水杨酸对‘照手桃’开花的影响

为给调控观赏桃花花期提供理论依据,研究了不同质量浓度的水杨酸(SA)在开花过程中对照手桃Prunus persica‘Terutemomo’开花的影响。在照手桃花前期及花中期进行SA喷施,测定其花芽、花蕾及枝条的可溶性糖含量、可溶性蛋白含量、C/N值及内源激素(GA、IAA、ZR、ABA)含量的动态变化。结果表明:2个时期SA各质量浓度处理使‘照手桃’的始花期推迟1~2 d,增强了开花过程中能量的储存,加快了可溶性蛋白的分解,增强了新陈代谢和激素活动,对开花有利。     

赤霉素对‘照手桃’开花的影响

为给观赏桃的花期调控提供理论依据,以‘照手桃’Prunus persica‘Terutemomo’为研究对象,在其花前期及花中期喷施不同质量浓度的赤霉素(GA),研究其对‘照手桃’开花的影响。结果表明:无论是花前期还是花中期的处理,GA对‘照手桃’花芽、花蕾及花瓣的生长起促进作用,并对‘照手桃’中的可溶性糖、可溶性蛋白、C/N值及内源激素(GA、IAA、ZR、ABA)产生有利的刺激效果,增强了‘照手桃’的新陈代谢,有利于‘照手桃’开花。     

喷施植物生长调节剂对蓖麻营养和生殖生长的影响

对蓖麻幼苗喷施不同浓度的植物生长调节剂(IAA、6—BA、GA3、KT),并以清水处理为对照,观测分析植物生长调节剂对蓖麻营养生长及生殖生长的影响。结果表明:100 mg/L的IAA、100~200 mg/L的6-BA、200 mg/L的GA3和100~200 mg/L的KT对蓖麻的地径和株高均有促进作用,KT则提早了始花期;IAA延迟了蓖麻的始花期,但提高了蓖麻花序总长度和雌花序的长度。其中200 mg/L IAA分别使花序总长度和雌花序长度增长了26.38%和56.17%。植物生长调节剂影响种子的大小和色泽,对种子含油率无明显影响。     

花期喷施生长调节剂和氨基酸肥对枣树结实和育性的影响

以两个枣品种为试材,研究了花期喷施生长调节剂和氨基酸肥对自花授粉和自然授粉条件下的结实及种仁发育的影响。结果表明,低浓度的GA3(5~10 mg/L))虽可提高枣树的结实率但降低了枣果的可育率,当GA3浓度达到35 mg/L时结实率亦降低;150 mg/L的6-BA0、.02 g/L氨基酸肥对自花结实率、自然结实率、自然可育率都有降低作用。     

外源激素对牡丹花期延迟试验

研究了外源激素即植物生长调节剂对牡丹开花的影响,初步探讨了用化学方法对露地牡丹花期的调控机制,结果表明:在春季喷施500~1000mg/L萘乙酸时可使牡丹花期延迟2~4天;喷施1500~3000mg/L比久时可使牡丹花期延迟2~6天;水扬酸以1000mg/L和1500mg/L喷施时可延迟牡丹开花1~2天,以500mg/L喷施可使牡丹花期提前1天。     

不同处理对盆栽两用桃开花的影响

为了考察基质种类,根的带土坨状况及喷施赤霉素的浓度对盆栽桃开花性状的影响,安排了3因素3水平的正交试验,结果表明基质种类对盆栽桃的开花物候期影响最大,根的带土坨状况对盆栽桃的花期和花径的影响最大。基质2、全带土坨及喷施100m g/L赤霉素为最优试验组合,能够提前开花,增长花期,增大花径。     

赤霉素(GA3)对八仙花花期及开花品质的影响

以八仙花为试验材料,研究了不同时间,不同浓度的赤霉素对八仙花的始花期、花径、开花数、枝长等的影响,结果表明:GA3可促进八仙花开花,浓度高开花早,可提前1-3天;250mg/L GA3明显增大八仙花花径,与对照比达到极显著水平;随着GA3浓度增加,八仙花的开花数和小花数都增加;不同时期对八仙花进行处理,也对八仙花提早开花有一定影响。对春、夏梢八仙花花期研究表明,夏梢八仙花观赏品质优于春梢八仙花,且夏梢八仙花种植周期短,更加经济,更利于广泛栽培。     

不同化学疏花剂对桃坐果率和果实品质的影响

【目的】筛选适宜的桃化学疏花剂及其浓度,探究不同种类和浓度的化学疏花剂对桃坐果率及果实品质的影响。【方法】以3年生晚熟桃'秋甜'为试验对象,于盛花期喷施不同浓度的NAA、6-BA、石硫合剂3种化学疏花剂,以喷清水和自然坐果分别为对照,在果实采收时调查不同处理的坐果率和果实品质,研究不同处理对桃坐果率和果实品质的影响。调查的果实品质指标包括平均单果质量、果实纵径、果实横径、可溶性固形物含量、可溶性糖含量、可滴定酸含量等。【结果】与对照相比,喷施不同种类和浓度的化学疏花剂,'秋甜'桃坐果率均明显下降,且与NAA、6-BA、石硫合剂浓度呈负相关,即随其浓度的增加,坐果率明显下降。从保证产量和疏花疏果效果方面综合考虑,盛花期喷施20 mg/L NAA、0.2 g/L 6-BA或相对密度1.001 4 g/cm~3的石硫合剂效果较好,坐果率分别为24.04%、27.95%、26.63%。与对照相比,喷施不同种类和浓度的化学疏花剂均明显提高了平均单果质量。其中,以喷施相对密度1.002 8 g/cm~3的石硫合剂、20 mg/L的NAA、0.2 g/L的6-BA的平均单果质量较高,分别为388.54、384.56、380.12 g,且与其他处理差异显著。各处理均提高了可溶性糖含量,喷施20 mg/L NAA、0.2 g/L 6-BA或相对密度1.002 1 g/cm3的石硫合剂显著提高了可溶性固形物含量。喷施20、30 mg/L NAA或0.1、0.2 g/L 6-BA提高了可滴定酸含量。【结论】盛花期喷施20 mg/L NAA、0.2 g/L 6-BA对'秋甜'桃有较好的疏花效果,并且能提高果实品质。     

草果花期喷施激素对其坐果率与产量的影响

通过对草果花期分别采用NAA(50 mg/L)、2,4-D(20 mg/L)、GA(100 mg/L)、6-BA(100 mg/L)、爱多收(水剂,0.67 mL/L)、矮壮素(水剂,670 mL/L)、芸苔素(2000 mg/L)和2,4-D钠盐(250 mg/L)喷施,以清水为对照,分析了不同激素处理对草果坐果率及产量的影响。结果表明,(1)激素(含对照)对坐果率、单果重、单花序轴产量均具有极显著的差异影响,草果花期喷施激素后坐果率、单花序轴产量和单位面积产量都高于对照;(2)喷施2,4-D、2,4-D钠盐、6-BA和矮壮素后单位面积产量达4909.05 kg/hm2、4723.20 kg/hm2、4127.40 kg/hm2和4038.30 kg/hm2,分别比对照(239.25 kg/hm2)提高了1951.74%、1874.03%、1625.04%和1 587.78%,其中喷施2,4-D为生产中提高草果产量的最适激素。     

6-BA对蝴蝶兰不同品种开花的影响

采用不同浓度6-BA对蝴蝶兰不同品种进行处理,通过对其花蕾直径、始花期和盛花期的测定比较,结果表明:100mg/kg浓度的6-BA能显著地促进花蕾发育,品种间差异不显著;对始花期的影响因品种而异,浓度间和品种间差异均显著,品种2012用50mg/kg6-BA、75mg/kg6-BA、100mg/kg6-BA处理的植株比对照提前开花约4～5d;品种2022用75mg/kg6-BA和100mg/kg6-BA分别比对照提前3d和5d;品种2023,仅用100mg/kg6-BA使花期提前4d左右;6-BA能明显缩短盛花期,不同浓度间和品种间差异均显著。100mg/kg6-BA是促成栽培蝴蝶兰大红系的品种有效安全浓度。     

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.