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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]

Seeds establish dormancy to delay germination until the arrival of a favorable growing season. In this study, we identify a fate switch comprised of the MKK3–MPK7 kinase cascade and the ethylene response factor ERF4 that is responsible for the seed state transition from dormancy to germination. We show that dormancy-breaking factors activate the MKK3–MPK7 module, which affects the expression of some α-EXPANSIN (EXPA) genes to control seed dormancy. Furthermore, we identify a direct downstream substrate of this module, ERF4, which suppresses the expression of these EXPA s by directly binding to the GCC boxes in their exon regions. The activated MKK3–MPK7 module phosphorylates ERF4, leading to its rapid degradation and thereby releasing its inhibitory effect on the expression of these EXPA s. Collectively, our work identifies a signaling chain consisting of protein phosphorylation, degradation, and gene transcription , by which the germination promoters within the embryo sense and are activated by germination signals from ambient conditions. This study shows that the MKK3–MPK7 cascade positively regulates dormancy breaking by promoting the expression of some EXPA s, whereas ERF4 binds directly to the GCC boxes in the exons of EXPA s and suppresses their expression. During the dormancy-breaking process, the activated MKK3–MPK7 cascade phosphorylates ERF4 and promotes its rapid degradation, leading to release of its inhibitory effect on EXPA expression. [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]

Breaking of dormancy in african juniper (Juniperus procera) seeds is a challenge faced by nurseries attempting to grow large numbers of this plant for restoration projects. The purpose of this study was to develop a protocol for breaking dormancy and stimulating germination in african juniper. Seeds were presoaked in different concentrations (0, 1, 10, or 20 mg·L−1) of gibberellic acid (GA3), indole-3-butyric acid (IBA), and naphthalene acetic acid (NAA), and incubated under different air temperatures (10, 15, and 20 °C). The petri dishes were monitored daily for 84 days, to record germination percentage, rate, and uniformity, and the growth of shoots and roots, and biomass production. The highest germination percentages were obtained under 20 °C with a high concentration of NAA (20 mg·L−1). The greatest seedling growth was under 20 °C with IBA. The greatest seedling length was under 20 °C with a low concentration of IBA (1 mg·L−1). The greatest shoot fresh weight was under 20 °C with medium GA3 concentration (1 mg·L−1). Compared with the control, almost all growth regulator treatments stimulated higher germination percentages and vigor indices with increased temperatures.

This work aimed to determine efficient methods for dormancy breaking in Dimorphandra mollis Benth seeds. The seeds were collected from mother trees in the municipality of Buriti, Maranhão State, Brazil. They were submitted to the following treatments: control (T1); mechanical scarification with sandpaper No. 60 (T2); chemical scarification with 98% lye (sodium hydroxide) for 15 min (T3); chemical scarification with sulfuric acid 99.9% for 20 min (T4) and thermal-shock with water (T5). In a greenhouse, we used 16 seeds per treatment, divided into four replications, in a completely randomized design. The evaluations started on the third day after seeds were treated and it was carried out until 17 days after sowing. The percentage of emerged seeds and the emergence speed index were evaluate. The mechanical scarification treatment with sandpaper (T2) and the chemical scarification with sulfuric acid (T4) were efficient to overcome the seed coat impermeability, but the mechanical scarification is the safest method for users to overcome seed dormancy. [ABSTRACT FROM AUTHOR]

An increase in the productivity of potato plants and natural resistance of tubers to external influences during growth, while preserving the qualitatively new properties of tubers in the process of low-temperature preservation, can be achieved through the effect of bioactive compounds on the metabolism of potato plants in our work, we used a regulator derived from the hydrolysis of natural collagen down to low molecular weight fractions and pure glycine. The evidence of its effectiveness is based on shortening the growing season and increasing plant productivity as well as the content of bioactive and nutrient compounds in their storage organs, reducing losses during low-temperature preservation caused by natural biological processes, physiological diseases and damage by microorganisms. The paper deals with issues related to the growth and development of potato plants and their storage organs until the growing season is over and a possible increase of potato productivity after the planting material was treated with an amino acid growth regulator. [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]

Potato is an important food and cash crop which in Ethiopia is produced two or more times in a year. However, its productivity is low owing to a number of constraints including a) limited availability of quality planting materials, and b) poor tuber sprouting due to long dormancy period of improved varieties at the time of planting. Two consecutive experiments were conducted from November 2013 to June 2014: 1) to assess the effects of gibberellic acid (GA3) and storage methods on seed tuber dormancy breakage of two potato varieties; and 2) to assess the effects of dormancy breakage treatments and storage methods on subsequent growth, yield and related traits of potato crop. The treatments in the first experiment consisted of two potato varieties (Bubu and Bate), three levels of GA3 [0, 10 and 20 parts per million (ppm)], and three storage methods [in diffused light store (DLS), in pit store (PS), and in farm-yard manure (FYM)]. The first trial was laid out as a complete randomized design with four replications and conducted at Haramaya University, Ethiopia. The second trial consisted of seed from each treatment in the first experiment, planted in randomized complete block design with three replications on a farmers’ field. The results showed that varieties, application of GA3 and storage methods as well as the interaction among the variety and treatments significantly affected tuber dormancy period, sprouting characteristics and subsequent tuber yield. When tubers were treated with 20 ppm GA3 and stored under FYM, the dormancy period was reduced from 102.5 and 52 to 36.5 and 31 days in improved and farmer’s variety, respectively. Tuber treatment with 20 ppm GA3 and stored under DLS, PS, and FYM, increased marketable tuber yield by 31.6%, 29.6%, and 33.6%, respectively for Bubu variety and by 92.5%, 78.4%, and 80.9% for Bate variety, respectively compared to non-GA3 treated tubers stored under DLS, PS, and FYM. However, tubers of improved variety Bubu treated with 20 ppm GA3 and stored under DLS produced the highest marketable tuber yield of 34.20 ton per ha. Tuber quality attributes (specific gravity, dry matter, and total starch content) were affected only due to interaction effects of variety and GA3 application with the highest values at 20 ppm GA3 for improved potato variety Bubu. In general, the research indicated that treating seed tubers with GA3 and storing under DLS, PS or FYM promoted early tuber sprouting and better tuber yield of both varieties. These results suggest that, use of GA3 treatment combined with different storage methods enhances early tuber sprouting and increases tuber yield. Nevertheless, further research should be continued to evaluate different potato varieties, GA3 treatment, and storage methods under different atmospheric conditions and production seasons.

The Solanum torvum species can grow in soils with a heavy load of nematodes and pathogenic fungi. It is currently much in demand in intensive agriculture as a rootstock of Solanaceae species, such as eggplant and tomato. This study aimed at comparing treatments, in order to determine the best method to accelerate the germination of S. torvum seed batches. Three seed batches were submitted to four treatments to overcome dormancy (water, potassium nitrate, gibberellic acid and pre-imbibition in gibberellic acid). The first germination count, germination percentage, germination speed index, mean germination time and mean germination speed were assessed. Treatments with gibberellic acid, with either pre-imbibition or only moistened substrate, exhibited the best germination speed index, mean germination time and mean germination speed. The final germination percentage showed a significant interaction between treatments and seed batches. Therefore, the treatments affect the final germination in a batch-dependent manner.

In table grape production, protected cultivation in a vineyard in different regions and climates is currently a commonly used practice. The aims of this study were to provide key approaches to sustainably produce two crops of grape without overlap under protected environment in a single year. Spraying the degreening chemicals 400 mg/L ethephon +0.4% sulfur at 4 weeks of vine nutrient restoration after the harvest of the summer crop resulted in the highest percentage of sprouting inflorescence. The retention of 7–10 buds in the base shoot results in the high percentage of sprouting inflorescence. Bud breaking chemicals with 2.5% hydrogen cyanamide+2.0% Baoguoliang +0.02% Shenzhonggen significantly led to sprout inflorescence more efficiently. Cluster and fruit weights of the winter crop weighed significantly less than those of the summer crop. However, the contents of total soluble sugar and titratable acidity were higher than those of the summer crop. The anthocyanin content in the peel of the winter fruit was significantly higher than that in the summer fruit. The yield of the winter crop is controlled by the yield of the summer fruit. To maintain the stability of the two crops for one year, the ratio of yield in the winter to the summer should be controlled from 2:5 to 3:5 to ensure the sustainable production of two crops without overlap for ‘Summer Black’ grape. These results may help grape growers to overcome the impacts of rainy and hot climates with the help of protected facilities, and it could enable the use of solar radiation and heat resources in subtropical and tropical areas.

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., Competing Interests: The authors declare that they have no competing interests., (© 2023 The Authors. Food Science & Nutrition published by Wiley Periodicals LLC.)

Terminalia laxiflora Engl. & Diels. is an important indigenous and multi-purpose species in Ethiopia. However threatened due to low germination and its storage behavior is unknown. In this study, we aimed to (1) test pretreatments for breaking the dormancy of T. laxiflora seed and (2) determine its storage behavior. Seeds were subjected to four pretreatments such as soaking, scarification, high-temperature, and control. Experiments were done before storage and after 2 years of dry storage at cold temperature (− 10 °C) based on randomized design with four replicates. The first round of experimental results showed that T. laxiflora seeds with high temperature treatments at 78 °C for 10 min showed significantly higher germination percentage (80%). In the second round experiment, high-temperature treatment at 78 °C for 15 min, cold water soaking, high-temperature treatment at 78 °C for 10 min, hot water soaking, and high-temperature treatment at 78 °C for 5 min showed significantly higher germination percentage from the remaining treatments (75, 64, 58, 56, and 53%, respectively). To break the dormancy of T. laxiflora seed and attain good germination result, seeds should be pretreated with high-temperature at 78 °C for 10 min to test the initial germination before storage and should be pretreated with high-temperature (at 78 °C for 15, 10, or 5 min), soaked in cold, or hot water for 24 h to monitor the germination after storage. The two experiments show that T. laxiflora produces orthodox seed. [ABSTRACT FROM AUTHOR]

Summary: Dormant seeds of oilseed rape (OSR) can persist in the soil and cause OSR volunteers in subsequent crops. Several approaches were tested in the laboratory and in the field to determine whether dormancy induction and seed persistence can be reduced by using dormancy‐breaking exogenous compounds. In a laboratory experiment, OSR seeds were coated with KNO3, micronutrients, or gibberellic acid (GA) prior to a secondary dormancy test. In a field experiment, seeds were coated in a manner analogous to the laboratory experiment, and then buried 10 cm deep in the soil for 2.5 months. In a practical demonstration, OSR plants were sprayed with either urea ammonium nitrate (UAN) or a commercial product containing GA prior to seed maturity. Seed coating (laboratory and field experiments) reduced secondary dormancy and seed persistence in the field by up to 99%. The efficiency of the treatments for mitigating secondary dormancy (laboratory and field experiments) in decreasing order was GA > micronutrients > KNO3 > control. With pre‐maturity spraying (practical demonstration), UAN reduced primary dormancy by up to 77% and the development of secondary dormancy by up to 38%; GA had no effect. Dormancy and seed persistence of OSR seeds may be reduced by a pre‐maturity UAN treatment of OSR mother plants, or by applying appropriate exogenous compounds to OSR seeds. [ABSTRACT FROM AUTHOR]

Copyright of Revista Colombiana de Ciencias Hortícolas is the property of Revista Colombiana de Ciencias Horticolas 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.)

Protein synthesis in cotyledons and embryo axes of Norway maple (Acer platanoides L.) was studied in seeds stratified at 3 or 15oC. At 3oC stratification, germination of seeds starts after 9 weeks, at 15oC stratification germination does not occur. The changes of protein synthesis level in both temperatures had two phasic character. In embryo axes (3 and 15oC) protein synthesis grow up, but in cotyledons (3oC) synthesis of proteins decrease. Generally, activity of protein synthesis was higher at 3oC, as like as DNA level was higher. After imbibition, in cold and warm stratification, in embryo axes, many new protein are become visible. We expect, that two from this proteins, determined as A and B my be connected with the releasing from dormancy. In seeds stratified at 15oC, these proteins are occuring in vestigal amount or are completely absent.

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]

Camellia japonica L. is an evergreen shrub whose cultivars are of great ornamental value. In autumn, after flower bud differentiation, dormancy is initiated. As in many other spring flowering woody ornamentals, winter low temperatures promote dormancy release of both flower and vegetative buds. However, warm spells during late autumn and winter can lead to unfulfilled chilling requirements leading to erratic and delayed flowering. We hypothesized that storing plants at no light and low temperature could favor dormancy breaking and lead to early and synchronized flowering in response to forcing conditions in C. japonica ‘Nuccio’s Pearl’. Plants with fully developed floral primordia were stored at dark, 7°C, and RH>90% for up to 8 weeks. To monitor endodormancy release during the storage, we evaluated the content of ABA in flower buds and the expression profiles of five putative genes related to dormancy and cold acclimation metabolism in leaves and flower buds. In addition, the expression of four anthocyanin biosynthesis pathway genes was profiled in flower buds to assess the effect of the treatment on flower pigment biosynthesis. At 0, 4, 6, and 8 weeks of cold treatment, 10 plants were transferred to the greenhouse and forced to flower. Forced plant flower qualities and growth were observed. The abscisic acid content and the expression profiles of two dormancy-related genes (CjARP and CjDEH) suggested that dormancy breaking occurred after 6-8 weeks of cold treatment. Overall, plants treated for 6-8 weeks showed earlier vegetative sprouting, enhanced and homogeneous flowering with reduced forcing time. Prolonged cold treatments also reduced flower size and longevity, anthocyanin content, and pigment biosynthesis-related gene transcripts. In conclusion, the cold treatment had a promotive effect on dormancy breaking but caused severe drawbacks on flower quality.

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]

Respiration and heat production in the shoots of bilberry ( Vaccinium myrtillus L.) were studied at the beginning of growth after breaking bud dormancy by means of transfer of the shoots to indoor conditions (November-April) and upon natural sprouting in spring (May). The buds released from dormancy at the beginning of winter sprouted slower and showed lower respiratory activity than the buds that started growing in May. In May, cytochrome respiratory pathway in sprouting buds was 1.3 times more active than energetically ineffective alternative pathway, whereas activity of cytochrome pathway in December was 1.4 times lower as compared with the alternative. In November-December, the rate of heat evolution by the buds was 3-5 times lower than in April-May. In case of early breaking of bud dormancy, the share of respiration energy dissipated as heat was 30% on average. In the buds whose growth was induced later, the value of this parameter was twice as much. The ratio between heat evolution and respiration depended on temperature. High temperature more intensely activated heat evolution than respiration, which caused a decrease in the level of metabolic energy available for growth. In the temperature range of 5-15°C characteristic of the beginning of vegetation, the share of respiration energy dissipated as heat was 2-3 times lower than at 20-30°C, which reflects a great adaptability of V. myrtillus to climatic conditions of the region. Our data suggest that progression through a full cycle of winter dormancy is physiologically important for shoot growth. Early dormancy release brought about changes in respiration and energy balance of the shoots in the initial stage of extra-bud growth. [ABSTRACT FROM AUTHOR]

Camellia japonica L. is an evergreen shrub whose cultivars are of great ornamental value. In autumn, after flower bud differentiation, dormancy is initiated. As in many other spring flowering woody ornamentals, winter low temperatures promote dormancy release of both flower and vegetative buds. However, warm spells during late autumn and winter can lead to unfulfilled chilling requirements leading to erratic and delayed flowering. We hypothesized that storing plants at no light and low temperature could favor dormancy breaking and lead to early and synchronized flowering in response to forcing conditions in C. japonica 'Nuccio's Pearl'. Plants with fully developed floral primordia were stored at dark, 7°C, and RH > 90% for up to 8 weeks. To monitor endodormancy release during the storage, we evaluated the content of abscisic acid (ABA) in flower buds and the expression profiles of five putative genes related to dormancy and cold acclimation metabolism in leaves and flower buds. In addition, the expression of four anthocyanin biosynthesis pathway genes was profiled in flower buds to assess the effect of the treatment on flower pigment biosynthesis. At 0, 4, 6, and 8 weeks of cold treatment, 10 plants were transferred to the greenhouse and forced to flower. Forced plant flower qualities and growth were observed. The ABA content and the expression profiles of two dormancy-related genes (CjARP and CjDEH) suggested that dormancy breaking occurred after 6-8 weeks of cold treatment. Overall, plants treated for 6- 8 weeks showed earlier vegetative sprouting, enhanced, and homogeneous flowering with reduced forcing time. Prolonged cold treatments also reduced flower size and longevity, anthocyanin content, and pigment biosynthesis-related gene transcripts. In conclusion, the cold treatment had a promotive effect on dormancy breaking but caused severe drawbacks on flower quality. [ABSTRACT FROM AUTHOR]

Dormant tubers of two potato cultivars Kufri Jyoti and Kufri Chandramukhi were treated for 7 days with 5, 10, 15 and 20% CO2 concentrations at 18 ± 1ºC and 90-95% RH, and compared with GA treated tubers and with untreated tubers serving as control. During subsequent storage at the same temperature and RH, dormancy duration was reduced by 20 days with CO2 treatment and by 35 days with GA treatment. In Kufri Jyoti, GA treatment caused 2.6 fold increase in the concentration of reducing sugars and 0.8 fold increase in total sugars in the apical half of the tubers leading to early release of dormancy in apical buds but this increase in sugar content was not observed in the basal half where the buds remained dormant.

This study was conducted to prevent flower bud abortion in forcing culture of herbaceous peony. When dormant rootstocks of Paeonia lactiflora 'Taebaek' were subjected to dormancy-breaking treatment (0°C for 6 weeks) in November, this could hasten flowering in early spring. However plants chilled in August, September, or October produced abnormal flowers or resulted in flower bud abortion. To prevent flower bud abortion, we placed the dormant rootstocks at five pre-chilling treatments for 2 weeks in mid-September and October. The treatment conditions were 0°C for 2 weeks (C0, control), natural chilling in an open field for 2 weeks (NT), pre-chilling at 15°C for 2 weeks (P15), 15°C for 1 week → 10°C for 1 week (P15 → 10), and pre-chilling at 10°C for 2 weeks (P10). After these pre-chilling treatments, all of the plants were placed under a cold regime of 0°C for 6 weeks in order to break dormancy. In the C0 and NT treatments, a great numbers of flower buds were aborted from their stems. On the other hand, the P15 → 10 and P10 treatments increased to 74.7 and 81.0% for flowering, respectively. Pre-cooling treatment accelerated the growth of flower buds compared to the C0 or NT treatments. To promote blooming in the autumn season, rootstocks were also placed into three treatments (C0, NT, and P10) in early July. While the C0 and NT treatment were unable to produce flowering at all, the treatment P10 induced more than 80% flowering of plants. From these results, pre-chilling at treatment 10°C for 2 weeks was recommended as the optimum treatment to promote flowering without flower bud abortion in forcing culture for winter or autumn flowering. [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]

This study was conducted to investigate flower bud differentiation and to determine the chilling requirements for bud dormancy breaking and sprouting in Erythronium japonicum Decne. (Liliaceae). Dormant bulbs grown in an open field were randomly selected from June 2012 to December 2013 for observation of flower bud differentiation and development. The 3-4 year-old bulbs and > 10 year-old bulbs were used for vegetative bud development and flower bud development, respectively. For natural chilling treatments, the plants were transferred from an experimental field to a growth module every month from September to February. Artificial chilling treatments were applied at 5°C for 0, 2, 4, 8, and 12 weeks in October and November. The cumulative chill unit (CCU) of low temperatures below 5°C was calculated. Flower bud initiation and differentiation in E. japonicum were observed in May, and from June to July, respectively, followed by flower bud elongation in August. Sprouting and bud break did not occur throughout the experiment when dormant bulbs were transferred from September (0 CCU) to November (450 CCU). However, all plants sprouted when the dormant bulbs were transferred after January (1,794 CCU). Prolonged cold storage also promoted sprouting of dormant E. japonicum. No cold storage or 4 weeks (672 CCU) of cold storage at 5°C in October did not induce sprouting and bud break. However, when the dormant bulbs were stored at 5°C for 12 weeks (2,061 CCU) in October, percent sprouting increased to 72.7%. Chilling treatment for 8 weeks (1,483 CCU) or 12 weeks (2,155 CCU) at 5°C in November resulted in 72.7 and 100% sprouting, respectively. In conclusion, at least 1,483-1,794 CCU may be recommended for dormancy breaking in the forcing culture of E. japonicum. [ABSTRACT FROM AUTHOR]

A clear understanding of the mechanisms involved in releasing seed dormancy is important for effective plant conservation and regeneration of desert species. The dormancy types and dormancy release mechanisms of 19 Fabaceae species from four cold deserts in Xinjiang province, China, were studied. An imbibition experiment was performed to determine the presence or absence of physical dormancy. Other treatments included mechanical scarification, sulphuric acid scarification and simulation of summer temperatures typically encountered in the field. High summer temperature treatments included a maximum soil temperature of 80°C, 65°C and 40°C, conducted under dry and wet conditions. The results showed that all the species had orthodox seeds. Caragana korshinskii, Caragana intermedia, Caragana microphylla and Onobrychis taneitica seeds were not dormant. Glycyrrhiza uralensis, Ammodendron bifolium, Vicia costata and Eremosparton songoricum seeds had combinational dormancy (PY+PD) whereas the other 11 species had physical dormancy. The mechanical scarification and sulphuric acid scarification treatments were significant to break dormancy (>80%). Melilotus suaveolens and Oxytropis sp. seeds were temperature-insensitive. Sophora alopecuroides, S. salsula, E. songoricum, A. bifolium and Cassia tora seeds were wet-heat sensitive. Glycyrrhiza glabra seeds were dry-heat sensitive, while those of Halimodendron halodendron and Astragalus lehmannianus were sensitive to both dry and wet heat. Although high temperatures, typical of summer, promoted the breaking of physical dormancy, the proportion of seeds of which dormancy was broken differed among species. These differences were indicative of the conditions in which the species are found naturally. Species may have different adaptations that promote favourable regeneration. Given suitable temperature and moisture conditions similar to those in their natural environment, most species were capable of regeneration. [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]

Dormancy breaking and flowering of Paeonia lactiflora 'Taebaek' were controlled by natural cumulative chilling and GA treatments according to the transfer date in the central region of Suwon, Korea. Shoot emergence and flowering did not occur throughout the experimental period when dormant rootstocks were transferred to a glasshouse between September 10 and October 29, in which the natural cumulative chill (NCU) unit was nearly 0 h. The number of days from the transfer date to sprouting and flowering was shortened as the transfer date was delayed. All the plants flowered normally with shoot growth when they were transferred after December 31 (1,222 h NCU). All dormant buds that were treated with GA sprouted, regardless of transfer date, but failed to flower due to shoot blasting and flower bud abortion when they were transferred between September 10 (0 h NCU) and November 12 (185 h NCU). Shoot blasting was 38% when they were transferred on November 26 (429 h NCU). When GA was applied to the plants after December 17 (876 h NCU), they flowered without blasting. Plant height and stem diameter were not affected by GA treatment. GA treatment decreased the number of days to sprouting and flowering, and increased the number of flowers, irrespective of insufficient chilling accumulation, as compared to 1,222 h NCU on December 31. According to the above results, at least 1,222 h NCU could be recommended as a practical forcing method for dormancy release, subsequent growth, and normal flowering of dormant P. lactiflora 'Taebaek' in a temperate climate region. The GA treatment played an important role in breaking dormancy and significantly increased the percentage of sprouting, accelerated the days to sprouting and promoted the flowering of P. lactiflora 'Taebaek' when the plants had undergone insufficient chilling accumulation. [ABSTRACT FROM AUTHOR]

The aim of this study was to enhance the germination percentage and rate of Ferula assa foetida, a medicinally important vulnerable species, which have a low germination rate under normal laboratory conditions. The efficacy of different treatments including various levels of GA3, chilling and soaking with running water for germination improvement was tested. Analysis of variance indicated that Cold stratification and GA3 concentration had significant effects on seed germination percentage. Combined treatments chilling (4 °C) for both periods of 30 and 60 days were most effective in breaking dormancy. Among the combined chilling treatments, Maximum germination was obtained at combination treatment cold stratification (60 days) with 2000 ppm of GA3 solution and minimum germination was at socking in running water and control treatments. These results suggested that Ferula assa foetida seeds exhibit endogenous dormancy. A combination of cold stratifications and exogenous application of GA3 alleviated seed dormancy in a relatively short period of time. Germination rate was positively correlated with germination percentage. [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]

We analysed changes in AMP, ADP, and ATP concentrations and adenylate energy charge in Norway maple ( Acer platanoides L.) and European beech ( Fagus sylvatica L.) seeds during dormancy breaking (at 3 °C) and in the control variant at 15 °C. Values of the studied indicators in stratified beech seeds were generally higher at 15 °C, at least until germination (+3 °C). By contrast, in maple seeds, the values recorded during dormancy breaking by cold stratification were much higher than at 15 °C. Three peaks (usually in weeks 3, 6, and 8) were observed in maple seeds at 3 °C, but not at 15 °C. Among adenine nucleotides, AMP reached the highest levels in both species in both variants of the experiment. [ABSTRACT FROM AUTHOR]

The studies were carried out on Fagus sylvatica seeds during stratification and their germination. After imbibition beechnuts were subjected to cold (3 °C — temperature which breaks dormancy) or warm (15 °C — temperature unable to break dormancy) stratification and alternatively were treated with polyamine synthesis inhibitors: canavanine and DFMO (difluoromethylornithine). After cold stratification in embryo axes we found (using 2-D electrophoresis) about 150 new proteins absent in dry seeds. Exogenous spermidine increased the protein synthesis, percent of germinated seeds and accelerated breaking of dormancy. In contrast, canavanine and DFMO decreased dynamic of protein synthesis, quantity of proteins probably synthesised de novo, and percent of germinated seeds. The maximum of polyamine content in embryo axes during cold stratification preceded such the maximum during warm stratification. Irrespective of the influence of PAs and inhibitors of PA synthesis, the comparison of electrophoregrams and autoradiograms showed that different groups synthesised de novo appeared after different periods of cold stratification. Probably the part of this protein is associated with Fagus sylvatica seeds dormancy breaking. [ABSTRACT FROM AUTHOR]

Embryonal explants from water chestnut ( Trapa japonica Flerov) seeds germinated with high efficiency following a 40-d cold treatment at 5°C on half-strength MS (Murashige and Skoog) medium supplemented with 2.7 μ M N6-benzyladenine (BA), 0.5 μ M 1-naphthaleneacetic acid (NAA) and 0.5 μ M gibberellic acid (GA3). Control and chill-treated (different durations) embryonal explants were cultured onto media which contained half-strength MS medium supplemented with different concentrations and combinations of cytokinins [BA, thidiazuron (TDZ), kinetin, zeatin], auxin (NAA) and GA3. A liquid half-strength MS medium with 1.1 μ M BA and 0.5 μ M NAA resulted in the best shoot proliferation of control or chill-treated explants, and the addition of 0.5 μ M GA3 stimulated axillary shoot elongation. Germination and shoot proliferation were always greater for chill-treated explants compared with control explants under the same culture conditions. Shoots produced in vitro rooted 100% of the time in a liquid half-strength MS medium with 1.1 μ M BA, 0.5 μ M NAA and 1.1 μ M indole-3-butyric acid, and the regenerated plantlets were established successfully in a water chestnut paddy field. [ABSTRACT FROM AUTHOR]

The changes of ascorbic acid, dehydroascorbic acid, and glutathione content and related enzyme activities were studied in apple buds during dormancy and thidiazuron-induced bud break. An increase in ascorbic acid, reduced form of glutathione (GSH), total glutathione, total non-protein thiol (NPSH) and non-glutathione thiol (RSH) occurred as a result of induction by thidiazuron during bud break, whereas dehydroascorbic acid and oxidized glutathione (GSSG) decreased during the same period. Thidiazuron also enhanced the ratio of GSH/GSSG, and activities of ascorbate free radical reductase (AFR; EC 1.6.5.4), ascorbate peroxidase (EC 1.11.1.11), dehydroascorbate reductase (DHAR; EC 1.8.5.1) and glutathione reductase (GR; EC 1.6.4.2). The ascorbic acid content and the activities of AFR, ascorbate peroxidase, and DHAR peaked when buds were in the side green or green tip stage just prior to the start of rapid expansion, and declined thereafter. The GSH, NPSH, RSH, ratio of GSH/GSSG, and activities of GR increased steadily during bud development. [ABSTRACT FROM AUTHOR]

Changes in ribosome population, RNA species and DNA composition in flower buds of apples (Malus pumila Mill. cvs Ralls and White winter pearmain) were investigated during breaking of dormancy and development. After bursting of flower buds, total ribosomes increased approximately 4-fold, and the polyribosomal fraction increased from 66% to 94% of total ribosomes. The newly synthesized ribosomes were identified by incorporation of radioactive precursor. The observed decrease in specific radioactivity of the monoribosomes is caused by the recruitment of mononribosomes into polyribosomes after breaking of dormancy. In both cultivars, the 25S and 18S rRNA peaks increased to a high level on April 8. The peaks of low molecular weight RNA were apparently increased after initial swelling of the flower buds. The DNA of flower buds was separated into three bands by electrophoresis. The median band is the main band of nuclear DNAs. The ahead band and the slow-moving band are satellite components of nuclear DNAs, and they obviously rose after initial swelling of the flower buds. On April 8, when the flower buds had opened, two other small DNA bands could be detected. These results suggest that the changes in level of different ribosome populations, RNA species and DNA composition are related to dormancy breaking development of apple flower buds. [ABSTRACT FROM AUTHOR]

A reevaluation of breaking tuber dormancy with bromoethane to increase the concentration of potato virus Y in the tuber revealed a positive response, by ELISA testing, to the treatment. The degree of response increased with the maturity of the tuber. Response to treatment with rindite was generally stronger, although differences were slight. [ABSTRACT FROM AUTHOR]