Ali Soleymani
Abstract
Introduction Drought is the main cause of wheat yield loss. This fact accompanied with the increased water demand raises the essential question that how the increasing agricultural production can be maintained along with sustained utilization of water resources (Dugan and Flower, 2006). A technique for ...
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Introduction Drought is the main cause of wheat yield loss. This fact accompanied with the increased water demand raises the essential question that how the increasing agricultural production can be maintained along with sustained utilization of water resources (Dugan and Flower, 2006). A technique for efficient management of irrigation water is to use new models for determining water demand and scheduling irrigation along with decreasing the susceptibility of wheat to water deficiency and improving their tolerance to drought by breeding. Accordingly, modified Hargraves-Samani equation is more precise than FAO equation for arid and semi-arid regions of Iran (Hargraves and Samani, 1985). Furthermore, given the global validity of Hargraves-Samani model among other models, it can evaluate ET0 more precisely in arid and semi-arid regions. Najafi and Tabatabaei (2004) used the following modified Hargraves-Samani equation in ET-HS model for evaluating evapotranspiration. The objectives of the current study were to determine sound management of water use during sensitive growth stages of wheat and to minimize water use per wheat grain yield and dry matter production. Materials and methods In order to evaluate ET-HS model in determining wheat crop water demand in Isfahan, an experiment was conducted at research field of Department of Agriculture, Khorasgan Branch, Islamic Azad University, Isfahan, Iran in 2012. The study was based on a Randomized Complete Block Design with three replications and six treatments. The irrigation treatments included irrigation to supply 50, 75, 100, 125 and 150% of crop water demand on the basis of ET-HS model during growing season and control (conventional irrigation) which was irrigation on the basis of 70 mm evaporation from Class A evaporation pan during growing season. The parameters of ET-HS model used in the current study included altitude from sea level, latitude, actual sunny hours and mean wind speed. The coefficients of the equation of the model were determined and it was calibrated for Khatounabad Region of Isfahan. Accordingly, modified Hargraves-Samani equation is more precise than FAO equation for arid and semi-arid regions of Iran (Hargraves and Samani, 1985). Furthermore, given the global validity of Hargraves-Samani model among other models, it can evaluate ET0 more precisely in arid and semi-arid regions. Najafi and Tabatabaei (2004) used the following modified Hargraves-Samani equation in ET-HS model for evaluating evapotranspiration: ET(ij)= α j (T max j – T min j) [(T max j + T min j)/2 + 17.8] where, ET is crop evapotranspiration, α is calibration coefficient (which depends on regional climate and soil conditions) and Tmax and Tmin are daily maximum and minimum temperature. After calibration for a certain region, ET-HS model needs a few simple climatic variables, i.e. minimum and maximum daily temperatures, which are readilyavailable to farmers. In addition, in their studies on tomato and eggplant, Najafi and Tabatabaei (2007) concluded that ET-HS model is quite useful for estimating water demand and for scheduling irrigation. Since sound determination of wheat water demand is very important in planning irrigation management, wheat vapotranspiration models need to be evaluated and if water use is accurately managed, especially during sensitive growth stages, WUE will be improved. The data were statistically analyzed by software MSTAT-C and the means were compared by Duncan test at 5% probability level. Results and discussion The results showed that irrigation treatment had significant effects on, number of spikes, number of seeds in spike, thousand seed weight, grain yield, biological yield, harvest index, water used, water use efficiency based on total dry matter and grain yield. The highest number of spikes, number of seeds in spike, thousand seed weight, grain yield and biological yield was produced by plants irrigated to supply 100% of their water demand. As the water demand percentage were increased, these characteristic. Control treatment did not show significant difference with the treatments of irrigation to supply 100% of crop water demand. Treatments of irrigation to supply 50 and 75% of crop water demand which had the lowest number of spikes, number of seeds in spike, thousand seed weight, grain yield, biological yield did not show significant difference with each other. Therefore, low-irrigation (water stress) resulted in significant loss of these characteristic in both treatments. This response has been confirmed by Liu et al., (2016) .The highest WUE for total dry matter and grain yield were obtained from the treatment of irrigation to supply 50% of crop water demand. It exhibited statistically significant difference with all treatments except control. As the amount of irrigation water was increased, WUE for grain yield significantly decreased. It shows that the increase in grain yield was not able to compensate in increase in the amount of applied water. The lowest WUE for total dry matter and grain yield were obtained from the treatment of irrigation to supply 150% of crop water demand. Conclusions On the basis of ANOVA results, irrigation treatment had significant effects on all measured treatments. The highest the number of fertile spike, the number of grain in the spike and 1000 grain weight which was lead to production of the functional rate of seeds and harvest index in comparison with irrigation treatments. Therefore in similar condition with this study, the most suitable irrigation treatment according to the ET-HS model during the growth season is 100% treatment of water requirement.
Ali Azari Nasrabad; S. Mohsen Mousavi Nik; Mohammad Galavi; Alireza Siroosmehr; S. Ali Reza Beheshti
Abstract
Introduction Crop yield, including sorghum, is limited under drought conditions, as one of the most important abiotic stresses. Although sorghum can be able to deal with a lot of stress like heat, drought and salinity, but in arid and semiarid areas is usually affected by water stress in the reproductive ...
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Introduction Crop yield, including sorghum, is limited under drought conditions, as one of the most important abiotic stresses. Although sorghum can be able to deal with a lot of stress like heat, drought and salinity, but in arid and semiarid areas is usually affected by water stress in the reproductive stage and after the flowering and its yield is reduced. There are significant differences between sorghum genotypes about tolerant to periods of drought stress and reactions to these periods. Some researchers emphasize on the characteristics of flag leaf water relations, especially because of its remarkable interaction with resistance to drought stress. Morphophysiological traits including leaf relative water content widely were used as selection parameter in addition to grain yield for drought tolerance in various crops. In this study, some traits such as cell membrane stability and relative water content and the response of yield and yield components of sorghum genotypes under drought stress treatments (irrigation cut off at vegetative and reproductive growth stage and normal irrigation) were evaluated in field conditions. Materials and methods In order to evaluate the effect of water stress on grain yield and its components, cell membrane stability and relative water content of leaf (RWC) in sorghum (Sorghum bicolor L.), a field experiment as a split plot design was carried out with 3 replications in 2014 at the research farm of the southern khorassan Agriculture and natural resources research and education center. Water stress treatments including normal irrigation (control), irrigation cut off in vegetative growth stage(emergence of terminal leaf as rolled) and irrigation cut off in generative growth stage(50% of plants in start of flowering) as the main plot and 10 genotypes of sorghum including KGS29, MGS2, Sepideh, KGFS27, MGS5, KGFS5, KGFS17, KGF13 and KGFS30 was considered as sub plots. To determine the yield components, half a meter in length of each plot was harvested and the number of plants, number of panicle, grain weight, and number of seeds per panicle were recorded. To determine the yield and biological yield and harvest index after the removal of 2 and a half meter of margin line and beginning and end of each plot, plants was harvested from the surface of 3 square meters, after drying, biological yield of each plot was determined. To calculate the relative water content (RWC), flag leaf samples were taken from each plot and the samples were weighed immediately and then refrigerated for 24 hours in distilled water untill their full swelling, then the excess water was taken by tissue paper and then put into the oven at 72 ° C for 48 hours. After drying, the samples are weighed and leaf relative water content was calculated through wetherley formula (wetherley). To calculate the amount of damage to the membrane or membrane permeability, three plants of each plot were randomly selected and their flag leaf were removed. Then 4 discs of the leaves prepared was puted in distilled water for 24 hours at refrigerator temperature (4 ° C). Electrical conductivity of water in wich leaves had been laid was measured by the electrical conductivity meter (EC meter) and resulting values were used for calculations. After collecting data on yield and its components, simple analysis of variance was done using SAS software. The means comparison was done using LSD test at the 5% probability level. Results and discussion Results showed that water stress had significantly effect on grain yield, biological yield, harvest index, 1000 seed weight and seed number per panicle, cell membrane permeability and Relative water content of leaf and caused to decrement of Them. The grain yield reduction was about 42% at the highest level of water stress in comparison with the control. Also the genotypes were significantly different about all above characteristics. The genotype KGFS13 had the highest grain yield, biological yield and harvest index. Interaction between water stress and genotype showed significant effect on all traits except for 1000 seed weight and cell membrane permeability. The highest value for (RWC) was belonging to severe water stress. Also with increase of water stress, cell membrane leakage increased, as the lowest value of cell membrane leakage and therefore the highest membrane stability was belong to normal irrigation and the lowest membrane stability was commonly belong to medium and severe water stress. Conclusion There are significant differences between sorghum genotypes about tolerant to periods of drought stress and reactions to these periods, also grain yield and its components, biological yield, harvest index, relative water content and cell membrane stability were different between genotypes and water stress treatments. Generally, water relations in flag leaf and cell membrane permeability can be used as criteria for assessment of drought tolerance as well as grain yield.
Nezam Armand; Hamzeh Amiri; Ahmad Ismaili
Abstract
Introduction Beans in many developing countries as an important source of protein for numerous plants. Bean cultivation in Iran is about 240 thousand hectares with an average yield of 150 kg/he. Germination is an important stage in the life cycle of the plant and can have a significant impact on production ...
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Introduction Beans in many developing countries as an important source of protein for numerous plants. Bean cultivation in Iran is about 240 thousand hectares with an average yield of 150 kg/he. Germination is an important stage in the life cycle of the plant and can have a significant impact on production and yield. Quality of seed germination has a significant impact on plant growth traits. It is reported that germination of legumes such as beans directly affected by unfavorable environmental conditions such as drought and salinity are located. In several studies, the use of methanol as a carbon source for growth and crop yield under drought stress conditions is recommended. Methanol external application directly with the metabolic processes of plant growth and development, as well as the processes associated with defense mechanisms such as the activation of genes involved in the biosynthesis of jasmonic acid is linked. Some studies have shown that intake of methanol can improve the efficiency of nutrient uptake, especially in the face of growing environmental stress. Given that, there are numerous reports in connection with a positive impact on the vegetative phase methanol plant in Iran; however, few studies exist on the effects of methanol on germination indices. The aim of this study was to investigate the effects of methanol on indices of bean seed germination under drought stress. Materials and methods To investigate the effects of methanol and drought stress caused by PEG 6000 on germination indicators beans (cv. COS16) experiment factorial basis of completely randomized design in the summer at the Khatam Alanbia University of Technology. Parameters studied include different levels of ethanol contains: control (0), 10, 20 and 30 percent by volume and drought stress caused by PEG 6000 (0, -3 and -6 Bar). Drought stress using PEG 6000 at 25 ° C and the equation was applied Michael and Kaufman. Visiting of the samples once daily for 14 days and the number of germinated seeds were recorded at each visit. On the final day of testing, root and shoot were separated from the seeds and the germination indices such as germination percent, germination speed, radicle length, plumule length, radicle dry weight, plumule dry weight and endosperm consumption were measured. Results and discussion Analysis of variance showed a significant effect of drought stress and the use of methanol on germination percent, germination speed, radicle length, plumule length, radicle dry weight, plumule dry weight and endosperm consumption. The results showed that the interaction effects at all levels of drought stress, levels of 20 and 30 percent methanol lead to a significant reduction in germination indices bean. Drought stress at -6 bar, leading to a significant decrease in germination percentage, germination speed, radicle length, plumule length, radicle dry weight, plumule dry weight and endosperm consumption in comparison with treatment without water stress. In general, the results of this study showed that the use of methanol at germination stage was not involved not only in reducing the negative impacts of drought stress, but also non-drought stress conditions, the germination of beans had negative effects. Conclusion In this study, the results showed that aqueous solution of methanol under water stress treatments (0, -3 and -6 bar) leads to a significant reduction in all parameters evaluated in bean plants. According to research showing that methanol, seedling stage and flowering plants increased the productivity and yield. In this study, it was found that an aqueous solution of methanol in addition to no role in reducing the negative impacts of drought stress on germination of beans, but also leads to germination indices were lower.
Farzaneh Golestani Far; Sohrab Mahmoodi; Gholam Reza Zamani; Mohammad Hasan Sayyari Zahan
Abstract
Introduction In terms of production and area under cultivation, wheat is the most important crop in Iran. Weeds problem is possibly the mostserious agricultural problems in the wheat growing regions of the world (Kafi et al., 2005). Rye as an annual plant with long stems is frequently seen as weed in ...
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Introduction In terms of production and area under cultivation, wheat is the most important crop in Iran. Weeds problem is possibly the mostserious agricultural problems in the wheat growing regions of the world (Kafi et al., 2005). Rye as an annual plant with long stems is frequently seen as weed in wheat fields around our country (Krimi, 2004). Low environmental demands and allelopathic ability of rye accompanied with similar morphology and life cycle to wheat has increased its stability and occupied area in winter wheat fields (Pester et al., 2000). Competition is one of key issues in ecophysiological debates of plant communities. In competition as a type of Interference, weeds compete for light, water and nutrient resources with neighbor crops and thereby affect growth, development and yield of them (Evans et al., 2003). Considering the severe restriction of water resources in most regions of our country, drought stress is the most important stress, affecting crops (Kafi et al., 2009). Both resource availability and environmental conditions affect the result of a competition. Weed competition for water decreases soil water content which could finally causes water stress and reduces weed growth and crop yield. There are few studies about mechanisms of competition for water. Most of these studies have been implemented under controlled conditions. Nevertheless, these studies have led to an insight intothese possible mechanisms of competition for water (Zand et al., 2004). Materials and methods In order to study the effect of inter and intra-species competition on morphological and growth characteristics of wheat (Triticum aesativum L.)and rye (Secale cereale L.)under drought stress conditions, a pot experiment was conducted in the greenhouse of college of Agriculture at University of Birjand in 2012. The experiment had factorial arrangement based on completely randomized design with three replications. The factors were wheat density (0, 8, 16, 24 plants/pot), rye density (0, 2, 4, 6 plants/pot) and drought stress (irrigation at 20 and 60% moisture depletion of field capacity). Number of leaves and their SPAD index in wheat and rye were measured at the time of spikes emergence of wheat, while plant height, peduncle and cluster length and stem diameter of wheat were measured at 95 days after planting (the end of the growing period). Results and Discussion Results showed when density of wheat and rye increased, height (maximum of 23.51% and 13.39% in wheat and 24.45% and 6.56% in rye respectively), leaf numbers (35.80% and 30.73% in wheat and 71.37% and 31.71% in rye respectively) and SPAD (12% and 11.38% in wheat and 13.75% and 0.38% in rye respectively) were significantly decreased. Drought stress also significantly decreased the height and leaf number of wheat (17.58% and 8.48% respectively) and rye (7.64% and 26.75% respectively) and significantly increased the SPAD index of wheat and rye (20% and 7.78%, respectively). Increasing of drought stress however had not effect on cluster length, significantly decreased the peduncle length (26.03%) and stem diameter (3.49%). When the rye and wheat density increased, length of wheat cluster (maximum of 13.70% and 24.21% respectively), length of wheat peduncle (maximum of 17.39% and 22.72% respectively) and wheat stem diameter (maximum of 11.11% and 18% respectively). Conclusions Result totally showed that in drought stress conditions, intra specific competition had just significantly affected on SPAD index, but inter specific completion had significantly affected on both SPAD index and leaf number of wheat and height and leaf number of rye. Simultaneous presence of drought stress and plant competition resulted in severe reduction of these traits with a further reduction in wheat compared to rye. Accordingly, in the wheat fields where rye is considered as an important weed, the damage of this weed is even higher when drought stress occurs and therefore, controlling this weed in water limited conditions is of major importance.
Alireza Beheshti
Abstract
Introduction One of the most important and widespread environmental stresses is drought which has made limitation in agricultural productions. Many researches were done about drought stress. Plant improvement for drought tolerance is very complicated and difficult due to unpredictable environmental conditions ...
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Introduction One of the most important and widespread environmental stresses is drought which has made limitation in agricultural productions. Many researches were done about drought stress. Plant improvement for drought tolerance is very complicated and difficult due to unpredictable environmental conditions and variability of cultivars responses in different degrees of drought stress. Alfalfa production on regions by alternative interval drought conditions is very important because of its adaptability and having tolerant germplasm. Alfalfa with specific morphological characteristics and adaptability of these traits to environmental stress especially drought conditions caused high production potential in these regions. Main parts of cold and even temperate regions of Iran cultivated unimproved populations or local ecotypes of Hamedani alfalfa. Material and methods In this study alfalfa ecotypes seeds were obtained from these regions. This study was done to evaluate drought tolerance in 11 Hamedani alfalfa ecotypes through tolerance indices in the growing season 2011-2012 using randomized complete block design with three replications in two separate farm experiments at Torogh Research Station. The first experiment was complete irrigation (non-water deficit) once in a week as usual. Second experiment was drought conditions by changing in irrigation interval and making water deficit in ecotypes through 10 and 14-day irrigation intervals alternatively among growing season. The tolerance indices STI, SSI, GMP and MP evaluated by using of alfalfa ecotypes’ dry matter in both stressed and non-stressed conditions. Ecotypes distribution was drown on three dimensional graph based on these indices. Results and discussion The positive and significant correlation between dried forage yield and MP, GMP and STI indices in both stressed and non-stressed conditions showed that these mentioned indices were the best indices. Chaleshtar and Famenin alfalfa ecotypes had the most potential of dried forage yield in both stressed and non-stressed conditions and had the first and second STI ranking respectively. STI index in comparison with the other indices was the better estimator for genotypes yield in both YP and YS conditions because it can separate A type genotypes from the other types. STI results revealed that Ghahavand, Chaleshtar,Sedighan and Famenin ecotypes were the most tolerant and Gharghologh and Hamedani were the most sensitive ecotypes. A genotype with higher STI is an indicator for higher yield potential in both conditions. Famenin and Chaleshtar alfalfa ecotypes had the higher MP with 8.8 and 8.7 and Gharghologh had the lower with 7.6. High TOL was an indicator for ecotype stress sensitivity and lower TOL lead to select the drought stress tolerate genotypes. Ordobad ecotype with 3.5 and Malek kandi with 0.9 TOL had the least and most index tolerance respectively.SSI indices Ordobad and Malek kandi caused the most drought sensitive and drought tolerate genotypes respectively. The results showed that between the studied genotypes, Ordobad with 1.9 SSI and Malek kandi with 0.5 SSI were the the most sensitive and tolerate genotypes respectively. Although Malek kandi with low SSI is relatively drought tolerate ecotype but its low yield prevent to select this ecotype. Chaleshtar and Famenin alfalfa ecotypes had the greatest dry matter yield potential in both condition and were the most tolerant ecotypes in this study. Classification of ecotypes in both stressed and non-stressed conditions showed that they allocated in four separated groups depending on yield in normal and stress environmental conditions.
Soghra Khoramipour; Masoud Dehdari
Abstract
Introduction Salinity stress has second rank on crop yield limitation after drought stress in the world. Sorghum is very sensitive to salinity in the vegetative and early reproductive stages متن یا آدرس وب سایتی را تایپ کنید یا سندی را ترجمه کنید. لغو ترجمه ...
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Introduction Salinity stress has second rank on crop yield limitation after drought stress in the world. Sorghum is very sensitive to salinity in the vegetative and early reproductive stages متن یا آدرس وب سایتی را تایپ کنید یا سندی را ترجمه کنید. لغو ترجمه از: فارسی but, it has minimum sensitive to salt stress at flowering and grain filling stages. Identification of molecular markers linked to genes controlling key traits that associated with salinity stress tolerance is an important breeding goal programs in the marker assisted selection. Therefore, to study the salt tolerance of 10 genotypes of sorghum and its relationship with microsatellite markers this research was designed. Materials and methods Two separate experiments were conducted at the Agricultural College of Yasouj University in 2013. In the first experiment salinity tolerance of ten grain sorghum (Sorghum bicolor L.) genotypes at four salinity levels, including 1.92, 5, 10 and 20 dSm-1 (By addition of NaCl in Hoagland solution) at seedling stage as factorial experiment based on randomized completely design with three replications were investigated. In the two-leaf stage salt stress treatments were applied gradually. 20 days after the salt stress application the important morphological and physiological characteristics were measured and subjected to statistical analyzes. In the second experiment, DNA was extracted from leaf of above mentioned varieties and PCR was performed using 10 SSR primer pairs. The obtained electrophoresis profiles were scored as zero (no band) and one (present band). Association between markers and some important traits were investigated using binary logistic regression. Results and discussion The results of the analysis of variances in the first experiment revealed that the effect of genotype, salt treatment and their interaction were significant (p≤0. 01) for all the recorded traits. Leaf proline content had the highest genotypic coefficients of variation in moderate saline (52.10%) and non-saline (41.6%) conditions. The highest (95.24%) and lowest (21.15%) broad sense heritability were estimated for leaf area and Mg2+ content, respectively. Based on stress intensity values, Na+/K+ ratio (SI=0.96) most affected by salinity (EC=10 dSm-1) treatment. Based on genotype classification using the 3-dimensional plot of STI, YS and YP, Sor834, Sor1011, Sor1006 and Sor857 were identified as suitable genotypes in both salt stress and non-stress conditions. In general, by conceding all aspects Sor834 and MTS showed the most tolerance and susceptible genotypes to salinity, respectively. The results of second experiment showed a possible association between some markers and some measured traits. Four SSR markers including Xtxp20, Xtxp354, Xtxp331 and Xtxp285were linked to salt stress tolerance index (STI). Conclusions In general, the results of the first experiment proved genetic diversity of salt tolerance of sorghum at seedling stage. The high heritability of some traits indicated the low role of environment in their control which is accordance to high selection effieciency. Na+/K+ ratio can be used as selection criteria for salinity tolerance of sorghum at seedling growing stage. The above introduced markers may be used into molecular tools for improved of salt tolerance of sorghum in breeding programs.
Seyed Abdolreza Kazemeini; Mojdgan Alinia; Ehsan Shakeri
Abstract
Introduction Salinity stress is one of the most important environmental stresses in arid and semi-arid regions of the world (Pandolfi et al., 2012) .It is reported that, salinity stress by decreasing dry weight and K concentration could be reduce growth and yield of different crops. Generally, salt stress ...
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Introduction Salinity stress is one of the most important environmental stresses in arid and semi-arid regions of the world (Pandolfi et al., 2012) .It is reported that, salinity stress by decreasing dry weight and K concentration could be reduce growth and yield of different crops. Generally, salt stress causes a number of changes in plant metabolism. Of them, ion toxicity, osmotic stress and production of reactive oxygen species (ROS)such as singlet oxygen (O2), superoxide radical (O–2), hydrogen peroxide (H2O2), and hydroxyl radical (OH–) are the most prominent responses in plant tissues. The generation of ROS could be limited or scavenged by antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) (Apel et al., 2004). Blue panic grass (Panicum antidotale Retz.) is distributed through out the Indo-Pakistan region. It is found growing in a variety of soils and climatic conditions with a predominant distribution in arid and semi-arid regions. Blue panic is a highly productive grass with considerable nutritional value that can produce 150–180 tons of fresh biomass per hectare per year with 15-18% protein content (Sarwar et al., 2006). Some studies indicated that decrease of photosynthesis is the main damage of salinity stress that its result is reducing the dry matter production (Netondo et al., 2004).Grattan et al (1999) reported that application of nitrogen fertilizer improved growth and/or yield of different cops in stress conditions.Some studies also indicated that corn (Aalipour et al., 2011) and sorghum (Esmaili et al., 2008) dry matter decreased by increasing salinity but,using nitrogen fertilizer could reduce the negative effect of salinity stress. In most of these studies, the fact that applied nitrogen improves the growth under extreme saline conditions suggests that applied nitrogen increased plant salt tolerance.On the other hand, in comparison to higher levels of nitrogen application, salinity stress in lower levels of nitrogen application, had higher detrimental effect on decrease of dry and fresh weights (Grattan et al., 1999).This study aimed at finding out what amount of nitrogen fertilizer must be applied in saline soils and, furthermore, its main objective was to investigate the interactive effects of salinity and nitrogen fertilizer on growth and antioxidant activity of blue panicgrass. Materials and Methods This experiment was conducted at green house of College of Agriculture, Shiraz University, in 2014. The experiment was carried out in factorial arrangement based on completely randomized design with four replicates. Treatments included nitrogen at four levels (0, 10, 20 and 30 mg kg-1 soil) and three levels of salinity (0.4, 9 and 18 dS m-1). Studied features were included plant height, leaf area, root and shoot dry weight, root and shoot fresh weight at flowering stage, as well asthe activity of antioxidant enzymes (SOD, POD and CAT), proline and Sodium/potassium ratios in stem and root were measured. Analysis of variance of the data was carried out using SAS (2002) software. LSD test was applied to compare means of each trait at 5% probability level. Excel (2010) software was used to draw figures. Results and Discussion Results showed that effect of nitrogen, salinity and their interaction were significant on all traits (except for leaf fresh weight, leaf dry weight and leaf number). Salinity stress decreased stem fresh weight, leaf fresh weight, root fresh weight, plant height, leaf area and root/stem dry weight ratio. In comparison with control treatment, the activity of antioxidant enzymes (SOD, POD and CAT) and proline increased 13.78, 6.17, 7.44 and 26 times in high levels of salinity (18dSm-1) and nitrogen (30 mg kg-1), respectively. Sodium/potassium ratio in stem and root were significantly decreased under nitrogen treatment.Generally, 20 mg/kg nitrogen could reduce the negative effects of salinity stress but, application of 30 mg/kg nitrogen significantly decreased all traits under salinity levels.The results also indicated that, soil salinity reduced K uptake and increased Na concentrations in plant tissues,as a result,stem fresh weight, leaf fresh weight, root fresh weight, plant height, leaf area and root/stem dry weight ratio were decreased. Conclusion In general, the obtained results indicated that in high salinity levels, application of nitrogen fertilizer in dose of higher than 20 mg/kg may cause more salinity and osmotic pressure, as well as may decrease water and nutrients uptake and plant growth. In other words, under low salinity level, nutrients deficiency can be the main limitation factor for plant growth.
Ali Reza Pazoki; Elham Niki Esfahlan
Abstract
Introduction Summer savory (Satureja hortensis L.) is a genus of aromatic plants of the family Lamiaceae. There are about 30 different species called savories, which summer savory and winter savory are the most important in cultivation. Satureja species are native to warm temperate regions and may be ...
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Introduction Summer savory (Satureja hortensis L.) is a genus of aromatic plants of the family Lamiaceae. There are about 30 different species called savories, which summer savory and winter savory are the most important in cultivation. Satureja species are native to warm temperate regions and may be annual or perennial (Hadian et al., 2008; Rechinger, 1982). Soil salinity is one of the main environmental stresses affecting the growth of plants and their yield (Allakhverdiev et al., 2000). Adaptation of plants to environmental stresses such as salinity performs by accumulation of metabolites as carbohydrates and proline (Sanito di Toppy and Gabbrielli, 1999). Ascorbic acid is a powerful antioxidant that leads to inhibition of the free radicals by reduction (Fecht Christoffers et al., 2003). Gibberellins are commercial mushroom cultures obtained from pure and natural product known that used in plants. There are four types of GA; the best known is gibberellic acid which has positive effect on metabolites related to salinity tolerance (Hedden and Proebsting, 1999). Material and methods Due to study the effect of salinity stress on some non-enzymatic mechanisms of savory under ascorbate and gibberellin application, a pot experiment was done in a greenhouse located in Pakdasht region and Islamic Azad University, Eslamshahr and Yadegar-e-Imam Khomeini (RAH) Shahre-rey Branchs in 2013. The experimental design consisted of a sixteen treatments, arranged as factorial based on completely randomized design with four replications, giving a total of 64 pots. Five-weeks old savory plants were sprayed with ascorbic acid (0 and 4 mM) and gibberellins (0 and 4 mM) before inducing salinity stress with different concentrations of saline water (0, 25, 50 and 75 millimolar). Control plants were sprayed with distilled water. Saline water was delivered to plants twice a week and last for three weeks. The proline by Bates et al (1973), Protein by Bradford (1976) and soluble and non soluble carbohydrates by Kochert (1978) were determined. The obtained data were subjected to analysis of variance using Duncan Multiple Range Test (P≤0.05) using SAS software. Results and discussion The results showed that, with the exception of ascorbate effect on shoot soluble carbohydrates, the other main effects of experimental factors were significant on all non-enzymatic mechanisms of savory tolerance. So the intense salinity showed the highest decreased in physiological traits such as shoot and root protein (304.93 mg/L and 147.71 mg/L) and shoot and root non soluble carbohydrates (11.27 and 8.25) and improved shoot and root proline (27.46 mg/L and 16.52 mg/L) and shoot and root soluble carbohydrates (18.49 mg/l and 16.32 mg/l) to decrease the harmful effects of salt stress. The results revealed that only triple interaction effects of experimental factors were significant on shoot soluble carbohydrates and shoot and root non soluble carbohydrates and protein. So, the shoot soluble carbohydrates and Shoot and root proline content has 8.23, 1.92 and 3.73 manifold increase than control in 75 mM NaCl and ascorbate and gibberellin foliar application alternatively. Therefore it can be concluded that shoot soluble carbohydrates is the most main non-enzymatic mechanisms of salt tolerance in savory especially in ascorbate and gibberellins foliar application. Some reports indicated that ascobate increased proline content in bean and pea (Alqrainy, 2007) and okra (Baghizadeh et al., 2009) that are coordinate to our findings. Hoda et al (2010) revealed that GA improved both Shoot and root soluble and non soluble carbohydrates as the best and rapid non-enzymatic mechanisms of stress tolerance in citrus. Conclusion The results showed that salinity stress increased shoot and root soluble carbohydrates and proline and reduced shoot and root non soluble carbohydrates and protein. At the same time, spraying 4 ascorbate and 2 mM GA affected all associated non-enzymatic traits to salt stress resistance, however the additive effect of GA was more than ascorbate.
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 Rezaei Tavallaei; Abbas Khashei Siuki; Mohammad Hasan Najafi Moud; Rasoul Mazloom Shahraki
Abstract
Germination is the first stage of plant growth, which is one of the important stages of the life cycle sensitive plants and is a key process in the emergence of seedlings. In this study, germination power plants under drought stress cotton plant, is studied. Treatments consisted of two drought levels ...
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Germination is the first stage of plant growth, which is one of the important stages of the life cycle sensitive plants and is a key process in the emergence of seedlings. In this study, germination power plants under drought stress cotton plant, is studied. Treatments consisted of two drought levels (100 and 50% of full irrigation) and four cotton cultivars (Khordad, Varamin, kc-8801 and kc-8802) with 3 replications. Seeds of the stress of research in the field of Kashmar research on irrigation was performed on the four varieties of cotton, is provided. Studies show that 50 percent of the irrigation component germination rate, germination and seed vigor levels 5 and 10% compared to full irrigation is significant. The amount of these components in different varieties, for example, what the biggest difference in the Khordad 2 - 0.8 and 1.2 - 1 is the lowest of Varamin. In general it can be concluded that drought improved germination of seed cotton is produced.Oblivuse of study results, drought stress effected on germination factors and stress was incresed germination rate, germination presentage and Seed vigor index. The result showed that seeds germination of drought stress treatment is more than full irrigation treatment. This important result is effected on precociuse cotton crop and increasing of amount of seed consumpsin.
Volume 9, Issue 3 , October 2016, Pages 314-314
