نشریه پژوهش های بذر ایران
سال پنجم شماره 2 (پیاپی 10، پاییز و زمستان 1397)

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 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. 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. 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.   Highlights: Calculating D50 in cottonseeds, using different methods. Using nonlinear regression models to calculate D50 in cottonseeds. Developing a proper method which is more accurate, and better lends itself to calculating D50 of cottonseeds.

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). 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). 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. 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 copper-accumulated areas, choosing proper cultivars can slightly mitigate the damages caused by copper. The Chamran cultivar seems to be a better candidate for these conditions.   Highlights: Evaluation of the effect of Pb(NO3)2 stress on germination characteristics of wheat. Using three-parameter sigmoid model for the evaluation of biochemical changes and germination of wheat under Pb(NO3)2 stress.

Nowadays exploitation of hetrotoxic characteristics  of hetrotoxic plants regarding  harmful effects of synthetic herbicides can most important role in weeds management and their control. In fact chemical compounds which is released by root, stem, leaf, flowers, seeds pollen, fruit and seeds can be used as bio herbicides and bio pesticides. The purpose of this srudy was evaluation of hetrotoxicity potential of Datura stramonium L. shoots on germination traits and photosynthetic pigments of wheat cultivars. An experiment was conducted to evaluate hetrotoxicity potential of aqueous extract of different organs of Datura stramonium L. such as stem, leaf, fruit and mixed of them on germination traits and photosynthetic pigments of two cultivars of wheat (Kohdasht and N8720) as factorial experiment based on compeletly randomized design in three replications in Weeds Scince Laboratory of Gonbad-e- Kavous University in 2017. Datura stramonium shoot was collected at fruit formation stage in the Moghan plain and seprated into stem, leaf and fruit firstly. Five ml of studied extracts as well as mixed of them were added on 25 disinfected seeds of studied cultivars separately. Results showed that wheat cultivars had a different response to organs extract and this difference also were significant for various organs extract as well as interaction effect of cultivars in organs extract. Mean comparison of interaction of cultivars and organs showed that germination percent of Kohdash were decreased under experimental treatments. The highest decrease effect was obtained in the leaf extract about 98.33%. In return, stem, fruit and mixed organs had an increase effect on germination percent of N8720 about 5.72, 5.72 and 1.41% respectively. Result of the germination rate was similar with result of germination percent. Radicle and shoot length of both cultivars under experimental treatments were decreased. Leaf extract had an highest inhibition effect on radicle and shoot length about 96.70 and 89.21% respectively. Content of total chlorophyll of both cultivars of Kohdast and N8720 were increased under aqueous extract of stem (24.64%) and fruit (14.62%). Where as, extract of other organs and mixed of them had a decrease effect on studied trait. The result of carotenoid also was similar with result of total chlorophyll. Persumably, difference in allelochemicals concentration in various organs of Datura stramonium and physiological chracteractics of studied traits in cultivars caused different behavior. According to the results, use of Datura stramonium biomass esspecially leaf, it is suggested as natural herbicides and strategy of non- chemical management. To accomplish this need to analyze phytochemical compounds of this weed.   Highlights: Extract of different parts of Datura stramonium weed had a different effect on germination traits and content of chlorophyll and carotenoids  of both cultivars of Kohdast and N8720. Leaf extract of Datura stramonium significantly decrease germination traits and content of chlorophyll and carotenoids of Kohdasht cultivar seedlings. 3- Use of Datura stramonium can be a good option for appearance of natural herbicides.

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. 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 1µM, 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. 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). 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 pre-treatment 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.   Highlights: Humic acid was the most effective seed priming treatment on germination characteristics, biochemical changes and seedlings growth of sesame. The effect of seed priming treatments on the germination characteristics of the Dezful cultivar was more pronounced than that of Yellow white.

Crop rotations are practiced to eliminate the effect of monoculture, but the succeeding crop may be influenced by the phytotoxins released by the preceding crop. Among plants, Brassica species contain allelochemical compounds as glucosinolate that is, under special conditions, released to environment and affects seed germination and plant growth. Wild mustard (Sinapis arvensis L.) as a weed of 30 crops in 52 countries which has a series of allelopathic effects that prevent germination of other plants. Products of glucosinolate- like ionic thiocyanate (SCN-) inhibited the root or shoot growth of many crop species. Also 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 inhibited the growth of some species at certain concentrations, might stimulate the growth of 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. In order to evaluate the allelopathic effect of mustard in agro ecosystems, a factorial experiment based on completely randomized design with three replications was carried out in 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 stage of barley (cv. Abidar) in two separate experiments. In the seed germination section, 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 showed that the highest amount of barley seed germination percentage and germination rate (100 and 19.5, respectively) were observed in control and the lowest amount (40 and 9.5, respectively) belonged to mustard root aqueous treatment with 70 percent concentration. The most 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 control to 1.66 mg per fresh weight in 70 percent concentration of aqueous extract treatment. The highest amount of proline (66.8 μM per fresh weight) in barley foliage was observed in 70 percent aqueous extract treatment. The results from this study showed that mustard allelopathic effect may be a possible mechanism controlling the barley germination and early growth stage in agro ecosystems. Generally, we were able to demonstrate short term auto toxicity and possible short-term allelopathy due to mustard has harmful effects on barley including reduced seed germination and emergence of barley seedling. Depending on the concentrations of Mustard extract, allelopathic activity will vary Mustard. 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.    Highlights: 1-Mustards aqueous extract reduced seed germination percentage and plant growth in barley. 2-Mustards aqueous extract increased proline and soluble sugars in barley, but it reduced amount of chlorophyll in this plant.

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 are willing to produce natural nanoparticles to continue their growth. Nano TiO2 has a high 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 in many crops is not an essential element for growth, it has beneficial effects on plants growth and development. Today, carbon nanotubes are one of the most important materials in industrial programs. These materials, with different methods and specific properties, can play an important role in the production of composite materials, application in medicine, electronic and energy storage. The Niger plant, with the scientific name of Goizotia abyssinica (L.F) Cass, belongs to the Asteraceae family. Its seed, 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 of germination characteristics and anthocyanins content in Niger medicinal-oily plant.   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 as the first factor while their concentrations in four levels (zero, 10, 30 and 60 mg/l) were 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.    The germination percentage, germination rate and mean of daily germination decreased by increasing of nanoparticles concentration. The favorable effect of TiO2 on germination index at the concentration of 30 mg/l and radicle dry weight at the concentration of 10 mg/l, was gained compared to control. The positive effect SiO2 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 was obtained compared to control. Also, the appropriate effect of CNT on germination index 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, was observed. According to the results of this study, it seems that the effect of nanoparticles in plants, in addition to the plant, species, type and concentration of nanoparticles, varies depending on the growth stage and physiology of the plant. It seems that nanoparticles at some concentrations can increase the water absorption of seeds and increase seedling growth with their positive effects. Anthocyanins are produced by exposure to stress due to their antioxidant activity. In general, it can be stated that increasing the concentration of nanoparticles caused and increased the oxidative stress in plant. Therefore, it is recommended by investigating the bad effects of nanoparticles on plants, if necessary, use nanoparticles at low concentrations (less than 60 mg/l) to increase the plant's efficiency.   Highlights: The effect of nanoparticles kind and concentration on seed germination indices and anthocyanin content of Niger seedling. Investigating the interaction of nanoparticle type and concentration as the physical priming factor of seeds on seed germination of multi-purpose Niger plant.

Seeds are a good option for propagation and protection of medicinal plants. Although Seed dormancy is an adaptive strategy for wild medicinal plants, but it is considered as an undesirable trait in domestication and cultivation of them, need to be solved. Echinophora platyloba seed has dormancy despite its remarkable medicinal properties. In order to break seed dormancy, three separate experiment including stratification, hormonal treatment and combination of both were performed. For stratification 10 samples of were placed in a wet bed at 5 ° C for 2, 4, 6, 8, 10, 12, 14 and 16 Week 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 then transferred to germination conditions. However, since the breaking of dormancy did not occur, this experiment was not discussed any more. For combined application of hormone and stratification, seeds were placed at mentioned concentrations of gibberellin for 24 hours at 20 ° C and then gibberellin solutions were removed and the seed transmitted to 5 ° C and 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. Stratification had a positive effect on seed dormancy breaking and 16 week chilling lead 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 at 8 weeks. 8-week stratification treatment at 5 ° C with 1000 ppm gibberellic acid was the best treatment to overcoming of dormancy in Echinophora-platyloba seeds. It seems that seed dormancy of Echinophora seeds is physiological, which broke down by moist chilling and simultaneous application of stratification and gibberellin successfully. Although Gibberellin had no effect on dormancy break, it reduced the need for stratification. Combined application of them showed synergistic effects on dormancy release.     Highlights: Echinophora seed’s dormancy was broken under stratification conditions, but GA had no effect on it lonely. The application of gibberellin reduced the chilling demands of Echinophora seeds and the combined application of them had a synergistic effect on dormancy break

Seed germination is one of the first 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). Also, under the influence of seed loss during storage, seed vigor, which is known as the first component of seed quality, decrease. The aim of this study was investigation of germination and biochemichal responses of the aged seed of Fenugreek to different temperature and humidity ranges. 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 included 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). In this experiment, the effect of seed aging, water potential and their interactions on 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 seed the germination percentage and rate and seedling vigor index tended to decrease with water potential reduce in temperature lower and higher than 20 degrees Celsius, and the amount of biochemical components of the seed (soluble sugar, soluble protein, proline, and catalase enzyme) also increase. In general, germination and biochemical indices of seed of Fenugreek are sensitive to water potentials, aging, and seed germination temperatures, respectively. In terms of osmotic potential decrese, the germination temperature of less than 20 ° C resulted in increased germination resistance of fenugreek seed to a more negative water potential.   Highlights: Study of germination and biochemical properties of fenugreek seed aged under different level of osmotic potantials and temperatures. In areas with a lower osmotic potential it is better to cultivate Fenugreek seed at temperatures below 20 °C.

Weeds, as the most important biological stress, reduce the efficiency of water use, waste of food, shading and secretion of toxic substances, leads to a 10 to 100 percent reduction in crop yields. The first step of the weed control understands the biology and life cycle of the weed particularly seed Eco physiological characteristics. Dormancy in weed seeds, including Redroot Pigweed seeds, is common. So, due to the importance of dormancy breaking and germination studies of weed seeds, the present study was designed to identify the methods for dormancy breaking and the germination of Redroot Pigweed seeds. This research started in autumn 2013 by collecting Redroot Pigweed seeds from fields of Alajujeh village, Khoda Afrin County, East Azerbaijan Province, and then it was carried out 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 employed for drawing the diagrams. Analysis of variance demonstrated that the effect of treatments on germination percentage and germination rate in Redroot Pigweed seeds at 1% probability level and the mean germination time at 5% probability level was significant. The results showed that among studied treatments, seeds holding for 18 months were most efficient seeds dormancy breaking at Redroot Pigweed. So that the highest germination percentage (92%), germination rate (29.18 seed/day) and lowest the mean germination (4.2 day) time were obtained in seeds holding treatment. Pre-chilling treatment also had significant effects in stimulating germination. As regards treatments of seed holding in low temperature and Pre-chilling accelerate the germination process and increase germination percentage, so, having precise information of these traits enables to study, a better management and control of this troublesome weed. In general, the results of this study show that among the treatments, holding seeds for 18 months at 6 ° C is the best method for solving Redroot Pigweed seeds weeds.   Highlights: 1- Seed holding in low temperature and Pre-chilling accelerates the germination process. 2- Seed holding in low temperature increases germination percentage.

Using of plant growth regulators is one of the methods can improve plant growth against environmental stresses such as salinity. Salicylic acid plays an important role in physiological processes regulation, including germination. Today, using of growth promoting bacteria has been increased and it causes to raise the seed vigor, uniformity, germination percentage and better seedling establishment. Growth promoting bacteria can be effect on increasing plant resistance to adverse environmental conditions by interposition in plant hormones production such as auxin, GA, cytokinins, and as well as the stabilization of nitrogen or phosphorus availability and other nutrients 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 at five levels (0, 50, 100, 150 and 200 mM). Results showed that all treatments had no significant effect on germination percentage. Radicle and plumule length, seed vigor index and seedling fresh weight was 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 the plants which may improve growth. Germination rate, Radicle and plumule length and seed vigor index were significantly increased by salicylic acid treatment. AZ and AZ+AZP increased germination parameters significantly than control. Generally germination factors were better improved by combination salicylic acid with AZ than AZP and AZ+AZP. These results could indicate the synergistic relationship between growth promoting bacteria and salicylic acid.   According to the results pre-treatment of melon seeds by 1 mM salicylic acid and Azotobacter can be proposed to improve seed germination and seedling establishment under salinity stress.   Highlights: Effect of salinity on seed germination characteristics of melon. Effect of biofertilizer and salicylic acid on germination and seedling growth of melon under salt stress.