factors that led to reduce the production of crops in Iran. Drought and salinity are major abiotic stresses that adversely affect crop productivity and ...
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Introduction Due to the presence of Iran in the arid and semi-arid regions of the world, drought and salinity are environmental stresses known as main factors that led to reduce the production of crops in Iran. Drought and salinity are major abiotic stresses that adversely affect crop productivity and quality. Their harmful effects are increasing due to global warming, and human activities such as overutilization of water resources, over-irrigation, and improper drainage, besides natural causes such as high evaporation rates in arid and semi-arid regions that led to decrease available water and increase salt accumulation in this sites. Drought and salinity have osmotic, ionic and nutritional constraint effects on plants. These effects lead to disturb photosynthetic path, growth retardation, metabolic disturbances and oxidative stress. Usually, these stresses happened at the same time especially in arid and semi-arid regions. Therefore, this study was conducted for determination growth and yield response of wheat to drought and salinity happened at the same time. Materials and methods In order to evaluate the response of unfarm 4 wheat cultivar to different irrigation water and salinity levels, a factorial experiment based on a completely randomized block design with three replications was conducted at research field of agriculture, University of Birjand in 2016-2017. The treatments consisted of different levels of irrigation (I1, I2, I3 and I4, respectively 125, 100, 75 and 50% of plant water requirement and I5 including rain fed with one supplementary irrigation) and two levels of irrigation water salinity (non-saline (S1=1.4 dS.m-1) and Saline (S2= 5.4 dS.m-1) water, respectively). The studied traits included plant height, leaf area, spike length, 1000-seed weight, plant fresh weight, plant dry weight, number of seeds per spike, spike length, biological yield, grain yield, and harvest index. Results and discussion The results of analysis of variance showed that the significant effect of different levels of irrigation at 0.1% level on all traits including plant height, leaf area, 1000-seed weight, fresh weight of plant, plant dry weight, spike length, number of seeds per spike , biological yield, economic performance and harvest index are (Table 3). In agreement with results of this study Wajid et al., (2002) reported that improvement of wheat yield with increasing irrigation levels. Plant height, 1000-seed weight, grain yield, and harvest index of wheat (Varamin cultivar) were significantly affected by irrigation levels (Eidizadeh et al., 2016). Soleimani (2016) also reported that the yield and yield components of wheat (in the climate of Isfahan) were strongly influenced by different levels of irrigation. The effect of irrigation water salinity was significant at 1% on plant height, leaf area and 1000-seed weight, but its effect on fresh weight of plant, plant dry weight, spike length, number of seeds per spike, biological yield, economic yield, and harvest index was not significant (Table 3). Irrigation water salinity on yield and yield components of different wheat cultivars including Chamran, Sistan, Hajiabad, Parsi, Yavarus, Behrang, U. 520, S-83-3, D-81-18 showed a significant decrease depending on variety. Interaction between irrigation and salinity levels of irrigation water showed a non-significant effect on the leaf area, spike length, and grain yield. The results of this study revealed that the highest and lowest value for different traits was observed at 125% plant water requirement and rain fed with one supplementary, respectively where the loss percent for plant height, leaf area, spike length, 1000-seed weight, plant fresh weight, plant dry weight, spike length, number of seeds per spike, biological yield, economic yield, and harvest index were 37%, 63%, 64%, 66%, 14%, 42%, 62%, 61%, 89%, and 75%, respectively. The results of Yousfi et al., (2010) showed that salinity of irrigation water at levels of 1.8, 12 and 17 dS.m-1 and irrigation at two levels of 100 and 35% of water field capacity by soil on biomass traits plant production, plant height, biomass, leaf chlorophyll and nutrient elements including nitrogen, potassium, calcium, magnesium and phosphorus had a significant effect at 1% level. Correlation results revealed that the highest correlation between grain yield and biological yield. Conclusions In general, the results of this experiment showed that reduction of irrigation levels (percent plant requirement) leads to reduction of growth and yield characteristics of wheat. Irrigation water salinity was significant decrease at 5.4 dS.m-1 level on plant height, leaf area and 1000-seed weight. Interaction between irrigation and salinity levels of irrigation water showed a non-significant effect on the leaf area, spike length, and grain yield. The results of this study revealed that the highest and lowest value for different traits was observed at 125% plant water requirement and rain fed with one supplementary, respectively. According to high soil salinity (Table 2), observation of the highest amount of biological yield and grain yield in 125% water requirement is acceptable due to prepare the full or partial water need for salt leaching.
Hossein Kamaei; Hamid Reza Eisvand
Abstract
Introduction Wheat (Triticum aestivum L.) is considered as the major cereal crop in the world in respect of the cultivated area and total production. High temperature resulting from delay in planting is one major environmental factor limiting growth and production of wheat, especially in tropical regions. ...
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Introduction Wheat (Triticum aestivum L.) is considered as the major cereal crop in the world in respect of the cultivated area and total production. High temperature resulting from delay in planting is one major environmental factor limiting growth and production of wheat, especially in tropical regions. Most of the Iranian soils, have a high pH and calcareous nature, and micronutrients solubility in these soils is low. Micronutrients plays a critical role in increasing plant resistance to environmental stresses. Iron as a micronutrient, is critical for chlorophyll formation and photosynthesis and is important in the enzyme systems and respiration of plants. Zinc is a ubiquitous micronutrient. It is required as a structural and functional component of many enzymes and proteins, and increases the yield and yield components of wheat. Manganese as a micronutrient, is necessary in photosynthesis, nitrogen metabolism and to form other compounds required for plant metabolism. Materials and methods To study the effect of iron, zinc and manganese foliar application on the physiological, agronomic traits and protein of wheat under late season heat stress, an experiment was conducted as split-plot based on randomized complete blocks design with four replications in Ramhormoz city located in south-western Iran. The experimental factors were included planting date in two levels (5 November and 20 December) as the main factor and micronutrients foliar application in six levels of non-foliar application (control), foliar application by water, iron, zinc, manganese and iron+zinc+manganese (each 3 lit.h-1) as the sub factor. Solutions for foliar application were prepared by using Iron chelate (6%), Zinc chelate (7.5%) and Manganese chelate (7%). The measured traits included leaf chlorophyll index, leaf proline content, cell membrane stability index, grain yield, biological yield, harvest index and grain protein content. To determine the leaf chlorophyll index used of chlorophyll meter digital. To determine the leaf proline content, method of Bates et al. (1973) was used. To determine the cell membrane stability index used of method Lutts et al. (1996). The grain yield was determined at maturity stage and through the harvest of all spikes from the level of 1 m-2 per plot and after removing 0.5 m from the beginning and end respective planting rows (rows 5 and 6). To measure the biological yield at maturity stage, after removing 0.5 m from the beginning and end respective planting rows (rows 5 and 6) from the level of 1 m-2 per plot all the plants were harvested and weighted for each plot separately. The harvest index was determined by the equation GY / BY × 100. The grain protein content was calculated as N% × 5.7 on a dry weight basis. N% in grain was determined by the Kjeldahl method according to A.A.C.C. (2000). Analysis of variance was performed using general linear model (GLM) procedure of statistical analysis system (SAS version: 9.3). The means were analyzed using the least significant difference (LSD) method at P=0.05 (LSD 0.05). Results and discussion Results showed that the delay in planting due to terminal heat stress decreased significantly traits of leaf chlorophyll index, cell membrane stability index, grain yield, biological yield and harvest index except for leaf proline content and grain protein. However, iron, zinc and manganese foliar application could increase significantly the measured traits in optimum and late planting date. Meanwhile, application of zinc spray showed the greatest effect in reducing the damage caused by terminal heat stress on measured traits. Conclusions In general, planting on 5 November and the use of micronutrients, especially zinc, as foliar application, can reduce the harmful effects caused by terminal heat stress and improve the physiological, agronomic traits and grain protein content of bread wheat in the region.
Hamad Dris; Seyed Keyvan Marashi
Abstract
Introduction Wheat is the most important crop in the country. However, a significant portion of this product is grown and produced in saline lands. In Khuzestan province, when we move from north the south, the land salinity is increased due to low slope, heavy soil texture and high water deficit. So, ...
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Introduction Wheat is the most important crop in the country. However, a significant portion of this product is grown and produced in saline lands. In Khuzestan province, when we move from north the south, the land salinity is increased due to low slope, heavy soil texture and high water deficit. So, the major areas in Ahvaz, Shadegan, Abadan, Khorramshahr, Mahshahr, Dashte Azadegan, Hoveizeh and even in parts of Shoshtar, Ramhormoz and Behbahan are confronted with this limitation. Estimates showed that at least 400,000 hectares of south of province require underground drainage. Many studies have shown that the application of growth regulators such as salicylic acid can increase plant tolerance during abiotic stresses, especially salinity stress. Therefore, this experiment aimed to investigate and compare the effects of different methods of salicylic acid hormone application on quantitative, qualitative and biochemical parameters of wheat in drained and non-drainage lands. Materials and methods This experiment was carried out in order to evaluate the effects of different methods of applying salicylic acid on quantitative, qualitative and biochemical parameters of wheat in drained and not drained lands, based on combined analysis with randomized complete block design with three replications. The first factor was two levels of drained lands (first experiment) and not drained lands (second experiment) and the second factor was different methods of salicylic acid application, which was 1- no spraying (control), 2- soaking of seeds 3- spraying at the beginning of tillering, 4- soaking of seeds + spraying at the beginning of tillering, 5- spraying at the end of tillering, 6- soaking of seeds + spraying at the end of tillering. In this experiment, salicylic acid was used at a concentration of 1 mM. Soaking of seeds in solution was done for 6 hours and washed with distilled water and then dried. Also, spray application of salicylic acid in different growth stages, was performed by motor sprayer. Determination of grain yield from one square meter was done from each plot after removal of margins. To determine the number of spikes per square meter, the number of spikes in harvesting area was counted and averaged in each plot. To determine the number of grains per spike, 10 spikes were selected randomly from all harvested spikes and their grains were counted and their mean was considered as grains number per spike. To determine the number of spikelets per spike, 10 spikes were cut in each plot randomly and the number of spikes was counted and their mean was considered as spikelets number per spike. 1000-grain weight was calculated based on the total weight of two 500 grains samples at the harvest stage. Chlorophyll index was determined by using chlorophyll meter at grain filling stage. Different concentrations of proline, in mg/g fresh weight, were measured by Bates method and wheat protein was measured by digestion method by Kejeldal device. Results and discussion The results showed that the effect of land type on spikes number per square meter, grains number per spike, spikelets number per spike, 1000-grain weight, grain yield, chlorophyll index, proline and grain protein percentage were significant at 1% probability level. The effect of salicylic acid levels on all traits was significant at 1% probability level. The interaction of land type and salicylic acid in terms of protein percentage was significant at 5% probability level and in term of spikes number per square meter, spikelets number per spike, 1000-grain weight, chlorophyll index and proline content were significant at 1% probability level. The maximum protein percentage (14.36%) was related to the no spraying of salicylic acid (control) in non-drainage conditions and the minimum in drained conditions (10.6%) was related to soaking of seeds + spraying at the beginning of tillering. The maximum and minimum grain yield in drained and non-drained lands by 3308 and 2017 kg.ha-1 was observed, respectively and the maximum and the minimum grain yield in different methods of salicylic acid application was in seed soaking + spraying at the beginning of tillering and without salicylic acid application by 3636 and 1759 kg.ha-1, respectively. Conclusions In general, the results showed that the effect of salicylic acid on drained lands increased the yield parameters and on not drained lands by reducing the effects of salinity stress and improving the damage caused by it could be effective in increasing of yield. However, in this condition, the lowest yield qualitative was observed.
Ardalan Zolfagharan; Bijan Ghahraman; Abolghasem Haghayeghi; Mohammad Jolaini
Abstract
Introduction Various studies have investigated the response of crops and pasture plants to water for non-saline waters and their reaction to salinity in full irrigation. A set of such studies can determine water-yield or salinity-yield relationships. However, quantitative research has been done to study ...
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Introduction Various studies have investigated the response of crops and pasture plants to water for non-saline waters and their reaction to salinity in full irrigation. A set of such studies can determine water-yield or salinity-yield relationships. However, quantitative research has been done to study the effects of salinity and drought stress. However, we are proposing perpendicular system as a new alternative to learn wheat yield under simultaneous water and salinity stresses. Materials and Methods Response of grain and straw of wheat, Back Cross Roshan 6611 cultivar, to combined effects of quantity and quality of water was traced under crossed sprinkler line source irrigation. The field area was 3232 m2 which was located in the west of Birjand city in southeast of Iran. The soil was sandy loam (=1.41 gr/cm3) and two different sources of water, normal (EC=1.5 dS/m) and saline (EC=5.5 dS/m) were adopted for two line sources, respectively. Crops located in the center of the field, were fully irrigated without any stress. While the other crops far beyond irrigation lines, were under water stress. Water salinity was differ among different points of the field and varied between 1.5 and 5.5 dS/m, based on the quantity of water received. After each irrigation procedure, the volume and salinity of water collected in 256 cans, which were placed in 2'2 square meters, were measured. At the end of the growing season, one square meter around the cans was taken to measure yield and yield components. General form of yield function for different salinities and irrigation water is Y=f (AW, EC) in which Y is the wheat yield in kg/hectare, AW is irrigation water depth during growth period in cm and EC is mean salinity of irrigation water in dS/m. Five types of production function (Linear, Cobb-Douglas, Quadratic, Laty-Dinar, and Transcendental) were evaluated using field data. Slide Write software was used for calculating R2, F-statistics, t-statistics and constant parameters of the equations. All statistics were tested at significant levels of 1% and 5%. The best function was selected based on goodness of fit and significance of factors. Results and Discussion The results showed that yield prediction of wheat and straw was better than other functions under the influence of combined conditions of drought and salinity with Cobb Douglas function. Datta et al. used second polynomial non-linear function among three linear, power and Second polynomial functions. Rosso and Baker concluded that Second polynomial function estimates the relationship between yield, salinity and water better than Maximum and Hoffman function. Kiani used transducer function for result analysis. The marginal rate of technical substitution indicated that each one of the factors can be substituted for the other one for a wide range in order to achieve equal amount of yield (grain/straw). These results are consistent with results of Rosso and Baker, Dota et al. and Letti and Dinar. Also, the results showed that in lower performances, the effect of water content on reduction of crop was higher than that of salinity. Conclusions 1-Regarding this research, reduction of grain and straw weight due to the reduction of irrigation water and increase in water salinity follows Cobb-Douglass function and outperforms other functions in predicting changes of grain and straw weight due to the effect of changes in two abovementioned factors. 2-Results showed that changes in grain and straw weights are more sensitive to changes of irrigation water than water salinity. 3-Using substitution rate curve, it is possible to substitute salinity and water content in order to achieve same yield.
Anita Yaghotipoor; Ezzat Allah Farshadfar; Mohsen Saeidi
Abstract
Introduction Selection index of ideal genotype (SIIG) technique, proposed in this paper, is one that is very simple and easy to implement. According to this technique, the best genotype would be the one that has the least deviation from the positive ideal parameter and the most deviation from the negative ...
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Introduction Selection index of ideal genotype (SIIG) technique, proposed in this paper, is one that is very simple and easy to implement. According to this technique, the best genotype would be the one that has the least deviation from the positive ideal parameter and the most deviation from the negative ideal parameter. The positive ideal parameter is a parameter with maximizes drought tolerance and minimizes drought tolerance, whereas the negative ideal parameter is a parameter with stress susceptibility. In fact, SIIG technique is derived from technique for order preference by similarity to ideal solution (TOPSIS) method (Hwang and Yoon, 1981). If for selection of drought tolerance genotypes, researchers can be used several methods simultaneously, presumably will increase the efficiency of selection (Zali, et al., 2015). SIIG technique that was proposed in this paper is a method that can select drought tolerance genotypes using different procedures. Materials and methods 20 genotypes were tested in randomized complete block design with three replications at the experimental farm of Faculty of Agriculture, Razi University of Kermanshah, Iran in 2014-2015. The SIIG technique is composed of the following steps: Step 1: Construct normalized selection matrix: The normalization of the decision matrix was done using the following transformation for each rij. r= x ∑ x i=1,…,n; j=1,…,m. Where rij is the normalized stability methods or different trait value. D=x x x x x x⋮ ⋮x x x →R =r r r r r r⋮ ⋮r r r Step 2: Determine the positive ideal parameter (maximum stability) and negative ideal parameter (minimum stability) genotypes: The positive ideal and negative ideal parameters are determined, respectively, as follows: A={r,r,…,r} A= maxrj∈Ω ,minr|j∈jΩ Where Ω is the set of maximum stability and Ω is the set of minimum instability. A={r,r,…,r} A= minrj∈Ω ,maxr|j∈jΩ Where Ω is the set of minimum stability and Ω is the set of maximum instability. Step 3: Calculate the segregation measures for each genotype: The two Euclidean distances for each genotype were calculated. The separation of each stability value from the positive ideal parameter is given as: d= (r−r) i=1,…,n Similarly, the separation from the negative ideal parameter is given as: d= (r−r) i=1,…,n Step 4: Calculate the relative closeness to the ideal parameter: The relative closeness (for selection stable genotypes) to the ideal parameters can be defined as: SIIG= d d+d i=1,2…,m, 0≤SIIG≤1. Results and discussion Twelve drought tolerance indices includingmodified stress tolerance index(MSTI), yield stability index(YSI), yield index(YI), stress susceptibility index(SSI), stress tolerance index(STI), tolerance index(TOL), geometric meanproductivity(GMP),harmonic mean(HAM), mean productivity(MP), drought resistance index(DI), relative drought index(RDI) and also selection index of ideal genotype were calculated. Using these indicators and priniciple component analysis genotypes 1, 12 and 15 were selected as tolerant genotypes. It is also 1, 12 and 15 genotypes with the highest selection index of ideal genotype values, near to one was accepted drought tolerance genotype, also 4 genotype with the lowest selection index of ideal genotype value, near to zero was accepted drought susceptible. The results were the same in different ways. Modified stress tolerance index, harmonic mean, mean productivity, stress tolerance index and geometric meanproductivity the harmonic mean and K1STI significant positive correlation with yield in stress and non-stress conditions were therefore the best indices to identify superior genotype. Conclusion The selection index of ideal genotype (SIIG) is a selective model and is used to select the most suitable genotype among genotypes in different environments. Using the SIIG method, drought tolerance indexes, different stability parameters or different traits can be determined as a single index, and the selection of superior genotypes is made more reliable and accurate.
M. Rajaie; M. Dastfal
Abstract
Introduction Salinity is one of the major environmental factors affecting the crop production of wheat (Triticum aestivum L.), specially, in arid and semi arid regions of the world. Remediation of saline soils and improvement of irrigation techniques are considered as alleviating methods in salt affected ...
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Introduction Salinity is one of the major environmental factors affecting the crop production of wheat (Triticum aestivum L.), specially, in arid and semi arid regions of the world. Remediation of saline soils and improvement of irrigation techniques are considered as alleviating methods in salt affected soils, but due to considerable costs, these methods are not feasible in every condition. Screening of varieties with tolerance to salt stress on the basis of yield, yield components and salinity tolerance indices is a suitable approach to deal with salinity and is important for future breeding programs (Houshmand et al. 2005; Poustini and Siosemardeh 2004; Saqib et al. 2005). Current study was carried done to evaluate different wheat lines and cultivars under saline condition of Zarindasht region; and to introduce a salt tolerant genotype for such circumstances. Materials and methods A field experiment was carried done to asses 14 wheat lines and cultivars under saline condition of Zarindasht region for two consecutive years. The experiment was in a completely randomized block design with four replications. Studied cultivars were: Chamran (as control), Sistan, Parsi, Haji Abad, Yavarous and Behrang. Also studied lines included of Line 34 and Line 73 which in companion with Sistan and Parsi cultivars were obtained from Yazd National Salinity Research Center. Lines 4 and 5 were the genotypes which had shown a considerable drought tolerance in experiments carried done in Fars Research Center for Agriculture and Natural Resources of Fars province. Other lines such as Ug 520, S-83-3, D-81-18, Line A were genotypes which had an optimum yield output in Darab region. The average soil and water salinity of the experiment location were about 6 and 9 dS m-1 respectively. In both years of the experiment leaf samples were collected at earring stage and sent to laboratory for analysis. The concentration of sodium, potassium and chlorine were measured in the prepared samples. During growing season days to spick and days to maturity were recorded in different lines and cultivars. At the harvest time, plant height, grain yield and thousand seed weight were determined. All data were subjected to compound variance analysis and means were compared with Duncan’s multiple range test. Results and discussion Results indicated that the highest yield belonged to Ug 520 genotype in both years of the experiment (2660 and 3170 kg ha-1 for first and second years of the experiment respectively). According to the obtained data for two year mean, Ug 520 showed 39 percent increase in yield production as compared to control. The evaluation of two-year yield means showed that after Ug 520, Line 5, Line 73, Line 4, Sistan, D-81-18, Line 34 and Parsi had greater grain yield than control (Chamra cultivar with 2095 kg ha-1). As it was expected durum wheat lines and cultivars had higher thousand seed weight than other genotypes. Shortest and longest period to reach to spiking stage were belonged to Behrang and Ug 520 respectively. Similar results were achieved for days to maturity. In respect to leaf analysis results showed that the lowest potassium concentration was observed in Behrang, while the highest concentration occurred in Ug 520. Approximately a vice versa trend took place for leaf sodium concentration, so that, Ug 520 had the lowest sodium concentration and the highest concentration was observed in another durum wheat cultivar (Yavarous). Grain yield of lines and cultivars showed a negative correlation with sodium concentration in plant leaf, while this relation was positive for potassium concentration and potassium to sodium ratio. Conclusion Results of the present study indicated that early ripening lines and cultivars with the ability to take up higher concentrations of potassium or lower concentrations of sodium had higher potential to tolerate salinity stress and produce greater yield than susceptible ones. Among studied genotypes, Ug 520 with highest yield, earliest ripening, and optimum salinity tolerance indices was recognized as the best genotype to be planted in Darab and Zarindasht regions. Acknowledgments The authors thank Yazd National Salinity Research Center for funding this project and providing the required seeds of wheat lines and cultivars.
Hasan Nouriyani
Abstract
Introduction Hormones are the most important crop plant growth regulators in response to genetic and environmental conditions. Paclobutrazol (PBZ) is a triazole plant growth regulators of the categories used in the early 1980s. According to some researchers, paclobutrazol reduced plant height (Yang et ...
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Introduction Hormones are the most important crop plant growth regulators in response to genetic and environmental conditions. Paclobutrazol (PBZ) is a triazole plant growth regulators of the categories used in the early 1980s. According to some researchers, paclobutrazol reduced plant height (Yang et al., 2001), increasing the number of tillers per plant and increasing the number of grains per spike (Bayat et al., 2010), increased tolerance to environmental stresses and non-environmental (Berova et al., 2002). Heat stress is one of the major limiting factors of environmental in wheat production and wheat germ stage is the most sensitive periods of high temperatures (Pradhan et al., 2012). The aim of this study was to evaluate the physiological characteristics of wheat grain growth and yield than using different concentrations of paclobutrazol foliar application is in optimal conditions and heat stress. Materials and Methods This study in two independent experiments were conducted each split plot in a randomized complete block design with four replications carried out in Dezful area, Iran in 2013-2014. The first experiments on the cultivation of crop varieties recommended (November) and in order to phenological stages of plant growth to coincide with heat stress after pollination season, planting dates in other experiments the first was in February. In each experiment, four levels of paclobutrazol (0, 50, 100 and 150 mg per liter) at the beginning of stem elongation sprayed on to Shoot applied, As main plots and three cultivars of wheat (Star, Vee/Nac and Chamran) were considered as sub plots. Results and Discussion The results showed that in both optimum conditions and heat stress season, consumption growth regulator paclobutrazol significantly increased the effective grain filling period, 1000-grain weight and grain yield, but the effect of this treatment on the grain growth rate was not significant. Results of stepwise regression analysis showed that the duration of grain filling was the most important attribute of variations grain weight (R2=0.59) and then grain growth rate much of the rest of the changes are determined. Conclusions The yield of the late Star because of the late Star pollination and subsequent exposure to heat stress than in the final stages of the early Vee/Nac and middle Chamran, the gradient of the effective grain filling period, grain weight and higher grain yield under heat stress end of the season was compared to optimum conditions. Overall results showed that the effect of growth regulator paclobutrazol on characteristics of grain growth and yield were positive, therefore can be with the proper use from the damage resulted from heat stress, especially at critical stages of plant growth can be prevented.
Hamdollah Eskandari; Kamyar Kazemi
Abstract
Introduction Wheat, as the most important crop in the Southwest of Iran, encounters low precipitation and high temperatures during its grain filling period. Drought stress may occurs during whole crop growth period. However, the negative effect of drought stress on grain yield is so high when it occurs ...
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Introduction Wheat, as the most important crop in the Southwest of Iran, encounters low precipitation and high temperatures during its grain filling period. Drought stress may occurs during whole crop growth period. However, the negative effect of drought stress on grain yield is so high when it occurs after anthesis. Therefore, selecting cultivars with high resistance to late season drought stress id in high importance for wheat production. In tropical and subtropical regions, which has heat stress in late season, wheat genotypes usually face with source restriction. On the other hand, in different irrigation conditions, it has suggested that grain per spike and spike number per unit area are the most sensitive grain components to drought stress. In Khuzestan province, water deficit is usually occurred during late season after wheat anthesis. Thus, for sustainable crop production, selecting cultivars with high resistance to late season drought stress is crucial. Therefore, the current research was aimed to evaluate the effect of late season drought stress on source activity, grain yield and yield components of wheat genotypes and, introducing the most tolerant genotype to after anthesis drought stress. Materials and methods The experiment was carried out during 2005-2006 growing season in Ahwaz research center of agriculture and natural resource as a split plot based on RCBD with three replications where irrigation regimes (I1: control or fully irrigation and I2: no irrigation after anthesis) were assigned as main plot and wheat genotypes (Chamran, S-78-11, S-80-18 and S-82-10) were allocated to sub plots. In control treatment, plants were irrigated with a 10-days intervals. In order to evaluate the resource limitation, spikelet removal (removing 50% of total spikelet from one side of a spike) was used. After that, resource limitation was measured by dividing grain weight of removed spikelet by grain weight of control, then, obtained value was subtracted by one and multiplied by 100. At maturity, grain yield and yield component were measured. Results and discussion Results of the experiment revealed that the highest grain yield was achieved by S-80-18 under fully irrigation regime. However, this genotype produced the lowest grain yield under drought stress conditions, where its grain yield under drought stress was 31 percent lower than its grain yield under fully irrigation. The highest spikelet per spike and grain number per spike were belong to S-78-11 genotype under fully irrigation regime. However, this genotype had the lowest grain weight under two irrigation regimes compared with other genotypes. Grain per plant and grain weight were two traits which were significantly reduced by drought stress. In this case, decreasing in photosynthetic materials which were partitioned to grain was effective. On the other hand, late season drought stress reduces grain filling period and, therefore, grain weight. The grain yield of S-78-11 genotype was reduced four percent when faced with late season drought stress, suggesting that this genotype had the highest resistant to late season drought stress. The highest and the lowest source limitation were observed in S-78-11 (4.19 percent) and S-80-18 (5.10 percent) genotypes, respectively. However, except S-78-11 genotype, other genotypes were not significantly different. Source limitation was increased 50 percent in drought stress conditions compared with fully irrigation. In this case, all genotypes, except S-78-11 genotype, were not significantly difference. However, S-78-11 genotype (with 26.4 percent) and S-80-18 genotype (with 9.3 percent) had the highest and lowest source limitation, respectively. Conclusion The highest yield reduction under drought stress conditions was observed in S-80-18, where S-78-11 genotype showed the highest resistance to late season drought stress. In all genotypes, except S-80-18, resource limitation was increased by increasing in water limitation.
Majid Abdoli; Mohsen Saeidi; Saeid Jalali-Honarmand; Sirous Mansourifar; Mohammad Eghbal Ghobad
Abstract
Occurrence of drought stress at grain filling period is the prominent and inevitable characteristic of arid and semi-arid regions. The objectives of this research were to determine the effect of water deficiency and the role of current photosynthesis on grain filling, photosynthesis and gas exchange. ...
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Occurrence of drought stress at grain filling period is the prominent and inevitable characteristic of arid and semi-arid regions. The objectives of this research were to determine the effect of water deficiency and the role of current photosynthesis on grain filling, photosynthesis and gas exchange. Therefore, an experiment was carried out in a split-plot design based on a randomized complete block design with three replications at the Research Farm of Razi University in Iran during 2010-2011 cropping season. The irrigation treatments including non water stress (full irrigation over the whole season) and water deficiency stress (irrigation cessation after anthesis stage) were considered as main plots, while the factorial combination of eight wheat cultivars including Bahar, Parsi, Pishtaz, Pishgam, Chamran, Zarin, Sivand, Marvdasht and DN-11 line and the source manipulation treatments including control (Non source limitation), defoliation of flag leaf, defoliation of all leaves except the flag leaf, removing awns and shading over ears, were considered as sub-plots. The results showed that, post-anthesis water deficiency significantly decreased grain yield (22.2%) and 1000-seed weight (18.6%) compared to the control treatment and Removal of photosynthetic sources of assimilates reduced grain yield owing to grain weight reduction. The contribution of spike photosynthesis to grain filling (35.4%) was greater than the flag leaf (18.6%) and lower leaves (18.5%) and also, awns had the lowest contribution to grain filling (3.3%). Grain filling period was shortened during water deficiency stress, so that it reduced from 35 days under control conditions to 28 days under stress conditions, whereas it caused an increase in seed filling rate. Moreover, results indicated that photosynthetic source limitations caused an increase in photosynthetic rate and gas exchange. This increase reflects the compensatory role of photosynthetic rate of remained leaves in preventing yield loss.
Majid Abdoli; Mohsen Saeidi; Saeed Jalali-Honarmand; Siroos Mansourifar; Mohammad Eghbal-Ghobadi
Abstract
Evaluation of the physiological and biochemical traits can help to identify strategies for selection of resistant cultivars and increased crop yield production under diverse environmental conditions such as drought stress conditions. To this end, an experiment was laid out in a split–plot arranged ...
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Evaluation of the physiological and biochemical traits can help to identify strategies for selection of resistant cultivars and increased crop yield production under diverse environmental conditions such as drought stress conditions. To this end, an experiment was laid out in a split–plot arranged as a randomized complete blocks design with nine cultivars, two levels of water regimes and three replications during 2010-2011 seasons at the Research Farm of Razi University of Kermanshah. The results showed that post-anthesis water deficit significantly decreased grain yield, biomass and grain weight and had not significant effect on other yield components. In well watered and water deficiency stress, Sivand and DN-11 had the greatest grain yield, respectively. Chamran cultivar showed the lowest grain yield under post-anthesis water deficiency stress. Post-anthesis water deficiency stress significantly decreased leaf soluble proteins concentration, chlorophyll a, b and a/b ratio and greenness index. Despite the reduction of photochemical efficiency of photosystem II, relative water content and stem’s soluble sugar concentration under post-anthesis water deficiency stress, these reductions were not significant.
Mostafa Heidari; Fatemeh Mesri
Abstract
Drought stress is one of the most important environmental factors in reducing growth, development and production of plants. To evaluate the effect of different salinity levels on antioxidant enzymatic activity (CAT, APX and GPX), sodium and potassium uptake and two organic compounds (carbohydrate and ...
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Drought stress is one of the most important environmental factors in reducing growth, development and production of plants. To evaluate the effect of different salinity levels on antioxidant enzymatic activity (CAT, APX and GPX), sodium and potassium uptake and two organic compounds (carbohydrate and proline) in six wheat cultivars at seedling stage, a factorial experiment based on CRD was conducted with three replications at Biosynthesis Research Centre of Zabol University in 2007. The treatments were salinity at four concentrations including 0, 100, 200 and 300 mM NaCl and six wheat cultivars (Alvand, Falat, Gaskojen, Line4, Mahdavi and Shirazi). Results showed that increasing salinity level from 0 to 300 mM NaCl significantly increased the activity of only APX antioxidant enzyme, while decreased the activity of the two other antioxidant enzymes. Among the cultivars, Falat and Mahdavi had the highest level of APX activity at 300mM salinity level. Increased salinity levels enhanced carbohydrate and proline concentrations in all six cultivars. Among the cultivars, Alvand, Gaskojen, Lain4 and Shirazi which had the lowest APX enzyme activity, showed the highest carbohydrate and proline concentrations. Salinity caused reduction in potassium and an increase in sodium uptake. Falat and Mahdavi cultivars had the best controlling on sodium and potassium uptake due to possessing the highest APX activity as well as a desirable carbohydrate and proline content in aboveground parts especially at S3 salinity level. From the results of this study it can be deduced that osmotic adjustment is more effective in conferring the salinity tolerance to wheat cultivars than the antioxidant enzyme activity at seedling stage.
Farzad Paknejad; Majid Jami Al-Ahmadi; Alireza Pazoki; Mohammad Nasri
Abstract
In order to evaluate effects of drought stress on yield and yield components of two wheat cultivars under field condition, two similar experiments were conducted in 2004 in Field Research Stations of Islamic Azad Universities of Karaj and Torbat-e-Jam Unites. The study was arranged as factorial experiments ...
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In order to evaluate effects of drought stress on yield and yield components of two wheat cultivars under field condition, two similar experiments were conducted in 2004 in Field Research Stations of Islamic Azad Universities of Karaj and Torbat-e-Jam Unites. The study was arranged as factorial experiments based on a randomized complete block design with four replications. The first factor was consisted of nine different irrigation regimes including control (T1), irrigating when 60 and 80 percent of soil moisture was depleted at stem elongation to ripening stage (T2 and T3, respectively), at the start of flowering to ripening (T5 and T7, respectively), at flowering stage (T4 and T6, respectively), and irrigation termination at flowering and grain filling stages to ripening stage (T8 and T9, respectively). The second factor was included two wheat cultivars, Chamran and Marvdasht. Results showed a significant difference between different treatments of drought stress and control regarding yield and yield components. Irrigation termination from flowering onward led to the lowest grain yield, with 64 percent reduction compared to control. The lowest yield reduction equal to 19 percent beside control was obtained with irrigating at 60 percent soil moisture depletion from stem elongation up to end of growth period. According to these results, the most sensitive growth stages of wheat to drought stress were flowering and grain filling stages. Marvdasht despite its higher yield under sufficient moisture condition, and even under water-deficit through growth period, suffered more damage than Chamran from terminal irrigation termination. Under optimum condition of humidity, grains per spike and length of peduncle showed higher correlation with grain yield, respectively. When irrigation was withheld from flowering to ripening stage, weight of 1000 kernels showed a positive and significant correlation with yield, indicating that impact of water stress in this stage on yield was mediated by reduction of kernel weight.
Ali Shahidi; GholamReza Zamani; Heidar Ali Kashkuli; Mahdi Amirabadizadeh
Abstract
The main factor for managing and scheduling irrigation in dry zone, recognition of plant response to dryness stress. Most irrigation water in Birjand area have saline solution, therefore, salinity stress should be considered at the stimulatingly. Hens, this study was conducted in order to obtain the ...
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The main factor for managing and scheduling irrigation in dry zone, recognition of plant response to dryness stress. Most irrigation water in Birjand area have saline solution, therefore, salinity stress should be considered at the stimulatingly. Hens, this study was conducted in order to obtain the optimum depth of irrigation scheduling, considering dryness and salinity individually and stimulatingly during 2006 agriculture year, in agricultural research station at Birjand university. The experiment had three replications according to a randomized complete block design with split plot layout (factorial form), which considered three levels of water salinity (1.4, 4.5, 9.6 dS m-1) as main plot and four levels of irrigation water (50, 75, 100, 125 % of plant water requirement) and two wheat varieties as sub plot. The irrigation depth for different salinity levels and the two cultivars was determined. The crop yield under different conditions was determined using production functions, than the optimum irrigation area net income for available water (10000 m3) was assessed. The results showed that by increasing salinity stress, the irrigating depth of both wheat cultivars were a little decreased that was not reflected in real condition. The reason for reduction in irrigation depth is related to water price for different salinity levels that was accounted as constant, where, the crop yield during various salinity stress severities would be different. Also, under dryness stress, and increase salinity stress conditions for both wheat cultivars, the irrigation depth, were increased. The reason for this increase in irrigation depth was reduction in yield high levels of salinity stress that was resulted from changing of production function to the irrigating depth. Therefore, at high salinity stress levels, deficit irrigation would malfunction and would not be economically feasible. For all available water levels, the irrigation depth was higher for Ghods cultivar then Roshan cultivar. This factor was responsible for obtaining optimum irrigation area for Ghods cultivar compared to Roshan cultivar in various salinity levels and resulted that the net income of Roshan cultivar was more than Ghods cultivar in all levels. Overall, where the available water quantity is considered and quality is not favorable (saline) using Roshan cultivar is highly more economical in Birjand region.
