•Eight sunflower cultivars were studied under different drought intensities.•Drought stress caused to increase in catalase, carotenoid and proline.•Chlorophyll, Fv/Fm, RWC, stomatal conductance and ...cell membrane stability were decreased by drought.•Drought did not affect on peroxidase activity.
Plant species and cultivars have different physiological mechanisms in response to drought stress. A biennial field experiment was conducted to evaluate the effect of drought severities on enzymatic and non-enzymatic antioxidants, photosynthetic pigments, chlorophyll florescence and water relations in sunflower cultivars. Eight cultivars of sunflower (Azargol, Iroflor, Armavirovski, Lakumka, Alstar, Master, Sirna and Pumar) were subjected to well-watered, moderate and severe drought stress. Drought treatments were started at the beginning of stem elongation. The results showed that catalase activity, carotenoid content, proline content and electrolyte leakage were increased with drought severity, but chlorophyll-a, chlorophyll-b, maximum photochemical efficiency of photosystem-II, photosynthetic performance index, relative water content, and stomatal conductance were decreased. Peroxidase activity was not affected by drought stress. There was a positive correlation between enzymatic and non-enzymatic antioxidants. Catalase activity was correlated positively with proline content but negatively with chlorophyll content and chlorophyll florescence. Carotenoid had a negative correlation with chlorophyll-a as well as chlorophyll-b, but had a positive correlation with proline content.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
This study aimed to characterize if dust sprayed on soybean foliage impacts its yield and yield component characteristics. In 2017 and 2018, soybean Glycine max (L.) Merr. was planted using a ...factorial randomized complete block design with three replicates. Plants were sprayed with a 20 g m-2 of dust at four stages of the growth cycle, including third-node, the beginning of flowering, the beginning of podding, and the beginning of seed formation. Dust spraying was then continued twice weekly until the late full seed stage. Plant measurements included yield, yield components, stomatal conductance, peroxidase, and superoxide dismutase antioxidant enzymes activities. Results showed that depending on the time of application, the dust coverage created a range of yield loss in soybeans, most likely due to a reduction in stomatal conductance, grains plant-1 and 100-seed mass. Therefore, soybean fields that are regularly exposed to dust might be subjected to reduced yield.
Abstract
Drought limits plants growth. In many parts of the world, crop productions depend on water availability. Seed germination is a sensitive and low water stage in plants. A pot experiment was ...designed to test the effect of dew-irrigation on seed germination percentage of fennel, flax, and fenugreek. Irrigation treatments included dew-irrigation and control (non-irrigation). Results showed that dew-irrigation increased seed germination compared to control. Treatment of dew-irrigation had seed germination of 92.7%, 78.7% and 63.5% for flax, fenugreek, and fennel, respectively. But none of the seeds of control treatment germinated. Among plants studied, flax which is a cold season plant had the highest percentage of germination by dew-irrigation, and the plants that are the most heat-sensitive, such as fenugreek and fennel, had the lowest germination percentage. Results of this experiment determined that the moisture content in the air is capable to provide the necessary moisture for seed germination of the plants studied. In conclusion, dew-irrigation, due to supply low water, is better to be used at stages with lower water requirement such as germination. The ability of water supply by dew-irrigation at whole plant stage can be studied in the next experiments.
Excess rainfalls may be the cause of waterlogging in soil, which affects the growth and development of wheat. Therefore, the objectives of this study were to examine the effects of waterlogging on ...shoot and root growth and physiological characteristics of wheat. Three experiments were conducted: experiment 1 (E1): evaluation of seedling growth on ten Iranian winter wheat varieties with waterlogging periods (1–4, 4–8, 8–12, and 12–16 days starting from seed germination). Seminal roots and plumule were investigated at seedling. The others are E2: pretreatment of waterlogging (15 days) at tillering and stem elongation stages and its effects on shoot and root growth at anthesis stage and experiment 3 (E3): pretreatment of waterlogging (15 days) at tillering and jointing stages and its effects on yield and yield components and also evaluation of stress tolerance indexes. The results of the seedling growth test (E1) showed that 1–4- and 4–8-day waterlogging severity reduced seminal root length (94.5 to 93.7 %) and plumule length (86.2 to 50.0 %) compared to control. Results of E2 indicated that waterlogging stress decreased shoot dry weight, root dry weight, total secondary root length, and chlorophyll
a
+
b
content of flag leaf by 28–31, 44–35, 20–31, and 28–35 %, respectively. Also, result of E3 showed that the grain yields of wheat varieties at two conditions of stress were different in base tolerance indexes. In general, the responses of wheat varieties to waterlogging were different at the three experiments. The varieties that had the most of dry weight and length of the root were tolerant. Thus, it is possible to use these characteristics as an index for selecting the varieties with tolerance to waterlogging.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The effects of water stress on grain yield, its components, and physiological traits during the vegetative stage of wheat have been evaluated. Greenhouse trials were carried out by using factorial ...experiment based on randomized complete block design (RCBD) in three replications. Moisture stress was applied at vegetative growth stage (soil moisture was around 50% of field capacity from the beginning of stem elongation to flowering stage) and different wheat cultivars (such as Pishtaz, DN-11, Sivand and Marvdasht) were evaluated as the second factor. Water stress significantly decreased grain yield by decreasing the number of grains per spike. Under water stress from the beginning of stem elongation to flowering stages, Sivand and DN-11 cultivars had the lowest grain yield. The lowest and the highest reductions in grain yield and biological yield were detected in Marvdasht and DN-11, respectively. Results show that Marvdasht had the highest, while DN-11 had the lowest relative water constant (RWC) and performance index (PI) values. Water stress significantly decreased the chlorophyll content, PI and RWC values, at the same time significantly increased the carotenoid concentration, whereas the maximum quantum yield of photosystem II (Fv/Fm) did not change. According to the results, Pishtaz and Marvdasht cultivars are tolerant against drought stress and can recover very fast after stress is eliminated.
Considering the little amount of research on this crop in Iran and especially in Kermanshah, this paper was devoted to its study. In order to study the effect of sowing date and water stress on yield ...and yield components and seed sugar content in sweet corn cv.SC403, an experiment was conducted in the research farm and laboratories of the department of agronomy and plant breeding at Razi University, Kermanshah, in 2008. Research methods and results are reported.
Drought is the most important abiotic stress in Iran, which leads to a significant decrease in plant yield. Crops need a lot of water. Evaporation and transpiration determines the plant's water ...requirement. Water is one of the rare resources in Iran, which is affected by the amount of rainfall. In Iran, the cultivation of maize has been greatly promoted in recent years, and its use in livestock and poultry feeding and industrial uses has been noticed. Sunflower, as the main source of vegetable oil in the world, is of special importance, which requires a lot of water. Plastic mulch is especially important in reducing water consumption in arid and semi-arid areas.An experiment was conducted as a randomized complete block design with three replications at the Research Farm, Agricultural and Natural Resources Campus, Razi University, Kermanshah, Iran in 2016. The plants used in this experiment were maize and sunflower. Treatments included plastic mulch between the rows, plastic coating on the plant (only in maize) and control (without plastic). Treatments were applied at the beginning of the experiment and before germination.The plastic mulch between rows had the highest growth and yield of maize and sunflower than other treatments. In maize, plastic mulch between the rows had higher biological yield, harvest index, number of seeds per row, ear weight, and 100-seed weight than that of control, but there was no significant difference between plastic mulch between rows and plastic coating on the plant in terms of mentioned traits. There was no significant difference among treatments in terms of number of rows per ear, ear skin weight, and ear length. In sunflower, plastic mulch between rows had higher biological yield, head diameter, head weight, and 100-seed weight than control, and there were no significant differences between treatments in terms of harvest index, and number of seeds per head. The results of this experiment show that by applying plastic mulch, especially between the planting rows and before the seeds germinate, while reducing the length of the growth period and better use of moisture, the seed yield of maize and sunflower can be increased compared to not using plastic mulch by 38 and 41 percent, respectively. Other possible reasons for increasing grain yield under the conditions of using nylon mulch included reducing evaporation and increasing soil temperature at the beginning of the growth period.
In order to examine the effect of source and sink limitation and post anthesis water deficiency stress in determining of grain yield potential in nine modern bread wheat cultivars in the west of Iran ...with arid and semi-arid weather that is one of the main centers of crop diversity in the world, a split plot-factorial experiment based on randomized complete block design with three replications was used in crop year 2010-2011. Three treatments includes: control, flag leaf removal and removal of half of each spike was applied in the field research campus of agriculture and natural resources of Razi University. Water deficiency stress was started at anthesis and continued till physiological maturity (withholding of irrigation). Water deficiency caused significant reduction in the grain yield and the 1000 grain weight and caused significant increase in the number of fertile spikelets per spike. Flag leaf removal (source limitation) treatments showed that flag leaf contribution in grain yield production during grain filling in control and post-anthesis water deficiency stress condition were 10.1% and 13.4% respectively. In both conditions removal of spikelets spike⁻¹ (sink limitation) treatment had higher significant effect on fertility of spikelets, grains spike⁻¹, grain yield spike⁻¹ and 1000 grain weight than flag leaf removal. Flag leaf removal treatment in some cultivars not only had no reduction effect on grain yield and 1000 grain weight but also increased them. These results may be due to an increase in photosynthesis rate of remaining leaves and/or increase in amount of carbohydrates remobilization that is stored in the stems. This phenomenon is called the compensatory effect. In both water regimes, there was a correlation between lower grain weight, no grains spike⁻¹ and fertile spikelet spike⁻¹ and lower yield potential of ‘Chamran’ cultivar. But, ‘Zarin’ and ‘Pishgam’ cultivars due to higher grain yield potential in post-anthesis under water deficiency stress and control, performed more studies, to advise farmers to cultivate them. There are probably better than any other cultivars that are common in these regions and sowing of them by farmers will be associated with less risk.
Introduction: Nowadays, seed treatment with growth regulators or nutrients is widely used in the seed industry due to its significant effect on growth and yield, as well as resistance to diseases and ...pests. Therefore, in the present research, the effects of seed treatments with salicylic acid, humic acid, and zinc on two durum wheat cultivars were investigated under rainfed conditions.Materials and methods: This research was conducted as a factorial experiment based on a randomized complete blocks design (RCBD) with three replications in the research farm of the Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran, in 2019-2020. Factors included two cultivars of durum wheat (Saji and Zahab) and seed treatments (salicylic acid, humic acid, zinc, salicylic acid + humic acid, salicylic acid + zinc, humic acid + zinc, salicylic acid + humic acid + zinc, and control). Seed treatments were applied before sowing with a concentration of one millimolar (mM) salicylic acid solution, zinc solution (2%), and humic acid powder (95%) at the ratio of one kg or lit to 100, 100, and 300 kg of seeds, respectively. The investigated traits included the content of photosynthetic pigments and flag leaf area in the boot stage (code 45 on the Zadoks growth scale) and yield and yield components and seed protein percentage at the ripening stage.Results: The results of the analysis of variance showed that the effect of cultivars, seed treatments, and interactions between them was significant on the studied traits (except the number of spikes per square meter). The grain yield in durum wheat cv. Zahab was significantly higher than Saji. The grain yield of two cultivars in all seed treatments was higher than the control. Grain yield in Zahab was almost the same in all of the seed treatments, but in Saji, the highest grain yield was obtained in seed treatment with zinc usage (5033 kg. ha-1), and other seed treatments had the same effects. There was no significant difference between the two cultivars in terms of seed protein percentage, but the highest and lowest amount of seed protein was observed in salicylic acid + humic acid and control seed treatments with 13.14 and 12.11%, respectively. At the boot stage, the effects of cultivar and seed treatment on flag leaf area and the content of photosynthetic pigments (except carotenoids) were significant. Zahab cv. was superior to Saji in terms of flag leaf area and photosynthetic pigment content.Conclusion: Based on the results of this research, durum wheat cv. Zahab had a better performance than Saji. The effect of seed treatments with salicylic acid, humic acid, zinc, and the combination of these treatments had positive and significant effects on the grain yield compared to the control.
Stevia (Stevia rebaudiana B.) has auxiliary buds that often remain dormant for a long time and sometimes remain dormant until the plants change at the reproductive stage. This study was designed out ...to investigate whether decapitation and exogenous application of plant growth regulators enhance the productivity of stevia through breaking the apical dominance and increasing physiological characteristics. Experiment was carried out as a factorial in randomized complete block design with three replications. Factors were consisted two agricultural practices (Decapitation and No-decapitation) and eight foliar spray including without spray as control, water spray, GA3 (300, 600 and 900 µm) and CK (100, 200 and 400 µm). The results of the present investigation indicated a positive response on number of branches and leaves, leaves and stem fresh weight and total dry weight, in both harvests not only from the decapitation of apical buds but also from foliar application of CK (400 µM). Thus, it can be concluded that the decapitation practices in conjunction with foliar application of CK (400 µM) could be used to increase the dry-leaf yield of stevia. However, further studies are required to standardize the dose of CK (400 µM) to improve the yield and quality of stevia.
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