Drought stress
Layegh Moradi; Ebrahim Rohi; Farzad Hosseinpanahi; Adel Siosemardeh
Abstract
IntroductionWater deficit is one of the abiotic stresses that has many adverse effects on crop growth and yield. Understanding the mechanisms of the effect of drought stress on the plant plays an important role in managing different irrigation regimes to deal with adverse environmental conditions and ...
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IntroductionWater deficit is one of the abiotic stresses that has many adverse effects on crop growth and yield. Understanding the mechanisms of the effect of drought stress on the plant plays an important role in managing different irrigation regimes to deal with adverse environmental conditions and improve crop yield management. Quinoa as a nutritious crop has attracted particular attention in recent years. In arid and semi-arid conditions, quinoa can be successfully cultivated in marginal soils, indicating that quinoa is an unpredictable plant. Today, agriculture needs to increase production per unit area, despite the limited water resources. To achieve the best results from the cultivation of each crop, careful and calculated management is required. Irrigation intervals are one of the most critical strategies that can improve water use efficiency. Materials and methodsAn experiment was conducted to investigate the effect of irrigation intervals and amounts on the quinoa's physiological traits and yield at the University of Kurdistan research farm, located in Dehgolan plain. The experiment was arranged in a split-plot scheme based on randomized complete blocks design with three replications. Four irrigation intervals (4, 8, 12, and 16 days) were considered the main factor, and four irrigation levels (100%, 75%, 50%, and 25% of plant water requirement) were considered secondary factors. Giza1 cultivar, which was obtained from the Seed and Plant Improvement Institute, was used for cultivation. Relative water content, membrane stability index, chlorophyll a, chlorophyll b, total chlorophyll, carotenoid, carotenoid/total chlorophyll ratio, biological yield, grain yield, and harvest index were measured. Results and discussionThe relative water content of quinoa was decreased when the irrigation intervals increased. The highest decrease (13.87%) was observed in the irrigation interval once every 16 days compared to the control. The highest Relative water content was observed in the control treatment, while there were no significant differences between control and 75% water requirement treatments. The smallest (72.74%) and greatest (81.06%) membrane stability index were observed in 25% crop water requirement and control treatments. The highest chlorophyll a (10.68 mg.g-1 in dry weight), chlorophyll b (3.7 mg.g-1 in dry weight), and total chlorophyll (14.38 mg.g-1 in dry weight) content were observed in 100% crop water requirement with a 4-days interval, which was not significantly different from a 75% crop water requirement treatment with 4-days interval. The smallest (2.82 mg.g-1 in dry weight) and greatest (3.72 mg.g-1 in dry weight) carotenoid content were observed in 25% crop water requirement and control treatments. However, there were no significant differences between control and 75% crop water requirement treatment. Increasing the irrigation interval from 4 to 8 days reduced the biological yield and grain yield by 50.80% and 44.84%, respectively. The highest biological yield (4237 kg.ha-1) and grain yield (1602.6 kg.ha-1) were observed in the control treatment, which was not significantly different with 75% crop water requirement. The lowest (43.94%) and highest (50.78%) harvest index were obtained in the irrigation intervals of 4 and 16 days, respectively. Plants that were irrigated every 4 days at 25% of the plant water requirement had the highest water use efficiency (0.63 kg m-3). Among irrigation amount treatments, the highest harvest index was observed in 25% water requirement. Increasing the irrigation intervals increased the grain protein content so that the 16-days irrigation interval treatment had the highest protein content, although it was not significantly different from the 12-day irrigation interval. The lowest grain protein content was observed in the control treatment, which was not significantly different with a 75% crop water requirement treatment. Drought stress reduced the relative leaf water content, membrane stability index, chlorophyll content, leaf carotenoids, biological yield, harvest index, and quinoa seed yield. ConclusionThe results of the present study showed that despite the negative effects of drought stress on some physiological parameters, quinoa plant showed good relative resistance against water shortage, so that by providing just 25% of crop water requirements 812 kg.ha-1 could be achieved, which is considerable compared to many crops. Due to the fact that irrigation by 75% of plant water requirement did not reduce grain yield compared to control conditions, so this treatment can be used to irrigate the plant.
Drought stress
Ali Farhadi; Farzad Paknejad; Farid Golzardi; Mohammad Nabi Ilkaee; Fayaz Aghayari
Abstract
Introduction Lack of irrigation water resources has been identified as the most important problem in forage production. Therefore, to increase the productivity of crop production using limited water resources, it is necessary to pay attention to the cultivation of drought-tolerant crops. Sorghum has ...
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Introduction Lack of irrigation water resources has been identified as the most important problem in forage production. Therefore, to increase the productivity of crop production using limited water resources, it is necessary to pay attention to the cultivation of drought-tolerant crops. Sorghum has a high resistance to abiotic stresses and can perform well in comparison with other summer crops. Irrigation and fertilization are not only costly but also are of the most important factors affecting the quantity and quality of forage crops. Therefore, the present study was conducted to evaluate the effects of different levels of drought stress and nitrogen fertilizer on the sorghum forage yield and quality, and water use efficiency.Materials and methodsThis study was conducted as split-plots based on a randomized complete block design with three replications in Karaj, Iran, during the 2018 growing season. Drought stress at three levels (no-stress, moderate and severe stress; including the supply of 100, 75, and 50% soil moisture deficit, respectively) as the main factor and nitrogen fertilizer application from urea source at four levels (0, 150, 300, and 450 kg ha-1) as the sub-factor were evaluated. In all experimental treatments, nitrogen fertilizer was applied in two equal parts, at planting and 5-6 leaf stage. In the present study, drip tape irrigation approach was applied (with a diameter of 16 mm and drip distance of 10 cm). Irrigation cycle was considered constant for all plots and different levels of irrigation water were applied. In order to properly establish the sorghum crops, deficit irrigation regimes were started after 2-4 leaf stage. Sorghum forage was harvested at the milky-dough stage. Data were subjected to two-way analysis of variance (ANOVA) and the difference between treatment means was separated using LSD test. A significance level of 95% was applied by GLM procedure of SAS 9.1. Results and discussion The results of ANOVA showed that the main effect of drought stress and nitrogen fertilizer on the forage yield, irrigation water use efficiency (IWUE), plant height, and quality characteristics of sorghum forage (except hemicellulose) was significant (p≤0.01). Also, the interaction effect of drought stress × nitrogen fertilizer on the forage yield, IWUE, plant height, and crude protein content at the probability level of 1%, and on other quality characteristics of sorghum forage (except hemicellulose) at the probability level of 5% was significant. The highest dry-matter and protein yield (40.03 and 3.48 t ha-1, respectively) and the maximum plant height (224 cm) were obtained with full irrigation and application of 450 kg nitrogen ha-1, whereas the maximum IWUE for dry matter and protein production (6.793 and 0.672 kg m-3, respectively) was obtained under moderate stress and with the application of 450 kg nitrogen ha-1. By increasing the nitrogen fertilizer application from 0 to 450 kg ha-1 under full irrigation, moderate stress, and severe stress conditions, the dry matter yield increased by 167, 181 and 101%, respectively, protein yield increased by 238, 284 and 174%, respectively, forage protein content increased by 27, 36 and 39%, respectively, and relative feed value increased by 8, 6 and -2%, respectively. Overall, in order to achieve the maximum quantity and quality of forage and the highest water use efficiency in full irrigation and moderate drought stress conditions, application of 450 kg nitrogen ha-1, and in severe stress conditions, application of 300 kg nitrogen ha-1 can be recommended.Conclusion Generally, the results illustrated that the treatment of moderate drought stress (supply of 75% soil moisture deficit) with the application of 450 kg nitrogen ha-1, along with saving water and producing high forage yield, among the studied treatments resulted in the highest water use efficiency, DMD, NEL, and RFV, and the minimum ADF and NDF, can be recommended as the superior treatment for sorghum forage. In case of severe limitation of irrigation water resources, supply of 50% soil moisture deficit (severe drought stress) along with application of 300 kg nitrogen ha-1 can be recommended.
Drought stress
Atefeh Hashemabadi; Ali Nakhzari Moghaddam; Mehdi Zarei; Zeinab Avarseji
Abstract
IntroductionWheat is considered a strategic crop that provides food for half of the world's population. Therefore, increasing wheat yield per unit area seems necessary due to the limited area of cultivation. Nitrogen is an essential mineral element in plant tissues, which is necessary for plant growth ...
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IntroductionWheat is considered a strategic crop that provides food for half of the world's population. Therefore, increasing wheat yield per unit area seems necessary due to the limited area of cultivation. Nitrogen is an essential mineral element in plant tissues, which is necessary for plant growth and metabolic processes. In the lack of nitrogen, the plant is unable to complete a normal life cycle. Nitrogen deficiency in plants will lead to slow or stopping growth, chlorosis and necrotic spots. Basically, biofertilizers not only increase yield of the crops, rather, they affect the effectiveness of most chemical fertilizers. Also, the use of supplemental irrigation increases crop yield and improves water use efficiency. So, research on increasing wheat yield per unit area will be necessary. The purpose of this study was to evaluate the effect of supplementary irrigation, alkazot biofertilizer and nitrogen fertilizer on the qualitative and quantitative characteristics of wheat.Materials and methodsThis experiment was carried out as factorial based on randomized complete block design with three replications at the research farm of Gonbad Kavous University in growing season during 2016-2017. Alkazot biofertilizer in two levels of non-consumption and 100 kg ha-1 and into brush seed and nitrogen fertilizer in four levels of non-application and application of 50, 100 and 150 kg per hectare as first factor and supplemental irrigation in two levels (non-irrigation and irrigation in seed filling stage) as second factor. In this study, the Gonbad cultivar of wheat was used. Planting and harvesting dates were December 25, 2016 and June 1, 2017, respectively. In the present study, half of nitrogen fertilizer and biological fertilizer were applied in sowing date. The rest of the nitrogen fertilizer was applied after emergence of spikes before rainfall. In this study, the measured traits included plant height, number of spikes per square meter, number of seeds per spike, 1000-grain weight, grain yield, protein percentage and protein yield.Results and discussionIn the present experiment, alkazot fertilizer significantly affected plant height, number of grain per spike, 1000-grain weight, grain yield, protein percentage and yield. Overall, all of these traits under application treatment of alkazot fertilizer were more than non-application treatment with value of 4.16, 8.11, 12.04, 21.72, 3.74 and 26.40%, respectively. Supplemental irrigation also significantly affected 1000- grain weight, grain yield, protein percentages and yield. 1000-grain weight, grain yield, protein percentage and protein yield in irrigation treatment was 37.35 g, 5103 kg ha-1, 14.40% and 739.8 kg ha-1, respectively. In contrast, in non-irrigation treatment the amounts of these traits were 29.4g, 3787 kg ha-1, 15.00% and 573.8 kg ha-1, respectively. Effect of nitrogen on plant height, number of spikes per square meter, number of seeds per spike, 1000-grain weight, grain yield, protein percentage and yield were significant. Plant height, spikes per square meter, grain per spike, 1000-grain weight, grain yield, protein percentage and yield in non-application of nitrogen was 69.62 cm, 354.6 spike, 31.3 grain, 31.63 gr, 3502 kg/ha, 14.07% and 492.1 kg ha-1, respectively. The maximum amount of plant height, spikes per square meter, grain per spike, 1000-grain weight, grain yield, protein percentage and yield with value of 73.95 cm, 440.4 spike, 35.74 grain, 34.59 gr, 5364 kg ha-1, 15.54% and 831.8 kg ha-1 belonged to application of 150 kg N ha-1, respectively.ConclusionAccording to the results, 150 and 100 kg per hectare of nitrogen had a significant effect on all measured traits of wheat cultivar except grain per spike in case of alkazot biofertilizer. While irrigation in reproductive stage affected just 1000-grain weight, seed yield, protein percentage and yield. According to the results, it can be concluded that the amount of rainfall and temperature at the time of vegetative growth in Gonbad Kavous County was sufficient that in the reproductive stage, once supplementary irrigation with the use of alkazot and nitrogen resulted in good quantitative and qualitative yield.
Drought stress
Mohammad Chaharmahali; Yousef Sohrabi; Hassan Ebrahimi Koulaee; Mehdi Hassani; Hmed Mansouri; Hamze Hamze
Abstract
IntroductionSugar beet has long-growth period and high-water use. Thus, managing to reduce water consumption and decline growth period causes to increase the crop productivity. Sugar beet provides more than one-half of sugar produced in the United States and about 40% of sugar production in the world. ...
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IntroductionSugar beet has long-growth period and high-water use. Thus, managing to reduce water consumption and decline growth period causes to increase the crop productivity. Sugar beet provides more than one-half of sugar produced in the United States and about 40% of sugar production in the world. The root of this crop contains 13- 22% sugar content. In general sugar beet also has a major role in the human diet and it is the mainstay parts of the agriculture economy in Iran. The leaves of sugar beet comprise the main light receptor organ for a crop. Leaf area development early during the season causes more efficient use of sunlight since it is important to the formation and expansion of the canopy. Sugar beet in the primary growth stages needs a warm and sunny climate and optimum water supply for optimal photosynthesis and photoassimilate partitioning.Material and method This purpose study was performed in the research field of Hamedan in 2016. The experiment was conducted in a split-split plot based on RCB design with four replications. Experimental treatments were planting date at two levels as main plot (May 14 and June 28), irrigation at two levels as sub-plot (full irrigation and 75% of full irrigation or water requirement), and cultivar at 3 levels (two premature hybrids and the resistant cultivar to Rhizoctonia (Arya)) as sub-sub-plot at 2016 crop season. Studied traits were root yield, sugar content, sugar yield, and Enzyme activities such as SOD, PO, leaf chlorophyll, and some physiological and morphologic traits. SAS software version 9.1 was used to analyze the data. Also, the mean of the studied parameters was compared using the least significant difference test (LSD) at the level of 5 percent probability. Results and discussion Based on the results of the analysis of variance, the difference between planting dates in terms of superoxide dismutase content, root yield, sugar yield, white sugar yield, and water use efficiency was significant at the level of 1% probability. There was a significant difference between irrigation levels in terms of superoxide dismutase and water use efficiency at 1% probability level and membrane lipid peroxidation content, peroxidase enzyme, chlorophyll a, chlorophyll b, and carotenoid content at 5% probability level. There was a significant difference between the studied genotypes in terms of root yield and sugar yield at a probability level of 1% and in terms of white sugar yield and water use efficiency at a probability level of 5%. The interaction effect of culture date on genotype was significant in terms of the effect on the percentage of white sugar and yield of white sugar at the level of 1% probability. The interaction effect of irrigation levels in genotype was significant only on water use efficiency at the level of 1% probability. The results showed that irrigation level 75% of plant water requirement compared to 100% level increased, hydrogen peroxide content, membrane lipid peroxidation, peroxidase activity and superoxide dismutase activity by 14.83, 25, 17.38, and 26%, respectively and reduced chlorophyll a, chlorophyll b and carotenoid content by 15%, 12%, and 14%, respectively. Also, the amount of superoxide dismutase activity and root yield on planting on May 14 was 33% and 26% higher than planting on July 28, respectively. Root yield in 33868 and 33872 hybrids was higher than Aria cultivar. The results also showed that the difference between the planting dates of May 14 and June 28 in the two hybrids 33868 and 33872 was not significant in terms of sugar content, white sugar yield, and water use efficiency. Also, the planting date of June 28 increased the percentage of white sugar in both hybrids. Finally, two hybrids, 33868 and 33872, obtained the highest water efficiency in the treatment of 75% of the required water. ConclusionsIn the conditions that there is a possibility of delay in the cultivation of sugar beet, planting two hybrids, two hybrids 33868 and 33872, is recommended.
Drought stress
Sara Amini Pak Soltani; Seyed Ali Mohammad Modarres-Sanavy; Kamal Sadat Asylan
Abstract
IntroductionIran with an average rainfall of 240 mm per year is classified as arid and semi-arid regions of the world, so the occurrence of drought stress during plant growth is inevitable. In order to investigate the effect of biochar and wood vinegar on quantitative and qualitative characteristics ...
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IntroductionIran with an average rainfall of 240 mm per year is classified as arid and semi-arid regions of the world, so the occurrence of drought stress during plant growth is inevitable. In order to investigate the effect of biochar and wood vinegar on quantitative and qualitative characteristics of soybean under low irrigation stress, an experiment was conducted as split plots in a randomized complete block design with three replications during the 1398 crop season in the research farm of Tarbiat Modares, Faculty of Agriculture. The aim of this study was to investigate the effect of biochar and wood vinegar as organic sources on soybean nutrition as an important plant in the production of oil and protein needed by humans, through which the effect of these two treatments on plant resistance to water deficit stress.Materials and methodsThe main factors of this experiment were four irrigation regimes (Optimal irrigation, mild, medium, and severe irrigation deficit: withholding irrigation until the soil moisture content at plant root zone reaches 85, 65, 45 and 25%, of the soil available water respectively, and then irrigation to the field capacity). Water deficit stress was applied at the beginning of flowering of the plant and the sub-factors were anti-stress materials, ie three concentrations of wood vinegar (concentrations of 5000 ppm, 10000 ppm and 15000 ppm) and a biochar surface (5 t / ha) and control treatment (without anti-stress materials). Before planting, wood and biochar treatments were sprayed on soil surface according to the ratio of each experimental unit and post-growing wood vinegar treatment was applied at three-leaf, early flowering and podding stages as foliar application. Yield and yield components including plant height, plant leaf area, number of plant pods, 1000-seed weight and biological yields, seeds, straw and oil and greenness index were measured.Results and discussionThe results showed that drought stress had a significant effect on height, plant leaf area, number of pods per plant, biological yields, grain yield, straw and oil yield and 1000-seed weight and decreased with the application of water deficit stress. Fertilizer treatments were not significant on plant height, pod number and straw yield but had a significant effect on other traits. The interaction effects of irrigation and fertilizer treatments on plant leaf area, biological yield, grain yield and oil yield were significant.ConclusionsThe results of this study showed that the occurrence of drought stress has a negative effect on yield and yield components of soybeans. The highest plant leaf area, biological, grain and oil yield in optimal irrigation were related to biochar fertilizer treatment. According to the results of the study, it seems that in conditions of water shortage stress, the use of biochar will not be very beneficial. In these conditions, the use of wood vinegar is recommended for mild, moderate and severe water deficiency, maximum plant leaf area and biological, grain and oil yields were observed with the use of wood vinegar. Researchers have identified pyroligneous acid as a turning point in organic farming that has a major impact on the management and growth of maize and soybeans (Coffman et al., 2005). Wood vinegar and biochar, as organic matter and naturally derived habitat, can be redirected to improve crop yields under environmental stress.
Salinity stress
Asghar Mosleh Arany; Ali Reza Amini Hajiabadi; Somaye Ghasemi; Mohammad Hadi Rad
Abstract
IntroductionIncreasing world population, along with climate change and environmental stresses, has posed a serious challenge to adequate food supply. Salinity is one of the most important stresses affecting the reduction of agricultural products. In recent years, the use of new strategies for sustainable ...
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IntroductionIncreasing world population, along with climate change and environmental stresses, has posed a serious challenge to adequate food supply. Salinity is one of the most important stresses affecting the reduction of agricultural products. In recent years, the use of new strategies for sustainable production of food products under salinity stress has been considered, including plant growth promoting rhizosphere bacteria. Due to the strategic importance of wheat in food security, this study was designed and conducted with the aim of increasing the salinity resistance of wheat (Var. Narin) using plant growth promoting rhizosphere bacteria isolated from the rhizosphere of several halophyte plants in Yazd province. Materials and methodsPlant growth promoting traits such as ability to produce auxin, siderophore, hydrogen cyanide, and phosphate solubility and salinity resistance of isolated bacteria from rhizosphere of halophyte plants (Atriplex lentiformis, Seidlitzea rosmarinus, Halostachys belangeriana and Tamarix ramossima) in their habitats in Chahafzal in Yazd Province were investigated. Then, wheat seeds were inoculated with the best three bacteria in terms of plant growth-promoting traits and salinity resistance, and then was irrigated with water with salinities of 4, 8 and 16 ds m-1. After the growth period, total biomass, seed weight and spike components and seed amylose and amylopectin were measured. Results and discussionsThe studied bacteria including Bacillus safensis, B. pumilus and Zhihengliuella halotolerans had the ability to produce auxin, siderophore, hydrogen cyanide, 1-aminocyclopropane-1-carboxylic acid deaminase (ACC deaminase) and phosphate solubility. The highest amount of auxin production was measured in B. safensis (29.72 μg ml–1) and the highest amount of hydrogen cyanide production and phosphate solubility was in Z. halotolerans. The highest amount of ACC deaminase was measured in B. pumilus (8 μmol of α-ketobutyrate h–1 mg–1 protein). The results showed that increasing salinity levels decreased spike length, spike weight, number of spikelets, number of florets, number of seed, seed weight, amylose and amylopectin content of seeds. The length and weight of spikes at salinity of 16 dS m–1 decreased by 36% and 18%, respectively, compared to the non-salinity control. Instead, B. safensis, Z. halotolerans and B. pumilus caused an average increase of 35, 22, and 17.6% of the spike length at salinity stress levels (4, 8, and 16 dS m-1), respectively, compared to the uninoculated controls. Also, B. safensis, B. pumilus and Z. halotolerans bacteria caused an average increase of 69, 43 and 30% of spike weight in salinity stress levels compared to the uninoculated control, respectively. The number of spikelets and number of florets at salinity of 16 dS m-1 decreased by 27 and 43%, respectively, compared to the non-salinity control. In all salinity stress levels, B. safensis, Z. halotolerans and B. pumilus caused an average increase of 48, 26 and 13% of total biomass, and an average increase of 59, 23 and 7% of seed weight in all salinity stress levels compared to control. B. safensis, more than the other two bacteria, improved the total biomass and seed weight of wheat. ConclusionsPlant growth promoting rhizosphere bacteria in this experiment significantly improved the resistance of wheat to salinity stress. Comparison between the studied bacteria showed that B. safensis had a greater effect on the promotion of total biomass, yield and all traits of the studied components than B. pumilus and Z. halotolerans, due to the superiority of B. safensis in auxin production and increasing the ratio of potassium to sodium. It can be concluded that the auxin and the potassium are of key importance in increasing the reproductive performance of Narin cultivar. It is also concluded that the rhizosphere of halophytic rangeland plants can be a good source for the isolation of salinity-resistant bacteria to improve the resistance of wheat plants to salinity.
Salinity stress
Seid Saeed Sahafi; Seyed Mohsen Moussavi Nik; Seyed Ali Tabatabaei; Seyed Kazem Sabbagh; Seyed Ahmad Ghanbari
Abstract
IntroductionOne of the biggest challenges of agriculture in the present era is environmental stresses, especially drought and salinity stress and its destructive effect on food security. In this regard, this experiment was conducted with the aim of selecting of tolerant cultivar of barley to salinity ...
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IntroductionOne of the biggest challenges of agriculture in the present era is environmental stresses, especially drought and salinity stress and its destructive effect on food security. In this regard, this experiment was conducted with the aim of selecting of tolerant cultivar of barley to salinity stress and identifying tolerance mechanisms in new and old barley cultivars.Material and methodThis experiment was carried out during the two years of 2016-17 in the Milshbar Ardakan region located in Yazd province-Iran. Experimental treatments included 9 six-rowed barley cultivars including Nik, Mehr, Khatam, Reyhan, Goharan, Nosrat, Morocco, Afzal and Fajr 30 cultivars in three levels of irrigation water salinity including 4, 10 and 14 dS.m-1 were evaluated as a split plot experimental design so that water salinity as the main plots and cultivars as a sub-plots were randomly placed. The studied traits included yield and yield components as well as sodium and potassium levels, oxidizing enzymes and photosynthetic pigments.Results and discussionThe results showed that salinity treatment had a significant effect on day to emergence, day to tillering and grain yield. Salinity stress reduced grain yield components but this reduction was not significant. The effect of cultivar on plant phenology and day to emergence, tillering and ripening was significant, but on yield and yield components became insignificant. However, among the studied cultivars, Nik, Mehr, Khatam and Reyhan cultivars had higher yields and yield components. Among the salinity treatments, the highest grain yield was obtained at salinity of 4 dS m-1 with 5770.64 kg ha-1. With increasing salinity of irrigation water to 10 and 14 dS m-1, grain yield decreased by 18.04 and 27.55%, respectively, and reached 4729.29 and 4180.87 kg ha-1. The results of interaction showed that the interaction effect of year × salinity on grain yield components was significant and also the interaction of year × cultivar on 1000-Kernel weight and grain yield and year × salinity × cultivar on grain yield was significant. With increasing salinity stress, the amount of sodium ions in the shoots increased and potassium decreased, so the ratio of K/Na decreased. This mechanism was more effective in tolerant cultivars and in salinities of 4 and 10 dS m-1. With increasing salinity stress, the amount of oxidizing enzymes increased, so that with increasing salinity from 4 to 10 and 14 dS m-1, the amount of peroxidase enzyme was increased 1.59 and 2.23 times, catalase 1.52 and 1.95 times, and guaiacol peroxidase 1.47 and 2.89 times, respectively. With increasing salinity stress, all photosynthetic pigments increased. Among the cultivars, the amount of chlorophyll a and b in Morocco, Nik and Mehr was higher than other cultivars.ConclusionBased on the results of this experiment, it seems that tolerant cultivars, in addition to having high production potential, should have high potassium uptake mechanisms and high gene expression to produce enzymes that protect against oxidative stress in order to tolerate low to medium salinity stress.
Salinity stress
Sara Mohammadi Kale Sarlou; Raouf Seyed Sharifi; Hamed Narimani
Abstract
IntroductionSoil salinity is one of the most serious limiting factors for crop growth and production in the arid and semi-arid regions. Several strategies have been developed in order to decrease the toxic effects caused by high salinity on plant growth. Among them, use of bio-fertilizers such as plant ...
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IntroductionSoil salinity is one of the most serious limiting factors for crop growth and production in the arid and semi-arid regions. Several strategies have been developed in order to decrease the toxic effects caused by high salinity on plant growth. Among them, use of bio-fertilizers such as plant growth promoting rhizobacteria (PGPR), vermicompost and humic acid play a very important role in yield improvement. Inoculation of plants with native suitable microorganisms may decrease the deleterious effects of environmental stresses and increase stress tolerance of plants by a variety of mechanisms, including synthesis of phytohormones such as auxins, cytokinin and gibberellins, solubilization of minerals like phosphorus, production of siderophores and increase in nutrient uptake, N2 fixation. Vermicompost plays a very important role in plant nutrition and soil health. So, it seems that application of bio fertilizers such as PGPR, vermicompost and humic acid can improve crop yield under soil salinity stress. Therefore, the aim of this study was evaluation of yield, chlorophyll fluorescence indices and some physiological traits of triticale in response to humic acid and bio fertilizers application under soil salinity conditions Material and methodsIn order to study the effects of vermicompost, humic acid and seed inoculation with flavobacterium on yield, chlorophyll fluorescence indices and some physiological traits of triticale under soil salinity conditions, an experiment was conducted as factorial based on randomized complete block design with three replications in greenhouse research of the Faculty of Agriculture and Natural Resources, the University of Mohaghegh Ardabili during 2020. Experimental factors were included salinity levels (non-application of salinity as control, application of 50 and 100 mM salinity by NaCl), and bio-fertilizers application (no application of bio-fertilizers as control, application of vermicompost, seed inoculation with Flavobacterim, both application vermicompost and Flavobacterim) and foliar application humic acid (foliar application with water as control and foliar application of 2 g.l-1 humic acid). vermicompost was purchased from the Gilda corporation. Flavobacterim was isolated from the rhizospheres of wheat by Research Institute of Soil and Water, Tehran, Iran. The triticale cultivar "SANABAD" was used in the experiment with plant density of 400 seeds m-2. For inoculation, seeds were coated with gum Arabic as an adhesive and rolled into the suspension of bacteria until uniformly coated. The strains and cell densities of microorganisms used as PGPR in this experiment were 1×108 colony forming units (CFU). Relative water content: Weight of fresh leaf was measured just after detached from the plants then taken turgid weight after leaf was incubated in distilled water for 24 h to obtain a full turgidity. Dry weight of leaf was measured after it was dried at 60°C for 24 h in an oven. Relative water content was measured according to the following formula (Chelah et al. 2011).RWC (%) = [(FW-DW) / (TW-DW)] × 100Where, RWC, FW, DW and TW are relative water content, fresh weight, dry weight and turgid weight respectively.Chlorophyll content: A portable chlorophyll meter (SPAD-502; Konica Minolta Sensing, Inc., Japan) was used to measure the leaf greenness of the wheat plants. Quantum yield: The quantum yield was measured by the uppermost fool expanded leaf using a fluorometer (chlorophyll fluorometer; Optic Science-OS-30 USA).Electrical conductivity: Electrical conductivity was calculated by following the standard method of Jodeh et al. (2015). Electrical conductivity (EC) values were measured at room temperature of 23±1 °C using an electrical-conductivity meter. At plant maturity, grain yield in each pot were harvested five plants per pot. Statistical analysis: Analysis of variance and mean comparisons were performed using SAS ver 9.1 computer software packages. The main effects and interactions were tested using the least significant difference (LSD) test at the 0.05 probability level.Results and discussionMeans comparison showed that the both application of vermicompost, Flavobacterim and foliar application of 2 g.l-1 humic acid under no salinity condition increased maximum fluorescence (22.53%), variable fluorescence (94.69%), quantum yield (58.88%), chlorophyll index (28.91%), nitrogen index (3.88%), relative water content (50.48%)of flag leaf and grain yield (69.56%) in comparison with no application of bio-fertilizers and humic acid under 100 mM soil salinity. No application of biofertilizers and foliar application of humic acid at salinity of 100 mM increased the electrical conductivity and minimum fluorescence (F0) the flag leaf.ConclusionIt seems that application of bio-fertilizers and humic acid can increase grain yield of triticale under soil salinity conditions due to improving chlorophyll fluorescence and some physiological traits.
Salinity stress
Fatemeh Azadi; Akram Hatami; Hadi Salek Mearaji
Abstract
IntroductionSalinity as one of the most important abiotic stress that reduce the growth, development and yield of crops and the use of plant growth regulator is one of the beneficial methods to reduce unfavorable effects of salinity stress. Black cumin (Nigella sativa L.) is an annual plant from ...
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IntroductionSalinity as one of the most important abiotic stress that reduce the growth, development and yield of crops and the use of plant growth regulator is one of the beneficial methods to reduce unfavorable effects of salinity stress. Black cumin (Nigella sativa L.) is an annual plant from the buttercup family that used widely in traditional and industrial pharmacology and seeds or their extracts contain anti-diabetic, antihistaminic, antihypertensive, anti-inflammatory, anti-microbial, antitumour, galactagogue and insect repellent effects.Materials and methodsIn order to investigate the effects of foliar application of cytokinin on morpho-physiological traits, yield and yield components of black cumin (Nigella sativa L.) a factorial experiment was conducted based on randomized complete block design with four replications at the greenhouse condition. The experimental factors included salinity at five levels of 0, 3, 6, 9 and 12 dS m-1 and foliar application of cytokinin at three concentrations of 0, 100 and 200 μM. This experiment was performed inside 5 kg plastic pots with a height 21 and openings diameter 23 cm under greenhouse conditions. The substrate composition consisted of a 2:1:1 ratio of arable soil, rotted and sifted manure and aerated sand. The average day and night temperatures of the greenhouse were 27±2 and 18±2°C with relative humidity between 65 and 80%, respectively. Four plants were kept inside each pot and the rest were thinned. Foliar application of cytokinin was performed one stage at the beginning of flowering and the second stage one week after the first foliar application. Physiological traits such as electrolyte leakage, relative water content, chlorophyll pigments and proline were measured one week after the second spraying. Plant height, number of number secondary branch and yield components traits were measured after complete plant maturity.Results and discussion The results of analysis of variance showed that salinity treatment has significant effect on all traits. Salinity stress increases electrolyte leakage and proline, though it has a declining effect on other traits. Was not significant reduction in traits up to 3 dS m-1 of salinity. The highest grain yield with 2.42 g pl-1 was obtained in the control treatment and the lowest grain yield with 0.81 g pl-1 at a concentration of 12 dS m-1 of salinity. Cytokinin treatment has significant effect on all traits except chlorophyll a, proline and number of capsule in plant. Foliar application of cytokinin reduced unfordable of salinity stress in black cumin, and 100 μM concentration of cytokinin has high efficiency than 200 μM. The highest percentage of electrolyte leakage, proline and carotenoid content was observed at a salinity level of 12 dS m-1. The lowest of plant height, relative water content, chlorophyll pigments, number seed in capsule, number secondary branch, number capsule in plant, weight of thousand seeds and biological yield observed in 12 dS m-1 of salinity level. The lowest grain yield (1.51 g pl-1) was observed in the control treatment and the highest grain yield (1.83 g pl-1) was observed in the concentration of 200 μM of cytokinin. Foliar Cytokinin was effective on all studied morpho-physiological traits under salinity stress. Under salinity stress, cytokinin application only affected the number of grains in capsule and had no significant effect on yield and other yield components traits.Conclusion The results obtained in this study showed that the black cumin can tolerate salinity up to 3 dS m-1 without any significant reduction in its yield. 1000-grain weight, number of grains per capsule and proline content were the least sensitive to different salinity levels. Biomass yield was also the most sensitive, so that it showed a significant decrease in all salinity levels. The concentration of 100 μM cytokinin was better than 200 μM. The results showed that foliar application of cytokinin under salinity stress may be improve some traits, however, this does not constitute a definite increase in yield and yield components under salinity stress conditions and may not result in a change in grain yield.
Drought stress
Abbas Rezaizad; Sharareh Arman; Kamal Sadatasylan; Sirus Mansourifar
Abstract
IntroductionIn confectionary sunflower cultivation, drought stress at the stage of vegetative growth and plant density are two important variables that determine grain yield. In order to increase the 1000-seed weight and marketability of sunflower seeds, farmers usually consider plant density less than ...
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IntroductionIn confectionary sunflower cultivation, drought stress at the stage of vegetative growth and plant density are two important variables that determine grain yield. In order to increase the 1000-seed weight and marketability of sunflower seeds, farmers usually consider plant density less than oily sunflower, and on the other hand, for more root growth and dormancy resistance due to large heads, in the vegetative growth stage of sunflower they bring drought stress to the sunflower farm. In some regions of Kermanshah province, confectionary sunflower (local cultivar Songhori) is cultivated with very low density (1-3 plants per square meter). On the other hand, farmers, based on their experiences, in the vegetative growth stage (2-6 leaves), cut off the field irrigation, and this watering interruption may take 30-45 days. The purpose of stopping irrigation in such conditions is to grow more roots and prevent lodgings of plants due to the weight of the head. In the present study, the effect of cutting irrigation at vegetative stage and plant density on yield and other agronomic characteristics of local confectionary sunflower was investigated to identify the most appropriate treatments. Materials and MethodsThe present study was conducted using split plot experiment based on randomized complete block design with three replications in the farmers' farm of Kermanshah province in 2016. Drought stress was as the main factor at three levels including severe stress, moderate stress and non-stress. The sub-factor was three levels of plant density with changes in plant space on 60 cm planting rows in the form of 20, 40 and 60 cm. Important agronomic traits including number of days to star, number of days to full flowering, stem diameter, plant height, number of leaves, leaf area, head diameter, percentage of hollow, number of seeds per head, 1000 seed weight and yield were measured according to Schneider and Miller (1981). In order to measure the grain yield of each plot, the middle row plants were harvested after removing the marginal plants (one row and one plant from the beginning and end of each plot) and the grain yield was measured after threshing. Based on the harvested area, it was converted to kilograms per hectare. In order to statistical analysis, SAS Ver 9.1 statistical software was used to analyze the variance and the means of treatments was compared by Duncan’s multiple range test.Results and discussionThe results of variance analysis showed that drought stress significantly reduced plant height, days to maturity, seeds per head and stem diameter and increased days to flowering. Effect of Density was significant on all studied traits except plant height and number of leaves. While increasing density, stem diameter, head diameter, number and weight of seeds per head and 1000-seed weight was decreased and the hollow percentage of head, the number of days to flowering was increased. Mean comparison of data showed that grain yield under severe and non-stress condition was 2749 and 4543 kg ha-1, respectively. The highest and the lowest grain yield was belonged to plant spacing of 40 cm and 20 cm with 4599 and 3538 kg ha-1, respectively.Given the water crisis in Iran, the real value of water consumption should be considered and water loss should be prevented by using different methods in crop production. According to the mean grain yield, it can be seen that the average yield of mild drought stress (two less irrigations) is slightly different from the average yield in non-stress irrigation. The two removed irrigations in the mild stress treatment coincide with the time of grain filling of crops such as wheat, barley and canola or the cultivation of some spring crops such as corn. Irrigation in these stages is important in the grain yield of these plants. So by eliminating two irrigations after the establishment of the sunflower, the saved water can be used to irrigate other crops. On the other hand, low and high density treatments both had lower grain yield than intermediate density treatment. Plant spacing of 40 cm with high 1000-seed weight had higher grain yield than plant spacing of 20 and 60 cm, so that a plant distance of 40 cm can be recommended in confectionary sunflower. It can also be recommended that, after the establishment of the sunflower plant, by eliminating two irrigations before reproductive growth, without effective reduction of grain yield, water resources can be used for other crops such as wheat, barley and canola.
Biotechnology and environmental stresses
Mozhdeh Arab; Hamid Najafi Zarrini; Ghorbanali Nematzadeh; Seyed Hamidreza Hashemi-Petroudi
Abstract
IntroductionThe CBL-CIPK signaling network, which decodes calcium signals triggered by environmental stresses, is one of the most crucial signal transduction systems in plants. Proteins bound to calcium ions serve as sensor molecules, receiving cellular calcium ion signals and transmitting messages to ...
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IntroductionThe CBL-CIPK signaling network, which decodes calcium signals triggered by environmental stresses, is one of the most crucial signal transduction systems in plants. Proteins bound to calcium ions serve as sensor molecules, receiving cellular calcium ion signals and transmitting messages to the downstream gene cascade. Because of its tolerance to abiotic stresses, especially salinity stress, and its relationship to cereals, many researchers are interested in the molecular mechanisms of the halophyte grass Aeluropus littoralis. The in-silico discovery of the AlCIPK gene family and their expression profile in responses to salinity stress were considered in this analysis due to this plant's genome sequence's availability.Materials and methodsUsing local TblastN program, the CIPK protein sequences of Arabidopsis thaliana gene families were blasted against A. littoralis genomic sequences. BlastP was used to verify all sequences after redundant sequences were removed. The detected proteins were analyzed in various protein domain databases such as Pfam, PROSITE, and InterProScan to identify, annotate, and interpret domain structures. In all of AlCIPK, the SALAD approach was used to perform similarity clustering based on motifs patterns. The exon and intron arrangement were determined by comparing the predicted CDS against AlCIPK genomic sequences in the gene structure display server (GSDS). Expasy-Prosite was used to determine the domain structure. A signal-dependent software based on SignalP 5.0 was used to identify signal peptides in proteins. Exploring the expression pattern of AtCIPK genes at various growth and developmental stages using Genevestigator (https://www.genevestigator.com/gv/plant.jsp) and the EFP browser (http://bar.utoronto.ca/). Transcriptome research was used to examine the expression patterns of AlCIPK genes in leaf and root tissues under salinity stress and recovery conditions.Results and discussionBased on sequence homology with Arabidopsis genes, 20 CIPK genes were discovered in the A. littoralis genome. The Arabidopsis AtCIPK homologous proteins were used to name the Aeluropus CIPK genes. According to subcellular localization analysis, these proteins are active in a specific cellular compartment. The phylogenetic tree of 20 AlCIPK, 26 AtCIPK, and 33 OsCIPK showed that these 79 CIPKs are closely related. Exon/intron structure analysis was used to separate all AlCIPK into intron-poor and intron-rich classes. The expression of 25 AtCBL gene family members in 68 samples under salinity stress was compared using Genevestigator tools, which revealed that all 25 genes tested in different developmental/ environmental stages, including control and stress, had different expression patterns. A tissue-specific expression pattern was discovered after analyzing these AtCBL genes' expression pattern in both root and shoot tissues. In salinity stress and recovery conditions, the expression profile pattern of AlCIPK genes in leaf and root tissues was distinct. The distinct expression profiles of the AlCIPK gene family confirmed their functional and structural convergence.ConclusionSystematic study of members of this gene family revealed that CIPKs in Halophyte grass, i.e., A. littoralis, share main CIPK family characteristics with other monocotyledonous and dicotyledonous plants, which are likely important factors in this species' adaptation and stress tolerance. The lack of homologous AtCIPK24 genes in the Aeluropus genome is a key finding in this study, suggesting that the CBL-CIPK gene network in this plant has a distinct regulatory function, necessitating further studies. Future studies using the RT-qPCR method to examine the expression of AlCBL and AlCIPK gene family genes under different abiotic stresses could aid in understanding the mechanism of SOS-related gene expression regulation. This study's findings reveal the functional characteristics of the calcium gene family and provide essential information for future research on their functional roles.
Drought stress
Mohammad Passandideh; Majid Rajaie; Hossein Zeinalzadeh-Tabrizi
Abstract
IntroductionCanola is known as one of the most important oily plants in the world due to its good composition of fatty acids and oil content. As the first oilseed crop in Iran, Canola is recommended to increase its cultivated area to reduce dependence on oil imports with high oil quality compared to ...
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IntroductionCanola is known as one of the most important oily plants in the world due to its good composition of fatty acids and oil content. As the first oilseed crop in Iran, Canola is recommended to increase its cultivated area to reduce dependence on oil imports with high oil quality compared to other similar crops. Drought stress is one of the major environmental limiting factors for the successful production of crops, especially canola, in Iran and the world. One effective strategy to reduce the adverse effects of drought stress is to use new nutritional techniques like humic compounds and growth stimuli, including amino acids. Due to the lack of sufficient studies on the effects of growth stimuli on canola, the present study was performed to study the effects of four plant growth biostimulants on increasing canola tolerance to drought stress under Moghan conditions.Materials and methodsTo compare the effects of growth biostimuli on canola yield under drought stress, an experiment was conducted at Moghan Agricultural Research Station in the 2018-2019 crop years. The experiment was conducted as a split-plot in a randomized complete block design with three replications. Treatments included the main factor of irrigation regime at two levels, and the sub-plot included six treatments; control, amino acid foliar application, humic acid with irrigation, fulvic acid foliar application, seaweed extract foliar application, and the combination of second, third, and fifth treatments. In this study, plant height, number of pods per main stem, number of pods per lateral branches, total number of pods per plant, number of seeds per pod, 1000-seed weight and seed yield were measured. Before analysis of variance, the presence or absence of outliers was identified using Grubbs test. Normality of data was then checked by Shapiro-Wilk test. Finally, the analysis of variance was performed and the means were compared using the least significant difference (LSD) method at the statistical level of one and five percent using SAS software version 9.1.Results and discussionThe results showed that the effect of growth biostimulants could be different in non-stress and drought stress conditions, and biostimulants can reduce the effects of dry stress. in regular irrigation and non-stress conditions, the combined treatment uses of growth stimulants> humic acid> fulvic acid > seaweed extract> amino acid increased by 22.7%, 14.3%, 6.4%, 6.3%, and 3.4%, respectively, compared to the control treatment. In drought stress conditions, the highest effect was related to the combined use of growth stimulants> amino acids> seaweed extract> fulvic acid > humic acid, respectively, with an increase of 31.9%, 21.3%, 15.9%, 11.9%, and 11.1%, respectively, compared to the control treatment.ConclusionsUnder non-stress conditions, the effect of growth stimulants was related to all studied components yield, and the effect of humic acid, fulvic acid, seaweed extract, and amino acid were related to the number of pods. Under stress conditions, other yield components including, number of pods per main stem and lateral branches, plant height and number of seeds per pods had more effect on increasing yield. It can be concluded that the application of growth biostimulants while improving canola yield under normal moisture conditions, can increase its tolerance to drought stress.
Drought stress
Mohadese Ghazizade; Mohammad Reza Amerian; Hamid Reza Asghari; Hadi Asadi Rahmani
Abstract
IntroductionThe use of biological fertilizers can be effective and beneficial in abiotic environmental stresses specially in drought stress, arid and semi-arid regions of the world.Materials and methodsAn experiment was conducted to investigate the effect of deficit irrigation stress and Pseudomonas ...
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IntroductionThe use of biological fertilizers can be effective and beneficial in abiotic environmental stresses specially in drought stress, arid and semi-arid regions of the world.Materials and methodsAn experiment was conducted to investigate the effect of deficit irrigation stress and Pseudomonas bacteria on some morpho-physiological traits of two potato cultivars at the research farm of Shahroud University of Technology located in Bastam region in 2010. Treatments included irrigation cycles as the main factor at three levels (7, 10, and 14-days), Pseudomonas bacteria (inoculation and non-inoculation) and cultivar at two levels (Savalan and Agria) as the sub-factor with three replications.Results and discussionThe results showed that the highest dry matter accumulation in the aerial part was observed in the 7-day irrigation cycle and inoculation with Pseudomonas bacteria. The number of tubers was increased about 12.66% because of inoculation with Pseudomonas fluorescens per square meter. Savalan cultivar interaction and 7-day irrigation cycle also obtained the highest number of tubers with an average of 166.39 per square meter. The application of inoculation with Pseudomonas fluorescens increased chlorophyll A by 9.3%. It compared with non-bacterial inoculation. Chlorophyll B had the highest chlorophyll content in the main treatments of the 7-day irrigation cycle and Agria cultivar. The highest amount of potassium content was obtained at the rate of 2.06% at the highest irrigation cycle (14-day). The application of inoculation and non-inoculation with Pseudomonas caused the highest amount of proline at 14-day irrigation cycle. Inoculation with Pseudomonas bacteria increased the final tuber yield about 22.85%. Furthermore, Savalan cultivar increased the final tuber yield about 110.09% in the 7-day irrigation cycle compared to the 14-day. Finally, the 7-day irrigation cycle was the best irrigation cycle to increase the morpho-physiological traits, chlorophyll, number of tubers, and the final tuber yield. Inoculation with Pseudomonas bacteria increased the effectiveness of these traits. Also, the production of compatible osmolytes (proline and potassium) improved drought stress tolerance in 14-day irrigation cycle. Growth-promoting bacteria improves seed germination, root propagation, shoot and root weight, leaf area, chlorophyll content, hydraulic conductivity, protein, nutrient absorption and plant yield (Batool et al., 2020). Growth-promoting bacteria of polysaccharides increases biomass production under drought stress conditions (Daffonchio et al., 2015). Potassium is one of the most important osmolytes under drought stress conditions and adverse conditions (Anschütz et al. 2014). Cellular and physiological responses are carried out through organic salts as proline to reduce cellular damage during drought stress. It is an osmotic regulator (Merwad et al., 2018)ConclusionThe 7-day irrigation cycle was the best irrigation cycle to increase the morpho-physiological traits, chlorophyll, number of tubers, and the final tuber yield. Inoculation with Pseudomonas bacteria increased the effectiveness of these traits. Also, the production of compatible osmolytes (proline and potassium) improved drought stress tolerance in 14-day irrigation cycle.
Drought stress
Azam Yazdanpoor; Mahmood Soluki; Mehdi Dahmardeh; Issa Khammari
Abstract
IntroductionModification to withstand drought stress has always faced its own bottlenecks, therefore, in the first stage, cultivating drought-resistant plants such as quinoa is the best way to prevent of reduce in crop yields. Quinoa with a scientific name (Chenopodium quinoa) is a dicotyledonous plant ...
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IntroductionModification to withstand drought stress has always faced its own bottlenecks, therefore, in the first stage, cultivating drought-resistant plants such as quinoa is the best way to prevent of reduce in crop yields. Quinoa with a scientific name (Chenopodium quinoa) is a dicotyledonous plant and belongs the subfamily (chenopodiaceae). There is saponin in all parts of quinoa, including leaves, flowers, fruits, seeds, and seeds coat (Bhargava and Srivastava, 2013). Also is used as an antibiotic, fungal disinfectant and in the pharmaceutical industry (Dini et al, 2001).Potassium have an important role in quality, plant tolerance to various environmental stresses, elements displacement, equilibrium, biochemical and physiological processes including photosynthesis, protein formation and opening and closing of pores and formation of vessels. The use of livestock and poultry manures is important in soil management and sustainability and improves the physical, chemical and microbial properties of the soil. The present study was conducted to investigate the effect of livestock and chemical fertilizers on the quantitative and qualitative characteristics of quinoa under drought stress. Materials and MethodsThis experiment was conducted in the form of split-split plot in a randomized complete block design with three replications.in the field of research of the Agricultural Research Institute of Zabol University In year of 2019-2020 In this experiment, drought stress was the main plot, cow manure as a sub-plot and potassium fertilizer as a sub-sub plot. The measured traits included: number of spikes, 1000-seed weight, grain yield, biological yield, harvest index, proline, carbohydrate and protein. Protein was measured by Bradford (1976). Proline was measured using the method (Bates, 1973) as follows. Results and discussionThe results showed that the simple, double and triple effects of drought stress, cow manure and potassium fertilizer were significant different at the level of 1% probability on 1000-grain weight and grain yield. The highest 1000-grain weight and grain yield were obtained when using full irrigation treatment. The simple, double and triple effects of drought stress, cow manure and potassium fertilizer were significant different at the level of 1% probability on Carbohydrates and grain protein. Also, the highest amount of grain protein was obtained in the application of 20 t ha-1 of manure and no potassium fertilizer in the stage of grain filling and the highest amount of leaf carbohydrates in the treatment of 10 tons of manure and 200 kg.ha-1 of potassium in the cessation stage of irrigation in the flowering stage. The results also showed that the highest of grain yield was obtained when using 10 t.ha-1 of manure and 200 kg.ha-1 of potassium fertilizer during full irrigation. ConclusionThe results showed that the combined application of manure cow and potassium in full irrigation conditions improved the quantitative and qualitative characteristics of quinoa. The triple effects of drought stress× manure× potassium increased grain yield, 1000-grain weight, harvest index, proline, protein and carbohydrates. The highest grain yield was obtained in the simultaneous use of cow manure and potassium fertilizer in the complete irrigation stage. In fact, the using of manure in addition to retaining moisture under conditions of severe stress increases the absorption of essential elements and plant growth, and the absorption of elements such as nitrogen, increases the growth of aerial parts of the plant and stores more nutrients in these areas for re-transfer during seeds ripen. On the other hand, due to its positive effect on maintaining moisture in the plant and increasing the duration of photosynthesis due to the continuity of leaf area in the reproductive stage, potassium consumption can provide more nutrients to more flowers and thus increase yield. It becomes a plant. Under stress conditions, the amount of carbohydrates and proteins increased, which is due to plant adaptation.
Drought stress
Mojgan Heidari; Hamid Reza Tohidimoghadam; Farhad Ghooshchi; Seyed Ali Mohammad Modares Sanavi; Pourang Kasraie
Abstract
IntroductionSafflower (Carthamus tinctorins L.) is an annual oil plant from the chicory family (Asteraceae) which, due to its high oil (30-40%) high quality (having more than 90% of unsaturated acids, especially linoleic acid and oleic acid), has played an important role in expanding the cultivated area ...
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IntroductionSafflower (Carthamus tinctorins L.) is an annual oil plant from the chicory family (Asteraceae) which, due to its high oil (30-40%) high quality (having more than 90% of unsaturated acids, especially linoleic acid and oleic acid), has played an important role in expanding the cultivated area of oil plants and providing oil seeds. The global cultivated area of safflower in 2019 was about one million and 140 thousand hectares and the average global production of its seeds was about 590 thousand and 869 tons. Water shortage stress, as one of the most important non-living stresses, has a destructive effect on most stages of crop plant growth, such as germination, seedling establishment, the structure of organs and their activity, and makes it difficult to achieve the desired result. Priming is one of the methods that after placing the seeds in their bed and facing the ecological conditions of the environment, physiologically and biochemically, they get ready for germination, and it can be used to reduce the negative effect of dehydration stress in many from plants. There are several different methods for seed priming, including osmopriming, hydropriming, matrix priming, hormonal priming, and biopriming. Plant hormones (growth regulators) are useful agrochemical tools that help plants to consume nutrients more efficiently and demonstrate their genetic and physiological potentials.Materials and methodsIn order to investigate the effect of priming and foliar spraying of growth regulators on the morphophysiological changes and the yield of safflower oil seeds of the cultivar Pandeh under drought stress, An experiment was carried out in the research farm of the Faculty of Agriculture of Tarbiat Modares University as an autumn crop during the agricultural year of 2017-2018 in the form of one-time divided plots based on the design of randomized complete blocks with three replications. The experimental factors include three levels of irrigation (optimal irrigation (cessation of irrigation until the discharge of 25% of usable water), medium water stress (cessation of irrigation until the discharge of 45% of usable water), severe water stress (cessation of irrigation until the discharge of 65% of usable water)) in the flowering stage until The end of the growth period in the main plots and five levels of seed priming and foliar application of plants (pure water, gibberellic acid, salicylic acid, ascorbic acid, humic acid) along with a control treatment (without priming and foliar appication) as sub-plots were considered.Results and discussionThe results showed that with the reduction of irrigation to the level of severe water stress, the yield and seed oil decreased by 41.31 and 43.46%, respectively, and significantly (P<0.01) compared to optimal irrigation. Also, with the reduction of irrigation water to the level of medium water stress, the amount of malondialdehyde increased by 15.92% and was significant compared to the optimal irrigation. With priming and foliar application of growth regulators, height, total chlorophyll, yield, and seed oil increased and malondialdehyde decreased significantly (P<0.01).ConclusionBased on the overall results, drought stress had a negative effect on the morphological characteristics and yield and oil percentage of safflower seeds. With priming by pure water, although the physiological traits and yield were improved, it was not significantly different from the control treatment. Foliar application of growth regulators by increasing the amount of total chlorophyll and improving growth had an important role in increasing yield. Due to the lack of water in the flowering and seeding stage of safflower in most regions of Iran, foliar application by growth regulators such as humic acid, salicylic acid and gibberellic acid can play an effective role in improving yield under medium water stress by increasing biochemical traits such as proline.
Heat stress
Khadijeh Ghomi; Babak Rabiei; Hossein Sabouri; Ebrahim Gholamali Puralamdari
Abstract
IntroductionBarley is one of the most important crops in the world and ranks fourth in terms of nutritional importance and area under cultivation among cereals after wheat, corn and rice, but it has ranks first in terms of the extent of cultivation in a variety of climates. The world's food production ...
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IntroductionBarley is one of the most important crops in the world and ranks fourth in terms of nutritional importance and area under cultivation among cereals after wheat, corn and rice, but it has ranks first in terms of the extent of cultivation in a variety of climates. The world's food production is severely limited by environmental stresses. One way to sustain production for the world's growing population is to minimize the reduction in production caused by these tensions. Given that heat stress, in particular late season heat is the most widespread type of heat stress in the world, especially in the subtropical regions, and as a major constraint in the production of sustainable crop yields, including barley. Therefore, identifying heat-tolerant genotypes can be a valuable solution to this problem. The present experiment was undertaken to understand the impact of high temperature on yield and its attributing traits and to select heat stress tolerant parents and cross combinations for future breeding program.Materials and methodsTo fulfill the requirement of this objective, the experiment was conducted in two environments i.e. normal and heat stress. Infact This study was performed to evaluate the heat tolerance at the end of the season and to identify barley tolerant genotypes using stress tolerance indices on experimental farm of the Gonbad Kavous University during the growing season of 2015-2016. The experimental plant materials were 120 barley genotypes which were evaluated in a randomized complete block design with two replications under two conditions without stress and heat stress. In addition, seeds of each genotype were grown in two meter rows with 20cm distance between the rows and the plant density was 270 plants per m-2.Results and discussionThe results of this experiment showed that the highest yield mean in non-stress conditions was related to genotype Torsh and in stress conditions was related to genotype Line143-2. The results of analysis of variance for yield trait showed that the differences between genotypes and the interactions of genotype and environment were significant at the level of one percent for the trait, which indicates high diversity and different reactions of cultivars and lines in different environments. Comparison of indices also showed that YI, STI, GMP and MP indices had the highest significant correlation with yield under non-stress and stress conditions and the superior indices of this experiment were for screening heat tolerant genotypes. Cluster analysis based on indices and yield under stress and non-stress conditions divided the studied genotypes into three groups.ConclusionOverall, the results of cluster analysis and principal component analysis showed that genotypes Torsh, Zarjo and 4Shori had the highest tolerance and genotypes Line105, Nosrat, Line98-2 and Fajr30 had the lowest tolerance to heat stress. Obviously, it is necessary to repeat the experiment in other places to be surer of these results and to obtain definitive results. On the other hand, to obtain heat-tolerant cultivars, it is recommended to cross the Torsh, Zarjo and 4Shori genotypes, and to locate heat-tolerant control genes, tolerant genotypes (Torsh and Zarjo) cross with sensitive genotypes (Line105 and Nosrat) can be used as two parents.
Drought stress
Zaher Najari; Esmail Nabizadeh; Heydar Azizi; Kaywan Fotohi
Abstract
IntroductionSugar beet (Beta vulgaris L.) is one of the important commercial crops that supply approximately 35% of the world’s sugar and is widely cultivated in arid and semi-arid regions. Drought is one of the most important growth restricting environmental factors for crop species in arid and ...
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IntroductionSugar beet (Beta vulgaris L.) is one of the important commercial crops that supply approximately 35% of the world’s sugar and is widely cultivated in arid and semi-arid regions. Drought is one of the most important growth restricting environmental factors for crop species in arid and semi-arid regions of the world. Crop losses resulting from abiotic stresses such as drought or salinity can reduce crop yield by as much as 50%.Material and methodsto investigate the evaluation of different genotypes of sugar beet (Beta vulgaris l.) in terms of biochemical and antioxidant properties under normal conditions and water deficit conditions excrement was conducted in split-plot design based on complete random blocks with three replications in Miandoab Agricultural and Natural Resources Research Station at 2017-18 Crop seasons. Irrigation regimes at two levels, (normal Irrigation after 90 mm of evaporation and drought stress after the 10-leaf stage of sugar beet based on 200 mm of evaporation from the Class A evaporation pan) signed to the main plot, and 18 sugar beet genotypes were assigned to sub-plots. In this research root yield, coefficient of sugar extraction, Guaiacol peroxidase, Polyphenol oxidase, Superoxide dismutase, and proline content were measured. After collecting the data, the data were analyzed using SAS software version 9.1 and the comparison of the average of the studied characteristics was performed using LSD test at the probability level of five percent.Results and discussionIn the present study, the effect of the irrigation regime on all studied traits was significant except for the sugar extraction coefficient at the level of probability of 1%. Among the genotypes studied significant difference was observed in terms of all the studied traits, at the probability level of 1% Interaction of irrigation regime with genotypes on root yield, sugar extraction coefficient, guaiacol peroxidase, polyphenol oxidase, and proline content at 1% probability level and superoxide dismutase at 5% probability level was significant. The results showed that water deficit stress reduced root yield by 17.38% compared to normal irrigation conditions, while the content of glycol peroxidase, polyphenol oxidase, superoxide dismutase, and proline under water deficit conditions was an increase compared to normal irrigation conditions by 118.86, 82.1, 103.61 and 113.92 percent respectively. genotypes Mean comparison in terms of root yield showed that genotype No. 10 with an average of 85.77 t / ha under normal irrigation and 72.14 t / ha under water deficit stress had the highest root yield. Under normal irrigation conditions, the highest guaiacol peroxidase, polyphenol oxidase, superoxide dismutase activity, and proline content were belonged to genotypes 21, 15, 4, and 13, respectively. While underwater stress conditions, the highest values of these traits were recorded in cultivars 10, 20, 19, and 3, respectively. Based on the results of regression analysis under normal irrigation conditions, the Sugar Extraction Coefficient and proline content with the explanation of 80 percent of root yield variation were identified as the most important traits. Based on the results of path analysis, the two traits, directly and indirectly, showed a positive effect on root yield. Underwater deficit stress proline content, guaiacol peroxidase, and superoxide dismutase with 66.3% explanation of changes in root yield Were identified as the most effective traits on root yield. Besides, the mentioned traits had a positive effect on root yield based on the results of path analysis both directly and indirectly.ConclusionAmong the studied genotypes, cultivar F-20851 had the highest root yield in both irrigation conditions compared to other cultivars, so it can be concluded that the genotype has a high genetic potential for root yield production in different environmental conditions. Among Iranian cultivars, except for Paya cultivar, other cultivars had low ranks of root yield in both environmental conditions. It can be concluded that in addition to root yield, other enzymatic and biochemical properties of Iranian cultivars should be worked on to be competitive with foreign cultivars. In this study, proline content had a positive effect on root yield in both environmental conditions, so improving proline content could be a way to increase root yield in different environmental conditions.
Salinity stress
Fariba Sadat Fatehi; Ali Akbar Ehsanpour
Abstract
IntroductionSoil salinity as a limiting factor for plant growth and development and one of the environmental stresses that has attracted the attention of scientists. NaCl Reduces seed germination percentage, root length, fresh weight and dry weight of seedlings and fresh weight of hypocotyl. Salinity ...
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IntroductionSoil salinity as a limiting factor for plant growth and development and one of the environmental stresses that has attracted the attention of scientists. NaCl Reduces seed germination percentage, root length, fresh weight and dry weight of seedlings and fresh weight of hypocotyl. Salinity stress inhibits plant growth and development and reduces photosynthesis, respiration and protein synthesis in susceptible species. When plants are exposed to environmental stresses such as salinity and drought, the balance between the production of reactive oxygen species (ROS) and the activity of interfering systems in the clearance of these radicals by antioxidants is disturbed and ultimately oxidative damage. the reactive oxygen species (ROS) accumulates in the leaves and lead to the oxidation of important cellular constituents such as protein, chlorophyll, lipid and nucleic acids. Salt tolerance increases if free radicals are produced through the intensification of the antioxidant system. There is a relationship between oxidative depletion and increased tolerance to salt and other environmental stresses and the efficiency of the antioxidant system. Plants use complex antioxidant systems that reduce the oxidative damage caused by ROS to cellular parts. This system controls the amount of ROS under both natural and environmental stressful conditions, without which plants can not convert solar energy in to chemical energy All plant body cells have the ability to regenerate, that is, to proliferate or create a new plant. In fact, regeneration is the basis of plant tissue culture, which means creating a complete plant with roots and stems from undifferentiated plant cells. Regeneration of plants by culturing undifferentiated cells in this in vitro is a clear reason for the flexibility of plant cells that occurs in response to specific environmental signals.Materials and methodsIn this study, root regenerated plants as well as unregenerate plants from tobacco roots were cultured in MS medium containing concentration of zero, 100, 200 Mm Nacl were grown 4 a weeks and then growth indicators of including fresh and Dry weight, photosynthetic pigments content including total chlorophyll and carotenoids, concentration sodium and potassium, total phenol content, proline content, total antioxidant level, total ROS, Lipid peroxidation, auxin content as well as RAPID-PCR analysis Got it.Results and discussionIt was observed that fresh and dry weight of regenerated plants increased significantly over non-regenerated plants showed. It also increased the amount of photosynthetic pigments and reduced sodium and increased potassium, decreased total ROS and MDA and increased total antioxidant and auxin also relative to non-regenerated plants were observed in salt conditions, results obtained from RAPID-PCR analysis it showed somatic variation in regenerated plants comared to non-regenerated plants. Present research suggests that regenerated plants can enhances improved salinity resistance growth indices in saline conditions. In general, the results show that regenerated plants in both non-stress and salinity stress improved growth, physical and biochemical indices compared to non-regenerative plants. It was also found that regenerated plants R2 had better performance under salinity stress than plants regenerated plants R1 and non-regenerated plants. The occurrence of somaclonal variations between regenerated and non-regenerated plants has also been identified.ConclusionI n the present study, from regenerated and non regenerated tobacco roots were cultured in MS medium containing concentration of zero, 100, 200 Mm Nacl were grown 4 a weeks. The photosynthetic pigments were incresed while, sodium content reduced but potassium was increased, Total ROS decreased and MDA increased, total antioxidant and auxin also relative to non-regenerated plants were observed in salinity conditions. Results obtained from RAPID-PCR analysis showed somaclonal variation in regenerated plants comared to non-regenerated plants. Present data suggested that regenerated plants from root improved salinity tolerance and growth parameters in saline conditions.
Heavy metals
Parisa Sheikhzadeh; Nasser Zare; Shahrbano Abootalebi
Abstract
IntroductionHeavy metals are one of the most important abiotic stresses which can have detrimental effects on the growth, metabolic pathways, and physiological and biochemical characteristics of plants. Today, the accumulation of heavy metals in agricultural lands has an increasing trend that can affect ...
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IntroductionHeavy metals are one of the most important abiotic stresses which can have detrimental effects on the growth, metabolic pathways, and physiological and biochemical characteristics of plants. Today, the accumulation of heavy metals in agricultural lands has an increasing trend that can affect the production and quality of agricultural products as well as human health. Among heavy metals, cadmium (Cd) is one of the most important worldwide environmental pollutants. It can rapidly be taken up by plants and accumulates in plant tissues, and easily enter the food chain; so this heavy metal is a serious threat to humans, animals, plants, and environmental sustainability. Secondary metabolites play vital protective and adaptive roles in plants in response to biotic and abiotic stresses. In this study, the effect of cadmium stress on the physiological characteristics and secondary metabolite production, and cadmium accumulation in borage (Borago officinalis L.) was investigated under hydroponic conditions.Materials and methodsBorage seeds were germinated in Petri dishes, and the 5–6 cm seedlings were then transferred to hydroponic containers containing half of the Hoagland nutrient solution with continuous aeration. The cultures were maintained in a growth chamber with 16 hours of light and 25±2 °C. Cadmium treatments were applied at five levels (0, 81, 162, 243, and 324 μM cadmium) using cadmium nitrate (Cd (NO3)2 .4H2O) at the 6-7 leaves stage. European borage seedlings were sampled at five-time intervals (12, 24, 48, 72, and 108 hours after cadmium stress) treatments and cadmium content, physiological characteristics, and secondary metabolites of leaf samples were measured.Results and discussionThe results showed that the amount of photosynthetic pigments, chlorophyll index (SPAD), chlorophyll fluorescence, and secondary metabolites in borage leaves were significantly influenced by cadmium stress. With increasing cadmium concentration and exposure duration, the absorption and accumulation of cadmium in borage leaves increased significantly. Cadmium stress reduced the amount of chlorophyll a and b, total chlorophyll, and carotenoids at all sampling times in comparison with the control treatment. The maximal quantum efficiency of photosystem II and the chlorophyll index (SPAD) were decreased with increasing the cadmium concentration and exposure duration so that the lowest value of these traits was observed at 108 hours after treatment with 324μM cadmium. With increasing the cadmium stress severity, the amount of secondary metabolites including anthocyanin, phenol, and total flavonoids and also the amount of soluble sugars were significantly increased in the borage leaves. The highest amount of these metabolites was observed at 108 hours after treatment with 324 μM cadmium.ConclusionIn general, the results of this study showed that increasing the concentration and duration of cadmium stress negatively influenced plant photosynthesis by reducing the content of photosynthetic pigments and increasing chlorophyll fluorescence. On the other hand, increasing the concentration and duration of cadmium stress, increased the cadmium absorption and accumulation in the borage leaves as well as the amount of secondary metabolites.
behrouz asadi; seyed mohsen Seyedi
Abstract
Background and Objectives: Drought stress due to water deficit is a serious problem in agriculture, and it is one of the most important factors contributing to crop yield loss such as bean. The diversity of the genetic traits material is the basis of any breeding program and the existence of maximum ...
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Background and Objectives: Drought stress due to water deficit is a serious problem in agriculture, and it is one of the most important factors contributing to crop yield loss such as bean. The diversity of the genetic traits material is the basis of any breeding program and the existence of maximum variation is the greatest chance for success in the selection. Drought stress is known as an effective factor in reducing production in crops, that, in this regard, one of the ways to overcome unfavorable environmental conditions is identifying and spreading cultivars compatible with stress. Regarding the importance of bean genetic resources for use in breeding programs of this crop, this experiment was conducted to investigate yield of some of bean genotypes in normal and stress condition.Materials and Methods: In order to evaluation of genotypes of chitti bean based on tolerance and susceptibility indices, experiments were conducted in two environments without stress and drought stress in 2017 at research farm of Bean Research and education, Khomein. 24 genotypes of chitti beans along with Ghaffar cultivar as control (25 genotypes in total) were compared in Latis design with two replications. Genotypes seeds were sown on four lines with 3 m long. Irrigation was carried out under optimal and stress conditions after 50-60 and 100-110 mm evaporation from the surface of Class A evaporation pan, respectively. Evaluated traits included days number to flowering, days number to maturity, number of pods per plant, number of seeds per pod, 100-seed weight and grain yield. Some tolerance indices were calculated to evaluate the sensitive and tolerance of genotypes. Data variance analysis and statistical calculations were done by SAS statistical software.Results and Discussion: Drought stress reduced evaluated properties, significantly. Among the genotypes of chitti beans in optimal irrigation and drought stress conditions, KS21578 genotype had the highest grain yield with 2668.1 and 1581.5 kg ha-1, respectively. The lowest grain yield were achieved at KS21585 genotype and KS21591 genotype in optimal irrigation and drought stress conditions, respectively. Due to drought stress, grain yield of chitti bean genotypes decreased by 49.1%. Between stress tolerance indices the highest mean productivity index, geometric mean productivity index and stress tolerance index belonged to KS21578 genotype. The highest tolerance index was observed in Ghaffar cultivar (control). Also, the lowest stress susceptibility index was obtained in KS21585 genotype. The lowest mean productivity index belonged to KS21584 and the lowest geometric mean productivity index, tolerance index and stress tolerance index belonged to KS21591 genotype.Conclusion: According to the results of this study, KS21578 genotype had the highest grain yield under normal irrigation and drought stress conditions and the highest mean productivity index, geometric mean productivity index and stress tolerance index. Also, the lowest stress susceptibility index was obtained in KS21585 genotype. Based on chitti bean grain yield under normal irrigation and drought stress conditions and evaluation of stress tolerance indices as well as two-way diagram of geometric mean production indices and stress susceptibility index and considering maturity period, plant form and grain marketing 8 chitti bean genotypes were selected for testing.
