紫茎泽兰叶片凋落物对入侵地4 种草本植物的化感作用

为了明确紫茎泽兰叶片凋落物对入侵地草本植物的化感作用, 研究了不同浓度紫茎泽兰叶片凋落物水提液对入侵地草本植物多年生黑麦草、白三叶、辣子草和紫花苜蓿种子萌发和幼苗生长的影响, 同时结合土培试验研究了叶片凋落物在入侵地土壤中的化感作用。结果表明, 除多年生黑麦草外, 水提液对其他3 种草本植物种子萌发均产生了显著的化感抑制作用, 且水提液的浓度越高抑制效果越强; 低浓度水提液对紫花苜蓿和辣子草的幼苗生长存在显著化感促进作用, 高浓度的水提液对除多年生黑麦草外的其他3 种植物幼苗的生长存在显著化感抑制作用, 水提液对多年生黑麦草幼苗生长的影响不显著; 土壤中按照50 g·kg^-1的比例添加叶片凋落物后, 显著抑制了白三叶的生长, 而添加活性炭后, 白三叶的单株生物量相对于未添加活性炭的处理增加71.25%, 进一步证实叶片凋落物在土壤中的化感抑制作用。这说明外来入侵植物紫茎泽兰可能通过其叶片凋落物在入侵地土壤中降解, 释放化感物质, 抑制伴生植物的种子萌发和幼苗生长, 为自身创造有利的生长环境, 实现其成功入侵和扩张。     

Plant growth inhibition by the water extract of a crude oil

The water extract of a light Nigerian crude oil had pronounced effects on the growth, metabolism and development of radish (Raphanus sativus) plants. In addition to hydrocarbons (ca. 7 mg l^?1) the extract contained phenols (ca. 0.6 mg l^?1), carbonyl compounds, and carboxylic acids. Although seed germination was virtually unaffected, the growth of both above- and below-ground parts was significantly inhibited when the plants were watered with the extract rather than with well water. In addition, the onset of flowering was significantly delayed in the extract-treated plants, and the number of plants which ever flowered was reduced. Significantly increased respiration was observed in leaf tissue of the extract-treated plants, but photosynthetic carbon fixation was not significantly affected. The extract appeared to elicit effects similar to those caused by other forms of environmental stress, such as infections.     

The potential application of the endophyte Phomopsis liquidambari to the ecological remediation of long-term cropping soil

A broad-spectrum endophyte, Phomopsis liquidambari, was used as a microbial agent to determine the effects of rapid litter decomposition on soil phenolic compounds dynamics, the soil microbial community balance and plant growth. The litter decomposition ratio was closely correlated with lignin degradation. The soil phenol concentration increased with the acceleration of litter decomposition after the first 30 days and later decreased to below the initial level. Based on denaturing gradient gel electrophoresis (DGGE) analysis, soil bacteria, especially gram-negative bacteria that have the potential to degrade aromatic compounds, were found in high abundance when the soil phenol concentration was high. When the phenolic concentration decreased, soil fungi increased in abundance. With fungal application, seed germination significantly increased to 69.87% and seedling growth was enhanced. Rapid litter decomposition by Pho. liquidambari initially led to higher releases of phenolic allelochemicals, which led to the enrichment of soil gram-negative bacteria. In addition, increased soil nutrients and temporarily higher concentrations of phenolics from litter decomposition strengthen seedling growth, suggesting that the endophytic fungus Pho. liquidambari is a suitable candidate for remediation of long-term cropping soil.     

Earthworm-mediated maternal effects on seed germination and seedling growth in three annual plants

Many ecological studies have pointed out maternal effects in plants and shown that plant maternal environment influences germination of their seed and subsequent seedling growth. However, few have tested for maternal effects induced by soil macroorganisms. We tested whether two earthworm species (Aporrectodea caliginosa and Lumbricus terrestris) trigger such maternal effects on seed germination and seedling growth of three plant species (Veronica persica, Poa annua and Cerastium glomeratum). Our results show that, through maternal effects, A. caliginosa enhanced seed germination (V. persica and P. annua) and seedling growth (C. glomeratum and P. annua) while L. terrestris reduced seed germination only in V. persica. In some cases, the increase in germination rates of seeds produced in the presence of earthworms was associated with a reduction of nitrogen content in seeds. These results show that earthworms induce maternal effects in plants and that the size and direction of these effects depend on the combination of plant and earthworm species.     

Effects of urease inhibitors on nitrification in soils

The effects of 10 urease inhibitors on nitrification in soils were studied by determining the effects of 10 and 50 parts/10⁶ (soil basis) of each inhibitor on the amounts of nitrate and nitrite produced when soils treated with ammonium sulfate (200 μg of ammonium N/g of soil) were incubated (30°C) under aerobic conditions for 14 days. The urease inhibitors used (catechol. hydroquinone, p-benzoquinone, 2,3-dimethyl-p-benzoquinone, 2,5-dimethyl-p-benzoquinone. 2,6-dimethyl-p-benzoquinone. 2,5-dichloro-p-benzoquinone, 2,6-dichloro-p-benzoquinone. sodium p-chloromercuribenzoate, and phenylmercuric acetate) were those found most effective in previous work to evaluate more than 130 compounds as soil urease inhibitors. Their effects on nitrification were compared with those of three compounds patented as soil nitrification inhibitors (N-Serve. AM. and ST).Most of the urease inhibitors studied had little effect on nitrification when applied at the rate of 10 μg/g of soil. but had marked inhibitory effects when applied at the rate of 50 μg/g of soil. None inhibited nitrification as effectively as N-Serve. but phenylmercuric acetate inhibited nitrification more effectively than did AM or ST when applied at the rate of 10 μg/g of soil. Phenylmercuric acetate, 2,5-dimethyl-p-benzoquinone, and 2,6-dimethyl-p-benzoquinone had very marked effects on nitrification when applied at the rate of 50 μg/g of soil.     

Inhibition of nitrification process by seed oil from Acrocomia totai palm tree

Nitrification inhibitory properties of plant substances offer potential benefits for agricultural applications. In this study, hexane-extracted seed oil, and 10, 20, and 30 mg/pot dry powder of seed exocarp and mesocarp from Acrocomia totai were applied in a quick nitrification bioassay for 24 or 50 hr, as well as for 4 weeks laboratory soil incubation, to investigate their effects on nitrification process. Results showed that applied oil concentrations significantly reduced nitrification rates. The extent of inhibition was increased with the oil concentrations from 5 to 25 µl in both experiments. The exocarp and mesocarp powders also inhibited nitrification, but it was not as high as oil-induced inhibition. Analysis of oil fatty acids showed that oil consisted of 71%, 26%, and 3% of saturated, monounsaturated, and polyunsaturated fatty acids, respectively. This suggests that fatty acids or some unknown ingredients in crude oil could be the responsible inhibiting compound.     

Effects of soil,grass and legume root extracts on heterotrophic bacteria,nitrogen mineralization and nitrification in soil

The effects of root extracts of four grasses and two legumes and extracts of soils supporting these plants on the growth of five strains of heterotrophic soil bacteria, and on the rate of nitrogen mineralization and nitrification were measured in culture and in soil. All the root extracts inhibited the growth in culture of the five bacteria by 9–98 per cent. The legume-soil and one of the grass-soil extracts did not inhibit bacterial growth. Only two of the grass-soils, Andropogon lectorum and Pennisetum purpureum markedly inhibited the five bacteria. Incubation of soils with extracts of grass roots or grass-soil increased the rates of nitrogen mineralization and nitrification and incubation with legume root and soil extracts increased the rates of nitrogen mineralization and nitrification even further.     

Use of cyanobacterial polysaccharides to promote shrub performances in desert soils: a potential approach for the restoration of desertified areas

The importance of cyanobacterial polysaccharides of biological soil crusts in sand surface stabilization and soil nutrient retention has been long acknowledged. However, the role of cyanobacterial polysaccharides as a source of nutrition to vascular plants in crusted areas is ignored. In this study, the chemical composition of the polysaccharide synthesized by Phormidium tenue and the effects of its presence on seed germination and seedling metabolism of the shrub Caragana korshinskii were investigated. The crude polysaccharide synthesized by P. tenue was composed of 15 % protein and 58 % carbohydrate and showed the presence of 12 different types of monosaccharides. The addition of the polysaccharide significantly (P?<?0.05) increased seed germination and metabolic activity of the seedling of the shrub C. korshinskii. The optimal concentration for vigor index, root length, root vigor, and total N and P contents was 10 mg/L polysaccharide; for the germination rate, nitrate reductase activity, carbohydrate content, chlorophyll, and Mg²⁺ content, the optimal was 60 mg/L polysaccharide, while for K⁺ and Ca²⁺ contents, photosynthetic efficiency and superoxide dismutase activity was 120 mg/L. The presence of the polysaccharide increased seed germination rate, ion uptake, and photosynthetic activity by affecting the electron transport chain and decreased oxidative damage by eliminating reactive oxygen species in C. korshinskii, thus promoting shrub performance in crusted desert areas.     

Root-mediated allelopathic interference of bhringraj (Eclipta alba L.) Hassk. on peanut (Arachis hypogaea) and mung bean (Vigna radiata)

The root mediated allelopathic interference of Eclipta alba infested soil on growth, physiological parameters and antioxidant enzyme activity was conducted on Arachis hypogaea L. and vigna radiata L. It was found that rhizosphere soil significantly reduced the germination percentage, seedling growth and dry biomass depending upon the species sensitivity. The germination inhibition was correlated with membrane deterioration as proved by a strong electrolyte leakage, increase in malondialdehyde (MDA) and H₂O₂ content. The physiological parameters like chlorophyll content, photosynthetic rate (P_n), intercellular CO₂ concentration (C_i), stomatal conductance (G_s), and transpiration (E) also showed significant reduction in E. alba infested soil and non-significant increase in leaf temperature (L_t) of two test species. The test seedlings have circumvented the allelochemicals stress, by both significant decrease and non-significant increase in the antioxidant activities in E. alba infested soil in contrast to control soil. Rhizosphere soil contained significantly higher amount of water-soluble phenolics as the putative allelochemicals, which were vanillic acid, benzoic acid, ferulic acid, and p-coumaric acid. The study concluded that rhizosphere soil exerts an allelopathic influence on peanut and mung bean by releasing water soluble phenolic acids as putative allelochemicals in soil.     

DCD 在不同质地土壤上的硝化抑制效果和剂量效应研究

通过硝化抑制剂抑制土壤硝化作用是实现作物铵硝混合营养和提高氮肥利用率的重要途径之一。本试验采用室内模拟的方法, 在人工气候室(25 ℃)黑暗培养条件下, 应用新疆石灰性土壤研究了不同剂量的双氰胺(dicyandiamide, DCD)在砂土、壤土、黏土3 种不同质地土壤中对土壤硝态氮、铵态氮转化的影响及DCD 的剂量效应和硝化抑制效果。处理30 d 内, 各剂量DCD 处理对砂土的硝化抑制率为96.5%~99.4%(平均值为98.3%), 在黏土上为66.9%~85.6%(平均值为77.6%), 在壤土上为49.3%~79.4%(平均值为67.7%), 总体硝化抑制率表现为砂土>黏土>壤土。在砂土上DCD 的剂量效应不明显, DCD 用量从纯氮的1.0%增加到7.0%时, 土壤中硝态氮含量仅增加1.9~10.7 mg·kg^-1(培养30 d 时); 而在壤土和黏土中, 土壤硝态氮含量随DCD 浓度的增加而显著下降, 存在明显剂量效应。这说明施用DCD 可显著抑制新疆石灰性土壤的硝化作用过程, 在砂土、壤土、黏土中DCD 的最佳浓度分别为纯氮用量的6.0%、7.0%和7.0%, 并在培养30 d 内发挥显著作用。     

A standardized method for the determination of the intrinsic carbon and nitrogen mineralization capacity of natural organic matter sources

A new method was developed for the simultaneous determination of the intrinsic carbon and nitrogen mineralization capacity of organic matter (OM) sources by means of an aerobic incubation in suspension. The proposed method is based on determination of the oxygen consumption, monitored indirectly via pressure measurement, and on determination of nitrogen mineralization, through the periodical measurement of NH₄⁺-N, in a liquid suspension of the samples. The suspension is standardized in terms of nutrient composition and pH, and well-controlled incubation conditions that can be enforced as desired. This method rules out the effect of soil conditions and thus reflects the intrinsic properties of the OM. The method is faster and more reproducible than soil incubation tests that are currently used. In such a system, it is important that nitrification is inhibited to avoid oxygen consumption by nitrifiers and prevent the production of gaseous nitrogen compounds. Two nitrification inhibitors, N-allylthiourea and 2-ethynylpyridine, were tested at different concentrations for three reference samples, soil, bark and manure. Both inhibitors completely suppress NO₃⁻ formation without suppressing the heterotrophic microbial activity, thus allowing the correct determination of the oxygen uptake rate (OUR). When nitrification inhibitors were added, nitrous oxide could not be detected anymore in the gas phase of the system, which confirms that nitrification was inhibited and indicates that denitrification and nitrifier denitrification activity was negligible. N mineralization rates were determined by frequent sampling from the liquid phase of the system without disturbing the pressure measurement during the incubation and subsequent determination of NH₄⁺-N. The method presented allows for the reliable and relatively easy and cheap, simultaneous determination of carbon and nitrogen mineralization rates for a wide range of OM sources.     

有机无机肥配施对酸性菜地土壤硝化作用的影响

通过室内培养和田间试验, 研究了有机无机肥配施对酸性菜地土硝化作用的影响。培养试验条件为60%土壤最大持水量和25 ℃。 结果表明,土壤硝化作用模式为指数方程,延滞期10天。与纯化肥处理（NPK）相比,鲜猪粪配施无机肥（FPM+NPK）和猪粪堆肥配施无机肥（CPM+NPK）均能降低土壤硝化势和氨氧化潜势,猪粪堆肥配施无机肥还能增加土壤微生物量碳、 氮。鲜猪粪配施无机肥和猪粪堆肥配施无机肥处理在硝化培养和田间试验期间N2O释放量均没有差异,但硝化培养期间鲜猪粪配施无机肥的N2O释放量显著低于纯化肥处理,田间试验期间猪粪堆肥配施无机肥的N2O释放量显著低于纯化肥处理。培养试验结束后的土壤pH值与土壤硝化势间,以及硝化培养期间N2O累积释放量与土壤硝化势间均存在显著正相关关系。本研究表明, 有机无机肥配施显著影响土壤硝化作用以及硝化培养期间和田间N2O释放。     

3,5-二甲基吡唑对铵态氮硝化及作物生长的影响

采用室内培养试验和盆栽试验相结合的方法,以春小麦和水稻为供试作物,初步探讨不同用量的3,5-二甲基吡唑(DMP)对土壤铵态氮硝化、作物产量及氮素利用的影响。结果表明,在本试验条件下,施用占尿素N量0.6%～1.0%的DMP(折合0.8～0.9g/g,干土),可显著抑制土壤硝化作用的进行,其抑制效应随抑制剂用量的增加逐渐增强。与对照单施尿素相比,施用1.0%DMP可使土壤NH4+-N含量提高30%以上,NO3--N含量降低20%左右。施用占尿素N量0.8%～1.0%的DMP对春小麦产量影响不大,但能显著提高水稻产量和两种作物的氮肥表观利用率,促进植株体内的氮素向子粒中的转移。与等量DCD(双氰胺)比较,DMP处理的水稻子粒粗蛋白含量和氮肥表观利用率显著提高,但产量差异不显著。     

苦豆子和披针叶黄华种子萌发和幼苗生长对干旱胁迫的响应

以采集于河西走廊中部荒漠边缘的苦豆子(Sophora alopecuroides L.)和披针叶黄华(Thermopsis lanceolate L.)种子为试验材料, 以不同渗透势PEG-6000 溶液模拟干旱条件, 研究了2 种植物种子萌发和幼苗生长对干旱胁迫的响应特征。研究结果显示, 随着干旱胁迫程度的加剧, 2 种植物种子吸胀速率、萌发率、萌发指数、活力指数、苗高、根长和组织饱和含水量等指标均表现出明显降低趋势, 而幼苗干重、根干重和根冠比均呈先升后降趋势。2 种植物种子萌发对干旱胁迫均较为敏感, 苦豆子和披针叶黄华种子能够萌发的最低渗透势阈值分别为-0.65 MPa 和-0.42 MPa。2 种植物因干旱胁迫未能萌发的种子复水后萌发率均较高。分析认为, 2 种植物种子萌发和幼苗生长对干旱胁迫的响应特征对幼苗的成功定植和种群的自然更新具有重要生态学意义, 但在人工栽培时保证土壤墒情应是保障建植成功的关键措施。     

Laboratory evaluation of dicyandiamide as a soil nitrification inhibitor

Abstract

Laboratory studies to evaluate dicyandiamide (DCD) as a soil nitrification inhibitor showed that it is considerably more effective than several compounds that have been patented or proposed as fertilizer amendments for retarding nitrification of fertilizer nitrogen (N) in soil, but is considerably less effective than 2‐ethynylpyridine, nitrapyrin (N‐Serve), etridiazole (Dwell), 3‐methylpyrazole‐l‐carboxamide (MPC), or 4‐amino‐l,2,4‐triazole (ATC). Other findings in studies reported were as follows: a) DCD is more effective for inhibiting nitrification of ammonium‐N than of urea‐N; b) the effectiveness of DCD as a nitrification inhibitor is markedly affected by soil temperature and soil type and is limited by the susceptibility of DCD to leaching; c) DCD has very little, if any, effect on urea hydrolysis, denitrification, or seed germination in soil; d) products of DCD decomposition in soil (guanylurea and guanidine) have little, if any, effect on nitrification compared with DCD; e) in the absence of leaching, the persistence of the inhibitory effect of DCD on nitrification decreases with increase in soil temperature from 10 to 30°C, but the inhibitory effect of 50 μg DCD g^‐1 soil is substantial even after incubation of DCD‐treated soils at 20 or 30°C for 24 weeks.     

Phytotoxic effects of wheat extracts on a herbicide-resistant biotype of annual ryegrass (Lolium rigidum)

Thirty-nine wheat accessions were used to evaluate their extract phytotoxicity against annual ryegrass (Lolium rigidum Gaud.). Aqueous extracts of wheat shoot residues significantly inhibited the germination and root growth of a biotype of annual ryegrass resistant to herbicides of acetyl CoA carboxylase inhibitors (group A), acetolactate synthase inhibitors (B), photosystem II inhibitors (C), and tubulin formation inhibitors (D). The germination of the herbicide resistant (HR) biotype was inhibited by 3-100%, depending upon the wheat accession. The phytotoxic effects on ryegrass root growth ranged from 12% stimulation to 100% inhibition, compared to a control. The germination and root growth of a herbicide-susceptible (HS) biotype of annual ryegrass were also inhibited by the wheat extracts, with germination inhibited by 4-100%, and root growth by 19-100%. Bioassays with two known wheat allelochemicals showed that p-coumaric acid and propionic acid significantly inhibited the growth of both HR and HS biotypes of annual ryegrass. The two compounds completely inhibited the root growth of HR ryegrass at concentrations greater than 5.0 mM. In comparison with p-coumaric acid, propionic acid was more inhibitory to seed germination, shoot, and root growth of both ryegrass biotypes. The root growth of the HR biotype was more sensitive when exposed to wheat extracts, to p-coumaric acid, and to propionic acid. The results suggest that residues of certain wheat cultivars with strong allelopathic potential could provide a nonherbicidal alternative for the management of herbicide-resistant weed species.     

Effect of application rate of a nitrification inhibitor,dicyandiamide (DCD), on nitrification rate,and ammonia-oxidizing bacteria and archaea growth in a grazed pasture soil: An incubation study

Purpose

Dicyandiamide (DCD) has been used commercially in New Zealand to reduce nitrate leaching and N₂O emissions in grazed pastures. However, there is a lack of information in the literature on the optimum rate of DCD to achieve the environmental benefits while at the same time reducing the cost of the technology. The objective of this study was to determine the effect of DCD application rate on its effectiveness to inhibit ammonia oxidizer growth and nitrification rate in a grazed pasture soil.

Materials and methods

The soil was a Templeton silt loam (Immature Pallic Soil; Udic Haplustepts) collected from Lincoln University Research Dairy Farm with a mixed pasture consisting of perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) and was incubated alone (control) or with cow urine at 700 kg N/ha with 6 rates of DCD [0, 2.5, 5, 7.5, 10 (applied twice), 15 and 20 kg/ha] in incubation vessels. The incubation vessels were placed randomly in an incubator with a constant temperature of 12 °C. During 112 days of incubation, soil subsamples were taken at different time intervals to measure the concentrations of NO₃ ^?-N and NH₄ ⁺-N and the amoA gene copy numbers of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA).

Results and discussion

DCD applied at all the different rates inhibited nitrification in urine-treated soils, but the effectiveness increased with DCD application rate. In addition, AOB growth and the amounts of nitrate-N in the soil were significantly related to the application rate of DCD. However, AOA population abundance showed no relationship to the application rate of DCD. The DCD rate at which the AOB growth rate and nitrate-N concentration were halved (effective dosage that causes 50 % reduction in nitrification rate, or ED₅₀) was about 10 kg DCD/ha.

Conclusions

These results suggest that DCD applied at relatively low rates still slowed down the nitrification rate, and the current recommended rate of 10 kg DCD/ha for DCD use in New Zealand grazed pastures would result in a 50 % reduction in nitrification rate in this soil. The actual rate of DCD application used would depend on the cost of the product and the environmental and agronomic benefits that would result from its use.     

Net nitrification rate and presence of Nitrosospira cluster 2 in acid coniferous forest soils appear to be tree species specific

The impact of four coniferous tree species and their corresponding soil factors on N transformation rates and presence of ammonia-oxidising bacteria (AOB) was studied in an acid pine forest soil (Appelscha, The Netherlands). Pine soil had a relatively low net nitrification rate, while spruce, fir and larch soils showed high net nitrification rates. 16S rRNA and amoA sequences were only found in soils with high nitrification rates and belonged solely to Nitrosospira cluster 2. We conclude that tree species, possibly through their effects on soil C/N ratios, determines the presence of Nitrosospira cluster 2. Whenever AOB are present, however, the AOB community composition appears to be similar.     

亚热带松林中强酸性土壤自养和异养硝化作用的研究

The occurrence of nitrification in some acidic forest soils is still a subject of debate. Identification of main nitrification pathways in acidic forest soils is still largely unknown. Acidic yellow soil (Oxisol) samples were selected to test whether nitrification can occur or not in acidic subtropical pine forest ecosystems. Relative contributions of autotrophs and heterotrophs to nitrification were studied by adding selective nitrification inhibitor nitrapyrin. Soil NH₄⁺-N concentrations decreased, but NO₃^--N concentrations increased significantly for the no-nitrapyrin control during the first week of incubation, indicating that nitrification did occur in the acidic subtropical soil. The calculated net nitrification rate was 0.49 mg N kg^-1 d^-1 for the no-nitrapyrin control during the first week of incubation. Nitrapyrin amendment resulted in a significant reduction of NO₃^--N concentration. Autotrophic nitrification rate averaged 0.28 mg N kg^-1 d^-1 and the heterotrophic nitrification rate was 0.21 mg N kg^-1 d^-1 in the first week. Ammonia-oxidizing bacteria (AOB) abundance increased slightly during incubation, but nitrapyrin amendment significantly decreased AOB amoA gene copy numbers by about 80%. However, the ammonia-oxidizing archaea (AOA) abundance showed significant increases only in the last 2 weeks of incubation and it was also decreased by nitrapyrin amendment. Our results indicated that nitrification did occur in the present acidic subtropical pine forest soil, and autotrophic nitrification was the main nitrification pathway. Both AOA and AOB were the active biotic agents responsible for autotrophic nitrification in the acidic subtropical pine forest soil.     

林(果)粮间作中树木枯落叶对小麦发芽期和苗期的化感效应

树木枯落叶对作物的化感效应是建设林(果)粮间作复合体系所要考虑的重要问题之一。本研究采用陕西关中地区常见的12种树木枯落叶经室内混土分解培养后的不同浓度水浸提液作为培养基质,进行室内小麦种子萌发和生长试验,探讨了林(果)粮间作树种枯落叶对小麦的化感效应。结果表明:(1)杜仲处理和元宝枫处理促进了小麦幼苗苗高生长,提高了CAT活性,却降低了根系活力;泡桐处理和杨树处理促进了小麦种子萌发和幼苗生长;花椒处理抑制了小麦幼苗根长、生物量、CAT活性和根系活力;核桃处理在高浓度时明显抑制了小麦发芽速度指数、根长、CAT活性和叶绿素含量;梨树处理对小麦发芽速度指数、根长和叶绿素含量表现为低促高抑;苹果处理提高了小麦发芽速度指数、幼苗苗高、生物量和叶绿素含量;柿树处理和枣树处理抑制了小麦幼苗根长和生物量;桃树处理和杏树处理对小麦种子萌发表现为低促高抑。(2)统计学主成分分析表明,整体上对小麦发芽和生长起明显促进作用的树种是泡桐、苹果和杨树,其次是杏树和元宝枫;整体上对小麦发芽和生长起到明显抑制作用的树种是柿树、核桃和枣树,其次是花椒和桃树;而梨树起到低促高抑的作用,杜仲则相反。