جستجوی مقالات مرتبط با کلیدواژه « Seed dormancy » در نشریات گروه « علوم پایه »

There are many problems for the restoration and development of rangeland vegetation in the field of biological purpose, including the lack of proper germination of plant seeds. The seeds of many plant species cannot germinate despite suitable environmental conditions. Seed dormancy, hard and impenetrable shell and the presence of immature embryo are the main factors of seed not germinating. Seed dormancy is a temporary stagnation in seed life that enables it to complete its germination under favorable conditions and causes the distribution of germination in space and time. In general, research related to seed germination is one of the key and primary tools for biological projects. Because the results of this research can be used in the implementation of management programs for the preservation and development of vegetation. Researchers are trying to find suitable methods to break dormancy and increase the percentage and speed of germination of key plants by investigating the causes of dormancy in seeds. Among the native plants and indicators of winter rangeland in the south of the country, including the tropical areas of Kohgiluyeh Va Boyer Ahmad provinces, which are located in the Zohreh watershed, Zygophyllum eurypterum Boiss & Buhse. from Zygophyllaceae family, Sanguisorba minor L. from Rosaceae family and Salsola orientalis S. G. Gmelin (=Salsola rigida) belong to Chenopodiaceae family. Due to the destructive process of rangeland in the south of the country, resuscitation and development of the vegetation of these areas with indigenous and indicator species in line with biological operations is a priority. Therefore, the main purpose of the present study is to investigate and compare the germination stimulation methods of three indicator range species in order to introduce the best methods.

The present research was conducted to investigate the methods of dormancy of three index species of rangeland: Zygophyllum eurypterum, Sanguisorba minor, and Salsola orientalis in the rangeland of the Zahra watershed in the south of Kohgiluyeh and Boyer Ahmad provinces. For this purpose, after field investigations of the important habitats of the studied species, seeds were identified and sampled when they were fully ripened. The preliminary investigations revealed that all three species have sleep. Therefore, the germination test and determination of the best treatment for the mobility and improvement of germination of the studied species include the following treatments: Germination test using treatments including; Control, scraping, sulfuric acid 98% (for 20 and 40 minutes), potassium nitrate 0.2% and hot water. The experiment was conducted as a factorial in a completely randomized design with 4 replications. The measured traits included germination percentage, germination speed, length of root, shoot, seedling and seed germination index. Mean comparisons were done using Duncan's test.

The results showed that different dormancy treatments have a significant effect on the percentage of seed germination of the studied species (p<0.01). The highest percentage of S. minor germination was observed in potassium nitrate treatment (77.25%) and the lowest in sulfuric acid treatment for 40 minutes (27.5% ). The highest germination percentage of S. orientalis was observed in potassium nitrate treatment (67.50%) and the lowest in sulfuric acid treatment for 40 minutes (42.25%). The highest germination percentage of Z. eurypterum plant was observed in hot water treatment (70%) and the lowest germination percentage was observed in sulfuric acid treatment for 40 minutes (29.5%). Also, the results showed that different treatments have a significant effect on the germination rate of the studied species' seeds. The highest rate of germination of S. minor (3.05 seeds/day) and S. orientalis (1.85 seeds/day) in potassium nitrate treatment and the highest rate of germination of Z. eurypterum (2.3 seeds /day) was obtained in hot water treatment. The results of comparing the averages showed that the treatments used have different effects on the growth of the studied species. So that in S. minor plant, the highest effect on root length (5 cm) was the use of potassium nitrate treatments and scratching, and the highest length of shoot (5.62 cm) and seedling (10.6 cm) ) this plant was obtained in potassium nitrate treatment. In S. orientalis plant, the maximum length of root, shoot, and seedling was 1.8, 1.15, and 2.95 cm, respectively, in potassium nitrate treatment. Also, in Z. eurypterum plant, the maximum length of root, stem and seedling was 2.97, 2.85 and 5.82 cm respectively in hot water treatment. In all three species, the minimum length of root, shoot and seedling was observed in sulfuric acid treatment of 40 minutes. The results of the comparison of the averages show that there is a significant difference between the different sleep deprivation treatments on the seed germination index of the three species Z. eurypterum, S. orientalis and S. minor. The highest seed germination index of Z. eurypterum was obtained in hot water and potassium nitrate treatments, and the highest seed germination index of S. orientalis and S. minor species was obtained in potassium nitrate treatment.

In general, in this research, it was found that the highest percentage and speed of germination of S. minor and S. orientalis in the potassium nitrate treatment and Z. eurypterum in the hot water treatment were among the treatments of sleep failure. The lowest percentage and germination rate of all three species were observed in sulfuric acid treatment for 40 minutes. In S. minor and S. orientalis plants, the greatest effect on the length of root, shoot and seedling was obtained in potassium nitrate treatment. In Z. eurypterum plant, the maximum length of root, shoot and seedling was obtained in hot water treatment. In all three studied species, the lowest length of root, shoot and seedling and seed germination index were observed in sulfuric acid treatment of 40 minutes. Therefore, among the studied treatments for sleep failure, the best treatment for S. minor and S. orientalis species is potassium nitrate, and the best treatment for Z. eurypterum plant sleep failure is hot water treatment, Therefore, it is suggested to use the results of this research for related works in the direction of biological restoration of the studied area and pastures of other areas with similar ecological conditions.

Garden products, especially vegetables, need to use seed preparation technology due to their small volume and high value. Early planting of vegetables in sub-optimal environments is often done to get better market returns, although it simultaneously forces farmers to use high seed vigor to compensate for seedling production. To deal with this problem, farmers and seed companies around the world practice seed priming techniques because it facilitates the synchronicity of flowering and fruiting, resulting in improved yield. Different preparation strategies used for seed treatment are classified into conventional/invasive (hydro, osmo, hormonal, halo, solid matrix, nutrients, biological or nanopriming) and physical/non-invasive (magnetic, UV) categories. The advantages of seed preparation include: germination time, cost of replanting, additional irrigation and fertilization, weed management, uniform growth. A comprehensive review of seed preparation techniques applied to low-volume crops such as vegetables has not been considered. This review describes the advantages of different seed preparation techniques for vegetables.

Mountain Kelussia is one of the endangered species that in order to prevent the extinction of this valuable plant, it is necessary to protect its natural resources and make efforts to rebuild the damaged pastures. This requires the study of germination failure germination of seeds of this plant. The seeds of the mountain kelussia plant have dormancy, which reduces their vigor. This study was performed to investigate the effect of different sleep failure treatments on germination and seedling growth of kelussia. The experiment was conducted as a completely randomized design with four replications. Experimental treatments include potassium nitrate , gibberellic acid ppm, gibberellic acid ppm, gibberellic acid ppm, smoke treatment, hot water treatment in C, leaching treatment, temperature treatment of ° C , Temperature ° C, temperature ° C, temperature ° C for , , and weeks, scratching treatment and control treatment. The results showed that the effect of dormancy treatment on all characteristics related to germination and seedling growth of kelussia was significant. The results also showed that none of the treatments except seed storage treatment at ° C resulted in germination of kelussia seeds. With increasing the storage time of kelussia seeds at ° C, germination percentage, root length and dry weight, shoot length and dry weight, seedling length and dry weight, seed vigor and seedling also increased. In general, the results of this study showed that the best treatment to eliminate seed dormancy of kelussia seeds and seedling growth is to store watered seeds in cold conditions for weeks. The result of evaluating the compatibility of kelussia seedlings showed that it has grown in Boroujerd region and has the ability to adapt to this region.

The genus Taverniera from Fabaceae family is one of the most valuable plant species compatible with desert areas, which is very important in terms of forage production, soil conservation, and medicinal properties. The current research was carried out to investigate the effect of different treatments on seed dormancy breaking and germination stimulation of taverniera cuneifolia. Dormancy breaking treatments included H2SO4 (50% and 75% for 5 and 10 min.), scarification with sandpaper (for 1 min.), KNO3 (0.1% and 0.2% for 24 and 48 h.), hot water (70 and 90 ℃, each for 15 min.) and hydropriming (for 36 h.) with three replications. Results revealed that H2SO4 (75% for 5 min.) led to the highest germination speed and seed vigor index and the lowest mean germination time. Also, maximum germination percentage (78%) was observed under this treatment. Scarification with sandpaper also exhibited considerable effect on the germination percentage (76%). Thus, H2SO4 (75% for 5 min.) and scarification with sandpaper would be suggested as the most efficient treatments to break seed dormancy of Taverniera cuneifolia.

Among 57 genera having more than 500 species, the genus Astragalus, with a large number of species worldwide, is the first big genus in flowering plants. The species belong to 150 sections in Old World and 93 sections in New World, with 3500 species. In the point of species numbers, the genus is divided into three big groups; Small size, medium size, and big size sections. In the Old World, the species are widely distributed in Asia, Europe, and sparsely in African continents. To understand better the high diversity of the genus, it is necessary to seek the main factors of reproduction system, pollination, seed dormancy, soil seed bank, habitat, and speciation mechanism. In this paper, the author tried to explain the biology of the genus briefly. All diagnostic characters are divided into Morphology, Anatomy, Cytology, Physiology, and Chemistry.

The Glycyrrhiza glabra plant is a medicinal plant and it is used in pharmaceutical industries due to some compounds such as glycerolysis. The aim of this study was to investigate the effects of different treatments on different germination indices of Glycyrrhiza glabra L. species under laboratory conditions. Boiling water treatments, seed storage in heat and cold, non-treated (control) and culture in soil with 5 replications were applied on sweet seeds of expression. During different days, the number of germinated seeds was counted to a constant. Results showed that there were in Root, Shoot and Plant Length; Germination Percent; Germination Speed; Mean Germination Time and Allometric Coefficient. Results in the soil showed that the Root, Shoot and Plant Length were the highest, Allometric Coefficient and Germination Percentage has the lowest , Allometric Coefficient determined that stem and root growth in soil are in equilibrium. In maintenance treatment in boiling water, Germination Percent; Germination Speed and Allometric Coefficient had the highest amount, Mean Germination Time has the lowest. The results of boiling Treatment indicated that more than 40% of seeds germinated and were ranked first compare to other treatments. Treatments in freezer and oven heating compared to control treatment did not affect the rate of seed germination characteristics. Therefore, in general, it can be said that the presence of soil has led to better rooting and plant growth than other treatments, and the treatment of water-boiling water for five minutes by softening the shell can improve the Performance of seed germination characteristics.

The seeds tolerating drying and moisture content as less as 5% are known as orthodox seeds. The seeds of tree and shrub species growing in temperate zones belong to this group. In this investigation, seeds of 32 species, collected from natural habitats, were evaluated. The seed samples were processed for cleaning and then seed health and breaking seed dormancy were tested. The dormancy treatments included: pre-germination cooling test with different times, chemical and hormonal (GA3) agents with different concentrations and duration, mechanical and chemical scarification with two germination beds (Petri dishes with paper filter and pots containing sands). The trend of seed viability reduction was different among the study species. The seeds of Amigdalus scoparia and many pine species had high seed viability (44 to 88%) after twenty years but the species with small seeds like Alnus glutinosa, Fraxinus and Haloxylon had lower seed viability. The cause of decreased seed viability was related to the storage materials and their genotype. It was concluded that seed size and seed storage behavior would be useful as important factors to determine seed regeneration.

The genus of Hawthorn (Crataegus L.), belonged to Rosaceae family has medicinal and ornamental applications. Its seed germination is poor, due to stony endocarp and embryo dormancy. This study was carried out to determine methods to break dormancy in Crataegus pseudoheterophylla seeds. For this purpose, seeds were sown in plastic pots as a factorial experiment in randomized completely block design (RCBD) with 3 replications. Treatments including chemical scarification in KNO3 for 0, 2500, 5000, 7500 and 10000 mg l-1 and concentrate sulfuric acid (H2SO4 96 %) for 0, 30, 45, 60, 90, 120, 150, 180 and 210 minutes followed by continues regime (1 month at 23 °C, then 3 months at 4 °C) and alternate regime (1 month at 4 °C and, 2 weeks at 23 °C, then 1 month at 4 °C and 2 weeks at 23 °C, finally 1 month at 4 °C) were applied. Results showed that in KNO3, the highest germination percentage (19.33 %) and germination speed (4.18 number/day) was determined at 10000 mg l-1 alternate stratification and in sulphuric acid, the highest percentage germination (55 %) and speed germination (8.63 n/d) was determined for 120 minutes alternate stratification. The highest mean time germination in both scarification treatments was observed in continues regime.

Ornamental Amaranthus (Amaranthus cruentus) is one of the valuable ornamental, medicinal and edible plants .The A. cruentus seeds plant have problem in germination and number of few cultivated seed will germinated. Therefore, in present study the effect of treatments includes: sulfuric acid, freezing, boiling water, wetting and drying, cold and scarification were investigated on break dormancy of this plant seeds and germination percentage and velocity of germination were determined. This study were done based on Completely randomized design experimental design with with 4 replications in Petri-Dish in Germinator. Then, obtained data along the experiment were analyzed using SPSS package (p

Saltbush (Atriplex leucoclada) is one of the endemic halophyte plants of Iran, useful for desertification, restoring and modifying rangelands in arid and desert areas cultivation. To assess the effects of mechanical and chemical treatments in break seed dormancy and to stimulate seed germination in dimorph seeds of Atriplex leucoclada, two tests were performed in completely randomized design with three replicates for both of its two seed types. Treatments were: scratch pre-treatment, gibberellic acid or kinetin, ethephon, potassium nitrate or thiourea all performed for 24 h or 48 h at 4˚C or 20˚C, pre-treatment running water, moist chilling (20 days/4˚C) + 14-days treatment with gibberellic acid or potassium nitrate or thiourea, scratching with a sand paper, making a gap with a needle, hot water (70˚C or 90˚C for 15 min), sulphoric acid (75%), dry-storing (3 months/20˚C), stratification (3 months/4˚C). As the twice-scratched pretreatment caused the highest germination percentage (73.3%) and vigour index (8860) in the brown seeds and for the black ones these values were 63.3% and 7710, respectively. Overall, it is concluded the seed dormancy in both types of seeds in A. leucoclada could be physical.

Cultivation programming of medicinal plants is necessary for curing، limiting natural habitats، little reproduction and inexpedient cutting. The aim of this research to determine the most suitable treatment to overcoming seed dormancy and germination of Thymus transcaucasicus and Zataria moltiflora were conducted. Seeds of species were collected from their main habitats and treatments were tested including Gibberllic acid (for 100، 500 and 1000 ppm)، cold (10، 20 and 30 days)، Thio urea 1 Molar and KNO3. Seeds were sown in Petridishes for 15 days. This experiment was conducted in a completely randomized design with four replications. The results of analysis of variance showed that the effect of various treatments on Thymus transcaucasicus and Zataria moltiflora seeds germination percentage were highly significant different (p<0. 01). Treatments of gibberllic acid 100 PPM and Cold (10 and 20 days) have the highest seed germination percentage on Thymus transcaucasicus and KNO3 and Cold (10 and 20 days) on Zataria moltiflora seeds. The highest and lowest vigor index was in Thymus transcaucasicus، gibberllic acid 100 PPM (16. 2) and KNO3 (2. 4)، in Zataria moltiflora Thio urea 1 Molar (10. 9) and Cold 20 days (1. 37).

Breaking seed dormancy is an essential step towards germination improvement in Hordeum vulgare ssp. spontaneum. This study was conducted to evaluate the effects of physical, chemical, hormonal and stratification treatments on Hordeum spontaneum seed dormancy. In the current research two highly dormant genotypes of Hordeum spontaneum (TN1350 and TN951) were evaluated. To this purpose, 25 seeds in four replications were placed in 9 cm petri dishes containing filter paper saturated with distilled water (control), chemical or hormonal solutions. To induce the stratification treatments, seeds were kept in 35˚C (heat stratification) or 5˚C (cold stratification) for periods of 2, 4, 6 and 8 weeks. Results indicated that heat stratification increased germination significantly. Germination percentage of seeds under 35˚C treatments increased since the second week of treating and reached the maximum in the fourth week (47.5% in TN951 and 86.25% in TN1350). Results showed that GA3 in all used concentrations was the most effective hormone in inducing germination compaired to other used hormons in this study. The highest germination percentage in Hordeum spontaneum seeds was observed in 100 mg/l GA with increased germination percentage up to 68.75% in TN1350 and 31.25 in TN951. Results of this study revealed that seed dormancy in Hordeum spontaneum can be overcomed by GA3, and heat stratification. On the other hand, seed dormancy was apparently deeper in the genotype with darker seeds)TN951(which were also less affected by after ripening treatments.

Mesquite is an invasive and problematic weed in warm and dry areas and so its management is very important. In order to study the effective factors on mesquite seed germination, the following studies were conducted to investigate: 1- seed viability; 2- the effect of constant temperatures on seed germination including 5, 10, 15, 20, 25, 30, 35 and 40°C independent dark and independent light conditions; 3- Effect of temperature fluctuations on seed germination including 10/0, 20/10 and 30/20°C; 4- the effect of scarification with concentrated sulphuric acid and physiacal scarification on seed germination; 5- the effect of planting depth seed on seedling emergence; 6- the effect of drought stress including 0, 100, 200, 300, 400, 500, and 600 Mm PEG on seed germination; and finally 7- the effect of salt stress including 0, 100, 200, 300, 400, 500, 600, and 700 mM NaCl on seed germination. All experiments were performed as completely randomized designs with 4 replications. The results showed that seed viability of mesquite was 81%. The optimum temperature for seed germination was a constant temperature- 30°C. In general, constant temperature was more suitable than temperature fluctuations for seed germination. The best seed planting depth for seedling emergence was 2 cm. The most seed germination was observed under the effect of 20 min scarification with concentrated sulphuric acid. Physical scarification had no significant effect on seed germination. While the study of salt and drought stresses effect showed that the most seed germination (after control without NaCl and PEG), was due to concentrations of 100 and 200 mM, seed germination decreased with the increase of NaCl and PEG concentrations. Based on the present results, light did not play a crucial role on seed germination. Therefore, mesquite seeds were not photoblastic. These characteristics are very important in making mesquite an invasive weed. Having precise information of these traits, enables us to have a better control over the management of this troublesome weed.

Kelussia odoratissima Mozaff. is one of the pasture and native plants in Iran that has a special value. Seeds of this species have shown dormancy that causes reduction of seed germination this plant. Therefore in this research, 2 factorial experiment with completely randomized design and with 3 replication carried out to evaluate the effect of duration of moist chilling, in 7-level, concentration of nitrogenous compounds (Potassium nitrate and Thiourea) in 3-level and application time nitrogenous compounds in 2-level (before and after chilling), on seed germination capacity and germination velocity. Also a factorial experiment design performed to evaluate the effect of the type, concentration and application time of the same nitrogenous compounds on growth parameters of developed seedlings from 10 weeks pre-chilled seeds. Results of research showed that 10 week moist pre-chilling has significant effect on seed germination this plant and increased seed germination and germination velocity. Concentrations of 0.2 % potassium nitrate, or 0.5 % thiourea had positive effect, but concentrations 0.6% potassium nitrate or 5% thiourea had a negative effect on seed germination. Treated with 0.2 % of potassium nitrate had no effect on root length and dry weight but increased length, fresh weight and dry weight of stems and root fresh weight in the level of 5 percent in compared to control. In contrast the concentration of 0.6 % potassium nitrate, all of these traits decreased in compared to control. In this study both thiourea concentrations inhibited seedling growth.

Zygophyllum atriplicoides، a perennial shrub in the family Zygophylaceae، is one of the important halophytes in Iran. In this research، seeds of this species were collected from the salt zones near Isfahan City. Experiment was carried out in order to determine the salinity-alleviating effect of germination promoting compounds (GPCs) on its seed germination as factorial with completely randomized design with 4 replications. GPCs were including: nitrate (20 mM)، Thiourea (10 mM)، Ethephon (10 mM)، GA3 (3 mM) and water as control and salinity concentrations were 0، 40، 80 and 120 mM NaCl. In water treatment (0 mM NaCl) only 50% of seeds germinated and germination decreased with an increase in salinity to 40، 80 mM، and at 120 mM NaCl، seed germinated was less than 3%. Also salinity decreased capacity، velocity and synchronization index of germination. All GPCs significantly enhanced germination in control treatment (0 mM NaCl). Nitrate and thiourea increased 30-40 % seed germination than water treatment، but in 80، 120 mM did not have significant promotive effect on germination than water treatment. At 40 mM NaCl، Ethephon and GA3 application significantly promoted germination at all salinity levels. In 0، 40، 80 and 120 mM NaCl، Ethephon and GA3 promoted germination 92، 68، 51، 25 % and 100، 97، 86، 75 % respectively. Therefore، GA3 better than other chemicals، alleviated the inhibitory effects of all salinity levels on the germination of Z. atriplicoides and increased capacity، velocity and synchronization index of germination. In sum، our data suggests that innate dormancy of Zygophyllum atriplicoides seeds is non-deep physiologic type and salt-induced dormancy، is caused probably because of distortion of seed hormonal balance and exogenous GA3 application compensated this hormonal un-balance and led to dormancy breaking and germination of Zygophyllum atriplicoid seeds.