檫木花粉活力和柱头可授性研究

通过野外观察檫木Sassafras tzumu（Hemsl.）Hemsl的开花过程,用联苯胺—过氧化氢法测定其柱头可授性,TTC的方法测定檫木花粉活力。结果表明：柱头具可授性时间为8 d,檫木的花粉活力持续时间为32 h。根据测定时间发现柱头可授期和花粉活力较强期重叠较长,通过后期观察到檫木有结实,说明檫木具有正常的传粉机制和结实能力。     

桂花品种切花瓶插衰老生理研究

研究了不同桂花品种切花在开花和衰老过程中花朵的保护酶活性、丙二醛(MDA)、细胞质膜透性及可溶性蛋白质等的变化规律.结果表明:3个桂花品种花朵的可溶性蛋白质的含量均呈下降趋势,细胞质膜透性和丙二醛含量随花朵的衰老而增大;超氧化物歧化酶(SOD)活性前期上升后期下降,呈现出明显的峰值;过氧化物酶(POD)表现为上升趋势.综合比较各项指标测定结果,3个品种的瓶插寿命长短为:'晚籽银'桂＞'多芽金'桂＞'四季桂'.保鲜液对延长桂花花期有一定的效果.     

10个萱草品种花粉生活力及柱头可授性比较

为提高不同萱草品种杂交育种的成功率,确定不同萱草品种的最佳人工授粉时间,该研究选取10个萱草品种作为试验材料,采用TTC染色法测定其花粉生活力,联苯胺—过氧化氢法检测其柱头可授性,探究不同品种萱草之间以及不同取样时间对花粉生活力和柱头可授性的影响。试验结果显示：10个萱草品种间花粉生活力有很大差异,按照花粉生活力由强到弱依次排序为：‘牙买加使我疯狂’>‘粉肉’>‘群星’>‘静脉’>‘紫色黄心’>‘芭芭拉’>‘愤怒的眼睛’>‘贝拉’>‘粉美人’>‘布奇’;不同取样时间花粉生活力不同,绝大部分萱草品种在上午6:30～10:30花粉活力较高;另外,不同采样时间对柱头可授性的强弱影响不大,10个萱草品种在取样时间范围内都具有可授性,但一般表现为8:30～9:30和15:30～16:30各品种柱头的可授性强,早上6:30最弱。     

9个木槿品种花粉活力及柱头可授性比较

为研究不同木槿品种的花粉生活力及柱头可授性强弱,以9个木槿品种为试验材料,采用TTC染色法、I_2-KI染色法及联苯胺-甲萘酚染色法3种染色方法测木槿新鲜花粉的活力,并用联苯胺-甲萘酚染色法测定不同贮藏条件下木槿各品种的花粉生活力;用联苯胺-过氧化氢法测定木槿各品种的柱头可授性。结果表明:TTC染色法不适用于检测木槿花粉活力,I_2-KI染色法及联苯胺-甲萘酚染色法适用于检测木槿花粉活力。2种染色法测得的‘白边红心’的生活力都最高,I_2-KI染色法的生活力为53.48%,联苯胺-甲萘酚染色法的生活力为90.09%。‘牡丹木槿’的生活力最低,I_2-KI染色法的生活力为4.38%,联苯胺-甲萘酚染色法的生活力为42.96%。不同品种在3种贮藏温度下花粉生活力变化趋势相同,4℃条件下有利于延长花粉的贮藏时间。‘牡丹木槿’的柱头可授性最弱。     

地被香石竹花粉形态和生物学特性

运用TTC检测法、联苯胺-过氧化氢法、电镜扫描等方法,对地被香石竹‘春之歌’的花粉形态、花粉活力、花粉萌发、柱头可授性进行观察测定.结果表明:花粉外形为近圆球形,直径约为32 ～ 45 μm,具10多个萌发孔,外壁纹饰为颗粒状.散粉期的花粉生活力为49.5％,离体萌发率可达28.7％,花粉管不完全是单一萌发,柱头在绒毛1/3 ～ 3/4时可授性最强.为利用该品种进行香石竹杂交育种提供参考.     

常绿杜鹃品种‘XXL’的花粉活力及柱头可授性观察

以常绿杜鹃品种‘XXL’为研究材料,采用花粉离体培养法和联苯胺-过氧化氢法测定其开花过程中的花粉活力及柱头可授性,并对其柱头表面分泌粘液情况与其柱头可授性之间的关系进行研究。结果表明,在开花当天,常绿杜鹃品种‘XXL’的花粉活力较低(68.42±7.06%),柱头无粘液,柱头无可授性;在开花后2天,花粉活力达到最高值(80.75±9.44%);在开花后3-4天,花粉活力开始减弱,柱头仍无粘液,但柱头开始有可授性;在开花后5-7天,柱头开始分泌粘液,柱头可授性逐渐增强;在开花后8-11天,柱头分泌粘液量增多,期间的柱头可授性最强;在开花后12天,花瓣萎蔫,花粉活力降至最低(48.72±14.53%),可授性仍然很强。实验结果表明,常绿杜鹃品种‘XXL’适宜作为父本、母本开展杂交育种工作,其开花后2-6天为最佳采粉期,开花后8-12天为最佳授粉期。     

北川驴蹄草(Caltha dysosmoides)花部特征研究

北川驴蹄草(Caltha dysosmoides Tao Zhang et al)是2016年新命名的物种(四川特有),为保护利用这一新种,急需研究其生殖生物学特征。本研究于不同种群中选取50株进行标记,观察其花部特征,测试花粉活力以及柱头可授性。采用TTC法测定花粉活力;采用液体培养基对北川驴蹄草花粉进行离体培养;采用联苯胺-过氧化氢法测定柱头可授性(直到无活力为止)。实验结果表明:在自然条件下,北川驴蹄草4月~5月开花,单花花期一般为2 d。雄蕊短于雌蕊,花药紧贴花柱外侧,花药与柱头相距约3 mm,在整个花朵开放的过程中雌蕊和雄蕊的相对位置不变;花粉活力早上明显低于下午,且于花后1 h~4 h内增长较快,4h之后花粉活力增长较慢;柱头具有可授性,于花后3 h时柱头可授性相对较强。     

鸢尾属7个品种花粉活力及柱头可授性研究

为探索鸢尾属不同品种的花粉活力及柱头可授性的变化规律,从而提高其杂交效率,以鸢尾属7个品种为试验材料,对其开花过程中不同时间的花粉活力和柱头可授性进行观测,并对其结果进行UPGMA聚类分析。结果表明,7个鸢尾品种花粉活力最高期与柱头可授性最高期在时间上不吻合。‘贵格少女’开花后2h花粉即散尽,6-8h柱头可授性保持最高;蓝蝴蝶、黄菖蒲、马蔺、‘音箱’、‘紫褐’和‘平瓣粉’分别于花后2h、2h、4h、6h、6h、6h花粉活力达到最大值,4-24h、4-26h、4-24h、6-8h、6h、6-8h柱头可授性保持最高。在欧式距离D2=2.68处,7个鸢尾品种可分为两大类,第一类包括4个品种,按相似度依次为‘音箱’、‘平瓣粉’、‘贵格少女’和‘紫褐’。第二类包括3个品种,按相似度依次为黄菖蒲、马蔺、蓝蝴蝶。     

笔竹(Pseudosasa viridula)花粉活力及柱头可授性研究

通过研究不同条件下笔竹的花粉活力以及柱头可授性,为笔竹的有性繁育及杂交育种工作提供理论参考依据,并为竹类植物生殖生物学积累相关资料。采用I_2-KI染色法、花粉离体培养基法测定笔竹花粉活力变化;采用联苯胺-过氧化氢法对不同开花阶段的柱头可授性进行测定。结果显示:笔竹新鲜花粉活性最强;1 d中笔竹花粉活性在3∶00 pm左右达到最高;不同浓度的蔗糖、硼酸配比对花粉萌发具有显著影响,笔竹花粉在10%蔗糖+0.01%硼酸浓度的培养基上培养3 h,萌发率最高;不同储藏条件对笔竹花粉萌发具有显著影响,而4℃湿藏条件下保存短时间内可延长花粉活力至120 h;柱头具可授性,可授期仅2～3 h,成熟期(散粉时期)柱头可授性最强。结论:笔竹花粉在10%蔗糖+0.01%硼酸的培养基内培养3 h萌发效果最好;1 d内尽量采集3∶00 pm左右的新鲜笔竹花粉对散粉时期的柱头进行人工授粉效果最好;新鲜花粉易失活,低温不干燥的储藏处理可以短时间内延长花粉寿命。     

南非万寿菊温室栽培花粉活力和柱头可授性研究

近年来观赏性好、抗逆性强的园林新种质——南非万寿菊在欧美园林中极具流行趋势。为培育具有自主知识产权的新品种,该研究分别采用TTC法、I-KI法测定温室栽培条件下南非万寿菊花粉活力,利用联苯胺-过氧化氢法测定其柱头可授性。结果表明温室栽培条件下,南非万寿菊花粉活力极低,2种方法检测到P、LS、W的花粉活力分别为4.2%、2.9%、2.7%和8.7%、5.9%、5.6%;舌状花柱头可授性在舌状花开放后的第2～4天最强,管状花柱头基本没有可授性。     

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.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

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.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

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.     

Modelling of adequate pretwist for obtaining straight timber

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.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

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.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

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.     

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。