Effect of the nematicide carbofuran on the population development of the citrus parasitic nematodeTylenchulus semipenetrans and predacious soil mites in citrus orchard under organic manure regime of fertilization

Effect of the nematicide carbofuran on the population development of the citrus parasitic nematodeTylenchulus semipenetrans and predacious soil mites in citrus orchard under organic manure regime of fertilization. In an Egyptian citrus orchard under farmyard manure regime of fertilization an experiment was conducted for three successive seasons (1993–1995) to investigate the potency of the nematicide carbofuran against the population of the citrus parasitic nematodeTylenchulus semipenetrans Cobb. and any side-effects on predacious soil mites. An initial reduction inT. semipenetrans populations was observed after application, although a remarkable increase in the population occurred afterwards. In contrast, the average number of predators decreased, particularly in 1995. In organic plots without nematicide, predators increased to great numbers andT. semipenetrans caused negligible injury. In the fertilizer-free treatment, theT. semipenetrans population was low although that of predacious mites was high. The study indicated that carbofuran treatments reduced the population of predacious soil mites and in their absence the population of the parasitic nematode,T. semipenetrans was likely to increase.     

Bio-efficacy of sincocin AGTM to controlTylenchulus semipenetrans (Tylenchida,Nematoda) in citrus orchard

Field experiment was conducted at a site naturally infested withTylenchulus semipenetrans to explore the effect of sincocin AGTM as a biocidal agent at 2000 ppm in controlling citrus nematodes. Sincocin AGTM significantly reduced citrus nematode population in both soil and roots ofCitrus sinesis, and enhanced both growth of orange trees and soil mites especially the mesostigmatide mites. In treated soil, the nature nematode feeders, mesostigmatide mites were increased by 140% and 243%, one month and two months, respectively, post application.     

Response of seasonal pond plant communities to upland forest harvest in northern Minnesota forests,USA

Small seasonally flooded forest ponds have received increased attention due to a growing recognition of their abundance in many landscapes, their importance as habitat for a variety of organisms, and the contributions they make to species and ecosystem diversity. There also is concern over potential negative effects of forest management in adjacent uplands on seasonal pond ecology. Several studies have examined invertebrate and songbird responses to upland harvest around seasonal ponds. Less attention has been given to examining how seasonal pond plant communities respond to adjacent forest harvesting. We studied the response of seasonal pond plant communities to adjacent upland timber harvests, assessing whether buffers around ponds (15.25 m uncut and partially cut) mitigated changes in species abundance and community composition, relative to changes in ponds that were clearcut to the pond margin. We addressed our objective using an operational-scale experiment in northern Minnesota, which included pre-harvest sampling, replicated treatments, and uncut controls. After treatment, changes in tree basal area and canopy openness in the pond basins reflected reductions in upland basal areas. Specifically, control ponds had significantly higher basal area and lower openness than ponds cut to their margins, while ponds with uncut buffers and partially cut buffers were intermediate. Changes in plant communities were evident in the ground layer and shrub/large regeneration layer. After treatment and over time, the control stands did not change significantly in ground layer structure or shrub/large regeneration layer composition. The three upland harvest treatments displayed increasingly greater deviation from their starting conditions and from the control along a gradient of increasing treatment intensity, from the buffer treatment to the partially cut buffer to the clearcut. The response in the ground layer was largely associated with increased sedge and grass cover, while the response in the shrub/large regeneration layer was associated with increases of Salix sp., Alnus incana, and Populus tremuloides. Our results indicate that adjacent upland timber harvest can lead to altered plant communities within seasonal ponds, at least temporarily. Moreover, uncut forest buffers (∼15.25 m) surrounding seasonal ponds can mitigate plant community changes to some degree. If seasonal ponds are an important resource on the management landscape and a high percentage of upland forest is in a recently cut condition at any given time, than use of harvest buffers around seasonal ponds may be an appropriate approach for mitigating short term alteration of pond plant communities.     

Distribution of sulphur fractions in lysimeters previously treated with sulphuric acid,NPK fertilizer and a combination of acid and fertilizer

The retention of applied ³⁵S was studied in a lysimeter experiment, in which the lysimeters, consisting of soil columns with intact field and groundlayer vegetation, had previously been treated with either sulphuric acid, NPK or a combination of sulphuric acid and NPK.³⁵S was applied as Na₂³⁵SO₄ to all lysimeters in an amount corresponding to 2 kg S ha^?1, 3 months before the termination of the experiment. Of the applied ³⁵S, 4.7 ± 1.6% (the error term showing the standard error of the mean) was leached from the lysimeters; ³⁵SO₄^2?, was preferentially sorbed in the upper part of the B horizon, >61% being sorbed in the B horizon as a whole. The influence of previous treatments was seen in SO₄^2? content in the B horizon and also in the SO₄^2? concentrations in the leachates from the lysimeters. Sorption of ³⁵SO₄^2? was enhanced by the acid treatment in the A₀ and A₁/A₂ horizons. Ratios between water-extractable SO₄^2? and KCl-extractable SO₄^2? varied from 0.88 in the A₁/A₂ horizon to 0.46 in the lower part of the B horizon, indicating a preferential sorption of less available SO₄^2? fractions in that part of the soil.Significant positive correlations between soil organic carbon and various sulphur fractions, both labelled and unlabelled, indicated the importance of biological S transformations in the A₀ and A₁/A₂ horizons.Positive correlations between KCl-extractable Al and KCl-extractable SO₄^2? were found in the B horizon. Equilibrium calculations suggested that the SO₄^2? activity and Al³⁺ activity in leachates from control and acidified lysimeters were within the stability fields of basaluminite (Al₄(OH)₁₀SO₄), activities in leachates from the latter group of lysimeters, also being close to jurbanite (Al(OH)SO₄).     

水杨酸与植物诱导抗病性

水杨酸(SA)被认为是诱导植物抗病反应的重要信号分子之一。许多研究报道：水杨酸参与植物的HR(超敏反应)和SAR(植物系统抗病性)介导的与植物病理相关的PRP(也叫PRS，病程相关蛋白)基因的表达。章就SA与植物抗病性间的关系、SA抗病机理、SA在植物系统抗病性间的信号传递以及SA调节SAR基因表达的分子机理作以综述。     

Response of fungal and plant communities to management-induced overstorey changes in montane forests of the Western Carpathians

The effect of forest management on biodiversity is a crucial issue for sustainable forestry and nature conservation. However, the ways in which management affects macrofungal and plant communities and diversity of mountain temperate forests still remain poorly understood. We performed a random sampling stratified by stand age and stand type on the sites of temperate montane fir–beech forests. Diversity of macrofungi and the vascular plant understorey in beech- and spruce-dominated managed stands was investigated and compared to primeval forests located in the Po?ana Biosphere Reserve, Western Carpathians. Both the vascular plant and the macrofungal communities were altered by management, and the response of the macrofungal species (especially wood-inhabiting fungi) was more pronounced in terms of species composition change. Species turnover evaluation seems to be an important tool of forest natural status assessment, because alpha diversity did not change as much as species composition. Certain species of Carpathian primeval forests were confirmed as good indicators for natural forest change; others were proposed. Species pool and mean number of species per plot were the highest in unmanaged fir–beech forests, and species diversity significantly decreased in spruce plantations. The number of species decreased significantly due to the change of canopy tree species composition only in the macrofungal communities. As an outcome for forest management, we recommend keeping mixed forests involving all natural tree species and providing at least a minimal amount of dead wood necessary for wood-inhabiting organisms and leaving some area of unmanaged natural forests within complexes of managed stands.     

Response of plant,litter,and soil C:N:P stoichiometry to growth stages in Quercus secondary forests on the Loess Plateau,China

Ecological stoichiometry is an important indicator of biogeochemical cycles and nutrient limitations in terrestrial ecosystems.However,little is known about the response of ecological stoichiometry to plant growth.In this study,carbon(C),nitrogen(N),and phosphorus(P) concentrations were evaluated in plant tissues(trees,shrubs,and herbs),litter,and soil of young(≤40-year-old),middle-aged(41-60-year-old),near-mature(61-80-year-old),and mature(81-120-year-old) Quercus secondary forests on the Loess...     

外源乙烯利、萘乙酸和赤霉素对3种空气凤梨开花性状的影响

以铁兰属3种空气凤梨Tillandsia bergeri,Tillandsia stricta和Tillandsia montana为试验材料,叶面喷施外源乙 烯利、萘乙酸和赤霉素以促进其开花,结果表明:乙烯利对3种供试凤梨催花作用明显,花序长度和小花数均以100mg/L乙烯利处理为最高,但随着乙烯利质量浓度的继续增加,花序长度和小花数水平降低;在本试验条件下,对T.bergeri,T.stricta和T.montana,乙烯利催花最适质量浓度分别为400,200,400 mg/L.     

Response of LAI-2000 estimates to changes in plant surface area index in a Scots pine stand

We assessed the accuracy with which the LAI-2000 plant canopy analyzer measured changes in leaf area index (LAI) and plant area index (PAI) in a 25-year-old Scots pine (Pinus sylvestris L.) stand. Stand density was 2100 stems ha(-1) and mean tree height was 8.7 m. Needle and branch areas of the stand were reduced progressively to zero by the stepwise removal of branches on all trees growing in a circular plot with a radius of 25 m. An LAI-2000 estimate was taken after each step reduction. The needle and branch surface areas removed at each step were estimated from direct measurements and were compared with the changes in the LAI-2000 estimates. Initially (before removal of branches), directly measured PAI was 5.2 (needles = 86%, branches = 8% and stems = 6%). The LAI-2000 estimate of total surface area was 66% of direct PAI and 77% of direct LAI. There was a nonlinear relationship between the LAI-2000 estimate and directly measured PAI, such that their ratio (equivalent to the clumping factor) increased from 0.66 to 1.05 with decreasing PAI. At the last measurement, when only stems were left, the LAI-2000 estimate agreed well with the direct measurement of PAI. The LAI-2000 underestimated the direct measurement of LAI at the first three steps when LAI was > 2 and the proportion of woody area was small (< 20%). However, because the LAI-2000 estimate included stem and branch areas, it overestimated the direct measurement of LAI at the last three measurements when the proportion of woody area was large (> 20%).     

Germination response of alder and birch seeds to applied gibberellic acid and priming treatments in combination with chilling

The effects of seed moisture content (MC), gibberellic acid (GA₃) concentration, chilling and priming pretreatments on the germination of common alder (Alnus glutinosa) and downey birch (Betula pubescens) seeds were examined. After treatment, the seeds were allowed to germinate for 42 days at 15 °C or 20 °C (dark)/30 °C (light). Treatment responses were similar at both temperatures and in both species. GA₃ treatment of seeds in fully imbibed (FI) state for 30 days, or at the lower, target moisture content (TMC) for 30–90 days, significantly improved germination, but longer treatment periods reduced it (FI seeds) or had no effect (TMC seeds). Priming for two days improved germination in the FI seeds, but more than 4 days reduced it. Priming for up to 14 days had little effect on the germination of the TMC seeds.     

Pinus taeda L. response to fertilization,herbaceous plant control,and woody plant control

On an intensively prepared site, a complete fertilizer applied at planting, and control of herbaceous and woody plants for the first 4 years, increased Pinus taeda L. volume at age 5 to 25.9 m³/ha compared to 11.8 m³/ha without the treatments. The fertilizer and competition control factors affected pine growth independently of each other, and so their effects are additive. Herbaceous plant control was the most effective treatment, increasing pine volume by 63%. Declining dry weights of herbaceous plant material indicated that pine was dominant by age 6, so more responses from herbaceous plant control are not expected. Woody plant control did not significantly increase pine volume until the fifth year because the intensive site preparation retarded the development of the woody competition. The fertilizer contained nitrogen, phosphorus, and potassium, but analysis of pine foliage indicates phosphorus was the element causing the response of pine to fertilizer. By the sixth season, the herbaceous and woody plant material contained 31% of the nitrogen and potassium applied as fertilizer. The competing material also contained 7% of the phosphorus applied in the fertilizer. This showed that competitors can be major utilizers of fertilizer applied to pines.     

Mutagenesis, heterogeneous gene expression, and purification and amino acid substitution analyses of plant peroxidase, PrxA3a

We introduced mutations into prxA3a, a peroxidase gene of hybrid aspen, Populus kitakamiensis, to substitute the amino acid residues at the surface of the protein, and analyzed substrate specificities. PrxA3a and mutated enzymes heterogeneously gene expressed in Saccharomyces cerevisiae were purified by Ni affinity chromatography, hydrolysis of sugar chain (Endoglycosidase H_f) and gel filtration. The substrate specificities were altered by substituted amino acid residues. PrxA3a F77Y A165W acquired the substrate specificity to m-chlorophenol. PrxA3a F77Y and PrxA3a F77YA165W could polymerize sinapyl alcohol. In addition, PrxA3a A165W, F77Y, and F77YA165W improved cytochrome c oxidizing activity. These substituted amino acid residues should function as a catalytic site outside of the heme pocket.     

Conversion of native forest to exotic Pinus radiata plantation: Response of understorey plant composition using a plant functional trait approach

This study aimed to determine the response of native plant species to changed growing conditions, especially increased shade, following establishment of exotic Pinus radiata plantation on cleared native eucalypt forest. In the Northern Hemisphere, species tolerant to shading are typically herbaceous perennials, with large seeds, no obvious mechanism of seed dispersal, and spread by clonal means. We investigated whether life form, mode of seed dispersal, leaf area, specific leaf area (SLA), nutrient uptake strategy, seed mass, fire response, plant height, and clonal spread differed between understorey species of pine plantation and native forest. Further, we asked whether plant functional traits that confer tolerance to stress through shading differ from those in other floras. The study was conducted on the Delatite Peninsula in north-eastern Victoria, Australia. Vegetation of adjacent native forest and pine plantation were surveyed using eight 7 m × 7 m plots per site, randomly located within five paired sites. Differences in plant traits between land-use types were tested by Non-metric Multi-dimensional Scaling (NMDS), analysis of similarity (ANOSIM) and paired t-tests. Cluster analysis of the nine plant traits was used to define emergent groups, with differences between land-use types examined by ANOSIM and indicator species analysis. There was a significant change in the composition of understorey vegetation following conversion to pine plantation that included a decline in the richness of native species. NMDS of plant attributes showed a clear separation of native forest from pine plantation with land use strongly correlated in ordination space (r² = 0.611). Cluster analysis produced seven emergent groups of plant functional traits for 78 identified plant species. Phanerophytes split into two groups (myrmecochorous trees and shrubs; myrmecochorous shrubs), perennial herbs into four groups (upright herbs, myrmecochorous herbs, barochorous herbs, flat rosette herbs) with one group representing therophytes and anemochorous perennials. Perennial herbs with intermediate SLA and clonal spread were tolerant of the shaded conditions in pine plantation while the two groups of phanerophytes and the myrmecochorous herbs were largely excluded. Shared traits of excluded emergent groups included those that provided an over-riding adaptation to mineral nutrient stress, including myrmecochory, low SLA, ectomycorrhizal and ericoid mycorrhizal associations and N₂-fixation. These plant traits could not provide tolerance to stress through shading, which is better explained by the open canopied nature of the native forest.     

南京椴嫩枝扦插生根过程中植物激素的变化

以南京椴嫩枝插穗为研究对象,采用1 000 mg·kg-1 IBA粉剂处理插穗基部,对扦插生根过程中插穗皮部生长素IAA、玉米素核苷ZR、赤霉素GA3、脱落酸ABA含量以及IAA/ABA和IAA/ZR比值进行动态测定,探究嫩枝扦插生根过程中植物激素变化特点及其对生根的影响。结果表明:1)IBA处理可以显著促进南京椴嫩枝插穗生根,生根率接近67%;其生根过程可划分为愈伤组织形成期、根原基诱导期、不定根形成期和不定根生长期,各自对应时间约为10 d。2)IBA处理可以提高嫩枝插穗中IAA含量,IAA对于根原基的诱导和不定根的发生具有较为直接的影响作用,其含量升高有利于生根;GA3含量增加有利于根原基形成,而低水平GA3则更有利于不定根的生长;ABA和ZR含量升高不利于插穗生根,对于根原基的诱导和不定根的发生具有抑制作用;IAA、ABA在插穗根原基诱导和不定根形成过程中具有相互协调作用,IAA/ABA可作为衡量南京椴嫩枝扦插生根能力的指标。3)外源IBA处理可以促进插穗内IAA含量升高,调节ABA、ZR、GA3含量降低,促使IAA/ABA在诱导生根期快速增大,通过相关激素的调控,使插穗向有利于促进生根的生理状态转变。     

高速公路边坡植被恢复植物选择与组合设计研究——以新河高速公路为例

采用乡土植物、地带性植物优先原则,物种多样性原则进行恢复植物物种选择,同时结合植物群落的演替理论、植物种群的生态位理论、植被恢复的美学理论等对其恢复植物进行组合设计,提出了新河高速公路路域边坡及相似类型的裸露边坡地区在植被恢复中可供选择利用的5种植物组合：①苦楝（或香樟）＋美丽胡枝子＋葛藤＋坡柳＋狗牙根组合;②山黄麻＋清香木＋含羞草＋皱叶狗尾草＋地果＋牛筋草组合：③黄金间碧玉＋棕叶芦＋椭圆叶木蓝＋皱叶狗尾草＋掌叶鱼黄草＋竹节草组合;④五节芒＋绢毛木蓝＋委陵菜（或草玉梅）＋稗＋密花葛（或粉葛、苦葛）＋山麦冬组合;⑤羊蹄甲（或苹婆）＋香花崖豆藤（或多花崖爬藤）＋地果＋积雪草（或杠板归）组合。     

Bio-efficacy of two bacterial insecticide strains ofBacillus thuringiensis as a biological control agent in comparison with a nematicide,nemacur, on certain parasitic nematoda

A greenhouse experiment was conducted to determine the possibility use of commercial bacterial pathogen insecticide,Bacillus thuringiensis, as biocontrol agent againstMeloidogyne javanica andTylenchulus semipenetrans nematodes.The obtained results indicate that the two strains ofB. thuringiensis suppressed the total nematode populations and eggmasses of the two nematode genera. Also, the two strains ofBacillus remarkably reduced the percentages of hatchability of eggs of the two nematode genera. SAN 415Bacillus strain was highly effective than Dipel strain and surpassed it in this respect, but it was approximately similar to the standard nematicide Nemacur.

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Zusammenfassung Es wurde ein Gewächshaus-Versuch durchgeführt zur Untersuchung der Möglichkeit,Meloidogyne javanica undTylenchus semipenetrans (Nematoda) mittelsBac. thuringiensis biologisch zu bekämpfen. Die Ergebnisse zeigen, daßB. thuringiensis die Eigelege und die Populationsdichte beider Nematoden stark reduzierte. Auch wurde die Schlüpflähigkeit der Eier beider Nematodenarten durch Anwendung der zweiBacillus-Präparate deutlich verringert. Der SANBacillus-Stamm zeigte höhere, Wirkung als Dipel und entsprach etwa dem Standard-Nematizid Nemacur.

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With 2 tables     

Effect of intercroppingAsparagus scandens with sour organe seedling in comparison with nematicidal and root exudate treatments onTylenchulus semipenetrans larvae

The intercropping ofAsparagus scandens with sour orange seedlingsCitrus aurantium, gave a significant reduction onTylenchulus semipenetrans larvae in soil after two months of inoculated pots as compared with uninoculated one. There was no significant difference with vydate treatment under green house conditions. There was no adverse effect on plant's fresh and dry weighths for all treatments. The laboratory experiment revealed that there was a positive correlation between concentration, exposure time and toxic effect of root extract ofA. scandens onT. semipenetrans larvae, since 100% mortality were obtained after 24 and 96 h of exposure to the concentrations of 15 and 50 g/100 ml distilled water, respectively.With 2 tables     

Maturation and plant recovery from embryogenic cells of Japanese larch: Effect of abscisic acid in relation to their morphology

Two embryogenic cell lines characterized by different morphology and color, white and red, were obtained from an immature zygotic embryo of Japanese larch (Larix leptolepis Gord.). Mature somatic embryos with cotyledons and regenerated plants were obtained from both cell lines. However optimal concentration of abscisic acid (ABA) for maturation varied depending on morphology of ECs. From the white ECs which intermingled with somatic embryos of very early stage, mature somatic embryos were induced on maturation medium containing 50 μM of ABA. On the other hand, mature somatic embryos with cotyledons were observed from the red ECs which consisted of somatic embryos of more developed stage on hormone-free medium or 0.1 μM ABA containing-medium.     

室内观赏植物对甲醛、苯和TVOC污染的响应

采用密闭熏气法模拟居室装修后的甲醛、苯和总挥发性有机物(TVOC)污染环境,对10组常见室内观赏植物进行熏气处理,以熏气8h后植物单位叶面积吸污量及外观形态变化作为指标,评价了不同植物组合对污染物的净化效果和抗性能力。结果显示,被测植物组合在一定程度上均可有效吸收甲醛、苯和TVOC,不同植物组合在熏气处理后表现出不同程度的受害反应,综合分析结果表明库拉索芦荟+君子兰、龙血树+金边瑞香、白鹤芋+孔雀竹芋、天竺葵+长寿花、绿宝石喜林芋+春羽对甲醛、苯和TVOC的综合净化能力和抗性较好,且差异显著(p0.05)。     

Relationship between plant hormone level excreted by ectomycorrhizal fungi and growth of poplar NL-895

To explore the effects of plant hormones levels excreted by ectomycorrhizal (ECM) fungi on the growth of poplars, Populus × euramericana cv. NL-895 seedlings were inoculated with nine species of ECM fungi. We investigated the status of ectomycorrhizal formation and the effects of these fungi on poplar growth, and using the HPLC method, we measured the contents of four kinds of plant hormones, indole acetic acid (IAA), zeatin (Z), gibberellin (GA) and abscisic acid (ABA) in both the culture filtrate and the mycelium of these fungi. The results showed that the effects of nine ECM fungi on the growth of poplar NL-895 varied. The inoculated seedlings, whether or not obvious mycorrhizas were developed, grew better than those non-inoculated ones. All nine ectomycorrhizal fungi excreted the four plant hormones, but at different levels. The hormone contents in culture filtrate were higher than that in mycelium, which showed a definite relationship with poplar growth. Significantly, correlation analysis suggested the height and stem diameter of the poplar were positively correlated with zeatin contents in the mycelium, and were negatively correlated with the levels of ABA or IAA in the mycelium. __________ Translated from Scientia Silvae Sinicae, 2008, 44(7): 43–49 [译自:林业科学]