Drought stress
Pari Hasanvand; Golam Reza Zamani; Ali Akbar Maghsoudi Moud
Abstract
IntroductionOilseeds are the second main source of human food after cereals. Safflower is an oilseed crop with favorable and unique characteristics that make it a valuable oilseed crop. Safflower due to having long roots and the high ability for absorbing water from deep soil layers, is considered as ...
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IntroductionOilseeds are the second main source of human food after cereals. Safflower is an oilseed crop with favorable and unique characteristics that make it a valuable oilseed crop. Safflower due to having long roots and the high ability for absorbing water from deep soil layers, is considered as a low water-tolerant plant; but after the rosette stage, it becomes more sensitive to water stress such that since the first signs of inflorescence emergence up to the middle of the grain-filling period, it shows more sensitivity to this kind of stress. Increasing need for oil production on one hand and increasing levels of drought due to world climatic changes on the other hand makes it necessary to seek for more water stress tolerant plants such as safflower with relatively high yield capacity under low water content areas. Meanwhile the area under cultivation of safflower should increase. Agricultural and environmental factors can affect safflower seed yield and seed oil content. Therefore, it is important to investigate different environmental factors and their effects on growth and yield performance of safflower plants. Limitations of water resources makes it more difficult to grow safflower plants. Furthermore increasing levels of per capita oil consumption in Iran indicates that oilseed production must increase. Therefore, One of the objectives of this research was to identify and evaluate species and cultivars resistant to water stress and to find the plant stages sensitive to water stress.Materials and methodsIn order to evaluate the effects of water stress on some morphological, yield and yield components of different safflower cultivars, an experiment was carried out as split plots based on randomized complete blocks design with three replications at the experimental field 56° 58' E; 30° 15' N; 1754 meters above sea level of Faculty of Agriculture, Shahid Bahonar university of Kerman, Iran during 2019-2020 growing season. Water stress applied at three levels including 40, 60 and 100% of full crop water requirement in the main-plots and 6 Iranian safflower cultivars including Faraman, Goldasht, Golmehr, Parnian, Padideh and Sina assigned to the sub-plots. Physical and chemical properties and nutrient elements content of the soil before planting were measured using samples taken from of 0-30 cm soil depth of experimental location. Seeds planted manually and plots fully irrigated immediately after planting. Thereafter, plants irrigated throughout the growth period based on the calculated values of the water requirement of the plant.Results and discussionBased on results, the treatment 40% of the plant water requirement had a significant reduction effect compared to other treatments of water stress on the studied traits in all investigated cultivars. The results Data analysis showed that water stress had not a significant effect on lateral branch number, but it causes a significant reduction in all traits, Including the plant height, number of heads per plant, number of seed per head, head diameter, 1000 seed weight, seed oil content, oil yield and seed yield. Significant differences found among cultivars in term of all other plant characteristics. Meanwhile, Highest values of 1000 seed weight (37.2 g), oil yield (461.8 kg.ha-1) and seed yield (1592.6 kg.ha-1) observed in Faraman cultivar. The Interaction effects between irrigation treatment and cultivar were significant in case of number of heads per plant, number of lateral branches, oil yield and seed yield. However, the Faraman cultivar had more grain yield potential in water stress conditions than the other investigated safflower cultivars.ConclusionGenerally, results showed that the reaction of the six cultivars investigated in terms of plant height, number of heads per plant, number of seed per head, number of lateral branches, 1000 seed weight, head diameter, seed oil content, oil yield and seed yield were affected by water stress. The highest values of 1000 seed weight, oil yield and seed yield among the investigated safflower cultivars were related to Faraman cultivar. Meanwhile, cultivar Faraman showed higher seed yield potential under water stress conditions compared to the other cultivars. Therefore, to achieve higher yield, Faraman recommended to be grown under low soil water content condition.
Drought stress
Safora Dehbalaei; Ali Ashraf Mehrabi; Abbas Maleki; Mohammad Mehdi Poursiahbidi
Abstract
IntroductionWheat (Triticum aestivum L.) is one of the main crops of the cereal family, which is widely cultivated in the world and brings energy and protein to human society. Drought is the most important non-living stress in crops and due to the decrease in annual rainfall and increase in temperature, ...
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IntroductionWheat (Triticum aestivum L.) is one of the main crops of the cereal family, which is widely cultivated in the world and brings energy and protein to human society. Drought is the most important non-living stress in crops and due to the decrease in annual rainfall and increase in temperature, production and cultivation of tolerant cultivars with high yield potential will be very important. While available water for agriculture is becoming more limited, the production of drought tolerant cultivars is very important and should be considered. The aim of this study was to analyze the stability of quantitative and qualitative yield and to analyze the stability of bread wheat genotypes in rainfed and irrigated planting conditions in the form of field farms in 3 crop years 2016-2017, 2017-1996 and 2017-17 in Sarableh Agricultural Research Station located in the province. Ilam was implemented.Materials and methodsThis research was conducted as two independent experiments, each in the form of a randomized complete block design with three replications. The first factor includes planting in irrigated and rainfed conditions. The second factor also included 20 wheat genotypes. In irrigated conditions, irrigation was done according to the needs of the plant (normal) and in another experiment, only atmospheric benzoate was sufficient. In this study, yield stability was measured based on drought resistance and its effective traits in different bread wheat genotypes and quantitative and qualitative yield. Data were analyzed using SAS software version 22 for combined analysis and comparison using the least significant difference test (LSD).Results and discussionThe results showed that the highest grain yield in irrigated planting medium was related to SUP152 genotype (3245 kg ha-1) which was not statistically significant different from WHEAR genotype which was in the second category. The MILAN/SHA7 genotype was also in the third place. These three genotypes also had high values in terms of yield components. The highest grain protein in irrigated planting medium belonged to REEDLING # 1 genotype with 11.73% which was not statistically significant difference with FRNCL and SAAR genotypes which were in the second and third ranks. The lowest grain protein in aqueous medium belonged to WHEAR genotype. The highest grain protein was obtained in the dryland medium of GASPARD genotype (13.73%). ND643 genotype was also in the second category but there was no significant difference with the first category genotype. Gonbad genotype was also in the third category and was one of the top genotypes. The highest grain yield was obtained in the dryland planting medium related to PBW343 genotype at the amount of 2051 kg ha-1. The lowest grain yield in dryland environment was related to PAURAQ genotype at 1457 kg ha-1. PBW343 genotype was one of the best genotypes in terms of yield components in rainfed planting environment. Distribution of hybrids based on YS, YP and MP and GMP indices showed that WHEAR, MILAN, CHIBIA// PRLII, PBW343 and SOKOLL3 genotypes are in group A and are water resistant and have high grain yield in both environments. And were selected as superior genotypes for both rainfed and irrigated environments.
Drought stress
Sadegh Nasirpour; Mohammadreza Jahansouz; Ali Ahmadi; Esmaeil Afshoon
Abstract
IntroductionMaize (Zea mays L.) is ranked fourth among cereals in terms of area under cultivation and grain yield after wheat, barley and rice. Water scarcity or water stress is one of the most limiting factors in crop growth and crop yield, which reduces the average yield by 50% and even higher values. ...
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IntroductionMaize (Zea mays L.) is ranked fourth among cereals in terms of area under cultivation and grain yield after wheat, barley and rice. Water scarcity or water stress is one of the most limiting factors in crop growth and crop yield, which reduces the average yield by 50% and even higher values. Water stress in corn through adverse effects on inoculation and grain filling, reduced plant photosynthesis, reduced amount of material grown and as a result of grain shrinkage, reduced leaf area and disrupting physiological processes, reduces the number of grains per ear, weight Thousands of seeds, bio-yield and grain yield. Conservation tillage is one of the inevitable methods of conservation agriculture by which the effect of water stress on plant growth and yield can be reduced. In agro-ecosystems, conservation tillage, while preserving and improving water resources and the environment, improves crop production and makes it sustainable. Since Iran is located in the arid and semi-arid region of the world and drought has a negative impact on the yield of its products, the study of water stress and strategies to deal with it is of particular importance; Therefore, the purpose of this study was to investigate the yield response and yield components of maize to tillage systems and irrigation regimes in Karaj. Materials and methodsIn order to evaluate the effect of different tillage systems and irrigation regimes on corn yield, an experiment was conducted as split-plot in the form of randomized complete blocks with three replications in the research farm of the University of Tehran (longitude 35 degrees East, latitude 35 degrees and 48 Minute North) in 2016. The main factor in this experiment was tillage with two levels (no-tillage and conventional tillage) and the second factor was irrigation with three levels (without water stress, moderate water stress and severe water stress based on 75, 110 and 150 mm evaporation from Evaporation pan surface, respectively). Irrigation was done using plastic tapes (type) and the irrigation volume was controlled by the meter. Irrigation treatments were applied from the 4-leaf stage. The distance between the main, sub-factors and blocks (replicates) was 10, 2 and 10 meters, respectively, and there were six 10-meter planting lines within each experimental plot. Also, the distance between rows of corn in the plots was 75 cm and the distance between plants per row was 15.5 cm (density of 86,000 plants per hectare). To determine the water requirement, the Class A evaporation pan method was used and using daily meteorological data, Equations 1 and 2 were used:ETC = KC × ET0 (Eq. 1)ET0 = K p × E pan (Eq. 2)in them, ETc = Evapotranspiration of the desired crop (mm.day-1), KC= Plant coefficient, ET0= Reference evapotranspiration (mm.day-1), Kp= Plate coefficient (without unit), E pan= Evaporation of the pan (mm.day-1)ResultsThe results showed that the effect of tillage and tillage interaction at irrigation levels on any of the traits was not significant, but the effect of irrigation regimes on plant height, number of seeds per ear, 1000-seed weight, ear weight, grain yield, Biological yield, harvest index and water use efficiency were significant. The highest plant height was obtained in conditions without water stress (217 cm). Also, the highest number of seeds per ear was obtained under normal irrigation conditions, so that the application of severe stress reduced the number of seeds per ear by 26%. Severe water stress reduced the weight of 1000 seeds by 12%. Also, the weight of ear decreased by 38% compared to normal irrigation in severe stress and reached 151 g. The highest grain yield in normal irrigation was 12471 kg.ha-1, which severe stress reduced grain yield by almost 40%. A similar trend was observed in biological yield, with severe water stress reducing by 29%. In terms of water use efficiency, severe water stress increased it to 2.21 kg.m-3, which showed a growth of 31% compared to normal irrigation.ConclusionThe results of this study showed that the tillage system had no significant effect on any of the traits, but water stress had a negative effect on all traits except water use efficiency, so that plant height, 1000-seed weight, Number of seeds per ear, ear weight, grain yield, biological yield and harvest index decreased sharply but water use efficiency increased compared to treatment without water stress. Based on the results of this study, corn irrigation based on 75 mm of evaporation from the evaporation pan surface in similar climatic conditions is 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
Samira Gholipur Noveyri; Golam Reza Zamani; Majid Jami Al-Ahmadi
Abstract
IntroductionReduce moisture levels are the most important factor, which limit growth and yield production in arid and semiarid regions. Sesame is usually a plant in arid and semi-arid regions that is exposed to various stresses during its growth period. Depending on the plant susceptibility, each of ...
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IntroductionReduce moisture levels are the most important factor, which limit growth and yield production in arid and semiarid regions. Sesame is usually a plant in arid and semi-arid regions that is exposed to various stresses during its growth period. Depending on the plant susceptibility, each of the stresses can have different effects on their growth, metabolism and function. Drought stress affects a vast range of plant morphological, physiological and biochemical characteristics, for example, it results in altered water relations, suppressed cellular activities reduced content of chlorophyll and carotenoids induced generation of reactive oxygen species (ROS). Proline plays a major role in osmotic adjustment and protects the cells by scavenging reactive oxygen species (ROS). While Application of some elements reduces the negative effects of stress, including calcium ion, which has significant effects on the physiological processes of plants and improves morphological and biochemical traits of plants under stress. In recent years, several reports have been suggested to increase plant tolerance to stresses, such as the use of growth regulators and the relationships between polyamines and environmental stresses. The most important polyamines include putrescine, spermidine and spermine. Some of the physiological processes such as cell division and plant development could be altered by these growth regulators. Putrescine accumulates in plant tissues during stress, causing plants to withstand abiotic stresses, including drought.Materials and methodsIn order to study the effects of Putrescin and Calcium Nitrate application on some physiological and biochemical traits of sesame under different moisture levels a Spilt plot- factorial experiment was conducted based on block complete randomized design with three replications in research farm of Birjand university in 2018. In this experiment, Moisture levels treatments with tree levels were (100%, 75%, and 50%) as main factor and foliar application Calcium nitrate at tree levels (0, 5, 10 Mm) and Putrescine in two levels (0.5 Mm, spray with water) as the second factor were studied. In this experiment traits measured including chlorophyll a, chlorophyll b, chlorophyll index, Proline, number of grain per plant, number of capsule per plant, thousand–seed weight and grain yield. Results and discussionThe results of ANOVA showed that the interaction of Moisture levels × calcium nitrate × putrescine had significant effect on chlorophyll a, chlorophyll b, chlorophyll index, Proline, number of grain per plant, number of capsule per plant, and grain yield. Drought stress has had a significant effect on sesame seed yield and severe stress resulted in a decrease in seed yield. The highest grain yield respectively was obtained from 100% and 75% water requirement levels and the lowest with an average of (376.8 kg ha-1) from 50% water requirement. The highest proline was obtained from 50 percent water requirement and the lowest with from 100% water the difference between the minimum value and the maximum value was 64%.Interaction of calcium nitrate and putrescine on thousand–seed weight was significant (P≤0.05). The results also showed that the highest grain yield on all measured traits obtained when using foliar application of calcium nitrate (10 Mm) and putrescine. ConclusionsIt was observed that sesame has had a relative tolerance to moisture restriction so that 75% of water requirement stress could not have a significant effect on yield and yield components and stress of 50% water requirement was caused 40% reduction in grain yield in this plant. It was also observed that moisture stress led to has been increased proline production in the plant. Causes of increased proline content at conditions under stress can be the production of free radical and reactive oxygen species (ROS). Foliar application of putrescine and calcium nitrate was increased stress tolerance and improved yield and yield components of sesame. Concomitant use of putrescine and calcium nitrate had been a synergistic effect so that the highest foliar application efficiency was observed from the simultaneous use of 10 Mm calcium nitrate and 0.5 Mm putrescine.
Drought stress
Nasser Majnoun Hosseini; Mohammad Bagher Gholami; Esmaeil Afshoon; Mohammad Reza Jahansooz; Ehsan Rabieian
Abstract
IntroductionLegumes contain an average of 18-32% protein and are an important source of protein for low-income people (Majnoun Hussein, 2008). Chickpea (Cicer arietinum L.) Is known for its resistance to moisture changes; this plant shows physiological and morphological changes under conditions of water ...
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IntroductionLegumes contain an average of 18-32% protein and are an important source of protein for low-income people (Majnoun Hussein, 2008). Chickpea (Cicer arietinum L.) Is known for its resistance to moisture changes; this plant shows physiological and morphological changes under conditions of water scarcity (Ghorbanli et al., 2001). Chickpea grows in a wide range of weather conditions from the subtropical to Mediterranean regions of western Asia, northern Africa, and southern and southwestern Europe (Toker et al. 2007). Environmental stresses are the most important factor that limits crop production of chickpea. The most critical environmental stresses that have a negative effect on crop production are water and heat stresses (Rahbarian et al. 2011). By applying the effect of different levels of irrigation and plant density on yield and yield components of chickpea, grain yield, 1000-seed weight, the number of pods per plant and harvest index decreased during drought stress (Raei et al., 2008). Severe drought stress, by reducing the water uptake by the roots, disrupts the transfer of sap in the phloem, which ultimately leads to a decrease in nutrient uptake and the activity of antioxidant enzymes (Armand et al. 2016). Plant density is one of the most important management factors on crops that will affect plant yield. When competition for growth increases, the yield will be decreased. The selection of appropriate plant density should be based on environmental factors such as cultivar, cultivation target, weed competition, seed size, soil moisture content, and plant characteristics including plant height, plant density, leaf angle, and production capacity of the growing environment (Khajehpour, 2008). According to the above, this study was conducted to investigate the effects of different levels of irrigation and planting density on some agronomic traits of white chickpea in Karaj.Material and methodsTo investigate the effect of water regime and plant density on some agronomical traits of chickpea (Cicer arietinum), a split-plot experiment based on randomized complete block design with three replications conducted at the College of Agriculture and Natural Resources of Karaj, Iran in 2015. The water levels included eight levels (I1 =full irrigation at all growth stages, I2 = irrigation to grain filling and then stop, I3 = irrigation to podding and then stop, I4 = irrigation to flowering and then cut, I5 = 50% of full irrigation at all growth stages, I6 = 50% of full irrigation to grain filling and then stop, I7 = 50% of full irrigation to podding and then stop, I8 = 50% of full irrigation to flowering and then stop, considered as the main factor and plant density at three levels (30, 40 and 50 plants.m-1) as subplots. Geographical characteristics of this farm include 1321 meters above sea level, longitude 51 degrees east, latitude 35 degrees and 48 minutes north. This region has a hot and dry climate with an average rainfall of 33 years, about 248 mm.Results and discussionThe results showed that increasing water deficit stress reduced the growth traits and ultimately the grain yield of chickpea cultivar ILC 482. Increasing plant density increased the growth traits of yield components and grain yield. The highest grain yield (2892 kg. ha-1) was obtained in full irrigation (I1), and the lowest (1075 kg. ha-1) gained from I4. The highest grain yield (2068 kg. ha-1) was acquired at 40 plants m-1.ConclusionsThe results of this study showed that low water stress reduced the yield of chickpeas, but since Iran has low average rainfall, it is possible to achieve a good yield by using 50% irrigation at all stages of growth.
Nader Salamati; Amirkhosro Danaie
Abstract
Introduction Drought stress is the most important factor limiting the growth and grain yield of maize (Zea mays L.). Drought stress is one of the most important abiotic stresses that can seriously reduce crop yields depending on the season and the time it occurs. In arid and semi-arid regions, the plant ...
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Introduction Drought stress is the most important factor limiting the growth and grain yield of maize (Zea mays L.). Drought stress is one of the most important abiotic stresses that can seriously reduce crop yields depending on the season and the time it occurs. In arid and semi-arid regions, the plant undergoes periods of dehydration during its growth and must be able to tolerate these periods to produce proper yield (Emam and Niknejad, 2004). Cooper et al. (2006) reported that the capacity and ability to produce different maize genotypes under drought stress varied according to their morphological and physiological characteristics. Corn at different stages of development requires different amounts of water. The effect of dehydration on maize plants is marked by certain symptoms. These symptoms are seen as decreasing plant height and root length, delay in plant growth, leaf area depletion, seed production and biomass (Cakir 2004). The results of correlations indicate a significant positive relationship between potential yield (without stress) with MP, GMP, STI, TOL and HARM indices. The most positive and significant correlation between indices was related to GMP and STI (0.99) (Alipour et al, 2014). Due to the importance of maize as one of the important cereals in Iran, using irrigation method can be adapted to water shortage during drought. The purpose of this study was to investigate the effect of drought stress through different irrigation intervals and identify superior cultivar based on stress indices. Materials and Methods In order to investigate the response of new maize cultivars to water stress, an experiment was conducted at Behbahan Agricultural Research Station with latitude 50°:14´ east and 30°:36´ north latitude as a split plot in a randomized complete block design with four replications. It was implemented in two years (2014 - 2015). Drought stress including irrigation after 100 and 200 mm evaporation from Class A pan in main plots and three maize cultivars (S.C. 704, PH3 and PH4) were compared in sub plots. Results Comparison of mean water use efficiency in irrigation and cultivar interactions showed that 100 mm evaporation from Class A pan and V2 cultivar with yield of 1.299 kg maize per 1 m3 of water was in the first rank and position. The 100 mm evaporation treatment of Class A pan and cultivar V2 was ranked second with production of 1.155 kg of maize grain per cubic meter of water. Pearson correlation coefficient results showed that the highest correlation of grain yield with water use efficiency and 1000-grain weight were calculated as 0.8761 and 0.8478, respectively, indicating the effective role of 1000-grain weight in increasing maize yield. The highest values of SSI, STI, MP, TOL, GMP, HM and YI were for V2 and the lowest for V3. The lowest YSI index belonged to V2. In other words, the accuracy of the stress and non-stress treatments in V2 indicates that the above indexes are classified as ascending and descending, respectively. Therefore, higher values of SSI, STI, MP, TOL, GMP, HM and YI in each cultivar showed that the cultivar is resistant to drought stress or deficit irrigation. Therefore, the drought tolerant cultivar identification criterion can be high values of SSI, STI, MP, TOL, GMP, HM and YI. Thus, the values of the above indices and their use in selection of drought tolerant cultivars indicate an increase in grain yield under stress and non-stress conditions and can be recommended together to identify suitable cultivars for each condition. Conclusion Comparison of mean interaction effects between irrigation and cultivar in terms of water use efficiency showed that water use reduction in stress treatment decreased water yield in this treatment compared to non-stress treatment. The effect of reducing water use was even to the extent that it failed to cover the continuous decrease in yield in return for water consumption, and the treatment of 100 mm evaporation from Class A pan despite still consuming more water than the 200 mm evaporation treatment from Class A pan. Due to the increase in performance, water consumption was the most efficient. Positive and significant correlations of yield components with important traits of 1000-grain weight on one hand and highly significant correlation of 1000-grain weight with yields on the other hand indicate that the trend of increasing yield components with grain yield increased. Drought stress tolerance index was higher than other cultivars for SSI, STI, MP, GMP, HM and YI indices. Acknowledgements We would like to thank the Khuzestan Agricultural and Natural Resources Research and Education Research Center for their financial support and spiritual support for this research.
Hossein Hammami; Farhad Azarmiatajan; Mostafa Yaghoobzadeh
Abstract
Introduction As a major constraint limiting crop production worldwide, water deficit during plant growth period results inhibition effects on growth and yield of crops. Under drought stress, growth of crops inhibited by decline in water uptake, disturb photosynthetic path, growth retardation, metabolic ...
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Introduction As a major constraint limiting crop production worldwide, water deficit during plant growth period results inhibition effects on growth and yield of crops. Under drought stress, growth of crops inhibited by decline in water uptake, disturb photosynthetic path, growth retardation, metabolic disturbances oxidative damage and. Therefore, it is urgent to alleviate the adverse effects of drought stress for achieving high crop yields. Among various strategies to alleviate deleterious effects of drought stress, seed priming is thought to be an easily applied, low-cost and effective approach (Ashraf and Foolad, 2005). Seed priming include Hydropriming by water, osmopriming by ascorbic acid, potassium salts, poly ethylene glycol improved the drought resistance of different crops such as wheat (Farooq et al., 2013), lentil (Saglam et al., 2010), sunflower (Kaya et al., 2006), barley (Tabatabaei, 2013), and rice (Sun et al., 2010). Since, this study was conducted for determination growth and yield response of wheat to seed priming and different irrigation levels. Materials and mthods In order to evaluate the response of wheat to seed priming and irrigation levels, a factorial experiment based on a completely randomized block design with three replications was conducted at Research field of agriculture, University of Birjand, in 2017-2018. The treatments consisted of three levels of irrigation (I1, I2 and I3, 100, 75 and 50% of the plant water requirement, respectively) and four levels of seed priming (P1, P2, P3 and P4, 0 (control), -0.3, -0.6 and -0.9 MPa induced by PEG 6000, respectively). At the end of season growth period, plant height, tiller number, spike number, spike length, grain number per spike, 1000 seed weight, biological yield, and grain yield were measured and harvest index calculated. The traits were measured from 1 m2 of the center of each plot. Plant height, tiller number, spike number, spike length, and grain number per spike were average of ten plants. Results and discussion The results of this experiment showed that irrigation levels had a significant effect on measured traits including plant height, tiller number, spike number, spike length, grain number per spike, 1000 seed weight, biological yield, grain yield (P <0.01). However, no significant effect was observed on harvest index. Seed priming had significant effect on plant height and spike length (P <0.01), number of tillers, number of seeds per spike, biological yield, grain yield (P <0.05). Interaction effects showed a significant effect on all of the traits except harvest index. The results of this study showed that the application of osmotic priming seeds -0.3, -0.6, -0.9 MPa resulted in 2.13, 2.62 and 2.15 times of seed yield at 50% water requirement treatment compared to without seed priming treatment. The results of means comparison showed that osmotic seed priming by polyethylene glycol, resulting in a pressure of -0.6 MPa, under 50% of the water requirement treatment showed the highest grain yield compensate ability. However, in 75% of water requirement treatment, pre-treatment had no significant and positive effect on grain yield, even in -0.9 MPa treatment, had a negative and significant effect on seed yield. Therefore, the application of osmotic seed priming somewhat compensated the damage caused by water shortage on grain yield under stress conditions of 50% of water requirement. While in non-stress conditions, osmotic seed priming had no positive effect on grain yield.
Amin Faezizadeh; Alireza Shokuhfar
Abstract
IntroductionCorn (Zea mays. L) is an annual monocot plant from poaceaae family. The corn is C4 and is native to the tropical region. The breadth of its degree of adaptation and adaptation makes it possible to cultivate it in temperate and cold regions. The corn is the third highest cereal after wheat ...
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IntroductionCorn (Zea mays. L) is an annual monocot plant from poaceaae family. The corn is C4 and is native to the tropical region. The breadth of its degree of adaptation and adaptation makes it possible to cultivate it in temperate and cold regions. The corn is the third highest cereal after wheat and rice production, but its production is equal to the production volume of each of the world's two grains. The agricultural sector and its systems, with more than 90 percent of the country's water consumption, are the largest water consumer, wasting 80 percent of its traditional irrigation systems. Therefore, by reducing water resources, the reform of consumption patterns is the only way to overcome the depleted crisis. About 70% of the Earth's surface is covered by water, but unfortunately, the water crisis in many countries of the world, including the countries of the dry belt of the earth, such as Iran, is a concern. One of the effective ways to increase organic matter in Khuzestan soils, which are poor in organic matter, as well as increase in production per unit area, is the consumption of organic fertilizers. In Khuzestan Province, with the implementation of the sugar cane cake filter development project and simultaneously with the activities of sugar factories, large quantities of molasses, filter cake and bagasse produced by factories along with leaf and cane can be easily converted into compost as a result of microbial activity and as Organic organic fertilizer with a very favorable efficiency. The aim of this study was to evaluate the effect of organic fertilizer of cane sugar cane filter and drought stress on production factors and morphological traits of maize in Hamidyeh weather conditions. Materials and methodsThis research was carried out in 2016 in a farm located in Hamidieh with a longitude of 48 degrees and 10 minutes east and 31 degrees and 33 degrees north latitude and 13 meters above sea level. This study was carried out as split split plot in a randomized complete block design with three replications. The treatments consisted of drought stress at three levels: 60, 90 and 120 mm evaporation from class A evaporation pan as the main factor and the sugar cane cake filter was divided into four levels: 0, 25, 50 and 100 t/ha as a sub-factor. ResultsThe results showed that the effect of drought stress and fertilizer on sugar cane cake filter on Plant height, ear length, grain yield, seed number per row and 1000 grain weight affected the traits. The highest grain yield was obtained with an average of 5590.75 kg/ha irrigation with 60 mm evaporation and the lowest grain yield with an average 4170.05 kg/ha was obtained from irrigation 120 mm evaporation from the pan. Interaction between drought stress of 60 mm evaporation and sugar cane cake filter had a significant effect on plant height and grain yield. The highest grain yield (6170.55 kg/ha) was obtained from irrigation 60 mm evaporation and 50 t/ha sugar cane cake filter. On the other hand, the use of large amounts of sugar cane cake filter (100 t/ha) due to high salinity and salt accumulation in the root environment caused secondary oxidative stress and thus reduced economic yield. ConclusionTherefore, in general, the results of this research can be argued that the application of 50 t/ha sugar cane cake filter and drought stress of 60 mm evaporation from the class A pan are recommended in order to achieve maximum Production components. Application of filtering results in homogeneity of germination and accelerates the initial growth of the product, and in conditions without drought stress, increases economic yield. Also, under severe drought stress conditions (120 mm evaporation from the pan), the application of large amounts of sugar cane cake filter due to high salinity and the accumulation of salt in the root environment causes secondary oxidative stress and, consequently, reduced economic yield. Therefore, based on the results of this experiment and considering the abundance of this type of organic fertilizer in Khuzestan province and increasing its use as a soil reformer by farmers, it is suggested that in drought-free fields, after studying the long-term effects of sugar cane cake filter On the soil and nutrient cycle and in case of confirmation of the results, use should be made.
Mahmood Dejam; Majid Rajaie; Shima Johari; Sirus Tahmasebi
Abstract
IntroductionSalinity stress is one of the limiting factors in crop production especially in agricultural lands of arid and semi-arid regions. Under salinity stress, the availability of nutrients is reduced due to poor soil conditions. In contrast, the use of these elements by foliar spray is an appropriate ...
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IntroductionSalinity stress is one of the limiting factors in crop production especially in agricultural lands of arid and semi-arid regions. Under salinity stress, the availability of nutrients is reduced due to poor soil conditions. In contrast, the use of these elements by foliar spray is an appropriate method to increase the efficiency of nutrients absorption. Application of some elements by foliar spray reduces the negative effects of salinity. According to the reports regarding the positive effects of nitrogen, calcium and potassium as inducers of salt tolerance, this study was designed to investigate the response of cumin plant in hydroponic conditions to salinity stress and foliar spray of the above mentioned elements. Material and methodsThis research was conducted in 1395 in a research greenhouse in Fasa, Iran. A factorial experiment was conducted in a completely randomized design with three replications. The first factor was salinity stress in three levels including control (semi Hoagland solution), semi Hoagland solution + 75 mM sodium chloride and semi Hoagland solution + 150 mM sodium chloride. The second factor was foliar spray treatments consisted of control (distilled water), calcium nitrate, potassium nitrate, ammonium nitrate and calcium nitrate + potassium nitrate which were prepared with concentrations of 5/857, 7.214 and 2.857 kg per 1000 liters of water, respectively. These concentrations were selected in such a way that the nitrogen concentration used in all of them was equal. Salinity treatments were applied to Hoagland solution. Spraying of the desired compounds was carried out every two weeks until the end of the flowering stage. Results and discussionThe results showed that increasing in salinity stress reduced plant dry weight and leaves chlorophyll content in cumin. Foliar spray of calcium nitrate + potassium nitrate and calcium nitrate alone could somehow prevent the adverse effects of salinity on cumin. Compared to control, salinity level of 75 mM did not reduce the leaf relative water content in cumin. But increasing the salt stress to 150 mM reduced the relative water content of the leaves. While increase in salinity stress increased ion leakage, compared to control foliar spray of calcium nitrate, potassium nitrate, ammonium nitrate and calcium nitrate + potassium nitrate could reduce ion leakage in cumin. At salinity level of 75 mM sodium chloride, foliar spray of calcium, potassium and ammonium and at 150 mM sodium chloride, calcium spray could somewhat neutralize the adverse effects of salinity stress on chlorophyll a. The results showed that salt stress increased the sodium content of the cumin shoot. In fact, salinity stress disturbs the cationic balance of cumin and prevents the absorption nutrient elements and provides the possibility of more sodium absorption by cumin. In all salinity treatments, compared to control, foliar spray of the utilized compounds increased the number of umbel per plant. Calcium and potassium sprays with a competitive effect reduced the sodium absorption and to some extent could play a role in improving the yield components of cumin. ConclusionsOverall, the results of this study showed that increase in salt stress caused disturbance in leaf relative water content, ion leakage and chlorophyll content of cumin. However, foliar spray of calcium nitrate and potassium nitrate increased leaf relative water content and reduced ion leakage in cumin. Also, increase in salt stress caused a disturbance in cationic balance and prevented other cations such as calcium, potassium and magnesium to be absorbed while allowed cumin to absorb more sodium. Finally, the use of various spray combinations could improve the number of umbrellas per plant, the number of seeds per umbrella and the weight of 1,000 seeds of cumin in 75 mM salt stress conditions.
Mahdieh Soleymani Sardoo; Mohammad Galavi; Hamid Reza Fanaei; Mahmood Ramroudi
Abstract
Introduction Drought is the biggest factor limiting the production of agricultural products. One of the effective strategies for stress modification is the production and introduction of high yielding and drought tolerant cultivars in combination with low water management methods. Safflower (Carthamus ...
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Introduction Drought is the biggest factor limiting the production of agricultural products. One of the effective strategies for stress modification is the production and introduction of high yielding and drought tolerant cultivars in combination with low water management methods. Safflower (Carthamus tinctorius) is promising due to spring and autumn types and deep roots as a plant resistant to salinity stress and drought stress. The balanced and optimal nutrition of different types of fertilizers, especially micronutrient fertilizers, which have low absorption potential in soil, can be effective in achieving a quality product and balancing environmental and non-living stresses. One of these micronutrient elements is zinc. Irrigation method and suitable planting method depending on the weather conditions in each region are important components for suitable establishment and high yield. With regard to the special conditions of soil and water due to limitations in humidity, low soil organic matter and high soil pH, use of maximum capacity of new plants such as safflower in the field cultivation pattern by applying the correct methods of agricultural management is inevitable. Therefore, with the aim of increasing the productivity, experimental comparing the method of planting and soluble zinc Nano chelate on grain yield and water use efficiency and some agricultural characteristics of safflower under drought stress. Materials and methods In order to evaluation of yield, water productivity and some crop characteristics of safflower in different planting methods with Zn Nano chelate spraying under drought stress a split split- A completely randomized complete block design with three replications was conducted at Agricultural and Natural Resources Research and Education Station of Sistan in 2016-2017. Experimental factors including planting method in two levels (Flat and Furrow) as the main factor, irrigation regime at three levels (irrigation after 45% (control), 65% and 85% of admissible moisture depletion) as subsidiary factor, spraying of zinc Nano chalat in three levels (non spraying zinc, 0.5 and 1 g / liter spraying) as sub-subfactor. The irrigation time was determined according to the soil moisture curve using the Trim model of humidity (1TDR). At the end of the growing season, after leaving side effect from the start and end, 5 plants of the 2 middle rows of each plot were randomly selected and plant height and number of heads per plant were determined and by selecting head 10 random samples of each plot has also calculated the number of seeds per head. Seed 1000 weight was determined with a gravity of 0.01 g. In order to determine the grain yield with respect to the marginal effect, an area equal to 1.6 M2 (square meters) harvested. Water productivity was also calculated by dividing the grain yield per hectare into water consumption per hectare. Data were analyzed using MSTAT-C software and the mean comparison was performed based on Duncan multi-domain test at 5% probability level. Results The irrigation regime and spraying of zinc Nan ochelat was significantly affected by morphological traits, yield, yield components and water use efficiency. number of heads per plant, 1000- seed weight, grain yield and Water use efficiency was under the influence by the planting method. According to the mean comparisons, less irrigation significantly reduced and spraying of Zn Nano chelat increased the studied traits. Grain yield in Flat method increased 29% compared to Furrow method. Irrigation after 45% moisture depletion compared to irrigation after 85% moisture depletion of 61 percent increased grain yield but water use efficiency reduction by 11.5%. The spraying of zinc Nan ochelat with a concentration of 1 g / lit compared to non-spraying grain yield increased by 36 percent and increased water use efficiency by 37% and oil percentage by 12%. Conclusion Grain yield in flat planting method increased compared to furrow planting method. Irrigation after 45 percent moisture depletion compared to irrigation after 85 percent moisture depletion of increased grain yield but water productivity reduction. The spraying of Zinc Nano chelate compared to non-spraying increased grain yield and water productivity. According to the results of flat planting method with spraying of Nano chelate on 1 g. Li-1 under drought stress conditions, it can compensate and eliminate the stress-induced damage for economic production of safflower in Sistan weather conditions.
Mahmood Nazeri
Abstract
Introduction Wheat cultivars that are more tolerant to terminal drought are more suitable to Mediterranean conditions. To increase water use efficiency, the target environment shound be taken in to account, because one trait might be effective in an environment but ineffective in another environment. ...
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Introduction Wheat cultivars that are more tolerant to terminal drought are more suitable to Mediterranean conditions. To increase water use efficiency, the target environment shound be taken in to account, because one trait might be effective in an environment but ineffective in another environment. Phenological adjustment with pathern of seasenal precipetation adaptation, improve water use efficiency in drought conditions. Suitable flowering time is the most important trait that is correlated with increasing water use efficiency in drought conditions. Seed size is also important in moisture stress prone environment. Larger grains facilitate germination and emergence, good early ground cover and biomass, because at seedling stage when plant is more dependent on seed storages (heterotrophic stage), it provides adequate reserves for seedling growth. Spike growth period is a crucial stage and significantly affects grain yield determination. During this stage demand for assimilate increases due mainly to enhanced growth and competition between growing structures and organs, particularly, growing spike and elongating stem. This study was carried out to investigate the effect of moisture deficit yield on potentional and effective traits inpromising winter and facultative bread wheat genotypes. Materials and Methods In order to evaluate yield potentional and effective traits inpromising winter and facultative bread wheat genotypes, the present investigation, was carried out in 2008-09 and 2009-10 growing seasons in Torogh Agricultural Research Field Station, Mashhad in the North East of Iran in 36º 13´ N, 59º 40´ E and 985 m above see level, in split plot arrangements using randomized complete block design with three replications. Main plots were water limited conditions with three levels (L1: Optimum condition, L2: water deficit using rainshelter from milky grain stage to maturity; L3: water deficit using rainshelter from anthesis stage to maturity). Ten bread wheat genotypes, suitable for cold and dry regions (V1: (Toos), V2: (C-81-10),V3: (pishgam),V4: (C-84-4), V5: (Mihan), V6: (C-D-85-15),V7: (C-D-85-9),V8: (C-D-84-5502),V9: (C-D-85-5502), V10: (C-85-6)) were assigned to subplots. Grain yield and biological yield were measured by harvesting of whole plot, weighing and then thrashing. Harvest index was calculated using following equation: HI= Grain yield / Biological yield *100. Number of kernel per spike (NK/S), Kernels weight per spike (KW/S) were obtained by using at least 20 spikes. Number of fertile spikes per square meter, 1000 kernel weight (1000KW) also were measured. Anthesis and physiological maturity were determined by observing of anters in %50 spikes and changing color of %50 pedancles to yellow, respectively. Results and Discussions The results showed that water stress (L2 and L3 treatments)decreased grain yield (18.6% and 45.6%, respectively) due to reduction in thousands kernel weight (TKW) and kernels per spike in compairin with optimum conditions. The results showed that genotypes V5 and V4 had higher grain yield (7593 and 7170 Kg/ha, respectively) due to optimum amount of yield component, such as fertile spike per square meter (806 and 765 spike), thousands kernel weight (37.87 and 38.33 gr), kernels per spike(36.2 and 36.0 kernels) and grain weight per spike(1.17 and 1.23 gr) respectively. The results showed that the highest harvest index(HI) is happended in optimum condition (40.95%). The lowest harvest index(HI) was belong to (L3)water limited conditions from anthesis to maturity(36.37%), due to reduction in water use in post anthesis staegs in compairin with optimum condition. genotypes V5 (Mihan) and V4 were the best in both optimum and stress conditions, so could be recomanded to cultivation for similar conditions of this study. Conclusions Results indicated that genotypes, V5: (C-84-8, recently released and named Mihan) and V4: (C-84-4) had the best performace amoung other genotypes, respectively. These cultivars had higher grain yield in both optimum and stress conitioms other genotypes, wich is the most important charachter for slow stressing. So these cultivars could be recomanded to cultivation for similar conditions of this study.
S. Mohammad Alavi Siney; Jalal Saba
Abstract
This study was conducted to investigate the associations between physiological and agronomicaltraits of different bread wheat genotypes in dryland conditions. 20 genotypes (including 18 lines and 2 cultivars) were investigated in one experiment using randomized complete block design with four replicates ...
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This study was conducted to investigate the associations between physiological and agronomicaltraits of different bread wheat genotypes in dryland conditions. 20 genotypes (including 18 lines and 2 cultivars) were investigated in one experiment using randomized complete block design with four replicates in dryland conditions during 2006- 2007. Traits measurements were carried out at the anthesis and physiological ripening stages. In this experiment 16 agronomical traits and 10 physiological traits were measured. According to the results of canonical correlation analysis, it can be concluded that selection for agronomical traits including lower height and percentage of leaf dry matter as well as higher percentage of spike and stem dry matter, spike length, 1000- grain weight and yield would result in the selection of effective physiological traits such as, higher chlorophyll content index, leaf area, specific leaf dry weight, relative water content and photosynthetic water use efficiency and lower stomatal conductance under drland conditions.
Shirin Ghazian Tafrishi; Amir Ayenehband; Hossein Tavakoli; Saeed Khavari Khorasani; Mohammad Joleini
Abstract
In order to study the effect of drought stress on morphological traits, yield and yield components of sweet corn, a split plot factorial experiment based on RCBD was conducted with four replications at the experimental field of the agricultural and natural resources research center of Khorasan-Razavi ...
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In order to study the effect of drought stress on morphological traits, yield and yield components of sweet corn, a split plot factorial experiment based on RCBD was conducted with four replications at the experimental field of the agricultural and natural resources research center of Khorasan-Razavi (Tourogh station of Mashhad) in 2010,. Responses of three sweet corn hybrids (including two sweet and one super sweet hybrid) to three different water levels in two planting methods, were studied. Water levels [I1: 100%-(full irrigation or control), I2: 80% (moderate stress), and I3: 60% (severe stress) of field capacity] were assigned as main plots, while in sub plots, cultivar (Ksc403, Merit and Absizhen) and planting method (planting on the ridges or on the ditches) were combined as a factorial arrangement. Crop yield and 17 effective characteristics of sweet corn plants were studied in this study. Analysis of variance showed that there were significant differences between different hybrids in terms of evaluated traits. Drought stress also significantly affected all measured characteristics. Correlation analysis showed that in normal irrigation and drought stress conditions, ear length, leaves number above main ear and seed row per ear showed the greatest positive correlation with kernel yield. Stepwise regression analysis and principal component analysis showed that, 1000- seed weight, anthesis-silking duration (ASI) and kernel number in ear were the most limiting traits in sweet corn production.
Zohreh Baniabbass Shahri; Gholam Reza Zamani; Mohammad Hasan Sayyari Zahan
Abstract
Iran is amongst dry and semi-dry regions of the world and enjoys several diverse climates. The recognition of traits related to growth, yield and adaptation of sunflower, especially in relation to drought stress can remarkably affect the development of planting area and its yield increase. To study the ...
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Iran is amongst dry and semi-dry regions of the world and enjoys several diverse climates. The recognition of traits related to growth, yield and adaptation of sunflower, especially in relation to drought stress can remarkably affect the development of planting area and its yield increase. To study the effect of water deficiency stress and foliar application of Zn on sunflower (Helianthus annuus L.) yield and some of its physiological traits, a split plot experiment based on randomized complete block design was conducted with three replications at the Islamic Azad University of Birjand in 2010. The main plot was irrigation regime with four levels including I1= without stress (according to the plant’s water demand), I2= interrupting irrigation 1 time during the vegetative growth stage, I3= interrupting irrigation 1 time during the reproductive stage, I4= interrupting irrigation during the vegetative and flowering stages and the sub plot was foliar application of zinc sulfate with three levels including Zn1= without foliar application, Zn2= 0.5% concentration of zinc sulfate (2 kg/ha zinc sulfate or 659 gr ha-1 of zinc element), Zn3= 1% concentration of zinc sulfate (4 kg/ha zinc sulfate or 1319 gr ha-1 of zinc element). Results indicated that irrigation ceasing significantly decreased the number of seed head, 1000- seed weight, seed yield and oil yield, while the oil percent was not affected. According to the results, applying drought stress during the vegetative and reproductive growth stages decreased seed yield and oil yield as much as 20% and 31% in comparison with the control, respectively. In addition, Zinc sulfate treatment with 1% concentration increased the 1000-seed weight, seed yield and oil percent in comparison with other treatments. In this study seed yield showed a significant reduction under the influence of drought stress. The treatment of complete irrigation (according to the plant’s water demand) resulted in higher yields than other irrigation treatments. The greatest seed yield was obtained by foliar application of Zn with 1% concentration. Moreover, the least oil yield was observed where irrigation was interrupt during the vegetative and reproductive growth stages. Overall, application of Zn under water deficit conditions could be employed as a good strategy for reducing the detrimental effects of drought stress on growth and yield characteristics of sunflower.
Ali Senobar; S. Ali Tabatabayi; Farhad Dehghani
Abstract
To survey the effect of soil irrigation intervals on grain yield, yield components and harvest index of bread wheat cultivars, an experiment was conducted based on randomized complete blocks as a split plot design with 4 replicates during 2006-2007 at the experimental farm of Agricultural and Natural ...
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To survey the effect of soil irrigation intervals on grain yield, yield components and harvest index of bread wheat cultivars, an experiment was conducted based on randomized complete blocks as a split plot design with 4 replicates during 2006-2007 at the experimental farm of Agricultural and Natural Resources Research Center of Yazd. The main plots consisted of four irrigation treatments (8, 10, 12 and 14 days) and the sub-plots consisted of one line and three bread wheat cultivars (Backcross Roshan, Sistan, WS-82-9 and Pishtaz). The results indicated that the irrigation treatments had significant effects on grain yield, yield components and harvest index and there were significant differences between cultivars in terms of grain yield and yield components. Moreover, the interaction effect of irrigation interval x cultivar on grain yield and harvest index was significant (P<0.01). The maximum yield components and harvest index were obtained in 8 and 10 days intervals. 8 days interval showed the highest mean grain yield, while the lowest mean yield components, grain yield and harvest index were observed in 14 days interval. Comparison of the cultivars showed that Sistan and WS-82-9 had the maximum number of grains per spike and thousand kernel weight, respectively. Pishtaz and Backcross Roshan had the maximum number of spikes per square meter. Also, Sistan and Backcross Roshan had the highest grain yield while the maximum harvest index belonged to Sistan, Backcross Roshan and WS-82-9. Based on the study results, 8 days interval was recognized as a favourable irrigation period for achieving the greatest economical yield in the region, while WS-82-9 showed the greatest drought tolerance and Sistan was the most productive cultivar under well-watered conditions.
