Ozone,acidic precipitation,and soil Mg impacts on soil and loblolly pine seedling nutrient status after three growing seasons

Recent studies have suggested that the growth of loblolly pine (Pinus taeda L.) has declined in the southeastern United States, possibly due to acidic deposition and air pollutants, especially under conditions of low nutrient availability. Consequently, the potential for individual and synergistic impacts of O₃, acidic precipitation, and soil Mg status on the nutrient status of loblolly pine seedlings and soil was investigated over a 3 yr study period. Thirty-six open top chambers equipped with a rainfall exclusion/addition system were utilized to administer three levels of O₃ (subambient, ambient, or twice ambient) and two acidic precipitation treatments (pH 3.8 or 5.2) to seedlings growing in 24-L plastic pots containing soil having either 35 or 15 mg kg^?1 of exchangeable Mg. Each chamber contained 36 pots, and each treatment combination was replicated six times for a total of 1296 individual pots. After three seasons, throughfall and foliar nutrition data indicated that foliar leaching was not accelerated by increasing the acidity of precipitation from pH 5.2 to 3.8 and that increasing O₃ did not act to exacerbate foliar leaching. Further, foliar nutrient concentrations were not significantly affected by precipitation pH or O₃ treatments. Soil and soil solution data also indicate no accelerated soil leaching associated with chronic acidic precipitation. Differences in soil Mg treatments were reflected in soil solution and seedling Mg contents, but the 15 mg kg^?1 soil Mg treatment was not sufficiently low enough to induce Mg deficiency in the seedlings.     

Influence of O3, rainfall acidity,and soil Mg status on growth and ectomycorrhizal colonization of loblolly pine roots

Root biomass, length, and branching frequency, and number and type of mycorrhizal short roots were determined for loblolly pine seedlings grown at two levels of soil Mg and exposed to chronic levels of O₃ and simulated acidic rainfall. Seedlings were planted in a sandy loam soil having approximately 15 or 35 mg kg^?1 Mg and were exposed to subambient; ambient, or twice ambient concentrations of O₃ in open top chambers from May through October. Seedlings also received ambient amounts of simulated rainfall at pH 3.8 or 5.2. Root biomass, length, and branching frequency were not significantly affected by O₃, rainfall acidity, or soil Mg treatments. Seedlings grown in the subambient O₃ treatment had a greater number of short roots infected with mycorrhizae than seedlings grown in ambient or twice ambient O₃ treatments, but trends were not statistically significant. Increasing rainfall acidity and soil Mg concentration resulted in a significantly (P = 0.07) greater number of mycorrhizal short roots, due primarily to an increased occurrence of one corraloid mycorrhizal type. Results suggest that mycorrhizal fungi differ in their response to O₃, rainfall acidity, and soil Mg status, and suggest that mycorrhizal infection is more sensitive than seedling root growth to O₃, acidic rainfall, and soil Mg status.     

Effects of acidic precipitation and acidity on soil microbial processes

Effects of soil acidity on microbial decomposition of organic matter and transformation of N in an acid forest soil were investigated. In the oak-leaf-amended pH-adjusted acid soils, CO₂ production in 14-and 150-day preincubated samples decreased by about 6 and 37%, respectively. In the control (unamended) acidified soils, reductions in CO₂ production of 14% in 14-day preincubated samples and of 52% in 150-day samples were observed. Ammonia formation in the pH-adjusted acid soil was about 50% less than in the naturally acid soil. Increased rates of ammonification and nitrification were observed in the pH-adjusted neutral soil. Little autotrophic and heterotrophic nitrifying activity was detected in naturally acid and acidified forest soils. The rate of denitrification was rather slow in acid soils, and at greater acidities N₂O was the predominant end product. The abundance of N-fixing free-living bacteria was very low in acidic and acidified forest soils, and N gains by asymbiotic bacterial fixation in an acid forest ecosystem may be insignificant. These results suggest that further acidification of acid forest soils by addition of H₂SO₄ or by acid precipitation may lead to significant reductions in the leaf litter decomposition, ammonification, nitrification, and denitrification and thus reduce nutrient recycling in the forest ecosystem.     

Growth,physiology, and nutrition of loblolly pine seedlings stressed by ozone and acidic precipitation: A summary of the ropis-south project

Previously published results from a multidisciplinary research program, Response of Plants to Interacting Stress (ROPIS), initiated by the Electric Power Research Insitute are summarized here. The overall objective of the ROPIS program was to develop a general mechanistic theory of plant response to air pollutants and other stresses. Direct and indirect phytotoxic impacts of O₃ combined with induced deficiencies of key nutrients as a consequence of acidic deposition are important components in many of the hypotheses used to explain reported declines in forest growth. In order to address these concerns as they relate to loblolly pine (Pinus taeda L.) growth and develop a greater level of mechanistic understanding of stress response, a study was formulated with two major objectives: (i) over a multi-yr period evaluate the role of loblolly pine genotype in governing loblolly growth response to O₃; and (ii) determine the underlying physiological and edaphic basis for loblolly growth response to O₃, acidic precipitation, and soil Mg status. An open-top chamber facility located at Oak Ridge, TN provided controlled O₃ exposure for the genotype screening study (1986–88) and controlled O₃ exposure and rainfall exclusion and addition for the O₃-rainfall acidity-soil Mg interaction study (1987–89). A variety of experimental techniques, measurements, and statistical procedures were used over a 4-yr period to quantify various aspects of plant growth, physiology, and soil-plant relationships. Results from the genotype screening study indicate that although family-specific O₃ effects were observed at the end of the first year, no statistically significant O₃ effects on diameter, height, or total biomass were evident at the end of three growing seasons; nor were any significant O₃-family interactions found. In the interaction study, rainfall acidity and soil Mg level had only minimal affects on seedling growth and physiology. Ozone exposure produced significant changes in many variables, the most important being a net retention of carbon in above-ground biomass and a subsequent reduction in carbon allocation to the root system. This change could have important longterm implications for the tree's ability to obtain water and nutrients, maintain important rhizosphere organisms, and achieve a level of vigor that protects against disease and insect attack.     

The influence of acid precipitation and ozone on nitrogen nutrition of young loblolly pine

Field grown loblolly pine (Pinus taeda L.) seedlings from two half-sibling families were exposed to three levels of acid precipitation and four levels of O₃ in open top chambers at Auburn, AL. At the end of one growing season, dry weight and total N accumulation of seedlings was directly related. to rainfall acidity, possibly indicating a fertilizer response in the N deficient soil. Increasing O₃ levels elicited an increase in N content of permanent tissues that was not related to a dry weight response. The origin of this N was believed to be increased internal translocation associated with enhanced premature needle senescence observed at higher O₃ levels.     

Interseeded legumes with loblolly pine. I. Effect of phosphorus and legume variety on pine seedling establishment and mortality

A study was conducted to determine the effects of legume companion crops and phosphorus (P) fertilizer on the growth and survival characteristics of newly established loblolly pine (Pinus taeda L.) seedlings. At 12 months post‐establishment, there was no legume effect (P>0.05) on root lateral development or ropting depth for pine seedlings. Likewise, there was no legume effect (P>0.05) on aboveground biomass production of pine seedlings. Partridge pea (Cassia fasciculata Michx.) had a negative effect (P<0.05) on pine seedling total root biomass compared to other treatments. Pine seedlings grown with legumes allocated less resources to root development compared to pine seedlings grown alone. Pine seedlings grown alone or with cowpea [Vigna unguiculata (L.) Walp.] were subject to less mortality (P<.05) than seedlings grown with alyceclover [Alysicarpus vaginalis (L.) DC] or partridge pea. Phosphorus fertilization enhanced dry matter (DM) yield of legumes but had no effect on rooting depth of pine seedlings during the first 12 months of growth. After 12 months post‐establishment, the most pronounced effect of P fertilization was that of increased nitrogen (N) content of leaf, stem, and roots of pine seedlings. Native, annual herbaceous grass biomass in the control plots (no legume) reduced the amount of soil N to below pre‐planting levels, while soil N levels in all legume plots exceeded pre‐trial levels.     

石灰用量对酸性土壤pH值及有效养分含量的影响

采用室内培养法,设置不施生石灰和生石灰用量0.3、0.9、1.8、2.4、4.8 g/kg,共6个用量梯度,研究不同生石灰用量对酸性土壤pH值动态变化、有效养分含量的影响及土壤pH值与有效养分含量之间的相关性。结果表明,生石灰的施入,可以显著提高土壤pH值,改善土壤酸度。培养到第90 d,生石灰用量4.8、2.4、1.8g/kg处理较对照分别提高了2.88、1.16和0.74个pH单位。施用生石灰对土壤全氮含量影响不大,但对土壤无机氮影响显著。生石灰用量在0~2.4 g/kg范围内,土壤硝态氮含量随生石灰用量的增加而显著增加,增幅为12.4%~146.8%,当生石灰用量2.4 g/kg时,土壤硝态氮含量显著降低。土壤铵态氮的变化趋势则刚好相反,随着生石灰用量的增加而减少;土壤有效磷含量随着生石灰用量的增加先升高后降低;对于土壤速效钾来说,当生石灰用量0.9 g/kg,其含量随着石灰用量的增加而显著降低,降幅为2.9%~21.7%。施用生石灰可以显著提高土壤有效Ca含量,且随生石灰用量的增加而显著增加,增幅为32.3%~543.0%。生石灰的施用显著降低了土壤有效Fe、Mn、Cu、Zn的含量,且当生石灰用量≥2.4 g/kg时,土壤有效Mn、Zn含量均已处于极其缺乏的状况。土壤pH值与土壤全氮、铵态氮、速效钾、有效Fe、Mn、Cu、Zn呈显著线性负相关,与有效Ca呈极显著线性正相关,与土壤硝态氮、有效磷和有效Mg则符合二次函数,各相关系数均达到极显著水平。土壤养分与土壤酸度有着较好的相关性,在施用石灰改良酸性土壤时,要特别注意其施用量及土壤有效Mn、Zn等微量元素的及时补充。     

生物有机肥对黄瓜幼苗生长、基质环境以及幼苗根系特征的影响

以黄瓜为材料,以不施生物有机肥为对照(CK),以添加生物有机肥2%、4%、8%、15%(质量比)为处理,研究不同生物有机肥用量对黄瓜幼苗植株形态指标、基质养分和微生物数量、及根系特征参数的影响,并对所有参数进行主成分分析。结果表明,播种25d后,8%处理促进植株生长效果最显著,15%处理促进植株生长效果次之。所有测试期内基质速效磷、速效钾、铵态氮均随生物有机肥施用量的增加而增加;15%处理在播种10、18和25d后显著增加了脲酶活性,且在播种10d和25d后显著增加了蔗糖酶活性;15%处理在播种18d和25d后增加细菌和真菌效果最显著;8%处理在播种25d后增加根系鲜质量和干质量效果最显著,且增加总根长、根体积、根表面积效果最佳,通过主成分分析表明,在播种25d后8%处理综合得分最高。因此8%生物有机肥施用量是显著促进穴盘黄瓜幼苗生长和维持基质质量的最优施用量,为基质穴盘黄瓜育苗中生物有机肥合理施用提供参考。     

Changes in aggregate stability,nutrient status,indigenous microbial populations,and seedling emergence,following inoculation of soil withNostoc muscorum

The potential of the N₂-fixing cyanophyteNostoc muscorum for improving the aggregate stability of a poorly structured silt loam soil was studied in a greenhouse experiment. Inoculum rates were 1.61×10⁵ cells g^-1 soil dry weight (low rate) and 4.04×10⁵ cell g^-1 soil dry weight (high rate), approximately equivalent to a field application of 2 and 5 kg ha^-1 cells dry weight, respectively.N. muscorum numbers had increased 8-fold (low rate) and 10-fold (high rate) by 300 days after inoculation, indicating not only survival but proliferation. Increases in soil polysaccharides, determined as soil carbohydrate C, were 2.96–3.49 time the values in the non-inoculated soils and aggregate stability had incrased by an average of 18% on day 300. Inoculation withN. muscorum also had a pronounced effect on soil chemical and biological properties, with total C increasing by 50–63% and total N increasing by 111–120%. Increases in the soil indigenous microbial population were recorded, with numbers of bacteria 500, fungi 16, and actinomycetes 48 times the non-inoculated values on day 300 in the high-rate soil. The emergence of lettuce seedlings (Lactuca sativa var. Saladin) in undisturbed inoculated 300-day soils was 56% (low rate) and 52% (high rate) higher than in non-inoculated soils. However, homogenising soils and irrigating (to smulate ploughing and surface crusting) significantly reduced this increase in both treatments, although emergence in inoculated soils was still greater by 45% (low) and 24% (high). It is recommended that inoculated soils be left undisturbed prior to planting. The effects ofN. muscorum on soil physical, chemical, and biological properties indicate the possible benefits of cyanobacteria as soil inoculants, not only for the improvement of soil aggregate stability but also as a means of improving seedling emergence.     

Effects of magnesium and potassium soil applications on yields and leaf nutrient concentrations of red raspberries and on soil analyses

Abstract

Magnesium and potassium applications did not affect yield of Willamette raspberries in a study conducted between 1974 and 1977 in British Columbia. Potassium increased berry size but only in one of the three years that berry size was recorded. Leaf Mg, K, Ca and P concentration plateaus were established using biweekly sampling in 1977 and comparison with literature data of studies on a similar soil and with the same raspberry cultivar. New cane leaf K was relatively stable between August 10 and September 25, Mg between July 10 and August 15 and P between September 1 and 20. A relatively stable concentration plateau for Ca occurred between July 10 and August 5 but was not as consistent from year to year as were Mg, K and P concentration plateaus. Correlations between soil nutrient extraction values and corresponding leaf nutrient concentrations (during the established concentration plateaus) were found for both Mg and K, with Mg being better than K.     

Chemistry of bulk precipitation throughfall,soil water and stream water in a small catchment in Devon,England

Monthly mean concentrations of potassium, calcium, sodium, magnesium chloride and nitrate-nitrogen were determined from samples of bulk precipitation, throughfall, soil water and streamflow collected weekly between April 1975 and September 1977 in a small catchment in Devon, England. Soil water concentrations are compared with the analysis of exchange capacity in composite soil samples. Rain contributed much sodium and chloride to total catchment output, and potassium was selectively enriched in throughfall. Calcium and magnesium concentrations were high in soil water samples and on the soil exchange complex.     

Effect of plant growth-promoting bacteria and soil compaction on barley seedling growth, nutrient uptake, soil properties and rhizosphere microflora

Inoculants are of great importance in sustainable and/or organic agriculture. In the present study, plant growth of barley (Hordeum vulgare) has been studied in sterile soil inoculated with four plant growth-promoting bacteria and mineral fertilizers at three different soil bulk densities and in three harvests of plants. Three bacterial species were isolated from the rhizosphere of barley and wheat. These bacteria fixed N₂, dissolved P and significantly increased growth of barley seedlings. Available phosphate in soil was significantly increased by seed inoculation of Bacillus M-13 and Bacillus RC01. Total culturable bacteria, fungi and P-solubilizing bacteria count increased with time. Data suggest that seed inoculation of barley with Bacillus RC01, Bacillus RC02, Bacillus RC03 and Bacillus M-13 increased root weight by 16.7, 12.5, 8.9 and 12.5% as compared to the control (without bacteria inoculation and mineral fertilizers) and shoot weight by 34.7, 34.7, 28.6 and 32.7%, respectively. Bacterial inoculation gave increases of 20.3–25.7% over the control as compared with 18.9 and 35.1% total biomass weight increases by P and NP application. The concentration of N and P in soil was decreased by increasing soil compaction. In contrast to macronutrients, the concentration of Fe, Cu and Mn was lower in plants grown in the loosest soil. Soil compaction induced a limitation in root and shoot growth that was reflected by a decrease in the microbial population and activity. Our results show that bacterial population was stimulated by the decrease in soil bulk density. The results suggest that the N₂-fixing and P-solubilizing bacterial strains tested have a potential on plant growth activity of barley.     

Effects of weathering state of coarse‐soil fragments on tree‐seedling nutrient uptake

Fine earth accumulated within the weathering fissures of the coarse‐soil fraction (particles > 2 mm), so called “stone‐protected fine earth”, can provide a high short‐term nutrient release by cation exchange. It is thus hypothesized that unweathered gneiss particles cannot provide plants with exchangeable‐cation nutrients and that biological weathering is needed to include silicate‐bound nutrients into biochemical cycles. In a microcosm experiment, ectomycorrhizal Norway spruce (Picea abies) seedlings were grown on either weathered or unweathered paragneiss coarse‐soil fragments under natural hydraulic and climatic boundary conditions. A nutrient solution containing N, P, and K was added, however Mg and Ca could only be taken up from the coarse‐soil substrate. Solutes in drainage were analyzed during the experiment; plant nutrient uptake was determined after the experiment ended. Solute dynamics depended on the weathering state of the substrates: unweathered gneiss showed high initial Mg and Ca fluxes that diminished strongly afterwards, whereas weathered gneiss showed a much more gradual and sustainable release of these cations. Patterns in dissolved organic C and sulfate drainage indicated that the internal pores of weathered gneiss fragments contained organic material most likely as a result of living spaces from microorganisms. Plant biomass did not differ between treatments, however Mg content was higher in seedlings grown on weathered gneiss. Nutrient budgets demonstrated that the “stonesphere” of weathered gneiss can act as a quasi‐constant nutrient source whereas unweathered gneiss only provided high initial nutrients fluxes. In nutrient‐depleted, acidified fine‐earth environments, the coarse‐soil fraction may therefore act as a retreat for nutrient‐adsorbing tissues and as a buffer for nutrient shortages.     

Effects of simulated throughfall pH and sulfate concentration on a deciduous forest soil

A model deciduous forest soil (Schaffenaker loamy sand) was treated for 8 mo in the greenhouse in 25 cm reconstructed columns with simulated throughfall at pH 6.0 or 4.0, and SO₄ ^2? levels of 12.8 or 24.8 mg L^?1. Red oak seedlings grown in the microcosms showed no growth or foliar element response to the treatments. Sulfate loading had a greater impact on soil and leachate chemistry than pH. Higher available soil P in the A, horizon was associated with the pH 6.0 and high SO₄ ^2?2 treatment combination. High SO₄ ^2? loading also reduced exchangeable K⁺ in the A_1?. Other soil horizons were unaffected by either treatment. Leachate chemistry was not significantly altered by througfall pH, but significantly greater export of Na⁺, Ca²⁺, Mg²⁺, Al³⁺, and NO₃ ^?, and lower SO₄ ^2? loss, occurred with low SO₄ ^? input. Comparatively half as much NO₃ ^? loss was associated with high SO₄ ^2? deposition. The high rate of NO₃ ^? leaching appeared responsible for greater equivalent mass loss of cations from the low SO₄ ^2? treatment. Leachate removal of SO₄ ^2? approximated input after 8 mo. The capacity of this soil to adsorb SO₄ ^2? appeared relatively limited in the absence of normal element cycling. The sulfate component of simulated deciduous forest throughfall was shown to have a potentially greater impact than pH on ion leaching from forest soil. Additional consideration of the role of SO^2? ₄ deposition, in the context of throughfall rather than incident precipitation, is warranted in studies of acidic deposition effects on internal forest soil processes.     

广西蔗区土壤肥力和叶片养分状况调查研究

广西是我国第一大甘蔗产地,了解广西蔗区土壤肥力及叶片养分丰缺状况,可对广西蔗区提出针对性的施肥建议.对广西南宁、崇左、来宾、百色、柳州、河池、贵港、玉林和防城港等主要甘蔗产区进行土壤和叶片调研,各采集了110份样品进行养分测定分析.结果表明:(1)广西蔗区调研土壤pH值平均为5.21,pH值<4.5的强酸性地块占比为4...     

Effects of weed control and fertilization on soil carbon and nutrient pools in an exotic pine plantation of subtropical Australia

Purpose  

Soil carbon (C) and nutrient pools under different plantation weed control and fertilizer management treatments were assessed in a 7-year-old, F₁ hybrid (Pinus elliottii var. elliottii × Pinus caribaea var. hondurensis) plantation in southeast Queensland, Australia. This research aimed to investigate how early establishment silvicultural treatments would affect weed biomass, soil C, nitrogen (N) and other nutrient pools; and soil C (δ¹³C) and N isotope composition (δ¹⁵N) to help explain the key soil processes regulating the soil C and nutrient pools and dynamics.     

Dissolved organic carbon and nitrogen in precipitation,throughfall, soil solution,and stream water of the tropical highlands in northern Thailand

Dissolved organic matter (DOM) is important for the cycling and transport of carbon (C) and nitrogen (N) in soil. In temperate forest soils, dissolved organic N (DON) partly escapes mineralization and is mobile, promoting loss of N via leaching. Little information is available comparing DOC and DON dynamics under tropical conditions. Here, mineralization is more rapid, and the demand of the vegetation for nutrients is larger, thus, leaching of DON could be small. We studied concentrations of DOC and DON during the rainy seasons 1998–2001 in precipitation, canopy throughfall, pore water in the mineral soil at 5, 15, 30, and 80 cm depth, and stream water under different land‐use systems representative of the highlands of northern Thailand. In addition, we determined the distribution of organic C (OC) and N (ON) between two operationally defined fractions of DOM. Samples were collected in small water catchments including a cultivated cabbage field, a pine plantation, a secondary forest, and a primary forest. The mean concentrations of DOC and DON in bulk precipitation were 1.7 ± 0.2 and 0.2 ± 0.1 mg L^–1, respectively, dominated by the hydrophilic fraction. The throughfall of the three forest sites became enriched up to three times in DOC in the hydrophobic fraction, but not in DON. Maximum concentrations of DOC and DON (7.9–13.9 mg C L^–1 and 0.9–1.2 mg N L^–1, respectively) were found in samples from lysimeters at 5 cm soil depth. Hydrophobic OC and hydrophilic ON compounds were released from the O layer and the upper mineral soil. Concentrations of OC and ON in mineral‐soil solutions under the cabbage cultivation were elevated when compared with those under the forests. Similar to most temperate soils, the concentrations in the soil solution decreased with soil depth. The reduction of OC with depth was mainly due to the decrease of hydrophobic compounds. The changes in OC indicated the release of hydrophobic compounds poor in N in the forest canopy and the organic layers. These substances were removed from solution during passage through the mineral soil. In contrast, organic N related more to labile microbial‐derived hydrophilic compounds. At least at the cabbage‐cultivation site, mineralization seemed to contribute largely to the decrease of DOC and DON with depth, possibly because of increased microbial activity stimulated by the inorganic‐N fertilization. Similar concentrations and compositions of OC and ON in subsoils and streams draining the forested catchments suggest soil control on stream DOM. The contribution of DON to total dissolved N in those streams ranged between 50% and 73%, underscoring the importance of DOM for the leaching of nutrients from forested areas. In summary, OC and ON showed differences in their dynamics in forest as well as in agricultural ecosystems. This was mainly due to the differing distribution of OC and ON between the more immobile hydrophobic and the more easily degradable hydrophilic fraction.     

Salinity induced effects on the nutrient status of soil,corn leaves and kernels

Abstract

The effect of salinity in inducing soil macro and micronutrient deficiencies that can decrease crop growth was evaluated in a corn (Zea mays L.) field located in east central Wyoming. In this study water soluble Na was found to be a better predictor of salinity than pH and other cations. Soil saturated paste extracts had electrical conductivities that were negatively correlated with soil total K, Cu, Fe, and Mn. Total N, NO₃‐N, PO₄‐P, Zn, pH, and water soluble Na, Ca, and Mg of the soil were positively correlated with EC. Significant positive relationships existed between soil EC and N, P, Mo, and Zn, and negative relationships with K, Cu, Fe, and Mn of corn leaves and kernels. Concentrations of nutrients in the kernels were positively correlated with corresponding nutrient concentrations in the leaves and with AB‐DTPA extractable soil nutrients. The analysis of variance of EC data indicated that soil samples possessing high salinity were higher in pH and contained significantly higher soluble Na, Ca and Mg, total N, N0₃‐N, PO₄‐P, and Zn and significantly lower Mn compared to samples having low salinity. The kernel weight per cob and plant height were significantly reduced as salinity increased.     

菌根化育苗对玉米生长和养分吸收的影响

【目的】丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)侵染作物根系形成菌根共生体系对于作物吸收磷具有重要作用,但该结果大多来源于室内受控试验,有限的田间试验因环境条件、试验材料与接种技术等差异致使AMF菌剂应用效果不一。本研究通过玉米菌根化育苗和田间移栽,分析了接种AMF对玉米生长、养分吸收、籽粒产量及养分含量的影响,以期推进菌根技术的实际生产应用。【方法】以自交品系玉米B73为供试作物,于2018年5月至10月在北京市延庆区进行了田间试验。田间小区设置基施磷(+P)和不施磷(–P)处理。供试AMF为Rhizophagus irregularis Schenck&Smith BGC AH01。玉米种子催芽后,分别播入加入AMF菌剂(+M)和菌剂过滤液(–M)的育苗钵内,培养两周后移栽至田间。玉米在田间条件下生长至拔节期时,使用便携式光合仪测定叶片光合速率与气孔导度,取样测定地上部与根部干重和养分元素含量,同时测定菌根侵染率;在玉米完熟期取样,测定籽粒百粒重、籽粒产量及养分含量。【结果】无论田间施磷与否,接菌植株根系的菌根侵染强度和丛枝丰度均显著高于不接菌植株。不施磷情况下,+M处理显著提高了玉米根系干重,玉米生长的菌根依赖性(163.7%)显著高于施磷情形(124.1%)。–P–M处理玉米叶片的光合速率和气孔导度显著低于其他3个处理。–P+M处理玉米叶片的光合参数、玉米地上部和根部磷含量与+P+M均无显著差异。与–P–M处理相比,–P+M显著提高了玉米籽粒产量和百粒重,同时也提高了籽粒中锌、锰、镁等矿质养分的含量,且与+P+M处理相比均无显著差异。【结论】玉米幼苗接种AMF后再移栽到田间,可以显著提高拔节期玉米根系的菌根侵染率,促进玉米地上部和根部对磷及锌、锰和镁的吸收,进而促进玉米的生长,提高籽粒产量和养分含量。本试验条件下,菌根化育苗可以达到与施磷同样的效果,在保障作物不减产的前提下减少磷肥施用量。