香花油茶不同无性系叶表型性状及叶绿素含量的差异

【目的】为香花油茶良种选育和生态经济型品种筛选提供参考。【方法】以生长良好的30个香花油茶无性系叶为材料,使用叶面积仪和Dualex植物多酚-叶绿素仪对叶表型性状和叶绿素含量进行测定。【结果】叶水分含量特征：叶含水量为52.07%～62.44%,含水量高于55%的无性系占比70%以上。叶表型性状：15号无性系的叶长最大,29号无性系的叶宽、叶面积、叶周长、形状系数均最小;各无性系叶表型性状的变异系数为9.18%～23.07%,叶周长的变异系数最小（为9.18%）,叶面积的变异系数最大（为23.07%）;叶宽、叶面积与其他叶表型性状间均存在极显著相关性;在主成分分析中,前2个主成分的累计贡献率达到92.708%,说明这2个主成分概括了6个性状的主要信息。其中,叶面积的特征向量值最大,其次是叶宽,叶面积和叶宽是区分香花油茶无性系最主要的叶性状。经聚类分析,香花油茶各无性系可被划分为3个类群。叶绿素含量：香花油茶不同无性系间叶绿素含量存在变异,变异系数为8.48%;25号无性系叶基、叶中的叶绿素含量与其他无性系有显著差异,叶尖叶绿素含量除与18号无性系无显著差异外,与其他无性系均有显著差异。...     

施肥和喷施芸苔素内酯对油茶春叶养分等指标影响试验

为了解不同肥料和不同浓度芸苔素内酯对油茶下一年春叶养分等指标的影响,选择长林4号、18号和166号优良无性系油茶品种,对其进行施肥（生物有机肥、油茶专用肥、复合肥）及叶面喷施芸苔素内酯的正交试验。结果表明：油茶春叶叶绿素SPAD值最高处理组合是长林4号、每株施生物有机肥1 kg和喷0.033 mg.kg-1芸苔素内酯;油茶春叶干物质含量最高的处理组合是长林18品系、每株施油茶专用肥0.5 kg和喷0.033 mg.kg-1芸苔素内酯;油茶春叶中氮和磷含量最高的处理组合是长林18品系、每株施油茶专用肥0.5 kg和喷0.033 mg.kg-1芸苔素内酯;叶片钾含量最高的处理组合是长林4品系、每株施生物有机肥1 g和喷0.067 mg.kg-1芸苔素内酯;钾对油茶春叶叶绿素SPAD值贡献率最高,氮对春叶干物质积累贡献率最高。     

南方4种木本植物相对叶绿素指标及其分布

利用SPAD-502叶绿素计测定我国南方九节、三叉苦、桃金娘和阴香4种植物的叶绿素相对含量.研究结果表明,成熟叶中的叶绿素相对含量均极显著大于嫩叶,而其在同一叶片不同部位的分布为:叶尖<叶中部<叶基,其中,叶尖与叶基有极显著差异(P<0.001),叶尖与叶中部仅在嫩叶中有极显著差异(P<0.0001).主脉左右两侧绿素相对含量分布为:左区>右区,在嫩叶中有显著差异(P<0.05),但在成熟叶与嫩叶的叶尖均无显著差异.叶绿素相对含量的最佳测定部位为全展开叶片的中部.本项研究可为不同目的叶片叶绿素含量测定与取样提供参考.     

竹节树无性系叶片生长特性与叶绿素荧光

对优选的6个竹节树(Carallia brachiata)无性系叶片性状(叶片干质量、叶面积、比叶重)、叶绿素相对含量和叶绿素荧光参数进行测定,并作单因素方差分析和聚类分析.结果表明:竹节树不同无性系叶片的干质量和叶面积差异不显著,叶绿素相对含量具有显著的差异性,不同无性系具有不同的光能吸收和利用能力;不同的无性系其叶绿素荧光的部分参数(Fo、Fv/Fm、Fv/Fo、ФPSⅡ、ETR)差异显著;竹节树无性系C-15植株与其他无性系相比具有较高水平的实际光化学效率(ΦPSⅡ)值,而非化学猝灭系数(qN)较低,同时具有较高的表观电子传递速率(ETR),表明竹节树无性系C-15有较高的光呼吸;相关分析表明,叶片生长较好的无性系其叶绿素相对含量较高,同时也具有较高的PSⅡ光化学效率;无性系C-15号具有较高的叶绿素相对含量及较强的光化学特性,可进行大力推广研发.     

油茶不同无性系叶片营养元素吸收情况评价

对油茶不同无性系叶片营养元素含量的测定,研究结果表明:油茶叶片营养元素N含量最高,其次是Ca和K,Cu含量最低;油茶不同无性系叶片营养元素差异均达到极显著水平;通过主成分分析结果,综合评价油茶不同无性系营养元素吸收情况,按综合得分排序依次是桂软3号、桂软2号、湘林A5、湘林70号、桂软1号、桂软11号、桂软22号、桂软24号、桂软23号。     

玉兰叶片叶绿素荧光特性的研究

用叶绿素荧光技术测定玉兰不同无性系叶片的叶绿素荧光参数,结果表明:玉兰同一叶片不同部位叶绿素荧光参数(Fv/Fm)存在着差异,叶片基部、叶片中左、右部高于叶片尖部.南北两侧Fv/Fm差异不显著.叶绿素荧光测定的功能叶片区域很大,从整株来看,从树冠顶层第2轮开始到树冠底层第2轮结束,中间的叶片都可以看成是功能叶片.叶绿素荧光参数日变化表现为降-升-降-升的动态曲线.8:00～10:00时为最高.18:00时逐渐上升,到20:00～22:00时上升到原来状态.     

遮光对油茶苗期生长及光合特性的影响

为了探讨不同遮光环境对油茶苗期生长及光合特性的影响,以国家审定的4个长林系列油茶优良无性系2年生苗木为试验材料,研究了苗期遮光对不同无性系油茶苗木生长、光合以及叶绿素含量的影响。结果表明:适当的遮光处理能够促进油茶苗木的苗高、叶长、叶宽、单叶面积和全株叶面积的生长以及叶绿素的合成;经过2个月的遮光处理,50%全光、25%全光和12.5%全光处理植株的苗高、叶长、叶宽、单叶面积、全株叶面积和叶绿素相对含量均显著高于全光CK植株;50%全光、25%全光和12.5%全光处理植株的基径生长量均低于CK植株;在一定的检测光照强度下,4个无性系油茶的净光合速率均随着遮光强度的增强而增加,50%全光、25%全光和12.5%全光处理植株的叶片净光合速率均均显著高于全光CK植株。研究结果可为培育具有相对竞争优势的油茶上山造林壮苗提供技术支撑。     

油茶叶绿素含量动态变化和耐阴性的探讨

通过测定不同样地油茶树上不同叶龄叶绿素含量的年变化,明确了油茶叶绿素含量的变化规律。同时分析了这一规律与油茶果实生长的关系,说明了环境条件对油茶叶绿素含量和叶片寿命的影响,为油茶林的经营管理提供了依据。     

不同光强对6个欧美杨无性系苗期生长及光合特性的影响

[目的]研究6个欧美杨无性系生长及光合特性对不同光强的响应差异,为欧美杨苗期快速选育高光效优良品种提供一定的理论依据。[方法]在大田用遮阴网设置CK(100%自然光强)、L1(55%自然光强)和L2(20%自然光强),测定欧美杨的苗高增长量、叶片形态、光合速率、叶绿素荧光特性、叶绿素含量及矿质元素含量。[结果]除11-26-9外,无性系的苗高总生长量随着光强的降低呈下降趋势;随着光强的降低,不同无性系的叶片形态变化趋势不一致,3个光强下无性系间的单叶面积、叶形指数和比叶面积存在差异;无性系在L2处理下的净光合速率(Pn)最低,胞间CO2浓度(Ci)最高;3个处理下,11-26-8的气孔导度均最大;在L1与L2下,11-26-9的F1/F0值均最大;无性系的叶绿素b含量与叶绿素总含量呈现相同的变化趋势;11-26-4、11-26-8和11-36-26的钾、钙、镁元素含量随着光强的降低而增加。[结论]不同无性系对光强变化的适应策略不同,部分无性系的高生长和净光合速率随着光强的降低而减小,降低光强没有破坏无性系的PSⅡ结构。多数无性系的总叶绿素含量、矿质元素含量随着光强的降低而升高。11-36-26无性系的生长势及抗弱光能力较弱。     

配方施肥对油茶幼树生长的影响

采用随机区组田间试验设计,以油茶优良无性系幼林为试材,研究了不同氮磷钾配方施肥对油茶幼树营养生长及叶绿素含量的影响。结果表明配方施肥对油茶优良无性系幼树树高、冠幅、梢长生长均有不同程度的促进作用,但不同的配方施肥和施肥量对油茶幼林的营养生长及叶绿素含量有很大的差异性,其中处理7油茶幼树各指标增量极显著大于其它处理。本试验氮、磷、钾(N∶P2O5∶K2O)最适配方为10∶5∶2。     

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.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

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.     

Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Effect of Drought on Growth and Mortality of Actively Growing Norway Spruce Container Seedlings Planted in Summer

Survival, root egress and height growth of 13-month-old actively growing Norway spruce ( Picea abies (L.) Karst.) container seedlings exposed to preplanting drying treatments (0, 4, and 8 days) and postplanting drought periods (1, 2, 3, and 4 weeks) were studied in the field between 5 July and 18 August 1999. The mortality of seedlings increased and the height growth and root egress decreased throughout the postplanting drought period. Postplanting performance was also affected by preplanting drying treatments. The results indicate that no risk of excessive mortality and growth restrictions occurs when actively growing seedlings are planted in summer, provided that seedlings are well watered before planting and the drought period does not exceed 3 weeks.     

Rehabilitation of diseased cacao fields in Peru through shade regulation and timing of biocontrol measures

The objective of this case study was to test the effectiveness of biocontrol for the rehabilitation of abandoned, diseased (moniliasis, witches' broom and black pod) cocoa and to develop testable hypotheses regarding the effect of shade and biocontrol timing. Three trial fields differed in their shade regimes. Biocontrol was administered starting either at flowering or pod filling. Disease incidence and yield were compared with cultural control alone. Biocontrol reduced moniliasis from 49% to 25%, independent of the shading regime and application time. Witches' broom was most severe without shade and unaffected by biocontrol. No significant effects on black pod were observed. Although biocontrol increased percentage healthy fruit independent of shading and timing, only the shaded plot with biocontrol from flowering onwards responded with increased yield. Our hypothesis is: 'In the rehabilitation of abandoned cacao, only fields under sustainable shade management and early onset of biocontrol can realise their production potential.' This revised version was published online in June 2006 with corrections to the Cover Date.