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1.
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. 相似文献
2.
Loblolly pine (Pinus taeda L.) seeds from sources with a mild climate under maritime influence (North Carolina) required shorter moist chilling to achieve maximum germination vigor than seeds from sources with a harsher continental climate (Oklahoma). Solid matrix priming (SMP) for 6 d achieved as much as 60 d of moist chilling to improve rapidity, synchrony and completeness of germination for three of the four families studied. SMP after moist chilling increased the rapidity, synchrony and completeness of germination. The benefit of SMP was greatest for non-stratified seeds and the benefit decreased with length of moist chilling. In general, delaying planting for one week after SMP had minor effects on germination when seeds were kept in the SMP matrix at 4°C. Delayed planting after SMP can increase germination rapidity and synchrony of seeds that have received long moist chilling and reduce the benefit of SMP in non-moist-chilled seeds. 相似文献
3.
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. 相似文献
4.
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. 相似文献
5.
《Scandinavian Journal of Forest Research》2012,27(1-4):43-49
The effects of red (R), far‐red (FR) and R + FR light on Norway spruce seed dormancy were studied at five different moisture contents (MC) between 5 and 20%. The degree of dormancy was studied by germinating seeds over a wide range of temperatures in the dark. The non‐irradiated control seeds were shallowly dormant, only a proportion of them germinated and within a limited temperature range. Red light progressively stimulated germination between 5 and 17% MC, but this effect was reversed if a FR treatment followed, although all germination could not be inhibited by one FR pulse. Far‐red light had a slightly stimulating effect at 19% MC. To generate seeds able to germinate over a wide range of temperatures in darkness, an artificial light pretreatment should be given to seeds at MC above 17% in order to receive maximum response. 相似文献
6.
《Scandinavian Journal of Forest Research》2012,27(6):479-486
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. 相似文献
7.
Demel Teketay 《New Forests》1996,11(2):155-171
The germination requirements of five Senna species: S. bicapsularis, S. didymobotrya, S. multiglandulosa, S. occidentalis and S. septemtrionalis have been investigated. Seeds possess dormancy which is caused by their hard seed coats hampering maximum, uniform and rapid germination. To overcome this dormancy, seeds of the five species were pre-treated with (a) mechanical scarification, (b) concentrated sulphuric acid for 15, 30, 45 and 60 minutes and (c) boiling water for 15, 30, 45 and 60 seconds. To determine the effects of temperature on the germination of seeds, pre-treated seeds from each species were incubated at 10, 15, 20, 25 and 30°C. Germination was also tested in the dark. Both acid treatment and mechanical scarification resulted in fast and uniform germination. The highest germination (95–100%) for all species was obtained from seeds treated with sulphuric acid for 60 minutes. Mechanical scarification resulted in 100% germination in all the species except S. septemtrionalis (59%). Boiling water improved germination significantly in S. didymobotrya (98%), S. occidentalis (82%) and S. septemtrionalis (97%), but had very little effect on S. multiglandulosa and reduced germination in S. bicapsularis. Senna seeds germinated over a wide range of temperatures with the optimum temperatures for germination falling around 20–25°C. Germination was either completely inhibited or very low at 10°C. Seeds of all species germinated both in light and dark conditions. 相似文献
8.
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. 相似文献
9.
利用木棉 Bombax ceiba 和美丽异木棉Chorisia speciosa混合种子,在0、4、和8℃条件下贮藏135d,每隔45 d测定一次种子场圃发芽率和活力指标,用2,3,5-三苯基氯化四氮唑法(TTC法)测定种子的初始和贮藏135 d的生活力。结果如下:木棉种子在相同贮藏温度条件下,随贮藏时间的延长,发芽率、发芽势、活力指数存在显著差异(P<0.05),贮藏温度和贮藏时间有极显著的交互作用,种子活力逐渐下降,贮藏135 d后种子发芽率在8.33%以下,基本失去发芽能力;美丽异木棉种子在不同温度下,随着贮藏时间延长,发芽率、发芽势、活力指数没有显著差异,贮藏温度和贮藏时间没有显著的交互作用,种子发芽率为新鲜种子发芽率的67.46%以上;利用TTC染色法(1.0%浓度)能反映出木棉的种子生活力;木棉种子0℃贮藏90 d发芽率好于4和8℃,可在生产中推广应用TTC染色法检测木棉的种子生活力;美丽异木棉种子0、4、8℃贮藏135 d的发芽率差异很小,0℃贮藏发芽率和活力指数较优。 相似文献
10.
Haruto Nomiya 《Journal of Forest Research》2010,15(2):123-130
Germination traits of three Japanese Ulmus species, including two summer-fruiting species, U. davidiana var. japonica (UD) and U. laciniata (UL), and an autumn-fruiting species, U. parvifolia (UP), were investigated. Germination tests that controlled light (16 h dark–8 h light/24 h dark) and temperature (alternating
20–30°C/constant 23°C) conditions were conducted just after seed dissemination. Under the preferred (light and alternating
temperature) conditions, UD germinated quickly and percentage germination was high (99%), whereas UL and UP germinated moderately
to slowly (65.2 and 23.8%, respectively) and the remaining seeds were primarily dormant. When the seeds were exposed to unsuitable
conditions for germination, secondary dormancy was induced in all three Ulmus species. Because primary and secondary dormancy of these species was not strict, the existing dormancy could be released
by moist conditions and low temperature during the winter. Thus, all three Japanese Ulmus can germinate either just after seed dissemination or in the following spring. Nevertheless, the predominant germination
of summer-fruiting UD just after seed dissemination seems to be advantageous for finding safe sites that might become available
after a large-scale fluvial disturbance. Similarly, the delayed germination of autumn-fruiting UP until the following spring
seems to be advantageous for preventing germination at the end of the growing season. Summer-fruiting UL had a more negative
response to favorable light conditions just after seed dissemination, which seems to be advantageous for establishment in
canopy gaps. These germination traits seem to be adaptive responses to the dominant disturbance regimes of their natural habitats. 相似文献
11.
《Scandinavian Journal of Forest Research》2012,27(5):404-414
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. 相似文献
12.
We investigated seed dormancy and germination in Ficus lundellii Standl. (Moraceae), a native species of Mexico's Los Tuxtlas tropical rain forest. In an 8-h photoperiod at an alternating diurnal (16/8 h) temperature of 20/30 degrees C, germination was essentially complete (96%) within 28 days, whereas in darkness, all seeds remained dormant. Neither potassium nitrate (0.05-0.2%) applied continuously nor gibberellic acid applied either continuously (10-200 ppm) or as a 24 hour pretreatment (2000 ppm) induced germination in the dark. Germination in the light was not reduced by a 24-h hydrochloric acid (0.1-1%) pretreatment, but it was reduced both by a 24-h pretreatment with either H(2)O(2) (0.1-5 M) or 5% HCl, or by more than 5 days of storage at 40 degrees C (4.5% seed water content). In a study with a 2-dimensional temperature gradient plate, seeds germinated fully and rapidly in the light at a constant temperature of 30 degrees C, and fully but less rapidly in the light at alternating temperatures with low amplitudes (< 12 degrees C) about the optimal constant temperature. The base, optimal and ceiling temperatures for rate of germination were estimated as 13.8, 30.1 and 41.1 degrees C, respectively. In all temperature regimes, light was essential for the germination of F. lundellii seeds. 相似文献
13.
Effect of solid matrix priming during moist chilling on dormancy breakage and germination of seeds of four fir species 总被引：1，自引：0，他引：1
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. 相似文献
14.
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. 相似文献
15.
Gary A. Ritchie 《New Forests》1986,1(1):29-42
An experiment was conducted to ascertain what relationships might exist among dormancy status, cold hardiness and stress resistance in 2+0 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), seedlings. Seedlings were lifted from a western Washington nursery on six dates spanning the 1980–81 lifting season. On each date samples of seedlings were subjected to the following treatment: (1) tumbling for 5 minutes, (2) desiccation of roots for 30 minutes at 30°C and 2.1 kPa vapor pressure deficit, (3) exposure of shoots to temperatures of –10°C, –15°C or –20°C for two hours and (4) unstressed control. On two lift dates sub-samples of seedlings were placed into –1°C storage and held for two months before the above stress treatments were administered. Bud dormancy status was determined, using a bud break test, on seedlings from each lift date before and after storage.After one growing season in the field percent survival, vigor, height growth and shoot and root weight were determined on stressed and unstressed seedlings. Survival and vigor were less affected by the stress treatments than were height and weight. Severity of stress was in the order –20°C > –15°C > desiccation > handling > –10°C. Degree of cold injury was directly related to seedling dormancy status whether dormancy status had been attained in the nursery from natural chilling or in frozen storage. Seedlings in a mid-range of dormancy release (between deep rest and quiescence) were most resistant to all imposed stresses. 相似文献
16.
Loblolly pine seed dormancy: constraints to germination. 总被引：1，自引：0，他引：1
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. 相似文献
17.
Two- to four-week stratification of red alder seeds slightly increased the speed of germination but did not improve total germination under alternating warm temperatures (30°C/20°C), yet significantly improved speed and total germination under cool temperatures (15°C/5°C) that simulated early spring outdoor nursery bed conditions. Only seeds that received four-week stratification achieved complete germination at the cooler temperatures. Strong seed source variation in response to seed treatments was observed at the cool regime. The Yacolt source germinated well regardless of seed treatments, even without stratification, while five other sources needed two to four weeks of stratification to achieve above 50% germination. Possible reasons for this variation are discussed. 相似文献
18.
Collection and care of sweetgum seed 总被引：2，自引：0，他引：2
F. T. Bonner 《New Forests》1987,1(3):207-214
Sweetgum (Liquidambar styraciflua L.), a widely distributed hardwood in the United States and Central America, shows potential for tropical forestry application. Fruit heads change from bright green to yellow in color as they mature, and they can be picked from standing trees or logging slash when the color change occurs. Fruits release their seeds after only moderate drying, and cleaning is easy with air-screen cleaners. Sweetgum seeds are orthodox in storage behavior, and they should be stored at moisture contents of 5 to 10% at 0° to 5° (5 years or less) or –18° (more than 5 years). The seeds exhibit a shallow dormancy that can be overcome with 2 to 4 weeks of stratification at 3°C. 相似文献
19.
Schelin Maria Tigabu Mulualem Eriksson Ingalill Sawadogo Louis Christer Odén Per 《New Forests》2004,27(3):251-267
Predispersal seed predation among individual Acacia macrostachya trees over two sites in Burkina Faso was assessed. In addition, the effects of seed predation on seed viability; germination responses to scarification (mechanical, hot water at 60, 70 and 80°C, and sulphuric acid for 10, 20 and 30 min) and dry heat (at 60, 70 and 80°C for 15, 30 and 60 min each) treatments were investigated under laboratory conditions. The results indicated a large difference in predation intensity among individual trees, as well as between sites. Predispersal predation significantly decreased seed germination, particularly when the number of insect larvae per seed increased. Scarified and unscarified seeds germinated equally well, except for hot water treatments of high temperature. This indicates lack of physical dormancy and dispersed seeds can readily germinate provided that conditions for germination are conducive. Seeds exposed to dry heat treatments also germinated close to 97% under low intensity and short exposure times. This suggests that fire, under natural condition, plays a key role in triggering germination of A. macrostachya seeds. 相似文献
20.
We characterized the effects of KNO3 pretreatment and germination temperature on dormancy breaking and germination of mature mountain ash seeds. Seeds treated with KNO3 and germinated at 25 ℃ followed by 5 ℃ had significantly higher germination percentages and germination potentials (51% and 49%, respectively), compared with controls. These treated seeds also exhibited reduced germination initiation times (minimum of 48 days), and elevated germination rate indices (up to 97). The germination of seeds subjected to long-term cold storage (2 years at 0-5 ℃) was also significantly improved by 3 days of 4% KNO3 pretreatment before germinating under a variable temperature regimen (5 ℃ followed by 25 ℃, and followed by 5 ℃). Germination percentages and germination potentials for these cold-stored seeds reached 67% and 54%, respectively, and the germination rate index increased to 126.99. Pretreatment of mountain ash seeds with KNO3 represents a practical, effective, and pollution-free method for improving germination, and can be implemented easily within a variety of nursery settings. 相似文献