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By identifying the factors that initiate seed dormancy release, we can reliably predict whether a seed will remain dormant within or exit the seed bank and become a seedling. With regard to annual weed species, assessing which factors efficiently break seed dormancy is critical for estimating the number of weed seeds that will develop into problematic weeds. To better understand dormancy breaking in Redroot pigweed (Amaranthus retroflexus), dormant seeds were treated with cold stratification (4°C for 30 days), application of gibberellic acid (at 500, 1000, 1500, and 2000 parts per million), ultrasound (for 10, 20, 30, and 40 min), soaking in hot water (90°C for 3, 5, 7, and 10 min), and 98% sulfuric acid (for 1, 2, and 3 min). The results showed that Redroot pigweed seed dormancy was effectively broken by cold stratification, gibberellic acid, and ultrasound. Short treatments with hot water had minimal effect while longer times or treatment with sulfuric acid stopped seed germination. In addition to germination percentage, germination rate, plumule length, radicle length, seedling length, seedling dry weight, and seed vigor index were also measured; similarly, application of gibberellic acid had the most significant effect on these parameters. The results of this study add to our knowledge of what processes effectively or ineffectively break Redroot pigweed seed dormancy and promote growth. [ABSTRACT FROM AUTHOR]

• The germination of cannabis treatments varied with landrace and treatments. • H 2 SO 4 , GA 3 , and KNO 3 enhanced the germination capacity of cannabis landraces. • Control produced vigorous seedlings compared dormancy-breaking pre-treatments. The current study evaluated the effectiveness of different pre-treatments for dormancy breaking and seed germination of five cannabis landraces. These landraces were collected from local growers in three regions of KwaZulu-Natal Province in South Africa, namely, Bergville (B), Hammersdale (H), and Ladysmith (L). Each genotype was assigned an alphabet and number based on where the seed material was collected. The five landraces were as follows, 'B1', 'K1', 'H1', 'L1', and 'L2'. The study was conducted using various pre-treatments, including potassium nitrate (KNO 3), hydrochloric acid (HCL), hot water (HW) at 70 °C, nitric acid (HNO 3), dry prechilling at 10 °C, gibberellic acid (GA 3), sulfuric acid (H 2 SO 4), and water, which served as the control. Before the germination test, the seed viability of cannabis landraces was assessed using the tetrazolium chloride (TCC) test. Afterward, the seeds were germinated in Petri dishes with cotton pads moistened with distilled water for five (5) days. The study was later validated under tunnel conditions. The parameters such as germination percentage, germination rate, seedling length, and seed vigour index of the germinated seeds were then measured. The landraces, dormancy breaking treatments, and their interactions showed significant differences (p < 0.001) in germination percentage, germination rate index, seedling length, and seed vigour index under both laboratory and tunnel conditions. In summary, GA 3 , KNO 3 and prechilling were the most effective pre-treatments to improve the germination and seedling growth of cannabis genotypes and breaking seed dormancy. Therefore, it was concluded that cannabis genotypes had physiological dormancy. [ABSTRACT FROM AUTHOR]

Copyright of Environmental & Social Management Journal / Revista de Gestão Social e Ambiental is the property of Environmental & Social Management Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Seed germination in Melocactus and other cactus species is hampered by dormancy. However, most studies failed to achieve high seed-germination rates, suggesting a complex mechanism of dormancy in Cactaceae. Thus, the objective of this study was to evaluate whether factors such as light and phytoregulators overcome the dormancy in the seeds of the friar's crown cactus (Melocactus zehntneri). Two consecutive experimental sets were designed: one with seed germination under filter paper conditions and different wavelengths and Photosynthetically Photon Flux Densities (PPFDs); and one in vitro experiment using a culture medium to evaluate the influence of different phytoregulators, such as gibberellic acid (GA3), benzylaminopurine (BAP) and ethephon (ET), both in the germination of seeds of M. zehntneri. Seeds of M. zehntneri are positive photoblastic. Red light and gradual increases in PPFD resulted in the highest germination rates (60.8–61.7%) and germination speed index (4.4–4.5). In vitro seeding in culture media increased the germination percentage to 76% in control without phytoregulators. Ethephon showed a major effect in releasing the germination of dormant seeds of M. zehntneri, totaling 98% of seeds germinated under in vitro conditions, while GA3 and BAP showed minor or no effect on germination. The present study resulted in an efficient in vitro technique for germination and a better understanding of cacti seed dormancy. [ABSTRACT FROM AUTHOR]

• Senna macranthera seeds are adapted to fire. • The heat and the aqueous extract of the smoke influence the seed dormancy break. • The gaseous smoke is lethal for seed germination. • Early dormancy breaking can reduce the vigor of buried seeds. Fire can trigger the germination of several forest species, as heat and smoke can break the dormancy of seeds buried in the ground. In this study, we applied heat, smoke and pyroligneous acid (PA) to dormant seeds of Senna macranthera (Fabaceae), a Brazilian Cerrado native tree, in order to evaluate the effect of forest fire triggers on its germination. We used dormant seeds soaked in distilled water, without the application of fire and smoke, as a control treatment. The test lasted seven days and root protrusion was used as a germination criterion. After this period, a viability test based on the longitudinal section was performed on the non-germinated seeds. The control germination after seven days was 0%, but the viability test confirmed that they were alive (integument swelling and green color cotyledons). There was a positive effect of fire on the germination of burnt seeds buried at a depth of 5 cm soaked in PA (14.0%), followed by burnt seeds buried at a horizon of 2 cm (11.2%) and those that were not soaked in PA (10.0%). Smoked seeds showed swelling of the tegument by the viability test, but they were dead, indicating that there was a negative effect (0%) of the gaseous smoke on germination. We conclude that the strong promotional effect of heat and liquid smoke (using PA) on dormancy breaking and seed germination of S. macranthera suggests that this species is fire-adapted. However, the gaseous smoke was lethal, revealing that this species has different responses depending on the type of trigger (heat or smoke) and fire conditions. [ABSTRACT FROM AUTHOR]

Seed germination in Melocactus and other cactus species is hampered by dormancy. However, most studies failed to achieve high seed-germination rates, suggesting a complex mechanism of dormancy in Cactaceae. Thus, the objective of this study was to evaluate whether factors such as light and phytoregulators overcome the dormancy in the seeds of the friar’s crown cactus (Melocactus zehntneri). Two consecutive experimental sets were designed: one with seed germination under filter paper conditions and different wavelengths and Photosynthetically Photon Flux Densities (PPFDs); and one in vitro experiment using a culture medium to evaluate the influence of different phytoregulators, such as gibberellic acid (GA3), benzylaminopurine (BAP) and ethephon (ET), both in the germination of seeds of M. zehntneri. Seeds of M. zehntneri are positive photoblastic. Red light and gradual increases in PPFD resulted in the highest germination rates (60.8–61.7%) and germination speed index (4.4–4.5). In vitro seeding in culture media increased the germination percentage to 76% in control without phytoregulators. Ethephon showed a major effect in releasing the germination of dormant seeds of M. zehntneri, totaling 98% of seeds germinated under in vitro conditions, while GA3 and BAP showed minor or no effect on germination. The present study resulted in an efficient in vitro technique for germination and a better understanding of cacti seed dormancy.

This research was carried out to determine the effects of germination temperature and 12 dormancy breaking applications on the germination of the seeds of the gum tragacanth (Astragalus gummifer Labill.) bush. The research was carried out in the Field Crops Department laboratory, Iğdır University Faculty of Agriculture, in 2019. Gum tragacanth seeds were germinated for 28 days in the dark at constant temperatures of 10, 15, 20, and 25 °C and variable temperatures of 20/10 °C, 20/15 °C, 25/10 °C, and 25/15 °C. As a result of the research, the highest total germination rate was determined at 10.7% at 25/10 °C and 25/15 °C temperatures. It was determined that there was 89.3% dormancy in gum tragacanth seeds. Then, 12 dormancy breaking methods (matrix priming, hydro priming, gibberellic acid (GA3, potassium nitrate, cold, moist stratification, warm moist stratification, warm+cold moist stratification, cold+warm moist stratification, cold water, hot water, mechanical scarification, and chemical scarification) were applied. After dormancy breaking applications were made, the seeds were germinated again at 25/15 °C. At the end of the study, it was revealed that the highest total germination percentage with 50.7% was obtained from the application of hot water for 2 minutes. On the other hand, it was determined that matric priming, hydro priming, gibberellic acid, potassium nitrate, cold, moist stratification, warm moist stratification, cold+warm moist stratification, mechanical scarification, and chemical scarification applications did not have any effect on removing the dormancy status of gum tragacanth seeds.

Copyright of Research in Agricultural Sciences is the property of Ataturk University Coordinatorship of Scientific Journals and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research was carried out to determine the effects of germination temperature and 12 dormancy breaking applications on the germination of the seeds of the gum tragacanth (Astragalus gummifer Labill.) bush. The research was carried out in the Field Crops Department laboratory, Iğdır University Faculty of Agriculture, in 2019. Gum tragacanth seeds were germinated for 28 days in the dark at constant temperatures of 10, 15, 20, and 25 °C and variable temperatures of 20/10 °C, 20/15 °C, 25/10 °C, and 25/15 °C. As a result of the research, the highest total germination rate was determined at 10.7% at 25/10 °C and 25/15 °C temperatures. It was determined that there was 89.3% dormancy in gum tragacanth seeds. Then, 12 dormancy breaking methods (matrix priming, hydro priming, gibberellic acid (GA3, potassium nitrate, cold, moist stratification, warm moist stratification, warm+cold moist stratification, cold+warm moist stratification, cold water, hot water, mechanical scarification, and chemical scarification) were applied. After dormancy breaking applications were made, the seeds were germinated again at 25/15 °C. At the end of the study, it was revealed that the highest total germination percentage with 50.7% was obtained from the application of hot water for 2 minutes. On the other hand, it was determined that matric priming, hydro priming, gibberellic acid, potassium nitrate, cold, moist stratification, warm moist stratification, cold+warm moist stratification, mechanical scarification, and chemical scarification applications did not have any effect on removing the dormancy status of gum tragacanth seeds. [ABSTRACT FROM AUTHOR]

Field bindweed (Convolvulus arvensis L.) is one of the most harmful weeds in the world. It is a common and problematic perennial weed in many crops such as corn, sunflower, cotton, vegetables and orchards in Turkey. Field bindweed has strong seed dormancy and its germination is delayed. A good understanding of the mechanism of seed dormancy is important for plant reproduction and control of field bindweed. This study was carried out in laboratories in order to determine the dormancy breaking methods (sulfuric acid, gibberellic acid, hydrochloric acid, microwave, cold-hot applications) 20°C and 27°C seeds from the Malatya Province and germination temperatures of seeds from different ecological regions where are the Adana, Ankara, Canakkale, Denizli, Erzurum, Hatay, Karaman, Kayseri, Konya, Malatya, Samsun, Sanliurfa, Tekirdag and Usak Provinces. The highest dormancy breaking happened in sulfuric acid 60 or 120 min (20°C) and keeping seeds 5 s in 90°C hot water (27°C). It has been determined that at germination temperature is between 10-40°C depending on the provinces where it was collected. The highest germination rate (96.3%) was observed in seeds of Erzurum province at 20°C. While there was no germination at 2 and 45°C, the highest germination rate (80%) at 40°C was also observed in the seeds of Erzurum province. [ABSTRACT FROM AUTHOR]

The ontogeny of seed plants usually involves a dormant dehydrated state and the breaking of dormancy and germination, which distinguishes it from that of most organisms. Seed germination and seedling establishment are critical ontogenetic stages in the plant life cycle, and both are fueled by respiratory metabolism. However, the scaling of metabolic rate with respect to individual traits remains poorly understood. Here, we tested metabolic scaling theory during seed germination and early establishment growth using a recently developed model and empirical data collected from 41 species. The results show that (i) the mass-specific respiration rate (R m) was weakly correlated with body mass, mass-specific N content, and mass-specific C content; (ii) R m conformed to a single Michaelis-Menten curve as a function of tissue water content; and (iii) the central parameters in the model were highly correlated with DNA content and critical enzyme activities. The model offers new insights and a more integrative scaling theory that quantifies the combined effects of tissue water content and body mass on respiratory metabolism during early plant ontogeny. [ABSTRACT FROM AUTHOR]

Physical dormancy of Robinia pseudoacacia seeds makes it a challenge for scientists and forest managers to obtain a homogeneous germination for larger seed samples. Water imbibition of the seeds can be achieved through manual piercing of the seed coat, but this method remains time consuming and heterogeneous. We tested several ecologically friendly methods to break seed dormancy, including manual pin puncture, water soaking, oven dry-heating (two temperatures) and sanding. Sanding was performed using an automatic grinder to control shaking duration (three durations) and get a homogeneous scraping of the coat. All methods, except dry-heating, resulted in successful dormancy breaking; water soaking was the least efficient method, attaining 57% germination. Sanding proved to be as efficient as puncturing (97%) but long duration sanding (10 or 15 min) could damage cotyledons, which would impede further development of the plant. Short-time sanding (5 min) proved to be the best method to reach high total germination and healthy (undamaged cotyledon) seedlings, and was successfully applied to 500 seeds. The reference puncture method and the automatic sanding were also tested on seeds of nine Fabaceae species and proved to be efficient for some species. Automated sanding can thus be used as a standard to break physical dormancy of black locust or other Fabaceae seeds to allow further comparative studies of plant populations or genotypes. [ABSTRACT FROM AUTHOR]

The major problem in seedlings production of jasmin box (Phillyrea latifolia) is the poor and irregular germination due to seed dormancy. The objective of the present study was to evaluate methods of seed pre-treatments to increase germination. The effect of different solutions of KOH and NaOH, wood ash lye, GA3 and cold or warm stratification on germination were evaluated. Sets of four replicates of 25 seeds were soaked for 24 hours in KOH and NaOH solutions of 0.2, 0.5, 1 and 2%, in wood ash lye solutions of 33, 66, 133, 166, 532 g L-1 and in GA3 solutions of 250, 500, 1000, 2,000, 3,000 mg L-1. A control set of seeds was imbibed in water for 48 hours. All sets went through zero, two, four and six months of cold (2-4 °C) or warm (15 °C) stratification. The seeds were incubated in petri dishes filled with moistened sand, at two alternating temperatures (20/15 and 30/20 °C) with a light period of 16 hours. From the results we conclude that: Chemical pre-treatments with KOH and ash lye and warm stratification increased germination to 96%. Treatment with water and warm stratification also increased germination to 79%. Treatment with 250 mg L-1 GA3 and six months warm stratification increased germination to 70% while higher concentrations had a negative effect. Cold stratification did not break dormancy. Optimum germination temperature in a growth chamber was 15-20 °C, while temperature at 20-30 °C inhibited germination. [ABSTRACT FROM AUTHOR]

Seed tolerance to the elevated temperatures of soils during the spring/summer seasons or due to the passage of fire is an important adaptation for Cerrado (neotropical savanna) seeds. The present work evaluated the influence of elevated temperatures on the seed viability and germination of the palm tree Acrocomia aculeata . The seeds were immersed in water at 70 °C (thermal shock) for 1, 3, 5, 10, 30, 60, 120, 300, 420 and 600 s. In another experiment, seeds were maintained in dry (heat treatment) or moist (stratification) conditions, at temperatures of 35, 40, 20/30, 18/35 °C, or at room temperature (mean 22 °C) for 15, 30 or 60 days. The effects of these treatments on embryo viability as well as on seed germination were evaluated. Embryo survival was high until 300 s of exposure to thermal shock; high mortality was observed with longer exposures. Thermal shocks did not stimulate seed germination, and high rates of seed deterioration were observed with exposure to high temperature for 300 s or more. Heat treatments, at any temperature, did not stimulate germination, while stratification at 35 °C for 30 and 60 days resulted in increased germination (13 and 25% respectively). The temperature of 40 °C, in both dry and moist conditions, resulted in the loss of embryo viability. Acrocomia aculeata seeds have a considerable tolerance to high temperatures; furthermore, stratification at 35 °C is probably important in overcoming seed dormancy in soil seed banks and constitutes a successful propagation method for the species. [ABSTRACT FROM AUTHOR]

Generative reproduction of Potamogeton praelongus in the laboratory is a possible way to preserve this critically endangered species in the Czech Republic (CR) as well as the whole of central Europe and to increase the low genetic diversity of its populations. Different methods of seed storage, breaking seed dormancy, cultivation temperature, seed age and interactions of these factors were examined to determine the suitable conditions for generative reproduction of P. praelongus in the laboratory. The most suitable storage method was keeping dried seeds in paper bags and submerging them in water for one month before the test. The best results of breaking seed dormancy were gained by near-natural methods – stratification, effect of microbial activity in water, scarification. Also methods using synthetic chemical substances and multiple dormancy breaking measures were successful. Seeds germinated better at 28 ± 1 °C than at 21 ± 3 °C. The best cultivation medium was river water. The strongest interaction was found between the storage method and treatment of seeds before cultivation. Seeds stored for about one year germinated better than fresh or shortly stored (6–9 months) ones. Optimal conditions for generative reproduction of P. praelongus in the laboratory were determined to be used for preservation of this species in CR. [ABSTRACT FROM AUTHOR]

The species Cochlospermum regium is a shrub that disseminates by seed, but with extremely low germination even under ideal conditions, that is a response to physical dormancy imposed by the seed coat. Thus, we aimed to evaluate the efficacy of dimethyl sulphoxide (DMSO) in overcoming dormancy in Cerrado ‘algodãozinho’ seeds compared to other traditional methods, in combination with growth analysis to assess seedling normality. The seeds in experiment I were submitted to the following treatments: (1) control: soaking in distilled water for 24h; (2) mechanical scarification: rubbing with sandpaper for 1min and soaking in distilled water for 24h; (3) acid scarification: immersion in sulphuric acid for 2h followed by soaking in distilled water for 24h; (4) immersion in DMSO at 65°C for 24h followed by soaking in distilled water for 24h; and (5) soaking in distilled water for 24h and immersion in sodium hypochlorite (NaOCl), 12% active chlorine, for 5h. The volume of solution used in all treatments was sufficient to completely submerge the seeds. Initial seed moisture content, seed dry mass, germination percentage, and germination speed index (GSI) were measured. In experiment II, seeds were immersed in DMSO at 65°C for 24h followed by soaking in distilled water for 24h or distilled water at 65°C for 24h and evaluated by the standard germination test and GSI. Shortly after germination, seeds from both treatments were transferred to trays containing sand as a substrate for subsequent seedling morphological and growth evaluation. Overall, the results show that mechanical scarification with sandpaper for 1min and seed immersion in DMSO were the best treatments for overcoming dormancy in seeds of C. regium, and DMSO caused no morphological abnormality in the seedlings. [ABSTRACT FROM AUTHOR]

In order to break seed dormancy, different temperatures (20, 30, 40, 50, 60, 70, 80 and 90°C) and durations (10, 20 and 30 minutes) were applied to black locust (Robinia pseudoacacia L.) and honey locust (Gleditsia triacanthos L.) seeds, in the Seed Laboratory of Dicle University - Faculty of Agriculture in 2009. According to the research results, the highest germination rate for black locust seeds was obtained in the case o190°C for 30 minutes pre-treatment (94.5%), whilst the lowest value was obtained for the 40°C for 10 minutes pre- treatment (7.5.0%). For honey locust the highest value was obtained at 50°C for 30 minutes (25.5%) and the lowest value was obtained in the case of control sample (6.8%). [ABSTRACT FROM AUTHOR]