施氮对油松幼苗生长及生理特性的影响

通过分析不同施氮量对油松幼苗生长及生理指标变化的影响规律,以筛选出油松育苗中适宜的氮肥施用量处理,为其育苗中科学施肥提供理论参考。试验在田间条件下,设置4个处理,氮肥施用量分别为0 g/株(对照,YS1)、6 g/株(YS2)、12 g/株(YS3)、18 g/株(YS4),小区试验设计,重复3次。结果表明:施用氮肥促进了油松株高增加,YS3与对照相比提高了20. 68%;叶绿素含量YS4最高,YS3与YS4之间无显著差异;根系活力YS3,YS4显著高于对照和YS2处理,YS3与YS4之间无显著差异; 5—9月,YS3可溶性蛋白含量分别高于对照40. 20%,70. 80%,72. 03%,75. 27%,87. 60%;可溶性糖含量YS4与YS3之间无显著差异,6—9月YS3均显著高于对照和YS2处理。综合分析认为,3年生油松苗适宜的氮肥施用量为12 g/株。     

16株枣实生优株生物学特性比较及其果实品质评价

【目的】综合评价实生优株枣果品质，以筛选出优异枣种质，为后期适于推广的鲜食枣优良新品种的选育提供数据支撑。【方法】对16株枣实生优株的植物学特征、物候期及果实品质性状进行观测，并对其果实内在品质进行主成分分析。【结果】16株枣实生优株的果实脆熟期集中在9月，其果实发育期历时90～119 d，除MX5B1与MX9B4均为早熟优株外，其余优株均为中熟优株；果实感官品质评价结果表明，MX5N3、MX9B4、MX10B5、DNJD5B5、DNJD5B6、DNJD6B4这6株优株果实的口感均较佳；单果质量最大的优株是MX5N3，其单果质量为24.41 g;16株枣实生优株果实中的维生素C含量为1 619.61～4 427.47 mg/kg，其中，BX5N6的维生素C含量最高；16株枣实生优株果实中的可溶性糖含量为20.36%～31.86%，其中，BD2B2的可溶性糖含量最高，显著高于其余优株的；16株枣实生优株果实中的可滴定酸含量为0.26%～0.58%，其中，BX4B8和MX9B10的可滴定酸含量均较高，均显著高于其余优株的；16株枣实生优株间果实中黄酮含量的差异较大，BX4B8、MX9B10...     

5个楸树无性系抗旱性的综合评价

利用盆栽方法进行干旱胁迫,对于5个楸树无性系的抗旱性进行综合评价。通过测定叶片解剖结构(叶片厚、角质层厚、上表皮、下表皮、栅栏组织、海绵组织及气孔特征)、生理和生物量(根冠比、耗水速率、叶片脯氨酸含量、叶片可溶性蛋白含量、叶片可溶性糖含量及叶水势)等15个与抗旱性相关的指标,通过主成分分析及隶属函数比较进行分析,结果表明:与楸树无性系抗旱性相关的15个指标归纳为3个主成分,在3个主成分中筛选出叶片厚、栅栏组织、气孔密度和叶片脯氨酸含量等4个指标与楸树抗旱性相关。根据隶属函数平均值大小对5个楸树无性系抗旱性进行排序,结果显示楸树无性系抗旱性从强到弱排序为:7080(0.678 4)>1-3(0.524 2)>004-1(0.221 6)>015-1(0.207 0)>1-4(0.103 2)。     

黑莓杂交F1代初选优株的调查与分析

为了选择黑莓优良单株以进一步培育其优良品系和品种,对20株黑莓杂交F1代优选植株的生长与结实性状进行了调查统计与分析。结果发现,各植株除了叶绿素SPAD值的差异较小外,其他性状指标之间的差异都较大,其中单株结果数量、平均单果质量和株产量的变异系数都在40%左右。文中还以枝蔓刺性状、果实大小和株产量为主要考察指标,优选出了候选优良品系单株6个,它们分别是:无刺、果大、丰产、中熟类型的6-6-3,无刺、早熟类型的5-8-2、6-8-1、7-10-6,有刺、果特大、生长势强、早熟类型的1-11-1,有刺、果大、叶色较深、晚熟的3-6-1。     

保鲜方式和果实大小对油梨果实品质的影响

【目的】为油梨采后保鲜和果品分级提供可行方案和新思路。【方法】以稳定开花结果的哈斯油梨为研究对象,于果实成熟期采摘,采后根据单果质量对果实进行分类,分别为大果(≥140 g)、中果(≥100 g且140 g)和小果(100 g),并设置5种保鲜处理,分别为常温储藏、冷藏保鲜、精油保鲜、气调保鲜、气调结合精油保鲜,待达可食状态后,对果实的总糖含量、可溶性固形物含量、维生素C含量、可滴定酸含量、粗蛋白含量、粗脂肪含量6项生理指标进行测定,采用隶属函数值法对不同保鲜方式处理下和不同大小果实的品质进行综合评价。【结果】与常温储藏相比,其他保鲜方式在一定程度上均延长了油梨的保鲜时长,可溶性固形物含量的差异最为显著。根据生理指标的隶属函数均值可知,5种保鲜方式下果实品质由优到劣排序依次为气调结合精油保鲜、冷藏保鲜、气调保鲜、精油保鲜、常温储藏。不同大小果实之间总糖含量、可溶性固形物含量、维生素C含量无显著差异,脂肪含量、粗蛋白含量以及可滴定酸含量随果实质量增加反而降低。根据生理指标的隶属函数均值可知,3种等级果实根据其品质由优到劣排序依次为中果、大果、小果。【结论】在5种保鲜方式中,气调结合精油保鲜效果最好。不同大小的果实之间生理指标差异不显著,且未呈现简单的线性关系,中果品质最好。     

基于主成分分析的软核山楂F2代果实品质评价与选优

该文以软核山楂F2代1200株群体优选出来10个性状表现较好的单株为试验材料，分别测定表型特征、内在品质、营养品质等共13个指标，采用差异显著性分析、主成分分析方法，计算出综合排名。结果显示：单果重主要在4.00～5.00g，纵、横径在17.00～23.00mm，果形主要为近圆形，果实硬度差异较大，可食率、含水量在70%～91%之间，性状优良。25-37糖酸比最高5.91，可溶性蛋白、维生素C含量最高的株系与含量最低的株系相差2倍之多，可溶性固形物含量变化不大。主成分分析中，提取了5个主成分，累计率达到90.28%，可以较好的反映10个软核山楂株系果实的综合营养品质，15-38、17-17、20-9这3个软核山楂株系果实品质最佳，果实外形硕大圆润、营养成分高。     

不同品系藜麦苗菜农艺性状及营养品质评价

为探索不同品系藜麦Chenopodium quinoa苗菜在浙西南地区农艺性状和营养品质的差异,对引自于国内的11个品系藜麦(Q_1～Q_(11))苗菜的主要农艺性状进行观测、并对可食用嫩茎鲜产量、营养品质进行综合评价。结果表明,11个品系藜麦苗菜在浙西南地区均可正常生长,播种至采收历期27 d,可食用嫩茎鲜产量为10 763.9～13 888.9 kg·hm~(-2),各品系的产量之间差异不显著;除维生素E未验出外,不同品系藜麦苗菜所含9个主要成分之间存在一定的差异,变异系数(CV)从大到小的排序为:锌钙硝酸盐β-胡萝卜素皂苷脂肪蛋白质草酸含水量,其中,锌含量变异系数最大,为34.94%;营养品质综合评价排序为:Q_9Q_5Q_(11)Q_1Q_6Q_(10)Q_4Q_8Q_7Q_2Q_3;营养分级为Ⅰ级有2个品系,为Q_5、Q_9,Ⅱ级有2个品系,为Q_1、Q_(11),其他7个品系分属于Ⅲ和Ⅳ级。根据研究结果,可将Q_5、Q_9品系作为藜麦苗菜推广的主要品系,Q_1、Q_(11)品系可作为优质高产藜麦苗菜品系选育的重要种质。     

特早熟甜柿西村早生栽培适应性观察

西村早生树势强，结果早，果形大，产量高。9月中旬果实开始成熟，较富有和禅寺丸早30天左右。定植后第2年开始挂果，第3年株产1．12kg最高株产9．65kg，第4年平均株产4－5kg，第5年为13.25kg最高单株产量26．35kg，每667m2产量平均为742kg。西村早生为甜柿中特早熟品种。果实扁圆形，单果重平均138g，最大单果重220g。果皮呈橙黄——橙红色，授粉后果实内种子达4粒以上，果肉有褐斑而自然脱涩，风味甜脆，品质中等，可溶性固形物含量14％，常温下存放10天左右，不易软化，商品性好。特早熟甜柿西村早生栽培适应性观察…     

桤木不同品系蒸腾特性与水分利用效率的研究

对H1、H12、J5和J10等4个四川桤木品系的蒸腾特性和水分利用效率进行了研究,结果表明(1)蒸腾速率日变化呈单峰、双峰曲线2种类型,具有明显的峰值,属轻蒸腾午休型.峰值出现时间因不同曲线类型和不同品系均有差别;蒸腾速率月均值以6月份(H1、H12)、7月份(J5、J10)的最高,分别是2.57、3.65、2.64、3.84 mmol·m-25-1;J10、H12品系的蒸腾速率月均值明显高于J5、H1品系;(2)净光合速率日变化4月呈单峰曲线,6～8月有单峰、双峰2种类型,以6月份最高,H1、H12、J5、J10的净光合速率峰值分别为12.20、18.56、15.64、18.43 μmoI·m-2s-1,8月份最低,分别为6.43、11.73、9.62和10.74 μmol·m-2s-1;(3)水分利用效率日变化以上午700～900最高,下午或傍晚较低;4月(H1、J5)、6月(H12和J10)的水分利用效率平均值最大,分别为4.82、5.80、2.98、3.34 μmol·mol-1,且H1和J5分别大于H12、J10.(4)通过多因子回归分析,影响蒸腾速率的关键因子是气孔导度、光照强度与空气温度,H1对光合有效辐射变化不敏感,受CO2浓度影响的品系H12受温度的影响较小,对水分比较敏感.     

引种野杏无性系及家系的抗寒性

【目的】为野杏的引种驯化及繁育栽培提供参考。【方法】以引种到辽西地区的野杏12个无性系和12个家系为研究对象,以引种地西伯利亚杏无性系和家系作为对照,测定了不同种源的引种野杏无性系及家系枝条的含水量,研究了低温胁迫（0、-20、-25、-30、-35、-40℃）下其可溶性糖含量、可溶性蛋白含量、过氧化物酶（POD）活性、超氧化物歧化酶（SOD）活性、丙二醛（MDA）含量、电导率的变化,应用隶属函数法对其抗寒性进行评价,并基于隶属函数值对各无性系及家系进行聚类。【结果】野杏无性系和家系的枝条电导率曲线均符合典型的“S”形曲线,MDA含量、SOD活性、POD活性均表现为先增后减,可溶性糖含量随温度降低呈上升趋势,可溶性蛋白含量随温度降低表现为先增后减,半致死温度为-42.33～-29.93℃。12个野杏无性系的平均隶属函数值为0.14～0.90,12个家系的平均隶属函数值为0.24～0.74。各无性系按其抗寒性由强到弱排序依次为J170、J19、J171、J148、J162、J144、J210、J105、J118、J101、J211、J270、J121,各家系按其抗寒性由强到弱排序依次为1...     

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.     

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.