Maryam Karimiyan; Fayaz Aghayari; Farzad Paknejad
Abstract
Introduction Many countries have used crop growth models to simulate crop response to environmental stress and various management methods in different decades (Mehraban, 2013). One of the goals of crop simulation models is to be used for crop yield prediction. Researchers have proposed and used various ...
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Introduction Many countries have used crop growth models to simulate crop response to environmental stress and various management methods in different decades (Mehraban, 2013). One of the goals of crop simulation models is to be used for crop yield prediction. Researchers have proposed and used various models so far, including: Crop Environment REsource Synthesis (CERES) (Jones and Kiniry, 1986), WOrldFOodSTudies (WOFOST) (Van Keulen and Wolf, 1986), Cropping Systems Simulation Model (CropSyst) (Stockle et al., 1984), etc. However, it should be noted that proposing such models requires the user to be highly skilled at calibration since there are lots of input variables measuring of which is a difficult task. Using some underlying functions, Cordery and Graham (1989) developed a model to simulate crop growth and water value in this process. The model, which in known as MEDIWY, was then calibrated for winter wheat under Bajgah field condition (Ziaei and Sepaskhah, 2003). Generally, using common data, the model which is measured in nearly all weather stations has the potential to properly estimate both growth indices and wheat grain yield under dry and irrigated farming. Its broader application requires doing more experiments in different weather conditions. Therefore, with regard to applicability of MEDIWY model, with at least input data, the present study is to evaluate this model by simulating wheat yield (Marvdasht cultivar) under different irrigation treatments in Karaj region. Materials and Methods The current research is conducted to study MEDIWY model in simulating wheat yield (Marvdasht Cultivar) under Karaj weather condition. In doing so, we used nine irrigation treatment data carried out in research farm of Islamic Azad University of Karaj during 2003-2004 crop year (Paknejad, 2005). Also, additional required information, such as meteorological data (amount of daily pan evaporation and rainfall) are obtained from Mahdasht weather station in Karaj region. Values concerning meteorological data (rainfall and pan evaporation) and irrigation are entered to this model as input variables. Considering that each of the irrigation treatments used in this study have a special irrigation regime and applied in different stages of growth, for more accurate calibration of MEDIWY model, irrigation treatments are divided to three groups based on level of drought stress so as to be able to calibrate each group separately. For the purpose of evaluating the model, several statistics evaluation methods are employed including: linear regression analysis of observed and simulated data and its comparison with 1:1 line method, Coefficient of Determination (R2), Root Mean Square Error (RMSE), Normalized Root Mean Square Error (NRMSE), and Model Efficiency (ME). Results and Discussion Results showed that after calibrating MEDIWY model for simulating wheat yield (Marvdasht cultivar) in Karaj region, the obtained values for RMSE, NRMSE, and ME were 265 Kg.ha-1, 5.7%, and 0.99, respectively, which represent appropriateness of statistical indices of calibrated part of the model. According to validation results, statistical indices of RMSE, NRMSE, and ME were 412 Kg.ha-1, 8.5%, and 0.99, respectively, which indicate that the calibrated MEDIWY model can simulate wheat yield values in Karaj region very well. According to findings of the current research, although MEDIWY requires less input data compared to other crop growth models, it has great potential and accuracy for simulating crop yield. Conclusions According to findings of the current research, although MEDIWY requires less input data compared to other crop growth models, it has great potential and accuracy for simulating crop yield.
Zohreh Emami Bistgani; S.A. Siadat; A. Bakhshandeh; A. Ghasemi Pirbalouti
Abstract
Introduction Thymus daenensis as a medicinal plant dispersed in high altitudes in Zagros Mountains range, western and south western Iran and has an extensive diversity of chemical composition of essential oil (Ghasemi Pirbalouti et al., 2014). Water stress has been considered as one of the limit ...
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Introduction Thymus daenensis as a medicinal plant dispersed in high altitudes in Zagros Mountains range, western and south western Iran and has an extensive diversity of chemical composition of essential oil (Ghasemi Pirbalouti et al., 2014). Water stress has been considered as one of the limit factors for plant production (Passioura, 2007). Drought condition frequently leads to oxidative stress primarily due to chloroplast damaging and injury, leading to over-reduction of the chlorophyll content and enzyme activity in calvin cycle and finally it can reduce grow and yield of plant (Monakhova and Chernyadev, 2002). Chitosan categorized as a biotic elicitor in plants which activates gene expression for secondary metabolites, increasing of plant production, conservation of plant against microorganisms, seed germination and for growing in plants (Yin et al., 2011). The objective of this experiment was to investigate the effect of drought stress and chitosan application on physiological traits including photosynthetic pigments, proline, soluble sugars, and lipid peroxidation in T.deanensis in Shahrekord climate condition. Materials and methods In order to determine, the effect of drought stress and foliar application of chitosan on photosynthetic pigments, proline, soluble sugar, lipid peroxidation and cell membrane permeability of T. daenensis an experiment was conducted in Shahrekord climate in 2014. The experiment was laid out as factorial arrangement in complete randomized with three replications. Drought stress levels included well-watered (field capacity), irrigated daily to 50% field capacity (mild stress), and irrigated daily to 25% field capacity (severe stress), combined with three chitosan levels 0, 0.2, 0.4 g L-1 and acetic acid. At first seeds were planted in spring of 2014 in greenhouse conditions and then transferred in climate conditions. Chitosan was sprayed three times, just prior to flowering stage, at 50% flowering and at full flowering. Photosynthetic Pigments. Chlorophyll and carotenoid content was determined by Arnon method (1967). Proline. Proline concentration was measured by Bates et al., (1973). Leaf soluble sugars content. Soluble sugars content was determined by Fsles, (1951). Lipid peroxide (MDA). The lipid peroxidation level in plant tissues was determined in terms of MDA concentration (Robbert et al., 1980). Cell membrane permeability. Membrane permeability was determined by measuring (Lutts et al.,1998). Statistical analysis. SAS software and MSTATC were used for data analysis and means were compared using least significant difference. Results and discussion Photosynthetic pigments: The effect of drought stress had significantly (p≤0.01) on chlorophyll a. It seems that, when water stress intensified, activity of reactive oxidative species and chlorophylls’ enzyme increased. In general, foliar application of chitosan did not change on photosynthetic pigments. Proline: The effect of drought stress, chitosan and interaction between drought stress and chitosan had significantly (p≤0.01) on proline. When water stress intensified, proline increased. The highest proline content was obtained (3.85) µmol g-1 from severe stress and 0.4 g L-1 chitosan. By decreasing of water potential, the synthesis of proline from glutamic acid increased (Liang et al., 2013). Soluble Sugars: The interaction between drought stress and chitosan did not significant on soluble sugars but when water stress intensified, soluble sugars increased. Lipid peroxide (MDA content): The effect of drought stress, chitosan and interaction between drought stress and chitosan had significantly (p≤0.01) on lipid peroxide. In the study the effect of water stress on apple seedling, MDA content increased (Yang et al., 2009). In this study, spraying with 4 g L-1 chitosan could compensated damage caused by drought stress. Membrane permeability: The effect of drought stress and chitosan had significantly (p≤0.01) on membrane permeability. Conclusion Drought stress provokes ROS production in thyme plant, the compensatory effect of chitosan on reducing the negative impact of stressful conditions on plant was mainly due to stimulation of osmotic adjustment through proline accumulation, and reduction of lipid peroxidase level and therefore improvement of the integrity of cell membranes.
S. Sabzi; Z. Tahmasebi; M. Barari
Abstract
Introduction After cereals, the second most important source of human food is legumes. Common bean is seventh major world food crop that has been widely affected by environmental conditions such as drought. Despite of the economic importance of common bean; few studies have been done on genetics and ...
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Introduction After cereals, the second most important source of human food is legumes. Common bean is seventh major world food crop that has been widely affected by environmental conditions such as drought. Despite of the economic importance of common bean; few studies have been done on genetics and genetic resource evaluation. Materials and methods Given the importance of stress in this study to evaluate the resistance of bean genotypes to different levels of drought stress, an experiment was performed to evaluate the influence of drought stress on common bean yield and its components, so a factorial experiment was conducted in a completely randomized design at greenhouse in Ilam University. In this experiment, four Common bean genotypes (Naz, Akhtar, Ks41128 and G11867) were evaluated for resistance to different levels of drought stress included of 70, 50 and 30% of field capacity. Drought was imposed 10 d after planting. The measured parameters include dry weight, plant height, grain yield per plant, pod length, number of pods per plant, number of seeds per plant. Results and discussion The results showed that there were significant differences between studied traits of genotypes studied, suggesting genetic variation of genotypes. Also there were significant difference between the drought levels for all traits and water deficient can decrease all studied traits although there were not any difference between mild and strong stress levels. The results of the reaction of genotypes to drought stress showed that KS41128 genotype highest yield percentage changes and yield components showed in drought stress condition. Two genotypes (Akhtar and Ks41128) had a higher than average yield under unstressed conditions but yield of Ks41128 is fairly strongly affected by stress, and another but is less affected by stress. Conclusions Regards to change percent of most traits, Akhtar (a genotype with light red seed, standing form, and addition to suitable marketing and quality) had the least change percent so could use for breeding programs to release water stress tolerance varieties.
H. Ataei Somagh; H. Habibi; M.H. Fotokian
Abstract
Introduction Drought stress is the most important factor of yield reduction of crops such as chickpea and a change in the amount of some internal components in plant. However, research has shown that chickpea has well respond to irrigation. Surfactants, as agronomical factors, are used in the water system ...
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Introduction Drought stress is the most important factor of yield reduction of crops such as chickpea and a change in the amount of some internal components in plant. However, research has shown that chickpea has well respond to irrigation. Surfactants, as agronomical factors, are used in the water system to adjust the amount of irrigation. So, the aim of present experiment was evaluated the effect of irrigation concomitant with surfactants solution on yield and morphological characteristics of four chickpea genotypes, at Shahed University research farm in 2012-13. Materials and methods an experiment was conducted as a randomized complete block design with factorial treatment structure with three replications, Treatments included of three irrigation levels (100, 200, 300 mm) evaporation of class A pan, two levels of surfactant solution (with and without application) and four chickpea genotypes Arman, Azad, Bionij and the Greet. Seeds genotypes tested were prepared from Kermanshah Sararood Dryland Research Center. The seeds after disinfection with fungicides Benomyl (2 per thousand), was done at a depth of approximately five centimeter. Surfactantsolution used for the testing of non- Ionic surfactant brand was Irrigaid Gold that it amount was fixed for all treatments and after the establishment of the plantlets, as water-soluble, were used. Results and discussion The results showed that the highest growth period, the number of branches per plant, number of pods per plant, number of fertile pods and seed obtained weight at 100 mm evaporation of class A with the use of surfactant. Azad and Arman had the highest and Bionij genotype had the lowest plant height and the highest grain yield (kg ha 9/1541) with irrigation at 100 mm evaporation achieved by the use of surfactant on Greet genotype. The highest average of dry matter (1189 kg per hectare) was obtained by irrigation at 100 mm evaporation with the use of surfactant for Azad genotypes.
Sh. Vakili Bastam; S.S. Ramezanpour; H. Soltanloo; Kh. Zeinalinezhad; A. Borzouei
Abstract
Introduction The world population is predicted to increase beyond 8 billion by 2030 implying major challenges for agricultural sector to secure food availability (Smol JP , 2012).Wheat is one of the main cereal crops, cultivated to meet great demands of the population for human feeding. It is the most ...
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Introduction The world population is predicted to increase beyond 8 billion by 2030 implying major challenges for agricultural sector to secure food availability (Smol JP , 2012).Wheat is one of the main cereal crops, cultivated to meet great demands of the population for human feeding. It is the most important staple for bread flour in Iran (Nour- mohamadi et al., 2009). A key challenge for plant growth is global water shortage (Flexas et al., 2013; Foley et al., 2011). A variety of strategies has been used to improve the drought tolerance of crops, including traditional selection methods and genetic engineering (Fleury et al., 2010). In this case, irradiation is an appropriate approach for improving the level of genetic variation a short time. Materials and methods This study was carried out to determine the response of mutant line# 'T65588' derived from 'Tabasi' radiated with Gamma rays to drought stress. Germination traits were investigated in osmotic stress induced by PEG and water related traits studied in drought stress at adult wheat stage both under completely randomized design with three replications. Results and discussion The results of analysis of variance indicated that germination features were intensely affected by the PEG treatment. Also genotypes differed significantly for germination rate, plumule length and radicle length. Significant drought stress × genotype effect in germination rate, plumule length, radicle length and plumule dry weight indicated that reaction of genotypes to polyethilenglycol was not simmilar. Drought significantly influenced water-related variables- RWC, RWL and ELWR- traits and caused depletion in RWL and increasing in RWC and ELWR. Conclusions Mutant line# 'T65588' in germination features had superiority on its wild genotype ('Tabasi') in drought stress conditions. Persistence in RWC content of cultivars in water stress conditions may serve as good indicator of drought tolerance. As mentioned above, the rate of increasing in RWC for mutant line#'T65588' was more than 'Tabasi'. RWC is closely related to cell volume, therefore it may more closely reflect the balance between water supply to the leaf and transpiration rate (Farquhar et al., 1989). Schonfeld et al (1988) observed a decline in the amount of RWC in wheat due to drought stress and reported the highest RWC in the tolerant genotype. Several researchers have shown that low rate of water loss (RWL) from excised leaves are related to drought resistance, and may be used as screening criteria in breeding programs (Winter et al., 1988). Our result is consistent with Golestani Araghi and Asad (1998) findings, who observed decrease in the RWL under stress condition in wheat. Big reduction in RWL in mutant line may indicate the more efficient use of water by 'T65588' mutant genotype. Based on Lonbani and Arzani (2011) suggestion, among the plant water relation parameters, ELWR could be a superior indirect selection criterion for grain yield. This trait is moderately heritable (Clarke and Townley-Smith, 1986) and can be easily estimated in a large population (Dhanda and Sethi, 1998). The rate of increasing in ELWR in mutant line#'T65588' in comparison to its wild variety ('Tabasi') was more, which is an another validation for assertion of Mutant line# 'T65588' in germination features and also water-related variables in adult plant had superiority on its wild genotype in drought stress conditions.
O. Nowruzi; E. Tavakol; S.A.R. Kazemeini
Abstract
Introduction Barley is the fourth most important cereal worldwide and it is well adapted to some of abiotic stresses.Late season drought stress is the most important limiting factor in production of barley. The existence of variations in response to drought stress, promotes breeders to look for the new ...
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Introduction Barley is the fourth most important cereal worldwide and it is well adapted to some of abiotic stresses.Late season drought stress is the most important limiting factor in production of barley. The existence of variations in response to drought stress, promotes breeders to look for the new genetic variations among barley genotypes in order to improve yield under water stress conditions (Jallel et al., 2004). Drought tolerance indices based on grain yield in both normal and water stress conditions enable breeders to identify drought tolerant genotypes (Zare et al., 2012). Materials and methods In order to identify barley drought tolerant genotypes and correlation between yield components and drought tolerance indices, 79 foreign genotypes and an Iranian control variety were evaluated under normal irrigation and water stress conditions in an experimental field at college of agriculture, Shiraz University, during growing season 2012-13. The experiment was conducted as split plot based on randomized complete block design in three replicates. Each barley genotype was grown on 4 rows of 2 meters length. In normal irrigation treatment, plants were irrigated every week to field capacity level, while irrigation was completely stopped after 3-leaf stage in water stress treatment. Yield and yield components including number of spikes, number of seeds per spike, thousand grain weight and biological yield were measured in both normal irrigation and water stress conditions. The following drought tolerance indices were calculated using grain yield under normal irrigation and water stress conditions: Stress susceptibility index (SSI) (Fisher et al., 1978), Mean Productivity (MP) and Tolerance index (TOL) (Rosielle et al., 1981), yield index (YI) (Lin et al., 1986), Harmonic Mean Productivity (HMP), Stress Tolerant Index (STI) and Geometric Mean Productivity (GMP) (Fernandez, 1992). Results and discussion Biological yield, spikes number and thousand grain weight exhibited a significantly positive correlation with the stress tolerance indices. The high correlation between drought tolerance indices and thousand grain weight (Shahmoradi et al., 2011), number of spikes and biological yield (Dolatpanah et al., 2011) have been also reported in previous researches. Among various drought tolerance indices, MP, GMP, HMP and STI demonstrated highest positive and significant correlation with yield under both normal irrigation and water stress conditions and they were introduced as the best indices for identification of drought tolerant genotypes. These results are in consistence with the reports in a similar research carried out by Khokhar et al. (2012). In addition, according to results of principal component analysis, the first two components named as tolerant and yield stability component and susceptibility component, respectively, were able to explain 97% of the total variation. Based on different statistical analyses, the genotypes number 88 and 145 were identified as the most drought tolerant genotypes. Cluster analysis based on tolerance indices and yield under both normal and water stress conditions classified 80 varieties into four separate groups related to their response to water stress conditions. Conclusion The yield components of thousand grain weight and number of spikes as well as biological yield can effectively contribute to selection of barley drought tolerant genotypes as it was demonstrated by their high correlation with drought tolerance indices. The results of this research on identification and clustering of tolerant and susceptible barley genotypes can be used in barley breeding programs and to increase the diversity of Iranian barley germplasm towards production of new drought tolerant cultivars.
O. Ansari; J. Gherekhloo; F. Ghaderi-Far; B. Kamkar
Abstract
Introduction Seed germination is a complex biological process that is influenced by various environmental and genetic factors. Temperature and water potential are two primary environmental regulators of seed germination. Tall mallow (Malva sylvestris)is an important invasive weed in southwest Iran and ...
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Introduction Seed germination is a complex biological process that is influenced by various environmental and genetic factors. Temperature and water potential are two primary environmental regulators of seed germination. Tall mallow (Malva sylvestris)is an important invasive weed in southwest Iran and also a medicinal plant. ). Tall mallow is native home in Western Europe, North Africa and Asia. This plant frequently found in cultivated fields, orchards, gardens, farmyards near manure piles, along roadsides, in towns, and in waste places and, can grow anywhere from 60 to 120 cm in length.Quantification of germination response to water potential is possible using hydro time model. In this study, application of hydro time model for Malva sylvestris L. Material and methods Experiments were conducted in 2015 at the seed laboratory of Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. Fruits of M. sylvestris were collected in April 2014 from Shushtar, Khuzestan (32°2'47"N, 48°50'18"E), located in southwest Iran. Seeds were separated manually from the fruits and stored in room conditions until their use. The laboratory temperature fluctuated between 30°C during day and 20°C during night. Germination response to water potential in different temperature were studied. Treatments included drought levels (0, -0.2, -0.4, -0.6, -0.8, -1, -1.2, -1.4 and -1.6 MPa) in temperatures of 15, 20 and 30 °C. The response of cumulative germination seeds to different potentials at different temperature was quantified using weibull function. All data were analysed by SAS ver 9.2. The hydro time model was fitted to cumulative germination. Goodness of fit of the hydro time models to all data was checked by constructing plots of the coefficient of determination (R2), the relationship between the observed and the predicted germination percentage and base water potential. Results Results indicated that temperature in addition to germination percentage also on germination rate was effective. Also results showed that germination percentage and germination rate increased with increasing temperature, while germination percentage and germination rate reduced as a result of water potential increment. Also, results showed that the hydrot time model fit to data of tall mallow had high R2 values. According to the hydro time, the hydro time constant (θH) declined significantly with increasing temperatures, so that the minimum hydro time constant (10.01 MPa h) was attained at 30 °C. The increment of temperature resulted in significant reduction of base water potential, and the highest base water potential (-1.13 and -1.11 MPa) was obtained at 15 and 20 °C, and the minimum base water potential (-0.6 MPa) was attained at 30 °C. The minimum standard deviation of base water potential in population (0.31) was obtained at 30 °C. Using hydro time model for quantitation of M. sylvestris L. Conclusion Germination response to water potential at different temperatures, led to acceptable results. Utilizing the output of hydro time model at different temperatures can be useful in prediction of germination percentage in different water potential.
P. Bayat; M. Ghobadi; M.E. Ghobadi; Gh. Mohammadi
Abstract
Introduction Chickpea (Cicer arietinum L.) is the most important pulse crop of rainfed systems, traditionally grown in rotation with wheat and barley in the west of Iran. Since the seed is the most important inputs in agriculture, it has the largest effect on increase or decreases the crop yield, so ...
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Introduction Chickpea (Cicer arietinum L.) is the most important pulse crop of rainfed systems, traditionally grown in rotation with wheat and barley in the west of Iran. Since the seed is the most important inputs in agriculture, it has the largest effect on increase or decreases the crop yield, so using of high quality seeds is very important. The vigorous seeds can germinate better and have higher germination and emergence percentage in exposure to environmental stresses and eventually produce more powerful seedlings (Salehian, 1996). The rate and percentage of seedling emergence are important factors that affect on plant density, plant growth rate, and finally crop yield in farm (Hussain et al., 2006; Begnamy and Cortelazz, 1996). Different laboratory tests has been proposed to determine the seed vigor such as accelerated aging test (Hampton et al., 2004), the electrical conductivity test (Khavari et al., 2009), cold test (Noli et al., 2008), osmotic stress test (Hampton and TeKrony, 1995), and etc. In osmotic stress test, seed is germinated in exposure to osmotic potentials prepared using poly-ethylene-glycol (PEG) or mannitol (Hampton and TeKrony, 1995). PEG is a neutral polymer available in a range of molecular weights, highly soluble in water and with low toxicity (Slama et al., 2007). Because of these properties, it has been used by several investigators to impose water stress in plants by decreasing the water potential. In this experiment, ability of osmotic stress test using PEG, as a laboratory seed vigor test, was studied to predict emergence and establishment of chickpea seedling in field. Materials and Methods The experiment was done at Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran, during 2012. The experiment was conducted under two conditions including laboratory and field. In laboratory experiment, 13 chickpea seed lots were germinated under osmotic potential -6 bar using PEG-6000. Different germination characteristics such as final germination percentage, germination rate, germination index, root and shoot length, root and shoot dry weight, and seedling vigor index were measured. In field experiment, these 13 chickpea seed lots were planted and seedling characteristics such as final seedling emergence percentage mean daily emergence, seedling emergence rate, and seedling emergence index were measured. The correlation coefficients of germination characteristics in laboratory test with the percentage and rate of seedling emergence in field experiment were evaluated. Results and discussion The results showed that, under both laboratory and field conditions, seed lots were different in seed germination and seedling emergence characteristics. Orthogonal analysis showed that the new seed lots had higher germination and emergence characteristics than the old seed lots under both laboratory and field conditions. The seed lots belonged to Desi type had higher germination and emergence characteristics than the Kabuli type, too. The correlation analysis showed that there was positive and significant correlations among seedling emergence percentage in field with shoot length and shoot dry weight in laboratory test. There was, also, positive and significant correlations among seedling emergence rate in field with shoot and root length, shoot weight and seedling vigor index in laboratory experiment. Conclusions Correlation between some traits in laboratory test and field experiment shows that the osmotic stress test has ability to predict percentage and rate of seedling emergence in the field up to 30%.
T. Raiesi; A. Sabouri; H. Sabouri
Abstract
Introduction One of the most important variables for establishment of the appropriate rice seedling under stress environments is high power of the germination and emergence. In this regard was conducted a research to study of genetic variation in aerobic rice and Iranian genotypes on the base of ...
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Introduction One of the most important variables for establishment of the appropriate rice seedling under stress environments is high power of the germination and emergence. In this regard was conducted a research to study of genetic variation in aerobic rice and Iranian genotypes on the base of tolerance to drought stress. Material and methods Seed germination test was conducted in three levels of osmotic stress (distilled water, -8 and -16 bar of manitol) and 52 rice genotypes as a split plot in a randomized complete block design with three replications. Genotypes consisted of 31 genotypes of the aerobic rice and foreign as well as 21 Iranian varieties of rice. Results The results showed that there were significant difference between osmotic stress levels, genotype and interaction between the levels of osmotic stress and genotypes for whole germination components. Considering all of above condition, the highest ranks in the overall comparison to Arunachalam method were belonged to genotypes aerobic and foreign named AE8, AE6, AE18, AE16 and AE29 and lowest ranks were for Iranian genotypes named Ghasroldashty, RashtiSard, Anbarbou, AliKazemi, Champabodar, Hashemi and DomSiah. Conclusions According to these results, foreign and aerobic genotypes showed relative superiority more than Iranian rice on the base of the characteristics of germination and with increasing levels of drought stress; foreign and aerobic genotypes were more tolerant.
D. Davani; M. Nabipour; H. Roshanfekr Dezfouli
Abstract
Introduction Maize (Zea mays L.) belongs to the family Poaceae and it is the first important cereal crop of the World (FAO, 2013). Salinity is one of the major environmental factors limiting plant growth and productivity. Maize is sensitive to salinity (Turan et al., 2009). Planting method is one of ...
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Introduction Maize (Zea mays L.) belongs to the family Poaceae and it is the first important cereal crop of the World (FAO, 2013). Salinity is one of the major environmental factors limiting plant growth and productivity. Maize is sensitive to salinity (Turan et al., 2009). Planting method is one of a crucial factor for improving crop yield. Planting methods in saline and non-saline conditions are different. Cytokinin (Rajala and Peltonen-saninio, 2001) and Auxin (Jung and Park, 2011) are known to play a significant role in plant tolerance to salt stress and to significantly improve the growth of crop plants grown under salinity. However, little information appears to be available on the relationship between salinity tolerance and auxin or cytokinins levels in plants. In this respect, the objective of this study was to study the effects of foliar applications of cytokinin and auxin hormones on yield and dry matter remobilization of grain Maize (Zea mays L.) under different planting patterns in saline conditions. Materials and methods The experiment carried out at Bushehr Agricultural and Natural Resources Research Center, Dashtestan station with 29° 16´ E latitude and 51° 31´ N longitude and 70 m above see surface during 2013 growing season. The field plowed by April at 2013 and then prepared and sowed by August at 2013. There were five rows with 75 cm distance. A split factorial design based on complete randomized blocks with three replications was conducted. Planting pattern (ridge planting, double rows of planting on ridge in zigzag form and furrow planting) as the main factor and time of cytokinin (0 as control, V5- V6 stage and V8- V10 stage) and auxin (0 as control, silking stage, two weeks after silking stage) foliar-applied was considered in a factorial. Cytokinin (Benzyl Adenine, Merck) and Auxin (Indole-3-Butiric Acid, Merck) were sprayed on the entire plant in the evening with concentration of 50 and 10 g. l-1, respectively. All morphological and yield component traits measured on 10 randomly selected plants of each plot. Yield was measured in 9 m2 for each treatment. Data analyzed using the SAS (Ver.9.1) and Significance of differences between means was conducted using Duncan’s multiple range test. Results The results showed that different planting patterns in terms of amount, efficiency and contribution of dry matter remobilization (DMT), amount, efficiency and contribution of current photosynthesis (CP), 1000 kernel weight, grain yield and harvest index were significant. Generally, results of this research indicate improved yield and yield components of maize due to the change pattern from one row to the furrow planting in salinity conditions. At the times of BA application, the maximum amount of amount and contribution of DMT Was dedicated to non-use. While the maximum amount of efficiency and contribution of CP Was dedicated to time consumed V8- V10 stage. The maximum amount of amount and contribution of DMT, amount of CP, 1000 kernel weight, grain yield and harvest index produced by time of auxin foliar-applied in silking stage and the most CP and biological yield was assigned to the non-use. It has been found that both auxin and cytokinin may have a role in mediating cell division in the endosperm during the grain-filling stage. Therefore, these hormones might regulate the grain capacity (sink size) for the accumulation of carbohydrates (Koocheki and Sarmadnia, 2012). It has been found that IAA actively participated in the mobilization and accumulation of carbohydrates in seeds (Darussalam Cole and Patrick, 1998). Auxin and cytokinins hormones are also thought to be involved in regulating sink strength either by mediating the division and enlargement of endosperm cells or by controlling the import of assimilates to the sink (Kaya et al., 2010). Conclusions It is concluded that furrow planting with CK application in V8- V10 stage (50 g. l-1) and IBA in silking stage (10 g. l-1) reduced effects of salinity on plant and produced the highest grain yield. Due to its effect on diminishing salt aggregation in relation to ridge planting, furrow planting prepare semi saline and saline areas for growing crops.
R. Seyed Sharifi; H. Kamari; Gh. Nagafi
Abstract
Introduction Salinity is one of the major abiotic environmental stresses, which affect almost every aspect of plant life and significantly reduces crop yield. Thus it is a serious threat to agricultural productivity especially in arid and semi-arid regions. The response of plants to salinity depends ...
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Introduction Salinity is one of the major abiotic environmental stresses, which affect almost every aspect of plant life and significantly reduces crop yield. Thus it is a serious threat to agricultural productivity especially in arid and semi-arid regions. The response of plants to salinity depends on several factors such as developmental stage, severity, duration of stress, and cultivar genetics. Several strategies have been developed in order to decrease the toxic effects caused by high salinity on plant growth. Among them use of microelements such as zinc plays a very important role in yield improvement. Zinc is an essential micronutrient for humans, animals and plants, which act as the metal component of enzymes or as a functional structural. A number of researchers have reported the essentiality role of zinc for plant growth and yield. Zinc is required for chlorophyll production, pollen function, fertilization and germination plays an important role. So, recent researches have shown that a small amount of nutrients, particularly Zn applied by foliar spraying can affect the susceptibility of plants to stress. Zinc (Zn) is known as an important micronutrient and its deficiency is recognized as a critical problem in plants, especially grown on saline conditions with high pH values. Materials and methods In order to study of effects of foliar application with Nano zinc oxide on contribution of stem reserves in grain yield, leaf appearance rate and some growth indices of barley (Hordeum vulgaris L.) in various levels of soil salinity, a factorial experiment based on randomized complete block design with three replications was conducted at research greenhouse of faculty of Agriculture, University of Mohaghegh Ardabili in 2012. Experimental factors were included soil salinity in four levels (no salinity, salinity of 25, 50 and 75 Mm) with NaCl and foliar application of Nano-Zinc oxide at four levels (0 as control,0.25, 0.5, 0.75 and 1 g/lit). Results The results showed that increasing of soil salinity decreased yield, leaf appearance rate and growth indices of barley. It was vise versa in foliar application of Nano-Zinc oxide. Maximum of dry matter remobilization from stem and aerial vegetative organs was obtained in salinity of 75 Mm× no foliar application of Nano-Zinc. Means comparison showed that maximum of yield (1.22 g per plant), leaf appearance rate (0.466 leaf/ day) and growth indices were obtained in 0.75 g/lit of Nano-Zinc oxide× without of salinity application and minimum of they were obtained in no foliar application× soil salinity of 75 Mm. It seems that in order to increasing of yield and some growth indices such as total dry matter, crop growth rate and relative growth rate under salinity condition, can be suggested that be applied 0.75 g/lit of Nano-Zinc oxide.
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.
S. Pazireh; A. Nezami; M. Kafi; M. Goldani
Abstract
Introduction Garlic is a plant with a relatively high tolerance to cold winter but extreme autumn and winter in cold regions are among the factors that affect the growth and survival of plants. So it seems that one of the critical success factors for fall planting is identification of cold tolerant plants ...
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Introduction Garlic is a plant with a relatively high tolerance to cold winter but extreme autumn and winter in cold regions are among the factors that affect the growth and survival of plants. So it seems that one of the critical success factors for fall planting is identification of cold tolerant plants in these areas. To evaluate and recognition tolerant plants to cold stress and to avoid some inevitable limitations in field evaluation, different types of artificial freezing tests have been developed. Electrolyte leakage test is one of this methods that is simple, repeatable and cheap and relatively fast which determines the degree of damage to cell membranes caused by the stress. When the plant tissues damage by cold, membrane activity decreases and electrolytes inside the cell leaks to the outside its. It has been reported by many researcher that cold stress increases electrolyte leakage and this trait can be used as a criterion for evaluation of freezing tolerance. Also the freezing temperature in which 50% of ions are leaked from the cells has been proposed to be used as the 50% threshold of damage of freezing stress. Materials and methods In order to evaluate freezing tolerance of garlic a factorial experiment was conducted in 2012 year based on completely randomized design with four replications under controlled conditions in faculty of agriculture, Ferdowsi University of Mashhad. Experimental factors consisted of two planting dates (19 September and 22 October) and four ecotypes of garlic (Bojnurd, Torbat- Heydarye, Neyshabur and Khaf). Plant after growth and hardening under natural environment exposed to eight freezing temperatures (0, -3, -6, -9, -12, -15, -18 and -21 degree ºC). After freezing, electrolyte leakagepercentage and lethal temperature for %50 of plants according to electrolyte leakage percentage (LT50el) were determined. After 21 days survival percentage was measured in the greenhouse. Results and discussion Electrolyte leakage percentage decreased in four ecotypes of garlic in the second compared to the first planting, but the greatest reduction (11.3%) was observed in the Khaf ecotype, while this reduction was 1.1% in the Torbat-Heydariye. In both planting dates electrolyte leakage was roughly stable until -15 degree ºC and it was increased at lower temperatures but increasing in the first was more than the second planting, So that by reducing the temperature from -15 °C to -21 °C electrolyte leakage increased in first and second planting by about 34 and 24 percent, respectively. Also, lethal temperature 50% of plants according to the electrolyte leakage percentage in the second planting date was about 1° C lower than the first planting. At the time of freezing stress, most plants were planted in September were at four-leaf stage and the plants were cultivated in October at the two-leaf stage and although the first planting plants were more time under normal conditions and thus acclimation, But electrolyte leakage was more in them. This case may be due to more food reserve in second planting plants. In the both planting date in the Bojnurd and Torbat-Heydariye ecotypes electrolyte leakage percentage was stable until -15oC and then increased with decreasing of temperatue, While in Neyshabur and Khaf ecotypes in the first planting the temperature reduction from –6 and -12 oC was increased electrolyte leakage. However, in the last two ecotypes (Khaf and Neyshabur) in the second planting date electrolyte leakage was relatively stable up to temperatures of -15 oC and at lower temperatures electrolyte leakage increased. It seems that more plant growth and development toward the higher growth leads to less tolerance in the first planting of plants. Lower values of lethal temperature 50% are indicating greater tolerance to cold and amount of this index was lower in October planting, so it can be said that early planting garlic (28 September) is likely leads to increase plant sensitivity to cold. There was high and negative correlation between electrolyte leakage% and survival percentage (r=-0.70*) in this survey. In other words, by increasing the survival percentage electrolyte leakage decreased. Conclusion In the first planting electrolyte leakage from Khaf and Neyshabur ecotypes increased with exposure to temperatures of -6 and -9 ° C, while in two other ecotypes this situation stared from -15° C temperature. While the in second planting in four ecotypes began the process of temperature -15 ° C. Different reactions of ecotypes to freezing stress, especially in the first planting is probably due to genetic characteristics geographical origin. Also, growth stage of plants were effective in the cold tolerance of them, So that Khaf and Neyshabur ecotypes in lower growth stages (second planting plants) compared to the advanced growth stages showed more freezing tolerance and it seems that the two listed ecotypes in the later planting have freezing tolerance more than the first planting. Torbat- Heydariye and Bojnurd ecotypes had more membrane stability and they showed better reaction in both fall planting under cold stress, despite the continuation of these studies under controlled and field conditions will provide more information about cold tolerance mechanism of this plant in real winter conditions.
H. Besharati; S. Memar Kouche-Bagh
Abstract
Introduction Nitrogen is one of the macronutrients which alfalfa required, Upon the formation of nodules on the roots, the plant obtains a large part of its required nitrogen from the air. The rate of nitrogen fixation in alfalfa is estimated about 60 to 500 kg ha-1 per year. Symbiosis between Rhizobia ...
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Introduction Nitrogen is one of the macronutrients which alfalfa required, Upon the formation of nodules on the roots, the plant obtains a large part of its required nitrogen from the air. The rate of nitrogen fixation in alfalfa is estimated about 60 to 500 kg ha-1 per year. Symbiosis between Rhizobia and legume plants begins by exchanging molecular signals between bacteria and plant root. Plant varieties, bacterial strains, soil conditions (heavy metals, temperature, water, aeration, nutrients, salinity, nitrate, pH etc.) are factors which affect the symbiosis. Lead is one of heavy metal, pollutes environment specially agricultural lands. Biological nitrogen fixation is sensitive to low concentrations of heavy metals in soil. Also the high sensitivity of the nitrogen fixation process to heavy metals, in soils contaminated with sewage sludge have been reported. Exploitation of Lead and zinc and related operation in Zanjan province released heavy metals including lead in surrounding agricultural land, So that the agricultural land where located in the vicinity of lead and zinc processing factory, are contaminated with heavy metals The aim of this study was to examine the effects of lead contamination on alfalfa symbiotic Rhizobium indigenous to Zanjan province, and nitrogen fixation in alfalfa plants. Materials and methods To isolate rhizobium native to heavy metals polluted soils, nodules bearing roots were collected from alfalfa farms of Zanjan province which located near Pb and Zn factories where soils were contaminated by heavy metals, then rhizobium bacteria were isolated. Resistance of isolates to Pb were examined using selective medium containing different concentration of Pb. To assess the relative resistance of strains to lead H.M medium was used. Different concentrations of lead (0, 25, 50 and 100 mg L-1) was added to the mentioned media as CdCl2. Considered isolates were cultured on media containing various concentration of lead as point spots. Five days after incubation at 25 ° C plates wereinspected, and based on the growth and Status and consistency of colonies compared to the control, isolates were grouped as resistant (growth as control), moderately susceptible (reduced growth as compared to control) and sensitive (no growth). For each isolates was determined as the maximum resistance level (MRL). To evaluate the ability of isolates to fixing N2 in Pb polluted soil, 5 isolates were selected based on their resistance to Pb as well symbiotic effectiveness, and then were used in green house experiment. Treatments were five sinorhizobium isolates (N6, N12، N17، N41andN51) as inoculants, and five concentrations of Pb(0, 5, 25, 50, 100 mg Pb per kg) were examined on growth of alfalfa plant. Alfalfa seed after surface sterilization (1% sodium hypochlorite solution), were germinated in incubator, and then were planted in pots. Each seed was inoculated with a milliliter of a suspension which contain selected isolates (107 cfu ml-1). 90 days after planting, plants were harvested and shoot dry weight was determined. The root nodules were evaluated and classified as described by Vincent (1982). The shoot nitrogen content was measured by Kjeltec method and the absorbed nitrogen in shoot. Results and discussion All of tested bacterial isolates could create nodules on alfalfa root systems. To evaluate the isolates resistance to lead contamination, they were cultured in media containing different concentration of lead, and then based on the growth of isolates compared with control, their resistance were evaluated. The results showed that, a few of them survived at the maximum applied concentration of lead (500 mg Pb L-1) and grew. MRL index (The maximum lead concentration where the isolates had visible growth), determined for each of isolates, then the percentage of isolates that had visible growth at different concentrations of Pb, were calculated . The Comparison interaction between isolates and lead level on shoot N concentration showed that by increasing the lead levels, in case of all inoculated isolates, decreased shoot N concentration and this reduction was significant in most cases.The highest shoot N concentration (3.3%) belonged to control (0 mg Pb kg-1 and 70 mg N treatments) and the lowest N concentration (2.4%) belonged to the 100 mg Pb kg-1 and inoculation with N6 isolate). Means comparison showed that by increasing lead levels, reduced plant dry weight, but this reduction was different in different strains, The highest shoot dry weight (0.81 g pot-1) belonged to inoculated plants with N51 strain at the level of 25 mg Pb kg-1,while the lowest (0.15 g pot-1) was observed in non-inoculated control at 100 mg Pb kg-1. Conclusion The tolerance of symbiotic microorganisms against environmental stresses is more than their host plants. Toxicity that comes from high concentrations of heavy metals in soil, inhibites root growth and development, as well disorderes early stages of legume- Rhizobium symbiosis and affects biochemical signals between them. Totally, 6.7% of isolates, including were very tolerant to lead, and their growth in media containing the highest lead, did not show any difference with control. While, some isolates were not able to grow on media containing more than 75 mg Pb L-1. About 64% of isolates tolerated concentrations of 25 to 150 mg per liter of lead. About 30% of the isolates survived in media containind up to 300 mg Pb L-1 , that is a good tolerance to lead contamination. Generally application of different levels of lead decreased shoot N content of plants, but reducing the N in inoculated plants were less than the control and nitrogen treatment. Although the tolerance of alfalfa against stresses is low compared to symbiotic bacteria, however, inoculation host plants with right rhizobia somewhat can be reduced the injury of heavy metals.
Y. Ahmadi-Khandangholi; Gh.A. Akbari; A. Izadi Darbandi; I. Alah Dadi
Abstract
To evaluate the effects of drought stress on the changes of yield and other traits of different ecotypes of fennel, a field experiment was conducted which was organized in split plots in the form of completely randomized blocks. The main treatment was irrigation with three levels of 80, 140, and 180 ...
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To evaluate the effects of drought stress on the changes of yield and other traits of different ecotypes of fennel, a field experiment was conducted which was organized in split plots in the form of completely randomized blocks. The main treatment was irrigation with three levels of 80, 140, and 180 ml of evaporation from the A-class evaporation pan which represented normal irrigation, mild drought stress, and severe drought stress, respectively. The constant factor was comprised of 51 ecotypes of fennel. Results showed that a mild drought stress can enhance essential oil content in seeds. The experiment also demonstrated that different levels of irrigation had significant impacts on total dry weight of aerial parts of the plant (in the five percent statistical level). The impact was also significant on total yield of seed, weight of 1000 seeds and essential oil content (in the one percent statistical level). Mean comparison results revealed that the highest seed yield belonged to the treatment group with the normal irrigation level. Means comparison results also showed that the highest seed yield belonged to the Alamout ecotype whereas the least seed yield belonged to the Tafresh and Yazd ecotypes. The comparison of means with regard to the effect of irrigation levels on essential oil content showed that the highest essential oil content was achieved at the mild stress treatment. The interdependent effects of irrigation levels on ecotypes had a significant impact on the total dry weight of the aerial parts of the plant based on the 5% significance level. However, the interdependent impact on the amount of essential oil was significant at 1% significance level. Mean comparison regarding the interdependent effects showed that the highest essential oil content was achieved in the Meshkin-shahr ecotype while treated with mild drought stress.
Volume 10, Issue 1 , April 2017, Pages 183-183
