IRANIAN JOURNAL OF SEED RESEARCH
Year:2019 | Volume:5 | Issue:2|Papers Count:10

Introduction: Germination speed is one of the most important germination indices, used in most studies to compare the effects of different treatments on seed germination. Researchers use the reverse time up to 50% maximum germination (1/D50) to calculate the germination rate. One of the methods used for calculating the D50 is the utilization of nonlinear regression models such as Logestic, Gompertz, Richard, Weibull and Hill. In addition, for the purpose of calculating this parameter, simple empirical models such as the model presented by Farooq et al. and Ellis and Roberts are used. The question which arises is which of these methods has more precision predicting D50. The purpose of this study was to calculate D50, using different methods in seed germination of cotton. Material and Methods: In this experiment, cottonseeds were placed at three temperatures of 15, 25 and 40° C with three replications, and germinated seeds were counted daily several times. To calculate D50, several nonlinear regression models including Gompertze, Logestic, Hill (the four-parameter), Richard and Weibull models were used. Moreover, for the purpose of calculating D50, the models presented by Farooq et al. and Ellis and Roberts were used. Results: The results showed that all nonlinear regression models exhibited suitable fit to germination data. However, logestic, Hill and Weibull showed better predictability of D50, compared with other models. Besides, D50 calculated by the Farooq model was similar to that estimated by nonlinear regression models, whereas D50 estimated by the Ellis and Roberts model was higher than that estimated by other models. Conclusions: The results of this study showed that both non-linear regression models and the model developed by Farooq could be used to calculate D50 of cottonseed. In general, the results of this study showed that nonlinear regression models could be used to calculate D50. In this research, Logestic, Hill, and Weibull showed good fit for cumulative seed germination data of cotton seeds versus time at different temperatures. These models have coefficients that have a biological concept that includes maximum germination percentage, time to 50% maximum germination and time to start germination. Moreover, when researchers only seek to measure D50 and are not familiar with the statistical software, they can use the empirical formula presented in this research.

Introduction: Heavy metal pollution is one of the most serious environmental problems. These metals which accumulate in food chain bring about a lot of hazards to both humans and animals. Among heavy metals, lead is considered to be the most dangerous heavy metal in the environment. It contaminates the environment through the lead-acid battery industry, paint and gasoline additives, insecticides, chemical fertilizers, car exhaust pipes and soldering. The objective of this study was to investigate the effect of Pb(NO3)2 on germination characteristics and biochemical changes of two wheat cultivars (Chamran and Kohdasht cultivars). Materials and Methods: The objective of this research was to evaluate germination and biochemical changes of two wheat cultivars under Pb(NO3)2 stress, using three-parameter sigmoid model. The experimental design adopted was factorial with a completely randomized design, as the base design, with 3 replications. The first factor was 2 wheat cultivars (Kohdasht and Chamran), and the second factor was 6 levels of Pb(NO3)2 (0, 0. 25, 0. 5, 0. 75, 1 and 1. 5 mg. L). Results: The results showed that with increases in levels of Pb(NO3)2 stress, germination percentage, germination rate, normal seedling percentage, seedling length, seedling weight and seed vigor index reduced for both wheat cultivars. The results of fitting three-parameter sigmoidal to characteristics indicated that the highest characteristics and X50 were obtained from the Chamran cultivar. The highest germination percentage (96%), germination rate (23 seeds per day), normal seedling percentage (93. 33%), seedling length (13. 07 cm), seedling weight (0. 07) and seedling vigor index (12. 18) were obtained from the Chamran cultivar under non-stress conditions. Pb(NO3)2 stress increased proline and catalase activity but reduced protein, proline and protein for the Chamran cultivar, as compared with the Kohdasht cultivar. Conclusion: Generally speaking, the results showed that Pb(NO3)2 had a significant effect on germination characteristics and catalase, proline and protein of wheat. Finally, it could be said that in copperaccumulated areas, choosing proper cultivars can slightly mitigate the damages caused by copper. The Chamran cultivar seems to be a better candidate for these conditions.

Introduction: Given the known harmful effects of synthetic herbicides, nowadays the utilization of hetrotoxic characteristics of hetrotoxic plants can have a very important role in weeds management and control. In fact chemical compounds, released through roots, stems, leaves, flowers, seed pollen, fruits and seeds can be used as bio-herbicides and bio-pesticides. The purpose of this study was evaluation of the effects of hetrotoxicity potentials of Datura stramonium L. shoots on germination traits and photosynthetic pigments of wheat cultivars. Materials and Methods: An experiment was conducted to evaluate hetrotoxicity potential effects of aqueous extract of different organs of Datura stramonium L. such as stems, leaves, fruits and their mixture on germination traits and photosynthetic pigments of two cultivars of wheat (Kohdasht and N8720) as a factorial experiment based on a completely randomized design with three replications in Weeds Science Laboratory of Gonbad-e-Kavous University in 2017. Datura stramonium shoots were collected at fruit formation stage in the Moghan Plain and were subsequently separated into stems, leaves and fruits. Five ml of the extracts in question and their mixture were added to 25 disinfected seeds of the cultivars under the study separately. Results: The results showed that wheat cultivars had different responses to the organ extract and this difference was also significant for various organ extracts as well as the interaction effect of cultivars in organ extracts. Mean comparison of interaction of cultivars and organs showed that germination percentage of the Kohdasht cultivar decreased under the experimental treatments. The highest decrease was obtained in the leaf extract, which was about 98. 33%. However, stem, fruit and mixed organs increased the germination percentage of N8720, which were about 5. 72, 5. 72 and 1. 41%, respectively. The result of the germination rate was similar to that of germination. Radicle and shoot length of both cultivars decreased under experimental treatments. Leaf extract had the highest inhibitory effects on radicle and shoot length, which were about 96. 70 and 89. 21%, respectively. Content of total chlorophyll of both cultivars of Kohdast and N8720 increased under aqueous extract of stem (24. 64%) and fruit (14. 62%). Nevertheless, extract of other organs and their mixture decreased the trait of interest. The result obtained for carotenoid was also the same as that one obtained for total chlorophyll. The speculation is differences in allelochemical concentration in various organs of Datura stramonium and physiological characteristics of the traits studies in cultivars caused the difference. Conclusions: Given the results, use of Datura stramonium biomass, especially the leaf, is suggested as a natural herbicide, which is non-chemical management strategy. To accomplish this, it is necessary to analyze phytochemical compounds of this weed.

Introduction: Today, various technologies have been developed to improve seed quality with the aim of increasing the percentage, speed and uniformity of germination and improved seedling establishment under different environmental conditions. One of these technologies is seed pre-treatment or seed priming. In this regard, some studies confirmed that pre-treatment of seeds with hormones and plant growth regulators improve germination behavior and its related indices, including average germination time, seed vigor, radicle length, plumule length, germination rate and seedling establishment in primed seeds of sesame. Cognizant of the sensitivity of the germination process as the first plant developmental stage and the importance of improving germination indices and sesame seedling establishment, the aim of this study was to evaluate the seed priming efficiency, using salicylic acid, methyl jasmonate and humic acid in the germination performance, biochemical changes and early seedling growth of two sesame cultivars including Yellow white and local cultivar of Dezful. Materials and Methods: This experiment was conducted as a factorial based on a completely randomized design with four replications in the seed technology Laboratory of Safi Abad Dezful Agricultural Research Center in the summer of 2015. The first factor was seed pre-treatment with distilled water (control), salicylic acid 0. 1mM, methyl jasmonate 1μ M, and humic acid 1. 5% and the second factor was two varieties of sesame including Yellow white and the local cultivar of Dezful. Germination percentage, germination rate, seed vigor index, radicle length, plumule length, allometric coefficient, proline content, soluble proteins and catalase enzyme activity were determined to compare the treatments. Results: The results of the experiment showed that seeds priming had a significant effect on germination percentage, germination rate, seed vigor index, radicle length, plumule length, allometric coefficient and seedling biochemical changes, and improved them. The effect of cultivar on all the traits studied, except mean daily germination and plumule length, was not significant. In this research, the Dezful cultivar had an average of 13. 52 seeds per day with higher germination rates, compared with the other cultivar (Yellow white). In addition, the interaction of priming × cultivar was significant only in seed vigor index and allometric coefficient, where the comparison of the mean values indicated that the highest seed vigor was obtained by using humic acid 1. 5% in the Dezful cultivar (10. 09), while the highest allometric coefficient in seed pre-treatment with methyl jasmonate was found in the Yellow white cultivar (1. 57). Conclusions: In this study, the most effective seed priming treatments for improving germination, biochemical changes and seedling growth of sesame was humic acid 1. 5%, recorded for the local cultivar of Dezful. Seed priming with humic acid 1. 5% was significantly better than the control and Dezful cultivar’ s germination performance was better than that of Yellow white cultivar; therefore it can be said that pretreatment of seed with humic acid with significant effects on germination characteristics of sesame can be more effective in establishment of seedlings. It is advisable to use this organic acid for better root system development and sesame seedlings establishment, which is a major problem at the beginning of the growing season.

Introduction: Crop rotations are practiced to eliminate the effect of monoculture. However, the succeeding crop may be influenced by the phytotoxins released by the preceding crop. Among plants, Brassica species contain allelochemical compounds as glucosinolate, which is, under special conditions, released to the environment and affects seed germination and plant growth. Wild mustard (Sinapis arvensis L. ) as a weed in 30 crops in 52 countries has a series of allelopathic effects that prevent germination of other plants. Products of glucosinolate-like ionic thiocyanate (SCN-) inhibit the root or shoot growth of many crop species. In addition, volatile compounds like isoprenoid and benzenoid released from Brassica tissue degradation may suppress many crops’ growth. It was also found in many studies that allelochemicals, which inhibit the growth of some species at certain concentrations, might stimulate the growth of the same or different species at lower concentrations. The present research was conducted to evaluate the effects of aqueous extract concentration of various mustard parts on barley seed germination and seedling growth. Materials and Methods: In order to evaluate the allelopathic effects of mustard on agro ecosystems, a factorial experiment based on a completely randomized design with three replications was carried out in the Botany Laboratory of Agriculture Faculty, Illam University in 2014. Experimental treatments included five concentrations of mustards foliage and root aqueous extract (0, 10, 30, 50, and 70 percent) that were studied at germination and early growth stages of barley (cv. Abidar) in two separate experiments. In the seed germination phase, the effects of aqueous extract of mustard on germination rate and germination percentage of barley seed were measured. In the study of the effect of aqueous extract of mustard on barley seedlings, weight and length of root and shoot, leaf chlorophyll content, proline and soluble sugars content were measured. Results: The results showed that the highest amount of barley seed germination percentage and germination rate (100 and 19. 5, respectively) were observed in the control and the lowest amount (40 and 9. 5, respectively) belonged to mustard root aqueous treatment with 70 percent concentration. The highest decrease in barley seedlings length and weight were observed at the highest concentration of aqueous extract. The amount of chlorophyll a decreased from 2. 39 in the control to 1. 66 mg per fresh weight in 70 percent concentration of aqueous extract treatment. The highest amount of proline (66. 8 μ M per fresh weight) in barley foliage was observed in 70 percent aqueous extract treatment. The results of this study showed that mustard allelopathic effect may be a possible mechanism controlling the barley germination and early growth stage in agro ecosystems. Conclusion: Generally speaking, the findings suggest that in the short run, mustard extract has toxicity effects on barley germination and growth so much so that aqueous extract has adverse effects on almost all th characteristics measured. Depending on the concentrations of mustard extract, allelopathic activity will vary. Further investigations are also needed to determine the influence of cultivar variations, and to identify the active compounds involved in mustard auto toxicity and allelopathy.

Introduction: The use of nanotechnology as a diverse and applied discipline is ongoing in almost all areas of science. Fertilizers and nano-nutrients have the effective properties which help the production of plants, depending on their needs to regulate the plant growth. Plants under stress conditions tend to produce natural nanoparticles to continue their growth. Nano TiO2 has a highly photocatalytic effect and as a catalyst, it is mainly used in water, electronic devices, conversion and storage equipment of energy as suspension. Sources of SiO2 are very diverse, including natural nanoparticles, anthropogenic particles and engineering nanoparticles. Although silicon is not an essential element for growth in many crops, it has beneficial effects on plant growth and development. Today, carbon nanotubes are one of the most important materials in industrial programs. These materials, with different production methods and specific properties, can play an important role in the production of composite materials and have applications in medicine, electronics and energy storage. The Niger plant, with the scientific name of Goizotia abyssinica (L. F) Cass, belongs to the Asteraceae family. Its seeds are used in pharmacy, food industry, green manure and for feeding birds and cows. Therefore, the purpose of this experiment was to investigate the effect of type and concentration of three nanoparticles on some germination characteristics and anthocyanins content in Niger medicinal-oily plant. Materials and Methods: In order to evaluate the effect of three nanoparticles on seed germination of Niger, an experiment was conducted as factorial in a completely randomized design with four replications. The treatments of TiO2, SiO2, and CNT were used as the first factor while their concentrations in four levels (zero, 10, 30 and 60 mg/l) were considered as the second factor. In this study, the traits of germination percentage, germination rate and mean of daily germination, germination and vigour index, length, fresh and dry weight of radicle and plumule, anthocyanin content and radicle resistance percentage were measured. Results: The germination percentage, germination rate and mean of daily germination decreased by increases in nanoparticles concentration. The favorable effect of TiO2 on germination index was obtained at the concentration of 30 mg/l and radicle dry weight at the concentration of 10 mg/l, compared to the control. The positive effect of SiO2 was obtained on germination index and radicle dry weight at the concentrations of 10 and 60 mg/l, the anthocyanin content and the fresh and dry weight of plumule at the concentration of 60 mg/l, compared to the control. In addition, the appropriate effect of CNT on germination index was observed at the concentration of 10 and 30 mg/l, the anthocyanin content and radicle dry weight at the concentration of 60 mg/l and plumule fresh weight at the concentration of 30 mg/l. Conclusions: According to the results of this study, it seems that the effect of nanoparticles in plants, apart from the plant itself, species, type and concentration of nanoparticles, varies depending on the growth stage and physiology of the plant. It seems that nanoparticles can increase the water absorption of seeds at some concentrations and increase seedling growth, which is because of their positive effects. Anthocyanins are produced by exposure to stress due to their antioxidant activity. In general, it can be said that increasing the concentration of nanoparticles causes the oxidative stress in the plant and the subsequent increase. Therefore, it is recommended that by investigating the bad effects of nanoparticles on plants, if necessary, use be made of nanoparticles at low concentrations (less than 60 mg/l) to increase the plant's efficiency.

Introduction: Seeds are a good option when it comes to propagation and protection programs of medicinal plants. Although seed dormancy is an adaptive strategy for wild medicinal plants, it is considered as an undesirable trait in their domestication and cultivation, representing a problem to be solved. Echinophora platyloba seeds have dormancy despite their remarkable medicinal properties. Materials and Methods: In order to break seed dormancy, three separate experiments, namely stratification, hormonal treatment and their combination were conducted. For stratification, 10 samples were placed in a wet bed at 5 ° C for 2, 4, 6, 8, 10, 12, 14 and 16 weeks and were compared, using a completely randomized design with three replications. For hormonal treatment, the seeds were placed in GA concentrations of 0, 500 and 1000 ppm for 24 hours and were then transferred to germination conditions. However, since the dormancy breaking did not occur, this experiment was not pursued any more. For combined application of hormone and stratification, seeds were placed at above-mentioned concentrations of gibberellin for 24 hours at 20 ° C and then gibberellin solutions were removed and the seeds were transmitted to 5 ° C and were compared for 2, 4, 6, 8 weeks with a CRD factorial experiment with three replications. The first factor was concentration of gibberellin in three levels and the second factor was the duration of stratification in 4 levels. Results: Stratification had a positive effect on seed dormancy breake and 16-week chilling led to highest germination percentage and rate and vigor indices. The combined application of hormonal treatments accelerated dormancy release and improved seed germination characteristics, which peaked in 8 weeks. 8-week stratification treatment at 5 ° C with 1000 ppm gibberellic acid was the best treatment for overcoming dormancy in Echinophora-platyloba seeds. Conclusion: It seems that seed dormancy of Echinophora seeds is physiological, which successfully broke by moist chilling and simultaneous application of stratification and gibberellin. Although Gibberellin had no effect on dormancy break, it reduced the need for stratification. Their combined application showed synergistic effects on dormancy release.

Introduction: Seed germination is one of the most important and complex stages in the plant life cycle and is affected by many hereditary and environmental factors. Various factors affect germination and seedling establishment. Among these factors are the characteristics of the maternal plant (nutrition, genetics), seed treatment stage at harvest time as well as environmental factors (temperature, water potential, and ventilation and soil compaction). In addition, under the influence of seed loss during storage, seed vigor, which is known as the first component of seed quality, decreases. The aim of this study was to investigate germination and biochemichal responses of the aged seeds of Fenugreek to different temperature and humidity ranges. Materials and Methods: This experiment was conducted as a factorial based on a completely randomized design with four replications in the Laboratory of Seed Science and Technology, Faculty of Agriculture, Yasouj University in 2016. The experimental treatments consisted of nine levels of temperature (5, 10, 15, 20, 25, 30, 35, 40 and 45 degrees Celsius), water potential comprised seven levels (zero (control),-0. 2,-0. 4,-0. 6,-0. 8,-1 and-1. 2 MPa) and seed aging at two levels (no aged (control) and aged seed). Results: In this experiment, the effect of seed aging, water potential and their interactions in each environment on germination indices (germination percentage and germination rate, length and weight vigor index) and biochemical indices (soluble sugar, proline, soluble protein and catalase enzymes) of Fenugreek seeds were significant. The results showed that in the aged seeds, the germination percentage and rate and seedling vigor index tended to decrease with water potential reduction at temperatures below and above 20 degrees Celsius, whereas the amount of biochemical components of the seeds (soluble sugar, soluble protein, proline, and catalase enzyme) increased. Conclusion: In general, germination and biochemical indices of seeds of Fenugreek are sensitive to water potentials, aging, and seed germination temperatures, respectively. In case of reduction in osmotic potential, the germination temperature less than 20 ° C resulted in increased germination resistance of fenugreek seeds to a more negative water potential.

Introduction: Weeds, representing the most important biological stress, reduce the efficiency of water use, bring about food waste, shading and secretion of toxic substances, leading to a 10 to 100 percent reduction in crop yields. The first step in weed control is understanding the biology and life cycle of the weed, particularly its eco-physiological characteristics. Dormancy in weed seeds, including Redroot Pigweed seeds, is common. Therefore, given the importance of studies into dormancy breaking and germination of weed seeds, the present study was conducted to identify the methods for dormancy breaking and the germination of Redroot Pigweed seeds. Materials and Methods: This research started in autumn 2013 by collecting Redroot Pigweed seeds from fields of Alajujeh village, Khoda Afrin County, East Azerbaijan Province. Subsequently, the study was conducted at the Laboratory of the Faculty of Agriculture of the University of Maragheh in 2014 and 2015. For data analysis, the GenStat 12. 1 program was used and the Duncan test was used at 5% probability level to compare the averages. Excel 2013 was also utilized for drawing the diagrams. Results and discussion: Analysis of variance demonstrated that the effect of treatments on germination percentage and germination rate in Redroot Pigweed seeds was significant at 1% probability level and on mean germination time, at 5% probability level. The results showed that among the treatments studied, seeds held for 18 months were the most efficient in breaking seed dormancy of Redroot Pigweed so that the highest germination percentage (92%), germination rate (29. 18 seed/day) and lowest mean germination time (4. 2 day) were obtained in seed holding treatment. Pre-chilling treatment also had significant effects on stimulating germination. Given that treatments of seeds held at low temperatures and pre-chilling accelerate the germination process and increase germination percentage, having precise information about these traits enables to study, manage and control this troublesome weed more effectively. Conclusions: In general, the results of this study show that out of the treatments, holding seeds for 18 months at 6 ° C is the best method for solving the dormancy problem of seeds of Redroot Pigweed weeds.

Introduction: Using plant growth regulators is one of the methods which can improve plant growth against environmental stresses such as salinity. Salicylic acid plays an important role in the regulation of physiological processes, including germination. Nowadays, the use of growth promoting bacteria is on the rise as it promotes seed vigor, uniformity, germination percentage and brings about better seedling establishment. Growth promoting bacteria can be effective in increasing plant resistance to adverse environmental conditions, which is due to the fact that these bacteria facilitate production of plant hormones such as auxin, GA and cytokinins, and bring about the stabilization of nitrogen or phosphorus availability and other nutrients Materials and Methods: This experiment was conducted as factorial in a completely randomized design with three replications. Salicylic acid factor (SA) was selected at two levels (0 and 1 mM). The bacterial treatments included Azotobacter (AZ), Azospirilum (AZP), complex of Azotobacter and Azospirillum (AZ + AZP), and without inoculation (C) and salinity treatment (S) was considered at five levels (0, 50, 100, 150 and 200 mM). Results: The results showed that none of the treatments had a significant effect on germination percentage. Radicle and plumule length, seed vigor index and seedling fresh weight significantly increased at 50 mM NaCl. Generally speaking, the elongation of plant organs when treated with low concentrations of salts may induce osmotic adjustment activity in plants, which may improve growth. Salicylic acid treatment significantly increased germination rate, Radicle and plumule length and seed vigor index. AZ and AZ+AZP increased germination parameters significantly, compared with the control. Generally speaking, the combination of salicylic acid with AZ better improved germination factors, in comparison to AZP and AZ+AZP. These results are indicative of the synergistic relationship between growth promoting bacteria and salicylic acid. Conclusion: Based on the results, pre-treatment of melon seeds with 1 mM salicylic acid and Azotobacter is suggested to improve seed germination and seedling establishment under salinity stress.