Physiology of crops under stress conditions
Sajad Esapour Nakhjiri; Majid Ashouri; Seyyed Mostafa Sadeghi; Naser Mohammadian Roshan
Abstract
IntroductionDue to the continuous water shortages in rice cultivation areas, unbalanced use of nitrogen chemical fertilizers, the need to pay less attention to the use of water in rice cultivation and balance in the use of chemical fertilizers in saving and preventing water loss is important. Periodic ...
Read More
IntroductionDue to the continuous water shortages in rice cultivation areas, unbalanced use of nitrogen chemical fertilizers, the need to pay less attention to the use of water in rice cultivation and balance in the use of chemical fertilizers in saving and preventing water loss is important. Periodic irrigation has been introduced as an important research finding to reduce water consumption and increase water use efficiency in paddy lands. As water stress increases, the uptake of nitrogen, phosphorus and potassium decreases.Materials and methodsTherefore, this study conducted for evaluation the effects of different irrigation regimes and N fertilizer on yield, and the content of micronutrients in brown and white rice was conducted in Rashat during cropping season of 2016-2017 and 2017-2018 in Rasht. Experiment was arranged in split split plot based on completely randomized block design with 3 replications in which water regimes were main factor included continuous submergence, 7 and 15 day interval irrigation and nitrogen fertilizer levels were sub factor included 50 , 75 , and 100 kg ha-1 and cultivars were sub sub factor included Gilanh and Hashemi. Before conducting the composite data analysis, Bartlett's test was used to ensure the homogeneity of experimental error variance. Analysis of variance and statistical calculations were performed using SAS software version 9.1 and the mean of the studied traits were compared using Duncan test at 5% probability level. In order to check the normality of the data, the normality test in SAS program was used.Results and discussionThe results showed that by increasing the irrigation interval, paddy yield decreased, while application of 75 and 100 kg ha-1 nitrogen fertilizer increased paddy yield in all three irrigation levels compared to the level of 50 kg ha-1 nitrogen fertilizer. There was a significant effect (at the level of one percent probability) between the treatment of irrigation regimes, nitrogen fertilizer and cultivar on brown and white rice and macro elements. The highest yield of rice for the Gilaneh variety was achieved under flooded irrigation treatment combined with the application of 100 kg ha-1 of nitrogen fertilizer, resulting in 12.4 T ha-1 in 2017 and 4.05 T ha-1 in 2018. Increasing the irrigation interval also increased the content of macro elements in brown and white rice. The highest protein content in brown rice was recorded at an average of 9.45% from the flooded irrigation treatment, with the application of 100 kg ha-1 of nitrogen fertilizer, specifically in the native Hashemi variety. The highest phosphorus in brown rice in the treatment of 7 days of irrigation, 75 kg of nitrogen per hectare in Gilaneh cultivar with a rate of 0.303% and the lowest amount in the treatment of 7 days of irrigation with 50 kg of nitrogen and in Gilaneh cultivar with 0.056 percent and the highest percentage of potassium in white rice in the treatment of 14 days of irrigation, 50 kg of nitrogen per hectare and in Hashemi cultivar with the amount of 0.246 percent and the lowest amount in the flooded treatment with Consumption of 50 kg of nitrogen in Hashemi cultivar was 0.143%.ConclusionThe results of this study showed that the application of nitrogen fertilizer has the ability to increase yield and yield components at all three irrigation levels and in both Hashemi and Gilaneh cultivars. In all three levels of irrigation in this study with increasing nitrogen fertilizer application with increasing vegetative growth, increasing the number of spikes per square meter, number of seeds per spike and paddy yield was observed. Consumption of 100 kg ha-1 of nitrogen fertilizer resulted in the highest yield of paddy in both cultivars and all three irrigation levels.
Salinity stress
Khadijeh Sourazar; Raouf Seyed Sharifi
Abstract
IntroductionSalinity is a global challenge issue that is drastically reducing agricultural production. More than 800 million hectares of agricultural land suffer from soil salinity. Intense salinity stress may cause accelerated aging enzymatic and metabolic disorders of the plant. Salinity stress leads ...
Read More
IntroductionSalinity is a global challenge issue that is drastically reducing agricultural production. More than 800 million hectares of agricultural land suffer from soil salinity. Intense salinity stress may cause accelerated aging enzymatic and metabolic disorders of the plant. Salinity stress leads to plant death by reducing photosynthetic carbon dioxide uptake and electron transport activity, chlorophyll degradation, reactive oxygen species (ROS) accumulation, and membrane damage. Methanol is one of the simplest alcohols, which is oxidized in the form of formaldehyde and carbon dioxide in the plant, and is produced in the form of amino acids (serine and methionine) and carbohydrates in various tissues of three-carbon plants (C3). Plants treated with methanol can increase their net absorption rate. Vermicompost provides a great potential to enhance crop productivity besides protecting soil health and environmental sustainability. Its application also enhances the physico-chemical, as well as the organic properties of the soil. Vermicompost is a solid product of organic residues enriched with earthworms and other micro-faunas that provide a significant source of growth regulator hormones, degrading enzymes (such as chitinase, cellulase, lipase, amylase, and proteases), and some essential vitamins. The aim of this study was the investigation the effects of vermicompost and methanol on the activity of antioxidant enzymes, compatible osmolytes and some traits of triticale under saline conditions.Materials and methodsAn experiment was conducted as factorial based on randomized complete block design with three replications in greenhouse research of Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili during 2022. Experimental factors were included salinity in three levels (no salinity as control, salinity 50 and 100 mM by NaCl), application of vermicompost at two levels (without vermicompost as control and application of vermicompost) and methanol foliar application in three levels (foliar application with water as control, foliar application 15 and 30% volume). "Sanabad" cultivar was used. The seeds were placed in a cold incubator (model IKH.RI90) for 12 days at 2°C for vernalization. The amount of vermicompost used in this experiment was 6 tons per hectare (equivalent to 83.08 g.pot-1). In this study, activity of CAT, PPO, POD, soluble sugar, protein, proline, MDA, H2O2, EC, RWC and grain yield were investigated. Electrical conductivity (EC) values were measured using an electrical-conductivity meter (Mi 180 Bench Meter model). The activity of antioxidant enzymes (CAT, PPO and POD) by the method of Sudhakar (Sudhakar et al., 2001), the total protein content of the flag leaf by the Bradford method (Bradford, 1976), the content of soluble sugars by method of Dubios (Dubios et al., 1956), malondialdehyde content by Stewart and Beweley's method (Stewart and Beweley, 1980), proline content by Bates et al.'s method (Bates et al., 1973) and hydrogen peroxide content was measured by the method of Alexieva et al. (Alexieva et al., 2001) on the flag leaf at the flowering stage (61 BBCH). At plant maturity, five plants of each pot were randomly harvested to measure grain yield per plant. Analysis of variance and mean comparisons were performed using SAS9.4 computer software packages. The main effects and interactions were tested using the least significant difference (LSD) test at 0.05 probability level.Results and discussionThe results showed that both application of vermicompost and foliar application of 30% volume of methanol under salinity 100 mM increased the activity of peroxidase (73.4%), polyphenol oxidase (89.6%), soluble sugar (20.3%), protein (38%), proline (101.9%) and relative water content (20.6%) in compared to no application of vermicompost and methanol under the same of salinity level. Application of vermicompost decreased MDA and H2O2 content (9 and 20% respectively) in compared to no application of vermicompost. Foliar application of 30% volume of methanol decreased MDA and H2O2 content (40 and 55% respectively) in compared to no methanol application. Maximum of grain yield was obtained in both application of vermicompost and methanol at 30% volume under no salinity.ConclusionBased on the results of this study, it seems that the application of vermicompost and methanol can increase the grain yield of triticale under salinity stress due to improving activity of antioxidant enzymes and compatible osmolytes.
Drought stress
Fatemeh Hosseini; Sayyed Saeed Moosavi; Mohammad Reza Abdollahi; Ali Sepehri
Abstract
Introduction: Wheat is the most important crop that occupies the most area under rainfed cultivation. Drought stress is the most important factor in wheat yield reduction. The scope of this stress is expanding day by day in the world. Drought resistance is a quantitative trait with a complex ...
Read More
Introduction: Wheat is the most important crop that occupies the most area under rainfed cultivation. Drought stress is the most important factor in wheat yield reduction. The scope of this stress is expanding day by day in the world. Drought resistance is a quantitative trait with a complex phenotype that is affected by plant growth stages. Breeding requirements for resistance to drought stress in wheat are two factors: high genetic diversity among cultivated and wild genotypes of wheat and selection based on traits related to this resistance. One of the important strategies to deal with moisture stress is using wild relatives of wheat, especially the genus Aegilops, as one of the important gene sources containing genes for resistance to environmental stresses. Based on this limitation, the use of wild wheat relatives is one of the important goals of wheat breeding programs. This research aimed to evaluate the relationship between grain yield and 32 different phenological and agro-physiological traits in ten ecotypes of Aegilops tauschii which was carried out under moisture-stress conditions and for two period. Materials and methods: This study was conducted for two consecutive periods in the research greenhouse of the Faculty of Agriculture of Bu-Ali Sina University in Hamedan. In this study, 33 phenological, morphophysiological, and root traits were evaluated in ten ecotypes of diploid wheat Aegilops tauschii (2n=2x=14, DD) under drought stress conditions. These ten different ecotypes of Aegilops tauschii were collected from different geographical regions of Iran.The mentioned ecotypes were evaluated in a randomized complete block design with three replications. At first, the seeds of the plant samples were grown in seedling trays containing equal proportions of perlite and cocopeat. Then, for the vernalization of the plants, after the initial germination of the seeds, in the two-leaf stage of the seedlings, the culture trays were moved to a cold room with a temperature of 4 degrees Celsius for about 35 days. After this stage, the vernalized seedlings were transferred to 10 kg pots, containing a combination of agricultural soil, sand, and rotted animal manure at a ratio of 50, 25, and 25%. After transplanting, the pots were irrigated at 100 percent of the soil's field or pot capacity for about two weeks. Then, in order to apply drought stress treatment, the humidity of the pots was kept at 45% of the field or pot capacity until the plants were harvested, by weighted moisture method. Results and discussion: Economic yield has a positive and significant correlation (p≤0.01) with the traits of grain water use efficiency, peduncle length, plant harvest index, main spike weight, grain weight in main spike, number of fertile spikes per plant, thousand-grain weight, plant height, excited leaf water retention, number of grains per plant, peduncle weight and leaf surface index. This was despite the fact that most of the phenological and root traits had a significant negative correlation with grain yield. According to the stepwise regression results, the traits of grain water use efficiency and the number of fertile spikes per plant with a positive coefficient and the traits of root diameter and days to heading, with a negative coefficient, as the most important traits affecting grain yield, were entered into the regression model respectively. The results of the path analysis indicated that the trait of grain water use efficiency had the most direct and positive effect on increasing grain yield. Also, the trait of water use efficiency, through the trait of day to heading, had the most negative indirect effect on grain yield. Conclusion: According to our findings, the selection based on higher values of grain water use efficiency and the number of fertile spikes per plant and lower values of phenological and root traits may lead to improvement of wheat grain yield under drought stress conditions.
Combined Stresses
Elaheh Seyfipour Naghneh; Najmeh Yarami; Abolfazl Azizian; Gholamhassan Ranjbar
Abstract
Introduction: In the irrigated agriculture of Iran, the quantitative and qualitative limitations of water resources and consequently, drought and salinity stresses, always threaten crop production. This problem exists in most regions of the country. Sesame is one of the oilseed and industrial ...
Read More
Introduction: In the irrigated agriculture of Iran, the quantitative and qualitative limitations of water resources and consequently, drought and salinity stresses, always threaten crop production. This problem exists in most regions of the country. Sesame is one of the oilseed and industrial crops that is somewhat resistant to drought and salinity and its placement in the cultivation pattern can provide some part of the country's need for sesame production and oilseed crops. Sesame is known as the queen of oil seeds because of its high percentage and quality of oil and high properties for health. The aim of this study was to investigate the water productivity, leaf area index, and some physiological traits of sesame Oltan variety including canopy cover temperature, Chlorophyll index, and water potential under simultaneous drought and salinity stresses. Materials and methods: A factorial experiment in randomized complete block design was conducted in Research Farm of Ardakan University during the 2019 to 2020 growing season with three replications. Experimental factors were four salinity levels of irrigation water including 1.5, 4, 7, and 10 dS.m-1 and three drought levels with different irrigation intervals as 4, 8 and 12 days, respectively. During the growing season, leaf area index, canopy cover temperature, and chlorophyll index were measured for four times (35, 50, 65 and 85 days after sowing). Leaf water potential was also measured in the mid-growing season. Water productivity for grain production was also determined. Statistical analysis was done using SPSS version 22 software and averages were compared with Duncan's test at 5% probability level. Results and discussion: Results showed that the irrigation interval had a significant effect on the leaf area index, leaf water potential, grain yield, and water productivity. Irrigation water salinity had a significant effect on all of the studied traits, the interaction of the drought and salinity stresses was not only significant on SPAD index. Increasing the irrigation interval from 4 to 12 days and increasing water salinity from 1.5 to 10 dS m-1 decreased the maximum leaf area index of sesame by 49% and 58%, respectively. Also, an increase in salinity from 1.5 to 10 dS.m-1 resulted in 18% increase in leaf temperature, 40% decrease in SPAD index, and 17% decrease in leaf water potential. The increase in drought stress also had no significant effect on leaf temperature, while it caused 14% increase in SPAD index and 15% decrease in leaf water potential. Increasing the irrigation interval from 4 to 8 and 12-day caused a 67 and 68% significant decrease in grain yield, respectively. There was no significant difference in the grain yield of 8 and 12-day irrigation interval. Increasing the water salinity from 1.5 to 4, 7, and 10 dS.m-1 decreased the grain yield by 35, 80, and 96%, respectively. Increasing the irrigation interval from 4 to 8 and 12 days caused a 55 and 51% decrease in water productivity, respectively. This index decreased significantly (95%) by increasing water salinity from 1.5 to 10 dS.m-1. Conclusion: Water productivity and maximum leaf area index decreased significantly by increasing water salinity and irrigation interval. An increasing trend in leaf temperature was observed with increasing salinity, which is due to the decrease in plant transpiration under exposure to salinity stress. The SPAD index showed a decreasing trend with the increase in salinity, while the increase in drought stress (increasing the irrigation interval) caused an increase in this index. Sesame leaf water potential also decreased by increasing salinity and drought stresses. Generally, results showed that leaf area index and studied physiological traits of sesame were more affected by water salinity stress than drought stress. The results of interaction also showed that in all investigated traits, except for leaf water potential, no significant difference was observed between 8 and 12-day irrigation interval at all salinity levels. In 1.5 and 4 dS.m-1 salinity levels, the difference in grain yield and water productivity were significant in 4 and 8-day irrigation interval, while there was no significant difference in 7 and 10 dS.m-1 salinity levels. Although the highest grain yield and water productivity were observed in the 4-day irrigation interval and 1.5 dS m-1 salinity level treatment, based on the results of physiological traits, grain yield, and water productivity of sesame, especially under water shortage conditions, it is recommended to use 12-day irrigation interval instead of 8-day because there was no significant difference in the water productivity.
Cold stress
Fatemeh Mohamadi Azar; Omid Sofalian; Ali Asghari; Asghar Ebadi; Rahmatollah Karimizadeh
Abstract
IntroductionWheat is one of the most important crops and an essential source of calories and protein in the world. Food security depends on agricultural production to supply the growing world population with certain nutrients. Plants are often exposed to stressful conditions. Stress can occur within ...
Read More
IntroductionWheat is one of the most important crops and an essential source of calories and protein in the world. Food security depends on agricultural production to supply the growing world population with certain nutrients. Plants are often exposed to stressful conditions. Stress can occur within minutes, days, or even months. Temperature is the most important environmental variable that affects the growth, development, and final productivity of agricultural grain products. Cold or freezing temperatures cause a lot of damage to agriculture, especially in cereal crops in subtropical and temperate regions. Most of the world's wheat fields are often under low-temperature stress. The ability of plants to tolerate cold without damaging their growth cycle is called cold tolerance. Crop plants, including wheat, tend to overcome cold stress through cold adaptation. In winter cereals, low-temperature stress in the vegetative stage causes chlorosis and wilting of leaves and eventually leads to necrosis and growth inhibition. Wheat needs an ideal temperature range for growth and ideal performance, and any deviation from it affects the natural growth process. In general, winter cereals like wheat have two varieties, sensitive to cold and resistant to cold. Numerous studies show that the intraspecies genetic diversity of wheat has not yet been fully exploited. The purpose of this study is to investigate the diversity of durum wheat lines under conditions of freezing stress, identify cold-resistant lines in durum wheat based on some morphophysiological traits, and determine the relationship between durum wheat traits and cold tolerance.Materials and methodsFreezing and laboratory experiments were carried out in the greenhouse and plant breeding laboratory of Mohaghegh Ardabili University in 2019 on 45 durum wheat genotypes as a factorial experiment in the form of a randomized complete block design with three replications. In this experiment, four control temperature treatments (without freezing), -8, -10 and -12 degrees Celsius were investigated. LT50 of several applied temperatures (-8, -10, and -12), and by analyzing Probit was calculated for each genotype. The mean comparison was done with the LSD method at the five percent probability level. Lines grouping was done by Ward's clustering method using the square measure of Euclidean distance.Results and discussionThe highest amount of LT50 trait was observed in genotype number 44, and the lowest amount was observed in genotype number 36. LT50, survival percentage, height, fresh weight of shoots, dry weight of shoots, saturated weight of shoots, number of leaves, relative water content, and electrolyte leakage were investigated. The correlation was calculated separately in stress levels. Lines with high height in terms of LT50 trait were also included in the group of resistant lines. Multivariate variance analysis based on unbalanced one-way variance analysis was used to determine the most favorable groups. The lines were placed in four groups in the control conditions, the stress of -8, and -12°C, and in five groups in the -10°C stresses. The traits of shoot weight, number of leaves, relative leaf water content and electrical conductivity had an important role in the average of the groups. Decomposition into factors was done in separate stress levels. Four factors were selected in control levels, and -8°C stress, and three factors were selected in the -10°C, and -12°C stress levels.ConclusionIn general, lines 35, 40, and 44 were recognized as lines with higher averages in all clusters, and lines 4, 5, 6, and 20 were placed in groups with lower averages. The traits of shoot weight, number of leaves, relative leaf water content, and electrical conductivity had an important role in the average of the groups. According to the final results of the study, lines 17, 24, 27, 35, 38, and 40 were recognized as resistant lines. Lines 3, 12, 18, 20, and 44 were found to be sensitive.AcknowledgmentsWe sincerely thank Gachsaran Agricultural Research Institute and Maragheh dryland Agricultural Research Institute for providing the studied lines seeds.
Salinity stress
Elham Afsharnia; Alireza KhavaninZadeh; Mehdi Karimi
Abstract
IntroductionWater and soil salinity is one of the most important environmental factors limiting the growth and performance of plants around the world, especially in arid and semi-arid regions. The increase in population on the one hand and the decrease of fresh water and soil resources on the other hand ...
Read More
IntroductionWater and soil salinity is one of the most important environmental factors limiting the growth and performance of plants around the world, especially in arid and semi-arid regions. The increase in population on the one hand and the decrease of fresh water and soil resources on the other hand has doubled the necessity of studying in relation to the identification of salinity resistant plant species and strategies for the efficiency of saline soil and water resources. Therefore, this study was conducted with the aim of finding and determining the salinity resistance of artichoke plant species and the growth rate of the species under different conditions of irrigation water salinity and evaluating the performance of vegetative and physiological growth parameters in field conditions in order to use this plant in areas with limited water salinity.Materials and methodsIn order to evaluate the salinity resistance of the artichoke medicinal plant species and to determine the salinity resistance of this species, an experiment was conducted with six salinity levels including (control), 9, 12, and 15 dS m-1 in a completely randomized design and in three replications in potted conditions. Four weeks after applying salinity stress, traits including photosynthetic pigments, dried leaves, leaf water content, leaf dry weight, ash content, SLA were measured. Finally, significant difference at 5 percent level statistically were calculated among treatments using analysis of variance and mean differences was calculated using Multiple Duncan test.Results and discussionResults showed that salinity treatment has a significant effect on the characteristics of total chlorophyll, percentage of dryness and leaf fall, percentage of leaf ash, leaf specific weight and moisture content of leaves at the level of five percent, and the Artichoke plant can tolerate salinity up to 9 dS m-1 but it is sensitive at higher levels of salinity. In other words, the salinity of 12 dS m-1 has reduced the germination of Artichoke species by more than 50% and caused a significant increase in ash percentage, as well as drying and leaf fall percentage by 50%, and significant decreasing in leaf water content, dry root weight while it significantly increased electrolyte leakage which can indicate a significant decrease in vegetative growth and performance of this species at this level of salinity. According to the results, per unit increase in salinity, the weight loss of Artichoke leaves was recorded as 11%. In general, Artichoke plant species, in terms of resistance to salinity, it has a relatively good tolerance, and it seems this plant species can be used for cultivation and production by using saline water sources up to 9 dS m-1 in condition of the study area.ConclusionsThe results showed that there is no significant difference in yield and growth of Artichoke by increasing water salinity up to 9 dS m-1 in the study area. In farm and pod condition, experimental treatments showed a significant effect on increasing leaf fall, ash and water content, leaf dry weight by increasing water salinity to 12 dS m-1 . In general, Artichoke as an important medicinal plant, is a moderate up to tolerant species in salinity and it seems it is a proper species for cultivation and plant production in area with saline water up to 9 dS m-1 in condition of study area. According to the results, it seems water salinity up to 12 dS m-1 significantly decreases vegetative growth of the species up to 50% but it is a need more studies for impact of salinity on flowering and seeding stages as well. we recommend more studies in different climate conditions to reveal impact of these conditions on salinity resistance of the plant species.AcknowledgementsWe thank the National Salinity Research Center for their cooperation in the implementation and providing water and land for experiments in this study.
Cold stress
Toktam Ahmadi; Seyed Hossein Nemati; Jafar Nabati
Abstract
IntroductionCold and freezing temperatures can cause serious damage to the potato plant (Solanum tubersum L.) and decrease yield. In intense cases, the cold stress can even destroy the entire production. Most potato cultivars are sensitive to cold, and temperature plays a crucial role in their geographic ...
Read More
IntroductionCold and freezing temperatures can cause serious damage to the potato plant (Solanum tubersum L.) and decrease yield. In intense cases, the cold stress can even destroy the entire production. Most potato cultivars are sensitive to cold, and temperature plays a crucial role in their geographic dispersal. Physiological responses of plants to cold stress include increased calcium transfer, changes in membrane lipid composition, enhanced antioxidant capacity, and accumulation of osmotic protectors. Compatibility, which involves the aggregation of cold-protecting polypeptides and osmolytes, is the primary method that plants use to cope with cold stress. Cold-compatible plants often store higher levels of soluble carbohydrates in their underground tissues. This study was conducted to investigate the mechanisms of cold tolerance in four potato cultivars: Agria, Fontane, Arinda, and Santé, highlighting the importance of cold stress to potato plants.Materials and methodsThe study was conducted using a completely randomized design with four replications. The factors considered were temperature (4, 2, 0, -2, -4°C) and potato cultivars (Agria, Fontane, Arinda, and Sante). To evaluate the response to cold, six-week-old seedlings were transferred to a thermogradient freezer with darkness and a temperature of five degrees Celsius. The temperature gradually decreased at a rate of two degrees Celsius per hour, and the seedlings were exposed to the desired temperatures (-4, -2, 0, +2, +4 °C) for one hour. Two weeks after exposure to cold stress, the percentage of survival, plant height, and the highest shoot dry weight of the cultivars were recorded. The content of malondialdehyde (MDA), soluble carbohydrates, total phenols, proline, catalase enzyme activity, peroxidase, and superoxide dismutase were evaluated. The statistical analysis was performed using Minitab v.17.3.1 software, and mean comparison was conducted using Duncan's multi-range test at a five percent probability level with standard error.Results and discussionThe results revealed that the survival rate in cultivar Santé significantly decreased with decreasing temperature. Cultivar Fontane exhibited a higher survival rate than other cultivars at a temperature of -4°C. The phenol content in cultivar Santé at -2°C was 81% higher than in cultivar Fontane. In cultivar Sante, the proline content increased fourfold as the temperature decreased from 4 to 0°C. In cultivar Fontane, the proline content increased with a temperature decrease from 4 to -2°C and then decreased with further temperature reduction. The soluble carbohydrate content increased with a temperature decrease in cultivars Santé, Arinda, and Agria, while it decreased in cultivar Fontane. Cultivar Santé exhibited the highest increase in MDA (malondialdehyde) content, whereas cultivar Fontane showed the lowest increment when the temperature decreased from 4 to -4°C. Regarding enzyme activities, the CAT (catalase) enzyme activity increased 9.2-fold in cultivar Santé at a temperature of 0°C. In cultivar Fontane, the highest CAT enzyme activity was observed at 2°C. The POD (peroxidase) enzyme activity showed the highest increase in cultivar Santé with a temperature decrease to -2°C. In cultivar Fontane, the SOD (superoxide dismutase) enzyme activity decreased with a temperature decrease to 2°C and then increased by 80% with further temperature reduction to 0°C. After exposure to cold stress, plant height decreased in cultivars Santé and Agria compared to the control, while it increased in cultivar Fontane with a temperature decrease. The highest shoot dry weight was observed in cultivar Fontane at a temperature of -4°C, whereas the lowest shoot dry weight was observed in cultivar Sante.ConclusionGenerally, this study showed that cultivar Santé is more sensitive to cold than cultivars Agria, Fontane, and Arinda. On the other hand, cultivars Fontane and Agria were found to be more tolerant. The studied metabolites and antioxidant compounds of cultivar Fontane were more significant under cold stress conditions, indicating more efficient defensive mechanisms compared to other cultivars. This ultimately resulted in better cold tolerance for cultivar Fontane.
Drought stress
Hamid Najafinezhad; Mohammad Ali Javaheri; Nader Koohi
Abstract
IntroductionLack of fodder for feeding livestock is one of the main problems of dry areas, especially in the southern regions of Iran. In this situation, the climate changes and the decrease of rainfall in the southeast of the country in recent years, have doubled the important of compatible plants with ...
Read More
IntroductionLack of fodder for feeding livestock is one of the main problems of dry areas, especially in the southern regions of Iran. In this situation, the climate changes and the decrease of rainfall in the southeast of the country in recent years, have doubled the important of compatible plants with the potential to produce fodder in water shortage conditions. Fodder cactus is a drought-resistant plant that adapts to dry and low-water conditions as a source for fodder production in dry areas. This research was conducted to explore the effect of drought stress on yield, water productivity, and some agronomic characteristics of cactus as a new crop in the climatic conditions of Shahmaran region of Kerman, Iran. Materials and methodsThe experiment was carried out in the form of randomized complete block design with four replications. Three treatments of normal irrigation, moderate and severe drought stress were considered based on 160, 210 and 260 mm cumulative pan evaporation. The cladodes (Opuntia ficus-indica) used for planting, originating from Tunisia. In each plot, 32 cladodes were planted at a distance of 2 meters between rows and 1.5 meter between cladodes on a row. At the time of irrigation of each treatment, volumetric soil moisture was measured at the active depth of root development using a calibrated Time-Domain Reflectometry device (Trime-FM, IMKO, Ettlingen, Germany). To calculate the fodder yield of cactus, the cladodes produced on plants in each plot were harvested and weighed. For measuring the length, width, and thickness of the cladode in each plot, 10 cladodes were randomly selected, and the average of each trait was finally determined. Results and discussionThe number of pads produced under the influence of drought stress was significant. The highest number of pads per plant was observed in the normal irrigation treatment (27.7 pads per plant) and the lowest in the severe drought stress treatment (15 pads per plant). The maximum thickness of the pad under normal irrigation condition was 2.4 cm and the minimum thickness was observed under severe drought stress condition. The main reason in reducing the thickness of the pad in water stress condition was the decreasing of the pad moisture content.The effect of drought stress on the length and width of the pad, was significant. Minimum length and width of the pad was observed with 29.5 and 18 cm in severe drought stress treatment and the maximum with 37.7 and 24.7 cm in normal irrigation treatment.The percentage of pad dry matter at the time of sampling was significantly affected by water stress treatments. The dry matter percentage was the lowest in the normal irrigation treatment with 8% and the highest in the severe water stress treatment with 12.7%.The weight of the each pad and the yield of wet and dry fodder per hectare were significant under the influence of different water stress treatments. The wet weight of the pad per plant was the highest in the normal irrigation treatment with 1245 g and the lowest in the severe water stress treatment with 870 g. Normal irrigation treatment produced the highest yield by producing 112 and 8.97 t.ha-1 of fresh and dry fodder, respectively. The lowest wet and dry yield belonged to severe water stress treatment with production of 46.77 and 6.05 t.ha-1.The highest water productivity for wet and dry cactus fodder was 41.02 and 3.29 kg m-3 respectively, which belonged to the normal irrigation regime. There was no significant difference between moderate and severe water stress treatments for dry fodder in terms of water productivity. ConclusionOverall, the research results showed that drought stress has a significant effect on fodder yield, water productivity, cladode thickness, cladode length and width, cladode weight, and crude protein of cactus fodder. Despite the physiology of the cactus and its resistance to water stress, with the increase of drought stress, the wet and dry yield, water productivity, and fodder protein content showed a significant decline. According to the results, reduction of 58.2% in wet fodder yield and of 32.5% in dry fodder yield were seen in severe drought stress treatment compared to normal irrigation. The average water consumption was 2507.6 m3.ha-1. According to the results, in order to benefit from the potential of the cactus to produce fodder, it is necessary to avoid long-term and severe drought stress. The vegetative growth period of cactus was mainly found in spring and early summer. With the cooling of the air from late fall to early March, the plant is going to be entered the stage of growth stagnation. Due to the evergreen nature of the plant, the fodder of this plant can be used for feeding livestock in the fall and winter seasons, when there is a lack of fresh fodder. This research determined that there is a possibility of growing and developing cactus plant as a new plant in Shahmaran region with a subtropical climate. Also, through cultivation of this plant with low water consumption, part of the fodder shortage for livestock in Kerman province can be resolved.
Breeding plants for stress conditions
Ahmad Shahizadeh; Rasool Asghari Zakaria; Marefat Ghasemi K.; Parisa Sheikhzadeh Mosaddeq
Abstract
IntroductionDrought stress is the most critical cause of wheat yield reduction in semi-arid regions. Drought affects wheat yield somewhat during the growing season, but yield reduction predominantly occurs during the reproductive and grain-filling stages. This research aimed at the identification of ...
Read More
IntroductionDrought stress is the most critical cause of wheat yield reduction in semi-arid regions. Drought affects wheat yield somewhat during the growing season, but yield reduction predominantly occurs during the reproductive and grain-filling stages. This research aimed at the identification of end-season drought stress-tolerant wheat genotypes based on tolerance and sensitivity indices using the ideotype genotype selection index (IGSI) and the multi-trait genotype–ideotype distance index (MGIDI) multi-trait selection indices.Materials and methodsIn this study, 18 bread wheat genotypes and two control cultivars were evaluated based on a randomized complete block design with three replications under two conditions: full irrigation and end-season drought stress. The experiment was conducted at the Ardabil Agricultural Research Station during the 2021-2022 season. The genotypes were sown in plots of 2.5 m × 3 m with a row spacing of 20 cm. The full-irrigation treatment received 100% of the crop's water requirement, while in the drought stress treatment, the irrigation stopped after heading. Standard agronomic practices were followed throughout the growing season and data on traits such as yield were recorded. Tolerance and stress indices, including tolerance index (TOL), mean productivity (MP), stress tolerance index (STI), modified stress tolerance index (MSTI), geometric mean productivity (GMP), harmonic mean (HM), stress susceptibility index (SSI), yield index (YI), yield stability index (YSI), and yield reduction percentage (YRP) were calculated. Statistical analysis was performed using ANOVA, and the means were compared using the least significant difference (LSD) test at the 5% probability level. Additionally, IGSI and MGIDI selection indices were also determined to evaluate the drought tolerance of the genotypes.Results and discussionThe experiment results indicated that based on lower YRP, TOL, and SSI indices, genotypes 11, 5, 9, and 10 were selected as tolerant genotypes. Nevertheless, genotypes 12, 2, 1, and 6 were superior based on higher STI and Harm indices. Also, genotypes 12, 1, 11, and 3 were best in the k2STI and YI indices. Additionally, genotypes 14, 4, 2, and 6 were tolerant based on the k1STI index, genotypes 11, 9, 5, and 10 in the YSI index, genotypes 2, 12, 14, and 4 in the MP index, and genotypes 12, 2, 4, and 1 in the GMP index. Using the multivariate selection indices of the IGSI and MGIDI, genotypes 11, 5, 1, and 12, with the highest IGSI value and the lowest MGIDI value, are among the genotypes with high end-season drought stress tolerance. This was confirmed through heat map cluster analysis and bi-plot diagram in principle components analysis. Also, genotypes 20, 16, and 19, having the lowest value of IGSI and the highest MGIDI, showed higher sensitivity to drought stress. The comparison of the means of the selected genotypes with the total means showed that these genotypes under the end-of-the-season drought stress conditions performed better in stress conditions (with higher Ys) and had less yield reduction compared to the average of other genotypes.ConclusionThe ideotype genotype selection index (IGSI) and the multi-trait genotype–ideotype distance index (MGIDI) for different genotypes based on the quantitative indices of tolerance and stress show that genotype 11, having a high value of IGSI and the lowest value of MGIDI is the most tolerant to end-season drought stress. The genotypes 5, 1, and 12 were ranked next. Based on these results, it is clear that different genotypes exhibit varying levels of drought tolerance based on the indices evaluated. Overall, the results of this experiment provide valuable insights into the potential for improving drought tolerance in wheat through the selection of tolerant genotypes using IGSI and MGIDI indices. The selected genotypes can be further evaluated for their agronomic and physiological traits to confirm their suitability for cultivation in drought-prone areas.
Cold stress
Leila Sadooghi; Aliakbar Noroozi; Ali Mohammadi Torkashvand; Ebrahim Pazira
Abstract
IntroductionCooling stress has led to irreparable damage to the paddy fields of Gilan province. Climate research has shown the prevalence of increasing climate-related hazards including frost, drought, hail, and flood. Environmental stresses, including frost, affect different rice growth stages and affect ...
Read More
IntroductionCooling stress has led to irreparable damage to the paddy fields of Gilan province. Climate research has shown the prevalence of increasing climate-related hazards including frost, drought, hail, and flood. Environmental stresses, including frost, affect different rice growth stages and affect the morphological and physiological characteristics of rice. Cooling stress is a major risk to be managed and quantitative determination of cooling stress hazard is very serious in realizing the hazard and planning to reduce it. In developing countries such as Iran, meteorological stations are usually scattered. For this reason, they use sensors such as MODIS, that are free and available to help compensate for these deficiencies. Nowadays, remote sensing technology and satellite data provide an opportunity to achieve high-resolution data. Therefore, with the development of GIS and remote sensing, real-time cooling stress monitoring can be achieved in large areas. Also, we used interpolation models so scattered observations can be converted into continuous prediction maps of the entire study area. The objective of this research is to investigate the cooling stress hazard in different rice growth stages, using remote sensing technology and MODIS satellite images in Gilan province.Materials and methodsIn this research, the MOD11A1 product provides daily land surface temperature (LST) data used from the MODIS sensor, and the coordinates of meteorological stations in Gilan province and the required data from these stations during the statistical period from 2000 to 2017 were obtained from the Meteorological Department. The rice growth stage was determined based on the information and statistics of the province and using MODIS sensor images and according to the critical temperature limit below which the plant experiences cold stress.Results and discussionCooling stress hazard zoning maps in ArcGIS software, according to the number of days when the cooling stress hazard in each of the plant growth stages (the germination, the seedling, the vegetative, and the reproductive stages) occurred in the region prepared. According to the root mean square error (RMSE) and coefficient of determination (R2) obtained, among the different interpolation methods, In different rice growth stages, the IDW method was chosen to prepare the zoning map.Then, the hazard zoning map was prepared according to the cooling stress hazard classification for the rice crop in different plant growth stages between 2000 and 2017 using the IDW method. Five different classes of cooling stress hazard rice were considered as very low, low, medium, high, and very high.ConclusionBased on the cooling stress hazard zoning maps during the 17 years investigated in the studied area, in the germination, seedling, vegetative, and reproductive stages, it showed that the highest cooling stress hazard is related to the altitudes of 1000 to 2000 meters in the mountainous areas, and during the growth stage germination and reproductive, the amount of this hazard is very high and we should choose the appropriate date for the germination period and every as we get to the sea, the level of hazard in all growth stages, even in the growth stages of germination and reproductive, is low and very low.
)
