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《林业科学》2017,(4)
【目的】揭示羊角槭的种胚发育与萌发抑制机制,获得破除休眠、提高种子发芽率的有效方法,以提高种群繁育效率,扩大羊角槭种群数量以缓解目前极度濒危的生存现状。【方法】连续3年调查统计浙江天目山自然保护区2株人工种植羊角槭种胚发育结实情况,通过白菜种子发芽试验研究种子不同部位(外种皮、内种皮、种胚)的萌发抑制作用,并通过不同处理(剥除外种皮、激素浸种与低温沙藏)探索打破种子休眠促进萌发的方法。【结果】羊角槭种胚发育不良且存在单株个体间差异,3年平均饱满种胚率仅9.73%~33.98%,饱满种胚平均生活力52.22%,饱满种胚率低于其他槭属植物。羊角槭内、外种皮与种胚均存在萌发抑制物质,外种皮与种胚提取物对于白菜种子的萌发抑制作用更强;内源ABA含量测试发现,种胚ABA含量最高,达1 818.58 ng·g~(-1),其次为外种皮1 053.34 ng·g~(-1)、内种皮859.05 ng·g~(-1),种子内各组织的萌发抑制作用与内源ABA含量直接相关;采用不同处理方法(剥除外种皮、激素浸种与低温沙藏)打破休眠试验发现,未剥除种皮种子低温沙藏及种子剥皮室温沙藏均不能萌发,而剥去外种皮种子经一定时间的低温沙藏可打破胚休眠,使得种子萌发率提高到30%;剥去外种皮种子进行不同激素(GA_3,6-BA)、不同浓度与浸种时间处理,发现激素浸种时间对于羊角槭种子发芽率有极显著影响(P0.01),浸种激素种类或浓度均对羊角槭种子发芽率影响不显著(P0.05);对剥除外种皮种子配合适当浓度的外源激素(GA_3,6-BA)浸种处理再行低温沙藏可提高羊角槭种子发芽率,其中以100 mg·L~(-1)GA_3或200mg·L~(-1)6-BA浸种12 h效果最好,种胚发芽率分别达到46.67%与43.33%,可作为羊角槭打破休眠促进萌发的适合方法推荐应用。【结论】羊角槭种子败育率高、空瘪现象严重,这与花粉供应限制有关,异株授粉作为自交补充有助于授粉成功、胚发育,在构建保护群落时应避免分散、零散的种植,减小个体间距、促进异交结实,以提高种群繁育效率;羊角槭种子同时存在外种皮强迫休眠和胚休眠,内源ABA是种子萌发的主要抑制物质;通过剥除外种皮结合激素浸种、低温沙藏能够提高种子萌发率。该研究对于扩大羊角槭种群规模、实现这一极小种群树种的种群恢复与可持续保育目标具有重要意义。 相似文献
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采用种皮透水性测定、生活力测定、种皮和种胚甲醇提取液测定等方法,对羊角槭基本生物学特征进行了研究。结果表明:羊角槭种子呈压扁状卵圆形,由外种皮、内种皮、种胚和子叶组成,无胚乳;种子千粒质量50.88g,其中种皮占完整种子质量的79.55%以上;种子中空籽和败育种子比例达63.81%,反映出较高的种子败育率;饱满的种子中有生活力者占56.67%;种皮具有一定的透水性,种皮和种胚甲醇提取液对白菜籽发芽有抑制作用,说明羊角槭种子自身含有发芽抑制物可能是导致种子深休眠的主因。 相似文献
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庙台槭为中国特有种,已处于濒危状态.通过小陇山林区庙台槭的调查分析,庙台槭是优良的园林观赏树种;自然生长受人为影响严重;结果树只占0.5%,庙台槭种子较饱满果实只占总数的3%,且果实受剌槐种子小蜂危害严重,未结实个体结实还需10~20年,自然繁殖受到威胁,只有实施人为综合保护措施,才能扩大种群并得到合理应用. 相似文献
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对樟科Lauraceae 3个属的代表性树种的种子休眠与萌发特性进行研究.结果表明:新采集的樟树Cinnamoumcamphora (linn.)Presl、檫树Sassafras Tzumu(Hemsl.)Hemsl和闽楠Phoebe bournei(Hemse.)Yang的种子胚形态发育正常,除檫树种子外,樟树和闽楠种子的离体胚能正常萌发,在黑暗条件下,3个树种的完整种子于15-35℃温度范围内,无论恒温和变温均不能萌发,闽楠种子仅在光照下30、35℃恒温和30℃日/20℃夜变温中较窄的温度范围内能萌发,但发芽迟缓、过程长、萌发率低;3个树种的种子均具生理休眠特性,种皮透气性差和存在发芽抑制物质是樟树种子休眠的原因,低温(5℃)层积80 d,不能完全解除休眠,在30℃日/20℃夜最适变温条件下.并给予适当光照,萌发率仅为41.00%;采用0.5%KNO3+0.10%GA3溶液浸种2 h后低温层积80 d,在光照条件下,萌发率可提高到74.00%;胚存在发芽抑制物质和种皮透气性差是引起檫树种子休眠的最初原因,经低温层积后,种皮防碍抑制物质向外渗透是种子不能完全解除休眠的关键因素,低温层积240 d,在25℃日/15℃夜最适温度下,光暗中的萌发率仅为59.00%-54.00%.而采用4%H2O2+0.10%GA3溶液浸种后低温层积.萌发率可高达87.00%;种皮透气性差,发芽要求特殊的温度和一定的光照是闽楠种子休眠的原因,低温层积60 d,在光照条件下,20、25℃恒温和30℃日/15℃夜变温适宜温度中,萌发率能达77.33%-85.33%. 相似文献
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隔年贮藏檫树种子形态成熟时,果皮虽已呈蓝黑色,但生理上尚未完全成熟。因此,当年采收的种子即使生活力很高,通常都不会前发。到次春,仍然有相当一部分种子不会萌发,一般场圃发芽率只有20~60%左右(表一)。倘若种子处理和贮藏不当,发芽率更低。这表明,檫树种子采收后,在生理上需 相似文献
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《Scandinavian Journal of Forest Research》2012,27(5):427-435
In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(3):206-217
The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage. 相似文献
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Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and
also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the
amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter
bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K
was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed
significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week−1 for leaves and from 0.0225 to 0.0633 week−1 for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed
during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly
between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species
provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient
enrichment capacity and slower decomposition rates which would minimize leaching losses.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(2):118-130
The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions. 相似文献
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Steven Maranz Amadou Niang Antoine Kalinganire Djeneba Konaté Bocary Kaya 《Agroforestry Systems》2008,72(3):231-239
Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional
data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral
contents and B1 and B2 vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising
germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B1 88 mg 100 g−1, B2 187 mg 100 g−1, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal
diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties
to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations. 相似文献
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《Wood material science & engineering》2013,8(2):76-84
Abstract Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1):53-61
This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1):15-27
The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions. 相似文献
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Astra Zaluma Lauma Bruna Darta Klavina Natalija Burnevica Kristine Kenigsvalde Andis Lazdins Talis Gaitnieks 《Forest Pathology》2019,49(6)
Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered. 相似文献
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本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。 相似文献