5种竹子花粉萌发率及开花特性

竹类植物属禾本科竹亚科,由于其开花周期长,常常是几十年甚至在百年以上,因此竹类植物开花十分少见(周芳纯,1998),且开花后多数死亡,使得有关竹子开花结实、花粉萌发及贮藏等方面的研究进展迟缓.目前对竹子开花现象已有报导(张文燕等,1992;程有龙等,1995;杜凡等,2000;赖广辉,2001;何其江,2003),但有关竹类花粉形态观察和萌发等方面的研究仍很少,前人仅对13个竹种的花粉萌发做过研究(张文燕等,1989).     

刚竹属3个竹种的开花生物学特性

通过对刚竹属3个竹种粉绿竹、黄条早竹、黄槽石绿竹的开花生物学特性及其花粉活力观察及比较,结果表明:在扫描电镜下各竹种间花粉形态比较一致,为球形或近球形,单极孔;外壁纹饰为细颗粒状.花粉活力的测定说明存在不同类型的花粉败育现象.竹子花粉的萌发试验说明竹花粉萌发率普遍较低,最高萌发率为58.7%,最低为21.7%.这些结果也为研究各竹种的不结实和实行人工授粉等研究提供基本的参考依据.     

竹类植物根部解剖的初步观察

我国竹类植物分布广泛,种类繁多。黄河流域以南都有天然分布。全国有500多种竹子,它们分属于大约40个属。竹类植物一些种类的鉴别,部分属及属以上某些价层的划分还没有得到完善,合理地解决。我们通过对国产在竹类植物的系统和分类上具有一定代表性的34种40余份竹子标本(分属于19属)的根部解剖观察,得出初步结论:根据竹类植物根部解剖特征可将竹类植物划分为两大类群,即散生竹类和丛生竹类。这两大类群的根解剖性质上又与目前按竹子花序划分的两大类群(箣竹超族和北美箭竹超族)密切相关,它从另一个侧面说明按花序建立的竹类植物的系统可能是符合自然规律的。但是,某些属(如(竹思)(竹劳)竹属、悬竹属等)根的解剖式样与其它属有明显的差异,这说明竹子的形态、结构等等方面具有更多的复杂性和多样性。某些竹种在根的解剖上有着具体而微的特征,因此,竹子根部解剖性质可作为鉴别某些竹类和划分许多竹属的依据,同时也可作为建立竹子自然系统的参考。     

试论竹类植物营养体分类

因为竹类植物不易开花,且无花种甚多,故加强营养体分类的研究,显得十分重要。竹类本身的营养体与生殖体是统一的。由于各器官进化的不平衡性,以导致同一生物体内某些器官已相当进化,但某些器官仍然比较原始,这种现象不仅表现在营养体的外部形态,也表现在内部解剖形态上,形成生物体的复杂性与多样性,这就为分类与鉴别工作带来一定困难,但也存在有利条件。以营养体外部形态鉴别竹属,有些属是可以鉴别的,但有些属却很难,如果综合利用解剖形态、习性与外部形态特征,将是有利得多。本文探讨了竹子营养体分类的依据,并根据这些依据编制了一个新的营养体分属检索表,以供各地试用,并有待以后补充修正关键词竹类;营养体特征;分属检索表     

竹类植物花粉的生活力和自然授粉

对12种开花竹类植物花粉的败育、生活力和自然授粉进行了观察和试验研究，花药和花粉在离体后生活力保存时间较短，尤其是离体花粉的生活力在1－2h会丧失贻尽，适宜竹花粉萌发的培养液的10％蔗糖液，若再加入5ppm硼酸能明显提高花粉发芽率。篌竹和斑苦 花分别属于花药合并粘连和无花粉的二类雄性不育型，其余10个竹种的花粉中均有三种类型的败育花粉，低温、干旱等不育环境使竹花粉发育受阻，不育花粉率增高，竹花的自然授粉不良，在盛花的竹株上接受不到花粉的竹花占33．3％，在部分开花的竹株上花粉自然授粉率公10％。     

国产16种竹叶的比较解剖研究

前言竹类植物开花结实不常见,营养器官的形态变幅又大,给竹子分类带来很多困难。近年来,不少学者试以新的科学手段与方法来探索竹子分类的新途径,例如在我国陈守良先生等应用电子计算机进行数量分类,对我国散生竹类的数量分类和确定分类等级进行了探讨;温太辉先生等根据竹秆的维管束类型进行了竹子分类的尝试;有的学者对竹子的染色体数目与其组型进行研究;还有的学者则正在进行化学分类的研究等。总之,大家都想用新的方法,来弥补单纯形态分类所存在的不足之处,使竹子分类逐步臻于完善。对于竹叶内部结构的观察,过去尚未有人作过系统的比较解剖,最近,陈守良先生等对竹叶表皮细胞的显微构造进行了较系统的观察,为竹子分类     

适时间伐是防止竹子开花的有效途径

竹子是大熊猫的主要食料,上世纪八十年代初,竹子的大面积开花,给大熊猫的生存带来了严重危机。开花是植物生活史上正常的生命现象,竹子(竹类)属于多年生一次性开花植物,一旦开花就意味着地上部分死亡。从保护大熊猫角度出发,人们对竹子开花给予了更多的研究和关注。     

竹类植物开花生理研究现状

竹类植物是重要的经济作物,也是大熊猫的主要食物。竹类植物开花周期普遍较长,开花后营养生长衰退,甚至大规模死亡。开展其开花研究可以进一步完善竹类植物开花理论,对于大熊猫保护工作也具有特别重要的意义。针对包括竹类在内的植物开花前后在植物遗传物质分子水平(miR156含量和DNA甲基化状况);植物内源激素水平(赤霉素等);植物营养状况(可溶性糖、叶绿素和氮含量等);以及形态结构等方面变化和规律的研究,可为揭示竹类植物的开花机制提供参考依据。     

竹子有性生殖及其多样性

主要从我国竹子开花现象、开花竹株形态、花期、花器构造、结实、竹子实生苗等方面对竹子有性生殖的多样性进行了评述,并探讨竹类资源有性生殖多样性利用存在的问题及对策,为我国竹类资源多样性开发利用提供依据。     

竹子有性生殖及其多样性

主要从我国竹子开花现象、开花竹株形态、花期、花器构造、结实、竹子实生苗等方面对竹子有性生殖的多样性进行了评述,并探讨竹类资源有性生殖多样性利用存在的问题及对策,为我国竹类资源多样性开发利用提供依据。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

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.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

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.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

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.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

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.     

CAD与建筑设计的关系

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。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.