6个油茶物种的光合特性

为了更好地对油茶种质资源加以利用,于10月份使用Li6400便携式光合作用测定系统对定植于广西南宁的普通油茶、香花油茶、博白大果油茶、广宁红花油茶、日本红山茶和南荣油茶共6个油茶物种的光合特性进行了研究。结果表明,不同物种光合特性存在较大差异。其中,普通油茶光合效率最高,日平均净光合速率达到7.24μmol.m-2s-1,日平均净光合速率最小的宛田红花油茶光合速率仅为普通油茶的51.52%,日平均净光合速率由大到小依次为普通油茶、香花油茶、博白大果油茶、广宁红花油茶、日本红山茶、宛田红花油茶。在模拟光辐射条件下,6个油茶物种最大净光合速率在8.4～10.5μmol.m-2s-1之间,普通油茶最高,宛田红花油茶最低;普通油茶的光补偿点仅为15.50μmol.m-2s-1,利用弱光的能力最强;香花油茶的光饱和点为499.7μmol.m-2s-1,利用强光的能力最强。     

2个油茶品种及6个近缘种的光合特性日变化规律

为了筛选油茶近缘种高光效种质资源,从而为培育油茶新品种提供优质材料,以2个普通油茶品种(‘湘林1’与‘湘林97’)和6个近缘种(博白大果油茶、越南油茶、浙江红山茶、溆浦大红山茶、攸县油茶、滇山茶)为试验材料,对其叶片的净光合速率、蒸腾速率、胞间CO2浓度、气孔导度、水分利用效率等光合参数进行了测定和分析。观测结果表明:滇山茶、攸县油茶、越南油茶、博白大果油茶和‘湘林1’与‘湘林97’叶片的净光合速率均呈“单峰”曲线的变化趋势,其气孔导度和蒸腾速率亦均呈“单峰”曲线的变化趋势,而其胞间CO2浓度却呈“V”型曲线的变化趋势;浙江红山茶和溆浦大红山茶的净光合速率均呈“双峰”曲线的变化趋势,其气孔导度呈“平稳”型曲线的变化趋势,胞间CO2浓度呈“W”型曲线的变化趋势,蒸腾速率呈“单峰”曲线的变化趋势,说明其均存在光合“午休现象”。相关性分析结果表明:净光合速率与气孔导度呈极显著正相关(P<0.01),与水分利用效率呈显著正相关(P<0.05);气孔导度与水分利用效率呈极显著正相关(P<0.01)。主成分分析结果表明:从5个光合参数中提取了特征根>1的主成分2个,其累计贡献率为83.545%;主成分1(F1)中净光合速率、气孔导度和水分利用效率的累计正向贡献率最多,主成分(F2)中蒸腾速率的累计正向贡献率最多;根据综合评价结果可知,2个普通油茶品种及6个近缘种的光合效率由高到低依次为:油茶‘湘林1’>滇山茶>油茶‘湘林97’>攸县油茶>博白大果油茶>越南油茶>溆浦大红山茶>浙江红山茶。     

油茶无性系果实成熟期光合特性的研究

为了从光合生理方面了解油茶新品种的产量性状,以油茶无性系高产品种、中产品种和普通品种为试材,采用LI-6400P便携式光合测定系统,在果实成熟期对其净光合速率(Pn)、蒸腾速率(Tr)等日变化参数及光合-光响应曲线进行了测定与比较分析。结果表明:其净光合速率日变化曲线均呈宽大的单峰型,不存在光合午休现象,3个品种类型的净光合速率均存在着显著的差异;3个品种类型上、下部叶片的蒸腾速率的日变化曲线均为单峰型,水分利用效率的日变化曲线均为"U"型;3个品种类型的最大净光合速率在11.574~14.04μmol.m-2s-1之间,光饱和点在369~500μmol.m-2s-1之间,光补偿点在19~23μmol.m-2s-1之间;逐步回归分析结果表明,影响高产品种叶片Pn的主导因子为气孔导度,光合有效辐射和参比室的CO2浓度是影响中产品种的主导因子,普通品种主要受胞间CO2浓度的影响。     

油茶主栽品种光合特性的比较

为筛选高光效的油茶主栽品种,从而为油茶品种评价和引种栽培提供理论依据。利用Li-6400xt便携式光合仪对15个油茶主栽品种的光合日变化、光响应曲线、CO_2响应曲线进行测定比较。结果表明:(1)油茶品种间日变化净光合速率均值、光响应净光合速率均值、最大净光合速率、暗呼吸速率、表观量子效率、光补偿点、光呼吸速率、羧化效率、CO_2补偿点存在差异;(2)相关性分析表明最大净光合速率与表观量子效率呈显著正相关;暗呼吸效率与表观量子效率呈显著正相关、与光补偿点呈极显著正相关。光呼吸速率与羧化效率呈极显著正相关。羧化效率与CO_2补偿点呈显著负相关。所以,在15个油茶主栽品种中,‘华鑫’‘华金’‘赣兴48号’‘湘林210号’‘长林4号’5个品种光合效率较高。     

太空诱变油茶M1代光合特性的研究

为了探明太空诱变油茶M1代的光合生理特性,笔者对油茶苗苗高、地径等生长发育指标及净光合速率、蒸腾速率、气孔导度、胞间CO2浓度、水分利用率等光合日变化参数进行测定和对比分析。结果表明太空诱变油茶M1代的苗高和地径都得到提高,且地径增长达到显著水平;太空诱变油茶M1代的净光合速率日变化为双峰型,在上午11：00时达到首峰,为10.83 mol/m2·s,下午13：00时出现次峰,为6.40 mol/m2·s;胞间CO2浓度变化趋势与净光合速率变化趋势刚好完全相反;蒸腾速率日变化与气孔导度日变化均为单峰型,且趋势完全一致;水分利用率变化趋势与蒸腾速率变化趋势相反。     

不同油茶无性系苗期光合特性比较

为了油茶(Camellia oleifera)的科学引种和稳产高产,对油茶的5个无性系幼苗的光合特性进行了比较研究。结果表明,油茶5个无性系的净光合速率日变化均呈"双峰"曲线,有明显的光合"午休"现象,为非气孔限制型。蒸腾速率(Tr)、水分利用效率(WUE)和净光合速率(Pn)的变化规律趋于一致,胞间CO2浓度(Ci)与Pn负相关。用直角双曲线修正模型进行光响应拟合,其拟合程度较高,油茶5个无性系的最大净光合速率在3.8~7.2μmol/(m~2·s)之间,光补偿点(LCP)在7.57~11.56μmol/(m~2·s)之间光饱和点(LSP)在752.55~833.33μmol/(m~2·s)之间。不同油茶无性系的光合能力对环境条件有不同的适应性,湘林97号的光合能力最强,湘林1号和湘林7号其次,湘林81号和湘林82号最弱。     

两个金银花品种光合作用日变化的比较

为了了解‘济草堂1号’和‘九丰1号’金银花光合作用日变化的差异,采用Li-6400便携式光合作用测定仪对10月和11月2个品种的光合特性日变化进行观测。结果表明:‘济草堂1号’的净光合速率均值为7.84μmol·m-2s-1,大于‘九丰1号’(7.66μmol·m-2s-1)。2个品种金银花的气孔导度、胞间CO2浓度、蒸腾速率、气孔限制值和水分利用率均存在一定差异,其中‘济草堂1号’金银花平均的气孔导度为0.22mol·m-2s-1、胞间CO2浓度为282.915μmol·mmol-1、蒸腾速率为3.42mmol·m-2s-1、气孔限制值为0.295%、水分利用率为2.265μmol·mmol-1,‘九丰1号’金银花平均的气孔导度为0.205mmol·m-2s-1、胞间CO2浓度为275.685μmol·mmol-1、蒸腾速率为3.53mmol·m-2s-1、气孔限制值为0.315%、水分利用率为2.165μmol·mmol-1。2个品种金银花净光合效率日变化均为双峰,其它光合特征参数日变化与之呈相对应的规律。     

不同产量类型油茶无性系光合特性的研究Ⅳ—花期

以油茶无性系高产品种、中产品种和普通品种3种类型为试材,采用LI-6400P便携式光合测定系统在花期对其净光合速率(rnpr)、蒸腾速率(rtr)等日变化及光合-光响应曲线进行了比较研究。结果表明:其净光合速率日变化曲线存在单峰和双峰两种类型,双峰曲线存在光合午休现象,光合午休是造成普通品种产量低的原因之一;3个品种上、下部叶片的蒸腾速率的日变化曲线均为单峰型,水分利用效率的日变化曲线均为"一降不起"的单峰曲线;3个品种的最大净光合速率10.561～14.716μmol.m-2.s-1之间,光饱和点在705～754μmol.m-2.s-1之间,光补偿点在45～60μmol.m-2.s-1之间;逐步回归分析表明:影响高产品种叶片rnpr的主导因子为光合有效辐射和叶面相对湿度;气孔导度、胞间CO2浓度是影响中产品种的主导因子,普通品种主要受光合有效辐射的影响。     

油茶果实生长期光合特性与经济性状关联分析

为了选筛选出不同光效水平的油茶种质,利用LI-6400便携式光合仪对6个进入盛果期的油茶品种的光合日变化、光响应曲线和CO2响应曲线进行了研究,同时检测了叶片中叶绿素含量和成熟后种籽与果实含油率等经济性状,分析了油茶果实生长期光合特性与经济性状的相关性。结果表明,不同油茶品种间各光合特性参数、叶绿素含量和经济性状指标等均存在差异,‘国油13’和‘湘林210’由于具有较好的光能和CO2利用率、较高的叶绿素含量和含油率等,以及较低的暗呼吸速率,表现出较高的光合效率。最大净光合速率、表观量子效率、羧化效率、光呼吸速率和CO2饱和点与含油率等经济性状呈显著正相关,暗呼吸速率、光补偿点和光饱和点与含油率等经济性状呈显著负相关。     

甘草叶片光合生理特征分析

通过对乾安地区人工栽培的甘草其叶片光合作用日变化曲线变化情况的测算研究,表明甘草叶片净光合速率日变化曲线呈单峰型,日间最大值出现在正午前后,平均净光合速率10.46±0.25μmol·m-2s-1左右;计算得知,甘草叶片光补偿点(LCP)=722.61μmol·m-2s-1,光饱和点(LSP)=53.22μmol·m-2s-1,光合速率最大值(Pmax)=20.7516μmol·m-2s-1,表观量子效率(Q)=0.031。     

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.