جستجوی مقالات مرتبط با کلیدواژه « آفتابگردان » در نشریات گروه « کشاورزی »

Considering the speed of environmental changes and the extent of the data obtained from breeding evaluations, there is a need to employ fast and reliable data analysis methods. Biplot graphical methods greatly contribute to the advancement of breeding programs by offering the possibility of quick, comprehensive, and accurate analysis of information, along with easy interpretation of the results. A number of 100 oilseed sunflower genotypes were evaluated in terms of plant height, number of leaves, leaf length, leaf width, petiole length, stem diameter, chlorophyll content, days to flowering, days to maturity, head diameter, relative water content, seed oil percentage, and seed yield in the form of simple 10 x 10 lattice design under normal and limited irrigation conditions during 2012 and 2013. To identify the superior genotypes in each irrigation conditions, the genotype-trait biplot analysis method was used. Under both irrigation conditions, a high correlation was observed between the traits including leaf length, leaf width, stem diameter, head diameter, seed oil percentage, and petiole length with seed yield. In terms of all studied traits under both irrigation conditions, genotype with code number of 8 was the best and genotypes with code numbers of 59, 42, and 72 and genotypes with code numbers of 19, 59, and 17 were the worst genotypes under normal and drought stress conditions, respectively. Based on the results, the traits including stem diameter and head diameter can be used as indirect selection criteria for seed yield improvement under normal and drought stress conditions, respectively.

Maintaining food security in light of excessive depletion of limited unrenewable water resources, requires the authorities to make efficient use of water and energy as well as enhancing the productivity of these factors in every sector, particularly in agriculture. In this study, the volume of irrigation water supplied from tube wells with the same water level, seed yield, productivity of water as well as energy consumption for sunflower irrigated with drip tape and furrow methods under farmer’s management were recorded and analyzed. The measurements were made over 2020-2021 on 14 fields across Esfahan province where sunflower was a primary crop. Data from the irrigation systems were analyzed using t-test and Pearson correlation coefficients. Based on the results, the average volume of irrigation water for drip tape and furrow methods were 6272 and 7987 cubic meters per hectar, respectively; showing significant difference. Comparison between the water requirement and the volumes of irrigation water applied by the farmers indicated deficit irrigation in 13 out of the 14 fields. Average sunflower seed yield for drip tape and furrow irrigation methods were 1894 and 1781 kg ha-1, respectively. In addition, average water productivity for the said irrigation methods were 0.3 and 0.23 kg ha-1, respectively; where no significant difference was found for any of the two foregoing parameters. There were inverse correlations between the volume of irrigation water and both seed yield and water productivity of sunflower, which were insignificant and significant, respectively. There were direct and significant relations between the volume of irrigation water and both energy consumption and energy productivity. For drip tape and furrow irrigation methods, the average values for energy consumption were 44871 and 44345 MJh-1, respectively which were not different significantly; and the amounts of energy productivity were 0.042 and 0.045 kg MJ-1, respectively which were not different significantly.

Climate change is a very serious threat to crops production in all regions around the world. Heat stress is a consequence of climate change that affects biochemical, physiological and molecular processes of crop plants, causing alterations in crop growth, development, and productivity. Terminal heat stress is the most widespread and type of heat stress in the world that limits crop productivity and ultimately food security. Sunflower is moderately tolerant to heat stress. It can tolerate higher temperatures without suffering from heat stress. However, sunflower is more susceptible to heat stress from early flowering to grain filling. Hence, it may be severely damaged when exposed to terminal heat stress. Biochemical and physiological responses in crop plants are modified under heat stress. It has been shown that tolerance to heat stress in crop plants is associated with an increase in antioxidant enzyme activities. The physiological and biochemical responses to heat stress vary among crop plant species and genotypes which can be used for development of cultivars with high temperature tolerance in crop plants.

This experiment was carried out in 2017-2018 growing season in Ahvaz, Iran, using as split-plot arrangement in randomized complete block design with three replications. Main plots consisted of three sowing date including; 11th November, 11th December and 11th Janauary, and five sunflower cultivars including; Qasem, Fantasia, Shams, Lakomka and Progress were randomized in sublpots. Sowing on 11th November was considered as normal sowing date, and sowing on 11th December and 11th January were delayed and late sowing dates, respectively. In the two latter sowing dates, flowering and grain filling periods were exposed to moderate and severe terminal heat stress.

Terminal heat stress in delayed and late sowing dates caused significant reduction in carotenoid content (27% and 56%, respectively), seed yield (30% and 32%, respectively) and oil yield (18% and 28%, respectively), but increased catalase (63% and 55%, respectively), peroxidase (107% and 56%, respectively) and superoxide dismutase (43% and 67%, respectively) enzyme  activities, carbohydrate concentrations (18% and 30%, respectively) and malondialdehyde concentration (46% and 98%, respectively), when compared to normal sowing date. There was significant differences among sunflower cultivars for most of studied traits. Lakomka cultivar with the highest values of biochemical and physiological indices such as chlorophylle content, antioxidant enzyme activities and carbohydrates concentration and with the lowest malondialdehyde concentration had the highest seed yield (1579 kg.ha-1) and oil yield (608 kg.ha-1) under terminal heat stress.

Exposure to moderate and severe terminal heat stress differently influenced physiological and biochemical traits in sunflower cultivars. The severity of terminal heat stress played an important role in the cultivars responses. Progress cultivar had the lowest reduction in oil and seed yield under terminal heat stress, however, cv. Lakomka showed highest seed and oil yield in all three sowing dates. Therefore, it can be concluded that cv. Lakomka is suitable for being sown in normal, delayed and late sowing dates due to least variability in its seed yield.

Nowadays, environmental pollution and its consequences have become one of the most serious human concerns, and management of pollution caused by the entry of hazardous substances such as radionuclides, pesticides, and heavy metals into the environment is of particular importance. Advances in technology and nuclear knowledge have led to increasing of release and accumulation of nuclear waste and radionuclides in the environment. Mining, production and processing of nuclear fuels and military operations are the most important causes of nuclear waste production. Because of the possibility of transferring radionuclides to the food chain, soil contamination with these pollutants creates many hazards to human health. There are various physical and chemical methods to eliminate nuclear waste, but most of them are expensive and complex. Phytoremediation is an emerging technology that uses plants and their associated microbes to clean up the polluted environment. This process is very simple, practical, economical and environmentally friendly. In this research, wheat and sunflower plants were used to remove uranium from soils of Saghand and Bandar Abbas mine's districts. Also, the effect of different concentrations of citric acid on the plants accessibility to this element was investigated.

PH meter and X-ray fluorescence spectroscopy were used to determine the pH and constituents of the soil. Also, liquid scintillation analysis was applied to determine the concentration and amount of uranium absorption.

In general, sunflower had better efficiency in absorption of uranium from soil of Saghand. In the case of uranium absorption from soil of Bandar Abbas, Wheat had better efficiency in the absence and low concentrations of citric acid, but with increasing acid concentration the accessibility of sunflower to the uranium in the soil increased.

In comparison to wheat sunflower had a better performance in uranium uptake from Saghand soil before and after acid addition. In the case of uranium uptake from Bandar Abbas soil, wheat had better performance in the absence of citric acid and in its low concentrations, while with increasing acid concentration, the uranium uptake by sunflower increased.

 Sunflower is a plant with high economic value and adapted to a wide range of climatic conditions. Spring cultivation is one of the ways to enhance in Iran the area under cultivation of this crop, which is usually accompanied by terminal low temperatures. In this regard, there is a need to identify and introduce indices for selecting tolerance to low temperatures in the reproductive stage.

This research was conducted in 2014 and 2017 as a split plot in the form of a randomized complete block design with three replications in Tarbiat Modarres University and Seed and Plant Improvement Institute, respectively. The main plots included planting dates in two levels and the subplots consisted of five inbred lines and three sunflower hybrids. Planting dates were adjusted to allow temperatures of 25± 2 °C and 15± 3 °C during and after anthesis. Single plant yield and physiological traits such as components related to remobilization from stem and receptacle base to seeds, dry weight of leaves and electrolyte leakage of receptacle tissue were evaluated on all treatments. Multivariate analyzes were performed on the measured traits.

The results of combined analysis of variance of the data showed that the interaction effects of experiment-planting date-genotype of all traits were not significant. The second planting date reduced grain yield in all genotypes. In both planting dates, the hybrids had the highest grain yield and the lowest electrolyte leakage. Low temperatures differentiated the yield behavior in the inbred lines. A significant negative correlation was observed between electrolyte leakage in the first planting date and grain yield in the second planting date. Also, the correlation between stem diameter in top of the stem in the first planting date was significant and positive with dry weight of the head and stem at anthesis, grain yield, 1000-seed weight and remobilization from receptacle base to the grain in second planting date. Stepwise regression analysis of plant yield in the second planting date on the measured traits in the first planting date showed a significant positive effect of head dry weight at maturity and stem diameter in top of the stem and a negative effect of electrolyte leakage. The first and second principal components, explaining 79% of the total data variance, were able to group genotypes based on differences in grain yield and its components, electrolyte leakage, stem diameter in top of the stem and resistance to assimilate transfer from storage to grain.

Increased cell membrane stability is an evolutionary mechanism by which some genotypes maintain their yield and performance to some extent under cold stress conditions. This trait along with the stem diameter in top of the stem can be used as indices for selecting inbred lines in segregating generations to withstand low temperature conditions in the second planting date.

To evaluate the effect of autumn sowing date on seed yield of sunflower cultivars, a field experiment was carried out as strip plot arrangement in randomized complete block design with three replications in safiabad agricultural and natural resources research and education center of Dezful, Iran during two growing seasons (201718 and 2018-19). Seven sowing dates (6th Sep., 23rd Sep., 7th Oct., 22nd Oct., 6th Nov., 21st Nov. and 6th Dec.) were assigned to vertical strips and five sunflower cultivars (Azargol, Barzegar, Progress, Farokh and Lakomka) were randomized in horizontal strips. Mean comparison of sowing date and cultivar interaction showed that the highest growth duration (204 days) belonged to sowing date of 21st Nov. and cv. Progress. The lowest growth duration (118 days) was for cv. Farokh in sowing date of 6th Sep. Delay in sowing date led to decrease in head diameter and thousand seed weight of all sunflower cultivars. Delaying in the sowing date also led to shorter plant height. The highest (42.8%) and the lowest (37.7%) seed oil content was observed in the first (6th Sep.) and the last (6th Dec.) sowing dates, respectively. Cv. Azargol (41.9%) and cv. Farokh (38%) had the highest and the lowest seed oil content. Mean comparisons of sowing date and cultivar showed that the highest seed yield (2985 kg.ha-1) belonged to the first sowing date (6th Sep.) and cv. Progress. The lowest seed yield
(232 kg.ha-1) obtained from cv. Lakomka in 6th Dec. sowing date. The results of this experiment showed that the period of 6th until 23rd Sep. is suitable sowing date window for autuom sowing sunflower in the north of Khuzestan province.

In confectionary sunflower cultivation, drought stress at the stage of vegetative growth and plant density are two important variables that determine grain yield. In order to increase the 1000-seed weight and marketability of sunflower seeds, farmers usually consider plant density less than oily sunflower, and on the other hand, for more root growth and dormancy resistance due to large heads, in the vegetative growth stage of sunflower they bring drought stress to the sunflower farm. In some regions of Kermanshah province, confectionary sunflower (local cultivar Songhori) is cultivated with very low density (1-3 plants per square meter). On the other hand, farmers, based on their experiences, in the vegetative growth stage (2-6 leaves), cut off the field irrigation, and this watering interruption may take 30-45 days. The purpose of stopping irrigation in such conditions is to grow more roots and prevent lodgings of plants due to the weight of the head. In the present study, the effect of cutting irrigation at vegetative stage and plant density on yield and other agronomic characteristics of local confectionary sunflower was investigated to identify the most appropriate treatments.

The present study was conducted using split plot experiment based on randomized complete block design with three replications in the farmers' farm of Kermanshah province in 2016. Drought stress was as the main factor at three levels including severe stress, moderate stress and non-stress. The sub-factor was three levels of plant density with changes in plant space on 60 cm planting rows in the form of 20, 40 and 60 cm. Important agronomic traits including number of days to star, number of days to full flowering, stem diameter, plant height, number of leaves, leaf area, head diameter, percentage of hollow, number of seeds per head, 1000 seed weight and yield were measured according to Schneider and Miller (1981). In order to measure the grain yield of each plot, the middle row plants were harvested after removing the marginal plants (one row and one plant from the beginning and end of each plot) and the grain yield was measured after threshing. Based on the harvested area, it was converted to kilograms per hectare. In order to statistical analysis, SAS Ver 9.1 statistical software was used to analyze the variance and the means of treatments was compared by Duncan’s multiple range test.

The results of variance analysis showed that drought stress significantly reduced plant height, days to maturity, seeds per head and stem diameter and increased days to flowering. Effect of Density was significant on all studied traits except plant height and number of leaves. While increasing density, stem diameter, head diameter, number and weight of seeds per head and 1000-seed weight was decreased and the hollow percentage of head, the number of days to flowering was increased. Mean comparison of data showed that grain yield under severe and non-stress condition was 2749 and 4543 kg ha-1, respectively. The highest and the lowest grain yield was belonged to plant spacing of 40 cm and 20 cm with 4599 and 3538 kg ha-1, respectively.Given the water crisis in Iran, the real value of water consumption should be considered and water loss should be prevented by using different methods in crop production. According to the mean grain yield, it can be seen that the average yield of mild drought stress (two less irrigations) is slightly different from the average yield in non-stress irrigation. The two removed irrigations in the mild stress treatment coincide with the time of grain filling of crops such as wheat, barley and canola or the cultivation of some spring crops such as corn. Irrigation in these stages is important in the grain yield of these plants. So by eliminating two irrigations after the establishment of the sunflower, the saved water can be used to irrigate other crops. On the other hand, low and high density treatments both had lower grain yield than intermediate density treatment. Plant spacing of 40 cm with high 1000-seed weight had higher grain yield than plant spacing of 20 and 60 cm, so that a plant distance of 40 cm can be recommended in confectionary sunflower. It can also be recommended that, after the establishment of the sunflower plant, by eliminating two irrigations before reproductive growth, without effective reduction of grain yield, water resources can be used for other crops such as wheat, barley and canola.

The sunflower is one of the most important oilseed plants in the world that its oil has nutritional and high economic value. Therefore, the selection of high yielding genotypes is especially important in this plant. In this regard, 11 new hybrids along with four cultivars Golsa, Ghasem, Shams and Farrokh were evaluated in a randomized complete block design with four replications in agriculture research station of Dezful during 2018-2020. In this study, the methods of genotype × trait (GT) and genotype by yield × trait biplot (GYT) were used to identify interrelationships between different traits and selection of the best sunflower genotypes. Based on polygon view of GT biplot, the genotype No. 1 had good characteristics regarding seed yield and traits related to yield. The vector view of GT biplot showed high correlation between seed yield with stem diameter, plant height, head diameter and seed number per head. Based on average tester coordinate (ATC) view of GYT biplot, the genotypes No. 1 and 6 in terms of all positive yield-trait combinations were recognized as the best genotypes and genotypes No. 12, and 7 as the weakest genotypes. According to the results, a significant positive correlation was observed between stem diameter, head diameter, plant height and early maturity in combination with seed yield. Therefore, it seems that traits of stem diameter, head diameter, plant height and early maturity could be used as a suitable selection criterions for increasing seed yield in sunflower.

The selection of high-yielding genotypes is especially important in sunflower. Therefore, this study was conducted to identify interrelationships between different traits and the selection of the best sunflower hybrids.

In this study, 11 new hybrids along with four cultivars Golsa, Ghasem, Shams, and Farrokh were evaluated in a randomized complete block design with four replications in the agriculture research station of Kermanshah during 2019-2020. The phonological, morphological characteristics and yield and its components including days to flowering, days to ripening, plant height, stem diameter, head diameter, seed number per head, thousand seed weight, and seed yield were measured. In this study, the methods of genotype × trait (GT) and genotype by yield × trait biplot (GYT) were used to identify interrelationships between different traits and selection of the best sunflower hybrids.

Based on polygon view of GT biplot, the genotypes No. 4 and 11 had good characteristics regarding seed yield. The vector view of GT biplot showed high correlation between seed yield with stem diameter, plant height and seed number per head. Based on average tester coordinate (ATC) view of GYT biplot, the genotypes No. 5, 3 and 4 in terms of all positive yield-trait combinations were recognized as the best genotypes and genotypes No. 7, 13 and 6 as the weakest genotypes. According to the results, a significant positive correlation was observed between stem diameter, head diameter, plant height and early maturity in combination with seed yield. Therefore, it seems that traits of stem diameter, head diameter, plant height and early maturity could be used as a suitable selection criterion for increasing seed yield in sunflower.

Generally, the results indicated that hybrids No. 5, 3 and 4 were recognized as superior hybrids from the point of yield and other agronomic traits. These genotypes have the potential to be used in research-extension trials for introduction as a new cultivar for cultivation in the Kermanshah region. Also, the traits of stem diameter, head diameter, plant height, and early maturity could be used as suitable criterions in selecting for increased seed yield in sunflower breeding programs.

In order to evaluate the planting date delay on phenological traits, yield components, grain yield, and linoleic and linolenic fatty acids of new sunflower hybrids, an experiment has been conducted as split plot in a randomized, completely block design, with four replicates at the field of oilseed section of seed and plant Improvement during 2014-2016 growing season. The treatments include seven sunflower hybrids (Barzegar, Farrokh, Haysan 36, Qasem, Shams, Azargol, and Haysan 25) on three planting dates (15 days after harvest of autumn (wheat), July 1, July 15, and July 30, respectively). The experimental results show significant effects of planting date on all traits except number of seeds per head and linolenic acid at the level of 1% and on the percentage of oil and linoleic acid at the level of 5%. The studied hybrids are significantly different in all traits except linoleic and linolenic fatty acids. The latest experimental hybrids include Barzegar and Azargol hybrids and the earliest hybrid is Farrokh. The highest grain yield is obtained from the date of the first sowing at the rate of 2840 kg / ha and in the case of delayed sowing the yield is reduced to 41%.

Studying the reaction of the different genotypes under different environmental conditions helps breeders to detect stable and high-yielding genotypes. In this regard, 11 new sunflower hybrids along with four cultivars (Golsa, Ghasem, Shams, and Farrokh) were evaluated in a randomized complete block design with four replications in four experimental field stations (Karaj, Sari, Kermanshah, and Dezful) during two cropping seasons. GGE biplot statistical method (genotype effect + genotype × environment interaction) was used to study the adaptation of genotypes in the studied environments. Results of combined analysis of variance indicated that the effects of environments, genotypes, and genotype × environment interaction were significant, suggesting that the genotypes responded differently in the studied environment conditions. Results of the GGE biplot method showed that the two first and second principal components of the GGE biplot explained 66.4% of the total seed yield variation. Based on the biplot polygon view, the hybrid RGK15×AGK1221 in Sari and Karaj locations and the hybrid RGK25×AGK330 and Shams cultivar in Dezful location were superior genotypes with the high specific adaptation. Besides, all environments had high discriminating ability so that could able to show differences between genotypes. Sari environment was the nearest environment to the ideal environment that had the highest discriminating ability and representativeness.

Evaluation of the effects of different environments on grain yield of sunflower hybrids (Helianthus annuus L) and determination of superior and stable genotypes in different places is considered as a model for stability and adaptation to the environment.

In order to investigate the interaction of yield stability on 12 sunflower hybrids, an experiment was conducted in a randomized complete block design (RCBD) with three replications in five regions (Karaj, Birjand, Firooz-Abad, Kashmar and Arak).

The evaluation of variance analysis in 1% probability indicated that the genotypes effect was significant for kernel yield. Also, the data collected from mean value showed that genotype Zaria is the most desirable genotype and genotype Progress the most undesirable. According to AMMI method variance analysis environment effect, genotype effect and genotype × environment interaction in 1% and 5% probability level was significant and the first two factors have covered more than 80% of data variance totally (IPC1= 52.4%, IPC2= 27.9%). AMMI1 model clarified due to having the least first main factor in interaction, genotype Zaria have known as the stable genotype. AMMI2 model shows that genotypes Zargol and Master in Arak, genotypes SHF81-90 and Zaria in Kashmar, genotypes Gabur, Favorite, Record and Progress in Birjand, genotypes Armaverski, Azargol, Lakumka in Karaj and Firooz-Abad have specific adaptation. Based on stability parameters (environmental variances, coefficient of variation, wrick's ecovalance, Shukla variances, regression coefficient, Eberhart and Russell) genotype Zargol recognized as the stable genotype and genotype SHF81-90 as the unstable.

Genotypes Zaria and Zargol identified as the most stable genotypes and genotype SHF81-90 as the unstable genotype generally. The result of stability parameters correlation describes that environmental variance and coefficient values parameters have positive and significant correlation with Eberhart and Russell, Shukla variance and Wricke's ecovalence parameters.

The rapid growth of the world's population, followed by an increase in the need for water, has put great pressure on water resources, so it is necessary to plan for the optimal use and increase of efficiency of this vital resource. Sunflower is one of the most important oilseed crops that is mainly cultivated in Kermanshah province. Therefore, determining the appropriate sowing time of this crop for maximum production and water use efficiency is of particular importance. Because field experiments are costly and time-consuming, researchers use crop growth simulation models to determine the optimal planting time for each crop in a specific environment and climate. The use of simulation models minimizes the limitations of field experiments and allows the analysis of plant responses to environmental stresses and management scenarios. The objective of this study was to determine the optimal planting date of the Farrokh sunflower cultivar in four regions of Kermanshah province (Kermanshah, Islam Abad, Sarpol Zahab, and Kangavar) in order to maximize yield and water use efficiency using the AquaCrop model.

A field experiment was conducted at the Research Farm of Razi University, Kermanshah, Iran in order to calibrate and validate the crop parameters in the AquaCrop model. The experiment was performed in a randomized complete block design with eight irrigation treatments in three replications. The irrigation treatments were the application of 60, 80, 100, and 120% of irrigation requirement (T1, T2, T3, and T4), 20 and 40% deficit irrigation in vegetative phase (T5 and T6), and 20 and 40% deficit irrigation in reproductive phase (T7 and T8). The crop water requirement was calculated based on the daily weather data collected from an automated meteorological station at the Research Farm using the FAO Penman-Monteith equation. During the growing season, canopy cover, biomass, and soil moisture were measured weekly. The crop parameters were calibrated based on the measured data in treatments T1, T3, T6, and T7 and validated with four treatments T2, T4, T6, and T8. In the calibration and validation stages, the statistical indices including compatibility index (d) and root mean square error (RMSE) were used to evaluate the model outputs. The calibrated model was used to simulate crop growth based on daily weather data for 30 years (1988-2017) in four synoptic stations in Kermanshah province (Kermanshah, Islam Abad, Sarpol Zahab, and Kangavar) and for several different planting dates. The crop water productivity was calculated based on simulated grain yield and seasonal crop evapotranspiration. Finally, the model outputs under different planting dates were analyzed to determine the most appropriate planting time from the perspective of maximum production and maximum water use efficiency.

Statistical indicators show that the model has simulated the parameters of biomass, crop canopy, and soil moisture in the calibration stage with good accuracy. T1 and T6 treatments in biomass simulation, T7, T6, and T3 treatments in crop canopy simulation, and T3 and T7 treatments in soil moisture simulation had the highest accuracy. The accuracy of the model outputs in the validation stage for biomass and canopy cover was as accurate as in the calibration stage, while the accuracy of the simulated soil moisture in the validation stage was not high except in T4 treatment. Based on the model results, grain yield, seasonal evapotranspiration and water productivity were determined. According to the results, it can be said that in the study period (1988 -2017), grain yield has generally increased with a slight slope. The results showed that the planting date, which maximizes grain yield and water productivity, varies in the studied regions. According to the model results, planting in the second decade of May and the second decade of June will lead to the highest grain yield and water productivity in Kermanshah, respectively. Planting in the third decade of May showed the highest grain yield and crop water productivity in Islam Abad. In Sarpol Zahab, which has the highest temperature among the studied stations, planting in the last decade of March and the first decade of April has the highest grain yield and water productivity, respectively. In Kangavar, which is located in the east of Kermanshah province and has the coldest climate, by cultivating sunflower in the last decade of May and the first decade of June, respectively, the highest grain yield and water productivity can be achieved.

Due to the fact that some crop parameters of crop growth simulation models are variety specific, in this study, the crop parameters of the AquaCrop model for Farrokh sunflower cultivar were calibrated and validated. The accuracy of the calibrated model for estimating biomass and canopy cover was higher than soil moisture. The simulation results showed that the values of the studied parameters (grain yield and seasonal evapotranspiration) have changes according to the planting time in each region. The highest crop yield can be obtained in Sarpol Zahab, Islam Abad, Kermanshah, and Kangavar regions (west to east of the province) by cultivation in the last decade of March, last decade of April, the second decade of May, and last decade of May, respectively. In all study areas except Islamabad, planting date that resulted in maximum water productivity was different from the planting date that had maximum grain yield station and delayed planting had the highest water productivity.

The sunflower is one of the most important oilseed plants in the world and its oil has nutritional and high economic value. Identification and selection of high-yielding genotypes with desirable characteristics are especially important in this plant. Evaluating sunflower genotypes under different environmental conditions would be useful to identify genotypes with high stability and yield potential. Therefore, this study was conducted to the selection of the best sunflower hybrids.

In this study, 24 new sunflower hybrids along with Golsa cultivar were evaluated in a simple lattice design with two replications in four experimental field stations (Karaj, Boroujerd, Shahroud, and Gorgan) during the 2020 cropping season. GGE biplot statistical method (genotype effect + genotype × environment interaction) was used to study the stability of genotypes in the studied environments.

Results of combined analysis of variance indicated that the effects of environments, genotypes, and genotype × environment interaction were significant, suggesting that the genotypes responded differently in the studied environment conditions. So, there was the possibility of stability analysis. Results of stability analysis using the GGE biplot method indicated that the two first and second principal components of the GGE biplot explained 67.7% of the total seed yield variation. Based on the polygon view of biplot, the genotype G13 in shahroud environment, the genotype G6 in Karaj and boroujerd environments, and genotypes G5 and G19 in Gorgan environment were superior genotypes with the high specific adaptation. Based on the hypothetical ideal genotype biplot, the genotypes G6, G14, G3, and G4 were better than the other genotypes for seed yield and stability and had the high general adaptation to all environments. Also, the results showed that all environments had high discriminating ability so that could able to show differences between genotypes. The Boroujerd environment was the nearest environment to the ideal environment that had the highest discriminating ability and representativeness.

Consequently, the genotypes G6, G14, G3, and G4 were better than the other genotypes for seed yield and stability. Therefore, these genotypes can be used for further testing, including adaptation tests.