Effect of solid matrix priming during moist chilling on dormancy breakage and germination of seeds of four fir species

The ability of solid matrix priming (SMP) to overcome seed dormancy ofseeds of four fir species (Pacific silver fir, subalpine fir, grand fir andnoble fir), was examined. Seeds were subjected to treatments that combinedmoistchilling and SMP (SMP-chilling) and their germination compared to that elicitedby traditional moist chilling. For the SMP-chilling, six solid matrices withdifferent water holding capacities were tested (sphagnum, cat litter, peatmoss,Agro-Lig Greens Grade, Agro-Lig Micro Fine and sand). For each of the speciestested, germination performance was significantly improved by SMP-chilling; theresults were dependent on the type of solid matrix, the matrix water contentandthe treatment duration. SMP-chilling, using the best solid matrices for each ofthe species tested, resulted in germination percentages and rates that were24–35% and 8–21% higher, respectively, as compared with thatyieldedfrom control moist-chilling. High germination percentages (79% or greater) ofthree of the four species (Pacific silver fir, subalpine fir, and grand fir)were promoted after just four weeks (grand fir in sand) or eight weeks oftreatment (Pacific silver fir in peat moss and subalpine fir in Agro-Lig GreensGrade). The germination rate of grand fir seeds benefited from SMP-chillingperiods longer than four weeks, but this resulted in germination during thedormancy-breaking treatment. The water contents of the solid matrices that wereoptimal in terms of eliciting the best germination performance were 320% (w/w)for peat moss, 40% for Agro-Lig Greens Grade and 5–15% for sand.Conducting SMP at chilling temperatures (4 °C) is a practicalapproach to shorten the time required for effective dormancy termination ofAbies seeds; treatment times were shortened by 27 days forPacific silver fir and subalpine fir and more vigorous seedling growth wasexhibited by grand fir and noble fir.     

Effects of storage conditions on dormancy and vigor of Picea abies seeds

The dormancy and vigor of Picea abies seeds were studied after five months of storage at 25 and 75% relative humidity (RH) and 5 and 12 °C. Dormancy was evaluated by studying germination response to light and moist chilling at 12 and 21 °C. Dormancy causing germination reduction in the dark was induced in seeds during storage at 25% RH (5–6% moisture content, MC) in darkness. The dormancy was greater when seeds were germinated at 12 than at 21 °C and after storage at 12 than at 5 °C. The effective dormancy relief by light indicates that germination was under phytochrome control. Moist chilling could partly replace light. According to accelerated aging and leachate conductivity tests, dry seeds could be stored at 12 °C for five months without affecting their vigor. After storage at 75% RH (11% MC) and 5 °C, the seeds germinated slowly and incompletely. The decreased germination response to light indicates that other processes than those mediated directly by phytochrome restricted germination of these seeds. The positive germination response to moist chilling suggested that secondary dormancy was induced in the seeds. However, vigor tests gave some evidence of simultaneous decrease of vigor. Storage at 75% RH and 12 °C decreased germination nearly to 0%. Germination of seeds stored at 75% RH could be stimulated by a short accelerated aging period.     

Loblolly pine seed dormancy: constraints to germination.

Stratification by moist chilling is often used to break seed dormancy in loblolly pine (Pinus taeda L.). The role that moist chilling plays at the cellular level in preparing the embryo for germination and early seedling growth was investigated. Moist chilling did not affect the embryo's ability to mobilize seed storage proteins, which is a biochemical marker of early seedling growth. Analysis of in vivo protein synthesis profiles indicated that moist chilling has only a subtle effect on gene expression in the embryo or germinant. The means by which moist chilling affects interactions between the seed coat and the living tissues of the seed also was studied. Although the seed coat is mainly a mechanical barrier to germination, seed coat replacement studies showed that moist chilling alleviates some factor(s) in the seed coat that significantly inhibit germination.     

Effect of harvest date,drying, short-term storage and freezing after chilling on the germination of rowan seeds

The effects of seed pretreatment and harvest date on the germination of European rowan (Sorbus aucuparia L) seeds were examined. In one experiment, seeds were subjected to drying, storage, soaking, warm and chilling treatments after harvesting in mid- and late August. In another experiment, fully imbibed (FI) seeds were given warm treatment for six weeks and then various durations of chilling (4?±?1°C) for up to 24 weeks. Thereafter, the seeds were adjusted to target moisture content of 35% and 30% or remained in the FI state and were then subjected to either subsequent chilling or freezing (?3°C) for up to 32 weeks. The treated seeds were allowed to germinate at a constant 15°C with 8 hours of lighting per day. Treatment effects were generally consistent for each harvest date. Seeds did not germinate unless they were chilled and germination rates were low unless the seeds were soaked. Warm treatment applied before chilling appeared to induce dormancy. The effect of storage varied with harvest date and storage treatment, with germination being highest for seeds harvested in late August. Mild freezing of ≥16 weeks duration following 16–24 weeks initial chilling resulted in >80% germination, more than could be achieved using chilling alone.     

Variability in cone and seed characteristics and seed testing in various provenances of Himalayan spruce (<Emphasis Type="Italic">Picea smithiana</Emphasis>)

We investigated the effect of provenance variation on cone and seed morphology and germination behaviour under different pre- treatments in Picea smithiana. Three categories of cones were recognized: large (13.18 cm × 3.30 cm 15.42 cm × 4.35 cm), medium (10.85 cm × 3.93 cm 12.18 cm × 3.98 cm) and small (7.69 cm × 3.06 10.98 cm× 3.39 cm). Significant variation was observed for various cone and seed characteristics. Seeds moisture content varied from 44.48% to 56.91%, seed size from 0.64 cm × 0.31 cm (largest seed) to 0.49 cm × 0.10 cm (smallest seed), and the seed weight from 2.45 g per 100 seeds to 1.36 g per 100 seeds on fresh weight basis of P. smithiana. The highest seed germination (72.0±7.53%) at 10°C was observed under chilling treatment in Tapovan provenance, while the minimum (15.0±5.71%) seed germina- tion was recorded at 25°C under control set in Tapovan provenance. Further among all the sources Pandukeshwar consistently had the highest average (38%) percent germination across all treatments. Compared to other temperature regimes and pretreatments, seeds subjected to 10°C and chilling treatment had the highest germination and took the least time for germination irrespective of provenance effects. Altitude (provenance) had little or no relationship with germination following laboratory treat- ments. Seeds from Tapovan provenance subjected at 10°C following chilling treatment may be suggested for further multiplication of this species.     

五味子种子先室内后室外坑内再室内层积催芽方法的研究

将当年自然成熟的五味子鲜浆果洗出的种子,用室温水浸种,72 h后混砂2倍,先室内暖湿层积催芽60-65天,后室外坑内低温湿润层积催芽150天,再室内暖湿层积催芽15天,于5月中旬播种。经检验,种子露白和种子胚根微露的粒数之和占供检种子中优良种子粒数的82.42%-94.44%;播种后40天,床播出苗率为75.4%,盆播出苗率为88.2%。     

冷湿层积法对印度冷杉(Abies pindrow)和长叶云杉(Picea smithiana）种子萌发的影响

研究赤霉素(GA3),冷湿和温度 对五个种源的印度冷杉(Abies pindrow)和长叶云杉(Picea smithiana)种子萌发的影响.种子被浸泡在GA3 (10 mg(L-1)中24小时,然后在3(5(C温度的条件下冷藏15天.设计4个温度(10(C, 15(C, 20(C 和 25(C)条件来促进种子的萌发.结果表明,浸泡和冷湿处理明显增加种子的萌发率.在10 (C时种子的萌发率最高.总体结果表明,种子被浸泡在GA3 (10 mg(L-1)中24小时,冷湿藏15天,可以有效地促进印度冷杉和长叶云杉的种子萌发.统计数据表明,浸泡处理、温度和种源以及与温度的相互作用都对种子的萌发有明显的影响.     

“Target moisture content” prechill overcomes the dormancy of temperate conifer seeds

Temperate conifer seeds are often considered to be shallowly dormant because a dormancy breakage treatment such as incubation of moist seeds at 4°C (prechilling) for 3–6 weeks improves germination. However, longer prechill durations can induce germination during the cold phase. Since the delicate radicles of prematurely germinated seeds are easily damaged and killed during sowing, potential benefits of extended prechilling are unknown.Described here for the first time is a target moisture content (TMC) prechill. In this dormancy breakage method the seeds are chilled at moisture contents high enough for removal of dormancy but low enough to produce surface dry, free flowing seeds that do not germinate during chilling. The method is a simple, effective and practical way to restrict the amount of water available to seeds from the start of a prechill treatment. The TMC prechill was applied to three conifer species, Douglas fir (Pseudotsuga menziesii (Mirbel) Franco), Lodgepole pine (Pinus contorta Douglas), and Sitka spruce (Picea sitchensis (Bongard) Carrière). All three species benefited from the TMC prechill. Extending the prechill period progressively improved germination by widening the range of temperatures over which germination occurred, raising germination capacity at most temperatures and increasing germination rate at all temperatures. The optimum prechill period combining high germination capacity and low mean germination time was 36 weeks for Douglas fir, from 36 to 76 weeks for Lodgepole pine and 36 or 76 weeks for Sitka spruce depending on incubation temperature. None of the seeds of any of the species germinated during the TMC prechill of up to 76 weeks at 4°C.This work is Crown copyright, reproduced by Kluwer Academic Publishers by permission of the Forestry Commission.     

Effect of Seed Maturity and Pretreatment on Dormancy and Germination of Sorbus mougeotii Seeds

The effect of harvest time on seed germination, desiccation tolerance and level of dormancy is not known in Sorbus mougeotii (Soyer-Will. & Godron). Dry weight (DW), moisture content (MC) and leakage conductivity (LC) were tested on seeds from six harvest times. Chilling requirement and germinability were tested on seeds without drying and after drying and rehydration. The effect of postharvest ripening of seeds with or without drying was also tested. The DW was stable during the last 6 weeks of maturation, whereas MC initially decreased but later increased simultaneously with an increase in LC. Seeds were desiccation tolerant, deeply dormant and after a chilling treatment germinated to a high percentage at all harvest times. The chilling requirement decreased significantly with later harvest, suggesting a decrease in level of dormancy. Drying and postharvest ripening reduced and synchronized the chilling requirement.     

Seed storage behavior of <Emphasis Type="Italic">Knema attenuata</Emphasis>, an endemic species of Western Ghats,India

We performed desiccation and storage trials to better under- stand storage behavior of Knema attenuata seeds. Mature seeds with moisture content (MC) of 31% exhibited 73% germination. During the period of desiccation (open lab condition) seeds with MC 23% showed 40% germination. After further drying to MC 21% germination was reduced to 16%. Complete loss in viability resulted when seed moisture was reduced to 18%. The seeds stored at -10°C, 0°C, 10°C and 28±2°C (open lab condition) lost their viability within 10 days. Seeds stored in sealed polythene bags and moist sand retained viability for more days than did seeds stored under all other storage conditions. Sensitivity of seeds to lower temperature and desiccation suggest that the storage be- havior of K. attenuata seeds is recalcitrant. Seeds stored in moist condi- tions can, at best, be stored for a period of two months.     

Breaking seed dormancy in European rowan seeds and its implications for regeneration

The effects of the presence of a medium, seed moisture content, warm and chilling treatments on the germination response of European rowan (Sorbus aucuparia L.) seeds of Irish origin were investigated with the aim of reducing precocious (or premature) germination and maximising germination after pretreatment. After adjusting seed moisture content, seeds of two lots were subjected to warm treatment for 0–6 weeks followed by 0–50 weeks of chilling. The seeds then were allowed to germinate at a constant 15 °C with 8 h lighting per day or 20 (dark)/30 °C (light). Some seeds were treated in the fully imbibed (FI) state in a medium (standard operational treatment). Seed lot effects were evident, but treatment effects were consistent in each lot. Warm treatment greatly increased germination and reduced precocious germination. The presence of a medium was not required to achieve high germination and seed moisture content close to the FI state was needed to maximise germination. Climate change may reduce the ability of this species to regenerate naturally, favouring other species that require less chilling.     

Primary metabolite mobilization and hormonal regulation during seed dormancy release in Cornus japonica var. chinensis

The combination of gibberellin acid (GA) soaking with moist chilling plays a pivotal role in seed dormancy breaking. However, knowledge involving physiological and biochemical mechanisms for such a response is limited. This work focused on the effects of GA₃ and moist chilling on overcoming seed dormancy as well as the response of endogenous hormones and nutrient reserves to dormancy release in Chinese dogwood (Cornus kousa var. chinensis). Seeds subjected to GA₃ soaking and moist chilling exhibited a high germination percentage (average 97%), and the combination of 500 mg·L^?1 GA₃ soaking for 3 days followed with moist chilling for 50 days was more effective than other treatments. For GA₃ treatments, lipids were initially hydrolyzed during the first stage of moist chilling (0–20 days), resulting in the increase of starch and soluble sugars, while proteins were kept relatively stable. During the second stage (20–50 days), contents of lipids, starch, soluble sugars, and proteins decreased by 46%, 82%, 61% and 59%, respectively. Abscisic acid (ABA) contents and ratios of ABA to GA₃ in GA₃ treatments decreased by nearly 70% and over 90%, respectively, when dormancy was terminated. However, endogenous GA₃ contents in all treatments significantly increased with prolonged moist chilling. The present results provide insight into the metabolic mechanism involving hormonal regulation and mobilization of reserves during the release of seed dormancy in Chinese dogwood.     

Target seed moisture content,chilling and priming pretreatments influence germination temperature response in Alnus glutinosa and Betula pubescens

Abstract

The response of common alder [Alnus glutinosa (L.) Gaertn.] and downy birch (Betula pubescens Ehrh.) seeds to germination temperature was examined following chilling and priming. Seeds of two seed lots of each species were subjected to combinations of chilling (4±1°C) and priming (20°C) treatments in fully imbibed (FI) state or a lower target seed moisture content (TMC) level (30% and 35% in alder and birch, respectively). After treatment, the seeds were allowed to germinate for 56 days at constant temperatures of 7.5, 10, 15, 20, 25 or 30°C. The response to temperature and pretreatment differed between species, but the effect was consistent in each seed lot within each species. In alder, the TMC seeds germinated well across the full range of temperatures, whereas there was an optimum temperature (22–23°C) for seeds given the FI pretreatment. Priming had no significant effect on the germination response of the TMC seeds in alder, but priming greatly improved germination in the FI seeds, especially at the lower germination temperatures (optimum 18–19°C). In contrast, in birch, the TMC seeds germinated better across the full temperature range, but the optimal germination temperature (15°C) was the same for all seed pretreatments. Priming improved germination in both the FI and TMC seeds in birch.     

Germination and storage characteristics of Prunus africana seeds

Prunus africana, from the moist highlands of sub-Saharan Africa, is subject to great exploitation because its bark is used in the treatment of prostate-related diseases. A better understanding of the biology of its seed could help the ex situ and in situ conservation of the species. Fifty per cent of fresh seeds (46.8% MC) from mature purple fruits harvested in Kenya germinated after 10 days incubation at 25°C. The germination rate was linearly related to constant temperature, giving a prediction for the minimum temperature for germination at ca. 0.6°C. All seeds germinated at 5°C during 4 months fully hydrated storage. P. africana seed is, thus, neither dormant nor chilling sensitive. The relationship between equilibrium moisture content and relative humidity was used to construct a sorption isotherm, against which seed desiccation and storage responses were assessed. Seventy six per cent of mature seeds survived drying to 4.5% MC (22% RH) compared to 17% of seeds from immature purple-green fruits. Although, 25–45% of mature seeds survived at 8–12% MC after 2 months, only 10% remained viable after 6-month storage at 5°C. This study proposes optimum conditions for the artificial regeneration of P. africana seeds and highlights the need for further experiments storing dry seeds at sub-zero temperatures.     

Seedling growth and establishment in natural stands of yellow-cedar (Chamaecyparis nootkatensis) seedlings derived from the use of modified seed dormancy-breaking treatments

Following dispersal from the parent tree, seeds of yellow-cedar (Chamaecyparis nootkatensis[D. Don] Spach) exhibit low germination, primarily as a result of coat-imposed dormancy. Dormancy of the mature (intact) seed is effectively terminated by traditional warm/cold treatments. A chemical treatment using the anaesthetic 1-propanol combined with a three day warm water soak (30 °C), a two day GA₃ treatment and 60 d of moist chilling not only promotes high germinability of yellow-cedar seeds, but also elicits vigorous post-germinative growth following seedling emergence under nursery greenhouse conditions. Here we compare the effectiveness of the more traditional warm/cold treatments with the chemical treatment in terms of their capacity to elicit vigorous growth and establishment in natural stands following transplant of seedlings from a nursery greenhouse environment. Two seed lots (42313 and 43697) and open-pollinated seed from parent trees 13-6 and 19-8 showed equivalent seedling growth in natural stands following the chemical treatment and two traditional warm/cold treatments typically used for dormancy breakage by the forest industry and by the Ministry of Forests in British Columbia. The chemical protocol offers the advantage of reducing the time required to break seed dormancy. We have now demonstrated that it yields seedlings that exhibit vigorous growth and are capable of withstanding the vagaries of the environment.     

Desiccation and storage behavior of bay laurel (Laurus nobilis L.) seeds

The effect of seed moisture content (m.c.) and seed storage conditions of bay laurel (Laurus nobilis L.) was investigated in relation to seed viability. In the first experiment, the effect of drying rate on seed moisture and seed germination was investigated. Fresh seeds, with their original moisture content displayed a germination percentage of 55.1%. When the seed moisture content was reduced by 2.0% in an oven, the germination percentage rose to 81.0%. When the seed moisture content was reduced even more by using the same method, the germination percentages decreased dramatically. Reducing the seed moisture content to 28.7 and 23.5% by drying the seeds in alternating room conditions resulted in an increase of seed germinability to 84.3 and 90.9%, respectively. The drying of the seeds for 45, 60 and 75 days reduced their seed germination to 66.8, 49.4 and 48.0%, respectively. Reducing seed moisture content below 15.0% resulted in practically nullifying seed germinability. The fact that bay laurel seeds cannot retain their germinability at lower moisture contents demonstrates that it is a species with recalcitrant seeds. In the second experiment, moist and dry storage conditions were tested under different temperatures and moisture contents. The storage experiment showed that the most effective way of conserving the bay laurel seeds is moist storage at 0 ± 1°C for 4 months without previous drying of the seeds.     

赤霉素浸种与低温层积对桂花种子发芽的影响

对桂花种子进行了层积前赤霉素浸种与低温层积相结合的催芽试验。结果表明，桂花种子具有休眠特性，低温层积能够增进桂花种子萌发。层积前用赤霉素浸泡促进桂花种子萌发的作用明显，试验以3000mg／L赤霉素浸泡2天和2000mg／L赤霉素浸泡2天或4天最好，极显著或显著地高于其它处理组合。赤霉素浸泡必须与低温层积相结合，其作用效果才能发挥，试验中以层积60天最好。清水浸泡促进萌发的效果不明显。     

Effect of natural brassinolide on germination of Ailanthus altissima seeds

The germination capacity of Ailanthus altissima seeds improved after the seeds were soaked with different concentrations of natural brassinolide (NBR). The germination rate and germination energy of the seeds increased by 17.6% and 18.8%, and the mean germination speed (i.e., germination time) of the seeds was shortened by 1.4 d under the optimal concentration (0.4 mg.L⁻¹) treatment, compared with the control. After hypocotyls of A. altissima were treated with NBR, the elongation of the hypocotyls increased. Among different concentrations of the NBR, 0.4 mg·L⁻¹ NBR appeared to be the optimal concentration for the elongation of A. altissima hypocotyls.     

Temperature Relations of Germination in Acer platanoides L. Seeds

The aim of this study was to describe the effect of temperature on the germination response of Acer platanoides L. seeds and the possible influence of dormancy. Moist chilled seeds (fruits) from eight trees were germinated at eight constant temperatures from 3 to 32C for 30 days. The highest germination was obtained at temperatures below 10C and the highest rate of germination was between 22 and 28C. The critical lower temperature for germination was estimated to be -2.6C, and the critical upper temperature between 30 and 35C. Temperatures above 10-15C increasingly inhibited the germination of seeds. Some of the non-germinated seeds were able to germinate after a second chilling period, possibly as a consequence of further release of primary dormancy and an indicated secondary dormancy. Seed survival decreased with increasing temperatures above 15C. The rate of germination was correlated with the accumulated thermal time at suboptimal temperatures. In conclusion, a constant temperature of 10C is recommended for testing the germination of seeds of A . platanoides.     

Optimal germination condition by sulfuric acid pretreatment to improve seed germination of Sabina vulgaris Ant.

Understanding the germination traits of plants is important not only for understanding natural regeneration processes but also for developing seedling production techniques for planting. Sabina vulgaris Ant. is a common species used for reforestation in semi-arid areas of the Mu-Us Desert, in Inner Mongolia, China, but its extremely low germination rate, both in situ and in vivo, is a bottleneck for seedling production. Sulfuric acid pretreatment was applied to improve germination, and the germination rate was compared for different soaking time (10, 30, 60, 90, and 120 min), different temperatures (10, 15, 20, 30, and 35°C) and under different lighting conditions (dark and light). Sulfuric acid treatment gave a high germination rate, reaching 60% at 30 days after sowing. However, the non-treated seeds produced no germination. The optimal treatment time in sulfuric acid was 120 min. Germination after sulfuric acid treatment increased at incubation temperatures from 10 to 30°C, but decreased at 35°C. Incubation at 25–30°C gave maximum germination of more than 50%. Light treatment had little effect on germination. Pretreatment with sulfuric acid improved water absorption by the embryo by creating cracks and cavities in the seed coat tissue. These results indicated that S. vulgaris seeds have physical dormancy caused by their hard seed coats, which prevents absorption of water into the embryo. A combination of pretreatment with sulfuric acid and incubation at 25–30°C was most effective in improving the germination of S. vulgaris seeds.