جستجوی مقالات مرتبط با کلیدواژه « یکنواختی جوانه زنی » در نشریات گروه « زراعت »

With regard to the ever-growing water deficit in the world, the adoption of the direct-seeded rice cultivation system has been suggested as an alternative to the transplanting method. One of the disadvantages of the direct-seeded method is low and non-uniform germination and emergence due to low seed vigor in rice. Priming is a technique which improves the rate and uniformity of seed germination under these conditions. Thus, this study aimed to investigate the effects of priming treatments on seed germination of different rice cultivars under different temperature conditions using the thermal time model.

This study was conducted in 2019 at the seed research laboratory of Gorgan University of Agricultural Sciences and Natural Resources. In this experiment, germination of primed and non-primed seeds in three rice cultivars (Nada, Anam, and Tolo) was investigated under different temperatures (15, 20, 25, 30, and 35°C). The priming treatments which consisted of control, hydropriming, and osmopriming with different chemicals (potassium chloride 2%, potassium nitrate 1%, calcium chloride 4%, glycine betaine 10 ppm, salicylic acid 10 ppm, and ascorbic acid 10 ppm) were investigated under different temperatures.

The results showed that priming treatments had no significant effect on the seed germination percentage of rice cultivars at different temperatures. The thermal time model based on binomial distribution fitted well to cumulative germination percentages in all priming treatments. Among the parameters of the thermal time model, the greatest priming effect was on the reduction of the thermal coefficient, followed by the reduction of the sigma coefficient, which resulted in the increased rate and uniformity of germination. Priming treatments had no significant effect on base temperature. Also, the responses of rice cultivars to seed priming treatments varied so that in Anam and Neda, priming with calcium chloride but in Tolo, hydropriming was more effective on the model parameters, especially thermal time to 50% of germination.

In general, priming treatments did not affect the base temperature of germination in rice cultivars, but they significantly affected the rate and uniformity of seed germination. As the latter issue is one of the main problems in the direct-seeded rice system, suitable priming treatments for each cultivar can be adopted to increase the rate and uniformity of seed germination and emergence in this system.

Germination and seedling emergence potential of monogerm sugar beet seed in the field, depends on seed quality. Also, crop yield and resource use efficiency of agricultural inputs depend on successful plant establishment in the field, and it is the vigor of seeds that defines their ability to germinate and establish seedlings rapidly, uniformly, and robustly across diverse environmental conditions. Our knowledge of variation in vigor and function of seed in crop yield, is limited. Accordingly, the quality characteristics of seeds, including seed vigor, are essential in the process of sugar beet breeding to provide cultivars with vigor and seed function good in the field. The present study was conducted to evaluate and rank single crosses and hybrids being improved in terms of different traits of seed vigor and determining the relationship between them to achieve maximum seed quality.

In this study, the seed vigor traits of 22 single crosses and 22 top cross hybrids, from crossing along with the sugar beet pollinating line, under greenhouse conditions in Sugar Beet Seed Institute in 2020-2021 were studied. The quality traits of single crosses and hybrids in two separate experiments in greenhouse conditions, each with 22 treatments were evaluated in a randomized completely block design with four replications.

The results showed that seedling emergence traits in single crosses and top cross hybrids resulting from their crossings in sugar beet were influenced by genotype. Genetic variation was observed between single crosses and hybrids in terms of seed vigor. Hybrids with low abnormal germination percentage, low non-germinated seeds and high germination uniformity in the laboratory have a significant increase in seedling emergence compared to other hybrids. Finally, hybrids that high germination uniformity in the laboratory, had the higher coefficient velocity of germination and were green in less time.

It seems that the uniformity trait of sugar beet seed germination has a decisive and significant role compared to the rest of the quality traits in the laboratory and can be used in breeding programs as an index of seed quality selection; Also, the multivariate cluster analysis method and the ideal genotype selection index (SIIG) of genotypes based on the qualitative traits of sugar beet seeds (seedling emergence percentage, seedling emergence rate, mean emergence time of seedling, emergence uniformity of seedling, mean dry weight of seedling) obtained a statistically significant difference in the cluster and their ranking in SIIG. It seems that the germination traits of sugar beet seeds can be used in breeding programs as one of the indexes of seed quality selection; Therefore, it is expected that selecting and screening superior genotypes to increase the quality of sugar beet seeds, it will lead to the improvement and increase of seedling emergence in the field and finally, will be accompanied by an increase in crop yield.

Germination is the most vital period in the plant life cycle that is influenced by various environmental and genetic factors. Among environmental factors, drought stress can greatly affect the germination and emergence of seedlings. The tolerance to this stress in the early stages of plant development is very important and seeds that can germinate in these conditions will have a successful establishment, proper density and high yield. Therefore, knowing the drought tolerance threshold in different genotypes of a plant can be very useful in recommending their cultivation in different regions. The hydrotime model is one of the common experimental models in studying the effects of drought stress on seed germination. This model has three parameters including base water potential, hydrotime coefficient and sigma, which indicate drought tolerance, germination rate and germination uniformity, respectively. These coefficients, especially the base water potential, can be used to introduce genotypes for cultivation in areas with different drought levels. Therefore, this study was conducted to investigate the response of different quinoa genotypes to drought stress at the germination stage with the help of hydrotime model coefficients.

To investigate the effect of drought stress on seed germination of different quinoa (Chenopodium quinoa Willd) genotypes, a factorial experiment was designed and conducted in a completely randomized design with four replications in the seed laboratory of Gorgan University of Agricultural Sciences and Natural Resources in 2019. For the germination test, 4 replicates of 25 seeds of each genotype were placed in a petri dish with a diameter of 8 cm on a layer of filter paper which added 3 ml of solutions prepared in different water potentials (0, -0.4, -0.8, -1.2 and -1.6 MPa) in an incubator at 25 °C. Depending on the germination rate, in the first days after the onset of germination, the number of germinated seeds was counted three to five times per day; with decreasing the germination rate, the number of counts was reduced to two times per day. The germination criterion was the radicle existence of one millimeter or more. The hydrotime model was used to investigate the germination response of quinoa genotypes to drought stress.

The results showed that all genotypes had high germination up to -0.4 MPa and their average germination percentage was above 90%; But as the water potential became more negative, the difference between the germination percentage of genotypes increased. According to the hydrotime model, there was a significant difference between different quinoa genotypes in terms of base water potential for 50% germination (ψb50), hydrotime coefficient (θH) and germination uniformity (σψb). The value of the ψb50 parameter ranged from -1.58 in genotype2 to -1.95 in genotype3. This indicates that quinoa is drought tolerant at the germination stage compared to sunflower, barley, wheat, safflower and canola. The lowest and highest hydrotime coefficients were observed in genotypes2 and 3 with 16.83 and 26.08 MPa/h, respectively (with an average of 20.93 MPa/h). Quinoa hydrotime coefficient is lower than rapeseed, wheat and safflower; In other words, the germination rate of the seeds of this plant is higher compared to the mentioned crops. The reason for this may be related to the size of the seed. The lowest germination uniformity was in genotype 3 (0.68 MPa) and the highest value observed in genotype 7 (0.46 MPa). The hydrotime and sigma coefficients are considered as indicators of germination rate and uniformity. The lower values of these coefficients are indicated the higher the germination rate and uniformity of the genotype, the faster the canopy closure and the higher yield.

In general, the results of this study show that the seeds have a high germination rate and with a high tolerance to drought stress at the germination stage; This increases the chances of faster establishment in the water shortage conditions. Also, the ability to tolerate drought in the germination stage of quinoa reduces the need for water consumption in this stage, which can be very useful and practical in developing management plans that lead to increased water use efficiency.

Schrophularia striata is one of the medicinal plants of the Scrophulariaceae family and contains phenolic compounds. Locals have traditionally used this herbal medicine to treat infections caused by wounds, gastrointestinal diseases, and eye diseases. Due to excessive consumption by indigenous people and climate change, especially increasing temperature, the cold required to eliminate seed dormancy is not presently available and its germination and growth has decreased. Therefore, this plant is at the risk of extinction. Since this plant is propagated in natural habitats through seed and due to deep seed dormancy, evaluation of different seed dormancy methods is necessary for conservation and domestication of this species. In this study, suitable methods to eliminate seed dormancy of this plant using chilling and gibberellic acid treatments were studied on the seeds collected from different habitats of Ilam province.

To investigate the effect of using chilling and gibberellic acid on Schrophularia striata dormancy, a split plot factorial experiment based on completely randomized design with four replications was conducted at the seed laboratory of Yasouj University in 2018. The first factor included the duration of moist chilling period (0, 4, 8, 12 and 16 weeks), the second factor included gibberellic acid (0, 300 and 600 mg/L) and the third factor included five habitats (Ilam, Ivan, Mehran, Abadan and Dehloran).

The results showed that the 16-week Chilling and zero gibberellic acid treatments had the highest germination percentage in all habitats, as the percentage of germination in Mehran, Ivan, Ilam, Abadan and Dehloran habitats was 66, 50, 36, 30 and 25%, respectively. Also, the highest germination rate was observed in all habitats at 16 weeks chilling and zero mg/L gibberellic acid concentration. The highest germination uniformity was obtained at 16 and 12 weeks of chilling.

Chilling period duration was effective on germination percentage and rate and with increasing chilling period, germination percentage and rate increased. This indicates that the seeds studied had some degree of physiological dormancy, and the seed of higher altitude habitats required longer chilling periods than those of the lower ones for germination. Also, according to the results of this experiment, chilling periods above 16 weeks should be used to increase germination percentage.

About 6.8 million hectares of agricultural lands in the country have different degrees of salinity, of which 4.3 million hectares have only salinity limits. The response of plants to salt stress is complex and depends on various factors such as concentration and type of solutes, plant species, plant growth stage and environmental factors. The use of salinity tolerant cultivars is currently one of the most effective ways to exploit and increase yield in saline and low saline soils. Chenopodium quinoa Willd. is a native plant of the Andean region of South America that was cultivated there from 5,000 to 7,000 years ago. The Food and Agriculture Organization (FAO 2002) designated Quinoa as one of the most important crops for food security of the world's population in the last century. Most Quinoa cultivars are capable of growing in salinity at concentrations of 40 (dSm-1) and even higher. This salinity is too high for most crops. Increasing the concentration of NaCl in the nutrient solution, followed by increasing the osmotic potential, adsorption of Na+ and Cl- ions during seed germination causes cell damage and ultimately inhibits or reduces germination. Therefore, the purpose of this study was to evaluate the effect of salinity caused by the use of poor quality water on yield and yield components of Quinoa as well as germination components of different Quinoa cultivars.

This study was carried out in cultivation in controlled environment (germination apparatus) at the Faculty of Agriculture, Shahid Chamran University, Ahvaz, Iran, in order to evaluate the reaction of cultivars and genotypes to salt stress conditions. In the experiment conducted under controlled conditions, the experimental treatments included salinity (NaCl) at six levels (0, 10, 20, 30, 40 and 50 dSm-1) and three genotypes and genotypes of Quinoa (Giz, Titicaca, Q26) was performed as factorial experiment in a completely randomized design with three replications. To find plant respanses and chose the best one using seed number and germination rate, percentage and germination rate, seed Vigor index, mean germination time, time to 10% germination, time to 50% germination and time to 90% germination were calculated according to the equations.

The results of analysis of variance showed that salinity stress had a significant effect on germination percentage and rate, and other measured germination indices (p < 0.01). Interaction of cultivar and salinity stress on root length, stem length, root dry weight and shoot dry weight, seed vigor index, germination uniformity, D10, D50 at 1% and germination percentage at 5% were significant. With increasing salinity levels from the control treatment to the highest salinity level (50 dSm-1), the decreasing trend of root and shoot length as well as root and shoot dry weight was observed. Titicaca showed the highest germination percentage and the highest seed vigor index in control treatment. In the salinity-free treatment, Titicaca showed the best and worst yield in Q26 at 50 (dSm-1) for 10% germination. Among other cultivars, Titicaca showed the highest root and shoot length and the lowest root and shoot length at 50 (dSm-1) under non-salinity stress conditions. Titicaca cultivar had the highest and Giz cultivar had the lowest germination and root dry weight. Titicaca cultivar in control treatment showed the highest root and shoot length with an average of 5.53 and 5.57 cm, respectively, while in salinity treatment of 50 dS/m-1 with an average of 0.4 and 0.3 cm minimum root and shoot length. Also, the best uniformity in germination with 20.2 hours was observed in Titicaca cultivar in control treatment.

At low salinity levels, acceptable yield was observed but in sever salinity condition most of the crops could not grow during the phenological stages. According to the results of this study and the study of quinoa behavior and high tolerance of the plant in the germination stage in the face of salinity stress, to improve salinity resistance in crops through breeding programs, and further study of salinity defense mechanisms in susceptible cultivars It is recommended. It seems that despite the significant effectiveness of all three cultivars and significant reduction in germination indices at high salinity levels Titicaca cultivar had a higher tolerance threshold than the other two cultivars, indicating the diversity of cultivars in response to physiological processes to salinity stress. It is also possible to use this cultivar with further research into breeding and breeding programs of other sensitive quinoa cultivars.

In order to evaluate germination behavior of Colchicum seed, an experiment was conducted as factorial based on a randomized complete design with four replications. The experimental treatments were all combination of priming at three levels (warm stratification, cold stratification, control), gibberellic acid at two levels (0,500 ppm) and incubation temperatures at 8 levels (2, 5, 10, 15, 20, 25, 30, 35). After applying the priming treatments, gibberellic acid treatment was applied and then the response of seed germination at constant temperatures were assessed in the germinator. The effect of temperature on germination components was significant. Germination was occurred only in warm stratification. Generally, germination was started by a very slow trend and after seeds were set at incubation temperatures, at least 40 days were lasted to germination occurred. There was no germination at 2°C. By increasing temperature at a range of 5-15°C, germination percentage was increased and then was stopped at 25°C. Germination uniformity at 20°C was more than other temperatures. The meanest germination time was observed at 20°C and the least mean germination time was at 15°C. Gibberellic acid (single application) had no effect on seed germination. Based on two regression models, the cardinal temperatures (Tbase, Topt, Tmax) were (1.38-1.72°C), (12.7516.10°C) and (24.12-25.65°C), respectively.

In many studies, the medicinal properties and impact of blond plantain on mechanisms of human physical activities has been proven. Salinity is an important abiotic stresses with detrimental effects on seed germination. An experiment was conducted to study germination characteristics of blond plantain under water and salinity stress conditions at different temperatures. The experiment was conducted at the University of Tehran Seed lab, Karaj, in 2015. Temperatures regimes included 5, 10, 15, 20, 25, 30, and 35°C. For each temperature, the treatment forsalinity and water stress was four water potentials (zero, -4, -8 and -12 bar) using sodium chloride. The effects of salt stress on seed germination of blond plantain at different temperatures showed the highest resistance to salinity at 20ºC. Salt stress at different temperatures reduced germination parameters. Increased temperatures resulted in better conditions for seed germination and increase the salinity stress tolerance. Increased severity of salinity causes the reduction of temperature range in which the seed can germinate.

In this study investigated the effects of seed quality on germination parameters and heterotrophic seedling growth in two maize varieties including single cross 640 and 704. For seed deterioration treatments we used accelerated aging test in 410C for 24, 48, 72 and 96 h. A factorial experiment in a completely randomized design with four replications was conducted in the laboratory. Results showed that the seed deterioration effects on all traits studied included speed germination, germination percent, germination uniformity, normal seedling percent, plomule length, allometric growth ratio and seedling length vigor index were significant for but there was no significant effect on heterotrophic seedling growth traits. The varieties also have significant effects at 1% level on all the traits except allometric growth ratio, final seed and root dry weight. Seed deterioration had no significant effects on shoot length, allometric growth ratio, seedling length vigor index in 704 and on germination growth rate in 640. With increasing of seed deterioration were decreased germination percent and uniformity. Seed deterioration was more intense on seed germination percent in 640. Heterotrophic growth parameters such as seed reserves use efficiency, fraction of seed reserves mobilization and final seed dry weight has higher averages to larger cotyledon in 640. At the end of the day increasing the seed aging caused decreases on germination and normal seedlings percentage in both varieties but 704 was more resistant to decay.

One of the important strategies for increasing germination speed and germination percentage, to produce high quality seedling and plant optimal establishment is seed priming. In order to evaluate reactions of a lentil seed to priming duration and concentrations of the applied material as priming, a factorial experiment based on a completely randomized design with three replications was done in the agronomy laboratory of agriculture and Natural Resources College of Gonbad Kavous University in 2013. Factors included priming duration (4, 8 and 12 h) and various concentrations of the priming (hydro priming, hormonal priming by gibberellic acid and salicylic acid with the concentrations of 50, 100 and 150 ppm and non primed seeds). Results showed that the interaction effect of the concentrations and duration of the priming was significant on whole measured traits except the seed vigor index, germination percentage and seedling dry weight at 1% probability level. The lowest duration of germination (5, 10, 90 and 95%) obtained in the hydropriming treatment (2.72, 5.43 and 18.17 hour). The highest radicle fresh weight was observed in hydropriming treatment in three studied durations priming. In this study; the highest rate of germination obtained from GA50ppm during 12 hours. GA50ppm increased Germination percentage (98%). The greatest radicle length, shoot length and relative growth rate were obtained in the treatment of the gibberellic acid 100 ppm during 8 hours. All the average, gibberellic acid 100 ppm in 8h had an additive effect on the most of the measured traits of the lentil seed. Therefore, it can be introduced as the best mixture treatment.

In order to determinate the cardinal temperatures and investigate the effect of temperature on seed germination and seedling growth of Securigera securidaca, a study was conducted in a completely randomized design with 8 temperature treatments (5, 10, 15, 20, 25, 30, 35 and 40oC) and four replications in research laboratory of faculty of agriculture at the Birjand University in 2013. Two-segmented linear regression model was fitted between germination rate and temperatures to determine cardinal temperatures for germination. Cardinal (minimum, optimum and maximum) temperatures of germination were determined as -1, 22.5 and 40.2oC respectively. Maximum rate and percentage of germination obtained in the range of 20-25oC. Maximum of radical length and dry weight, maximum of caulicle length and dry weight and maximum of vigor seedling were obtained in 20oC,10-20oC and 5-30oC respectively. Maximum and minimum germination uniformity (GU) was obtained in 25 and 5oC.

Due to importance of medicinal plants، understanding the seed germination response to temperature is agronomically important. A laboratory study was conducted to investigate the effect of different temperatures on seed germination of fennel، cannabis and sesame in a completely randomized design with four replications. Various constant temperatures (5، 10، 15، 20، 25، 30، 35 and 40° C) were considered. According to the results، the effect of temperature on germination rate and percentage in all species was significant. The seeds of fennel were not germinated in 5، 35 and 40 0C and seeds of sesame germinated only in 5 0C. Maximum rate of germination obtained in 30 °C for fennel and 25 °C for sesame and cannabis. The highest germination percentage of fennel، and cannabis and sesame were in 20، 25 and 30 0C respectively. The lowest of germination uniformity (GU) were observed in 20 0C for fennel and in 15 0C for cannabis and sesame. Amount of seedling vigor maximized for fennel and cannabis in 250C and for sesame in the 300C. The values of length and weight of radical and plumule were enhanced with increase of temperature and record on maximum in special temperature and then reduced slowly. The quantitative information provided by this study can be used in prediction of emergence under diverse temperature conditions. Germination of cannabis seeds occurred in a wide range of temperatures and this seed are less sensitive to temperature compared to the other two plants. Germination of fennel seeds was less، except at 200C. The sesame seeds had good germination at 15-35 0C.

Germination and seedling growth is important for plants establishment under saline conditions. So choosing the plants that have rapid and uniform germination under saline conditions may help initial establishment and seedling growth. In order to assess the response of sesame ecotypes to salinity, a factorial experiment based on completely randomized design was conducted with three replications under laboratory conditions. The first factor was five sesame ecotypes (MSC3, MSC6, MSC7, MSC12 and MSC14) and the second factor consisted of 11 salinity levels (1, 3, 6, 9, 11.4, 14.5, 16.4, 19.6, 21.1, 23.1, and 25.1 dS.m-1) that was provided from water wells in the region with electrical conductivities of 2.5, 10 and 23 dS.m-1 and then treatments were achieved by diluting or concentrating these saline solutions. The results showed that germination was decreased by increasing salinity, so that there was very low germination in the salinity level of 23.1 dS.m-1 and no germination was observed in the salinity of 25.1 dS.m-1. Salinity had significant effects on components of final germination percentage (FGP), germination rate (GR), germination uniformity (GU), time to reach 50% germination (T50), germination energy (GE), seedling vigor index (SVI), length of shoot and root to shoot dry weight ratio (R / S). With increasing salinity levels, however, these components were not equally affected. In salinity of 3 dS.m-1, the indices related to seedling growth was higher than the control and other treatments, and FGP, GU, GE and SVI indices were 8, 5, 10 and 66% higher than the control treatment, respectively. The highest correlation of FGP was observed with GE (0.98**) and GR (0.83**), which indicates that sesame ecotypes seeds with high germination energy will have increased amount of FGP. In high salinity conditions (23.1 dS.m-1), the maximum and minimum amount of FGP, GR and GE were observed in MSC6 and MSC12 ecotypes, respectively. MSC6 and MSC7 compared with other ecotypes had a higher SVI index. It seems that MSC6 ecotype had a greater tolerance range than other ecotypes under conditions of this experiment.

Germination is the first and most important developmental stage of plants which is influenced by genetic and environmental factors. Hydrotime model describes the relationship between water potential (ψ) and seed germination rate and percentage. This model quantifies the rate of germination progression (θH)، the stress tolerance of germination (ψb(50)) and the uniformity of germination (σψb). This indicators can be used to show seed lots or varieties vigor and evaluation of dormancy in seed and some treatments effects (e. g. priming، ABA or GA) on seeds vigor. Hydrotime model is not well known amongst Iranian researchers. This study aims at introducing the application of hydrotime model in germination data analysis. To achieve this، germination data of three plants (sweet clover: Melilotus officinalis، rye: Secale cereael and wheat: Triticum aestivum) in response to drought stress were used. The θH value quantifies the inherent rate of germination، which can vary among species and different physiological stages. The ψb (50) value is an indication of the average stress tolerance of the population. A population with a high ψb (50) value (less negative) will be inhibited germination at higher ψ (less stress) than will a population with a lower ψb (50) value. The value of ψb (50) for a seed population can be shifted to higher or lower values by the induction and release of dormancy. The σψb value is a quantitative estimate of the uniformity in germination in the population as greater σψb means a wider variation between the first and last seeds to germinate.

In order to study the effect of sodium chloride (NaCl), as a salinity stress factor, on sour orange seed germination indices, an experiment was conducted in a completely randomized design with 3 replica‌tions (each replication included 20 seeds) at the University of Guilan, in 2009. NaCl levels were 0, 7.8, 15.6 and 23.4 dS/m. The results showed that various levels of NaCl had significant effect on all the studied traits. Seed germination in 23.4 dS/m treatment started later than other treatments. The highest germination was in control and 7.8 dS/m NaCl treatments. The 15.6 and 23.4 dS/m NaCl treatments had the least germination percentage (85.7 and 46.9%, respectively). The highest germination index (length of germination period) was in 23.4 dS/m treatment followed by 15.6 and 7.8 dS/m and control with no significant difference. T50 was highest in 23.4 dS/m and lowest in control treatments. Mean daily germination, seed growth rate and seed vigor were highest in control treatment, with no significant difference with 7.8 dS/m treatment. Overall, it was found that germination of sour orange seeds is resistant to 7.8 dS/m NaCl, and they are able to germinate and grow in saline soils, as well.

An experiment was conducted for evaluation the allelopathic potential of extract soybean shoot on seed germination and seedling growth of four weed species tumble pigweed, smooth pigweed, common lambsqurters and black nightshade. For each species a factorial experiment was used in a completely randomized design with three replications. Plant shoots were gathered in flowering stage and individually dried and then ground. Water extracts with concentrations of 5, 10, 20 and 40 % were prepared and distilled water was used as control. Seeds of weed sat in petri dishes. Then, their germination percentage determined after 11 days. The results showed that root length, germination rate and percentage reduced in weed species when concentration rate was increased. Black nightshade had most germination percentage (88.14), root length (46.4 mm) and germination uniformity (1.5 days). Therefore, it affected with soybean shoot extract less than other weed species. Tumble pigweed had most germination rate (3 days) and its required time to achieved 10, 50 and 90% maximum germination, was about 2, 2.5 and 4 days respectively. Therefore, It was better than other species. Most inhibition effect of extracts on germination percentage belonged to smooth pigweed.