烟草丛枝菌根(AM)研究进展

丛枝菌根真菌（Arbuscular mycorrhizas fungi）作为生物调节剂、生物肥料和生物防治剂，在持续农业和自然生态中的作用越来越受到人们的重视。丛枝菌根真菌不仅能增强烟草对矿质元素的吸收、提高烟草抗逆性、增强抗病性、改善烟草根际微环境，而且能提高其产量和改善品质。本文从烟草丛枝菌根真菌资源、丛枝菌根对烟草的主要作用、丛枝菌根对植烟土壤主要作用3个方面简要综述了烟草丛枝菌根的研究进展。     

接种丛枝菌根真菌对玉米秸秆降解的影响

为研究接种丛枝菌根真菌(AMF)对玉米秸秆降解的影响,利用玉米秸秆为材料制成网袋,采用盆栽试验,以玉米(Zea mays L.)为宿主植物,分别接种Glomus intraradices和Glomus mosseae,于30,40,50,60d时收获后分析玉米秸秆降解量和C、N释放量,并运用Olson的指数模型Bt/B0=e-kt计算玉米秸秆及C、N的降解系数。数据表明,接种G.intraradices、G.mosseae显著提高了玉米秸秆降解量和降解系数,与不接种处理相比,分别高出5.21%,6.26%。C释放量、碳素降解系数也明显增加。接种处理减少了N释放量,且氮素降解系数随时间延长而下降。接种处理玉米秸秆的C、N降解系数不同直接反映了其降解速度的差异,进而影响了玉米秸秆的C/N,使秸秆更易于降解。研究结果显示出丛枝菌根真菌在生态系统氮循环中具有重要意义。     

氮肥高效施用在低碳农业中的关键作用

低碳农业是我国集约化农业发展的必然趋势。深入理解氮肥高效施用是实现低碳农业的关键,可以更加明确如何集成优化农业管理措施增加产量、减少农田生态系统碳排放、提高土壤固碳效应,综合实现固碳、减排、增产的低碳农业发展目标。本文概述了低碳农业评价指标的三个阶段性研究特点,从田间温室气体排放的综合温室效应拓展为涵盖固碳效应的净温室效应,再拓展为涵盖生命周期评价碳排放的综合净温室效应以及兼顾作物产量的温室气体强度。提出了如何利用当季作物试验来估算农田生态系统净碳收支、结合生命周期评价当季作物综合净温室效应和单位产品温室气体强度的方法。按照现阶段低碳农业的评价指标,以我国稻–麦轮作生态系统集约化生产的低碳农业模式为案例,解析氮肥施用在低碳农业各组成包括作物产量、固碳效应、CH₄和N₂O排放、农业措施碳排放中的重要作用,明确氮肥高效施用在农田生态系统综合净温室效应和温室气体强度中的关键作用,从而实现低碳农业可持续发展。     

保护性耕作对温室效应的影响

农业是非常重要的温室气体排放源,而不合理的农田管理措施强化了农田排放源的特征,同时弱化了吸收汇的作用。保护性耕作对温室效应的影响来自两方面,一方面是免耕减少了农田CO2排放,对CH4和N2O排放的影响不明确;另一方面是秸秆还田以后部分秸秆C以气体形式释放进入大气,增加了农田CO2、CH4排放,但秸秆还田相对其他用途提高了土壤固碳潜力,减少了总的温室气体排放量。通过耕作与秸秆管理对温室气体排放资料的整理分析,指明保护性耕作是一种有利于减少温室效应的农田管理措施,为保护性耕作的温室效应研究提供借鉴。     

不同菌根类型森林净初级生产力对降水的响应

基于全球森林数据库,建立了包括全球森林的菌根类型、净初级生产力(NPP)和年平均降水量等指标的新数据库,分析了6种菌根类型森林的各组分NPP对年平均降水量变化的响应。结果表明,在所有菌根类型的森林中,森林总NPP、地上NPP和树叶NPP都随年平均降水量的升高呈现上升的趋势;地下NPP、树木主干NPP以及细根和粗根NPP则因菌根类型的不同,对年平均降水量的增加呈现出降低或升高的趋势。从全球森林总NPP随年平均降水量变化的响应程度来看,年平均降水量对丛枝菌根+外生菌根类型森林总NPP变异的解释率最高,为31.79%;而对外生菌根+内外生菌根类型森林的解释率则最低,仅为4.85%。可见,菌根影响着森林NPP对降水量变化的响应程度,表明菌根类型是预测降水变化对森林NPP影响的重要指标。     

Quantifying greenhouse gas emissions from soils: Scientific basis and modeling approach

Abstract

Global climate change is one of the most important issues of contemporary environmental safety. A scientific consensus is forming that the emissions of greenhouse gases, including carbon dioxide, nitrous oxide and methane, from anthropogenic activities may play a key role in elevating the global temperatures. Quantifying soil greenhouse gas emissions is an essential task for understanding the atmospheric impacts of anthropogenic activities in terrestrial ecosystems. In most soils, production or consumption of the three major greenhouse gases is regulated by interactions among soil redox potential, carbon source and electron acceptors. Two classical formulas, the Nernst equation and the Michaelis–Menten equation, describe the microorganism-mediated redox reactions from aspects of thermodynamics and reaction kinetics, respectively. The two equations are functions of a series of environmental factors (e.g. temperature, moisture, pH, Eh) that are regulated by a few ecological drivers, such as climate, soil properties, vegetation and anthropogenic activity. Given the complexity of greenhouse gas production in soils, process-based models are required to interpret, integrate and predict the intricate relationships among the gas emissions, the environmental factors and the ecological drivers. This paper reviews the scientific basis underlying the modeling of greenhouse gas emissions from terrestrial soils. A case study is reported to demonstrate how a biogeochemical model can be used to predict the impacts of alternative management practices on greenhouse gas emissions from rice paddies.     

Geographical and plant genotype effects on the formation of arbuscular mycorrhiza in Avena sativa and Avena nuda at different soil depths

We have examined the influence of host plant genotype and geographical characters on the vertical distribution pattern of arbuscular mycorrhiza associated with Avena. The degree of colonization of oat roots at different soil depths (0–10, 10–20, 20–30, 30–40, 40–50 cm) was compared among three habitats from lower to higher altitude and six different cultivars in one specific habitat. Altitude had no impact on the percentage of root length colonized by mycorrhiza. However, oats growing at the higher altitudes formed more abundant arbuscules and vesicles within their roots. Plant genotype showed a significant influence on the percentage of root length colonized and abundance of arbuscules and vesicles, and there was much greater colonization of naked oat than of husk oat (common oat). The vertical distribution pattern of mycorrhizal root length was similar in terms of geographical and genotypic aspects, with the most extensive root colonization occurring in the topsoil and decreasing with increasing soil depth. However, the percentage of root length colonized by arbuscular mycorrhizal fungi (AMF) remained at about 20% colonization at a depth of 40–50 cm. Intraradical structures also showed a decreasing trend with increasing soil depth. The results suggest that an AMF “gene bank” may persist in the subsoil, and this may facilitate the ecological restoration of degraded agricultural areas.     

旱作水稻西瓜间丛枝菌根菌丝桥诱导水稻磷转运蛋白的表达及对磷吸收的影响

采用中间隔网的土培根箱试验,对旱作水稻或/和西瓜接种丛枝菌根真菌(简称AM真菌)幼套球囊霉(Glomus etunicatum Becker&Gerdemann),研究了旱作水稻/西瓜间形成菌丝桥并诱导水稻磷酸盐转运蛋白OsPT11的表达和对磷吸收的影响。结果表明:(1)根箱两侧均未接种AM真菌时,旱作水稻和西瓜根系均不形成菌根,水稻根系的磷酸盐转运蛋白OsPT11也不表达。(2)西瓜侧接种AM真菌时,西瓜与水稻间形成的菌丝桥引起水稻菌根的形成,并诱导水稻根系磷酸盐转运蛋白OsPT11表达。(3)菌丝桥侵染和直接接种侵染对旱作水稻和西瓜形成丛枝菌根能达到相同的效果,旱作水稻和西瓜的菌根侵染率分别为80%以上和70%以上。(4)在旱作水稻/西瓜间作系统中,当接种AM真菌时,水稻和西瓜根际有效磷含量显著高于对照处理,水稻地上部全磷含量降低,而西瓜地上部全磷含量升高。     

Implications of climate change for tillage practice in Australia

The world is experiencing climate change that in no way can be considered normal, and the challenge that this brings to agriculture is twofold. The first challenge relates to the continuing need to reduce greenhouse gas emissions that generate the changes to climate. Australia's National Greenhouse Gas Inventory estimates that agriculture produces about one-quarter of Australia's total greenhouse gas emissions (including land clearing). The main gases emitted are carbon dioxide, methane, and nitrous oxide. These gases are derived from high-value components within the agricultural production base, so reducing emissions of greenhouse gases from agriculture has the potential to provide production and financial benefits, as well as greenhouse gas reduction. Methane essentially derives from enteric fermentation in ruminants. Nitrous oxide and carbon dioxide, on the other hand, are strongly influenced, and perhaps even determined by a range of variable soil-based parameters, of which the main ones are moisture, aerobiosis, temperature, amount and form of carbon, organic and inorganic nitrogen, pH, and cation exchange capacity. Tillage has the potential to influence most of these parameters, and hence may be one of the most effective mechanisms to influence rates of emissions of greenhouse gases from Australian agriculture. There have been substantial changes in tillage practice in Australia over the past few decades – with moves away from aggressive tillage techniques to a fewer number of passes using conservative practices. The implications of these changes in tillage for reducing emissions of greenhouse gases from Australian agriculture are discussed.

The second challenge of climate change for Australian agriculture relates to the impacts of climate change on production, and the capacity of agriculture to adapt where it is most vulnerable. Already agriculture is exposed to climate change, and this exposure will be accentuated over the coming decades. The most recent projections for Australia provided by the CSIRO through the Australian Climate Change Science Programme, indicate that southern Australia can expect a trend to drying due to increased temperatures, reduced rainfalls, and increased evaporative potentials. Extremes in weather events are likely also to become more common. We anticipate that climate change will become an additional driver for continued change in tillage practice across Australia, as land managers respond to the impacts of climate change on their production base, and governments undertake a range of activities to address both emissions reduction and the impacts of climate change in agriculture and land management.     

Effect of inoculation with AM fungi on lead uptake,translocation and stress alleviation of Zea mays L. seedlings planting in soil with increasing lead concentrations

In this work, a greenhouse experiment, arranged in a randomized block design 2 × 6 factorial with six replicates, was conducted to estimate the effect of inoculation with arbuscular mycorrhizal fungi (AMF) on lead uptake, location and stress attenuation in mycorrhizal Zea mays L. seedlings. Treatments were the mycorrhizal inoculation (+M) or non-mycorrhizal inoculation (?M) and six lead concentrations (0, 50, 100, 200, 500 and 1000 μg/g) to soil. The results showed that AM fungal inoculation could attenuate the oxidative stress of lead to Z. mays seedlings. The higher height, basal diameter and biomass of seedlings were found in mycorrhizal Z. mays seedlings growing in the soil with increasing lead concentrations. Moreover, superoxide dismutase (SOD) activity was higher than that of non-inoculated seedlings. AMF increased accumulation of lead in the root system. In the presence of 200, 500 and 1000 μg/g lead, there were higher lead concentrations in roots of mycorrhizal seedlings than in non-mycorrhizal seedlings. Lead was identified to dominantly deposit in the hyphal wall, the hyphal inner chambers, the hyphal inner-chamber membranes and the vacuole inner-chambers membrane. It is, therefore, hypothesized that lead stress can be decreased through the AM fungal cell. The ability of arbuscular mycorrhiza immobilizing lead can alleviate the phytotoxicity of lead to Z. mays seedlings.     

Phosphorus uptake and growth of barley as affected by soil temperature and mycorrhizal infection

A glasshouse study was conducted to investigate the effects of soil temperatures of 20, 15 and 10°C on growth and phosphorus (P) uptake of barley (Hordeum vulgare L. cv. Galleon) inoculated with Glomus intraradices Schenck & Smith. Vesicular‐arbuscular (VA) mycorrhiza formation was significantly reduced as the soil temperature decreased. Plant growth depression due to temperature stress was more pronounced in mycorrhizal plants than in non‐mycorrhizal plants. The lower the soil temperature, the higher was the root‐shoot ratio. The ratio was also higher in non‐mycorrhizal plants than in mycorrhizal plants. Concentration of P in roots was influenced by mycorrhiza. Significant interaction between mycorrhiza and soil temperature was observed for root dry matter and specific P uptake (P uptake per unit weight of root). Compared to non‐mycorrhizal plants, specific P uptake in mycorrhizal plants was higher.     

干旱胁迫下丛枝菌根真菌对玉米生理生化特性的影响

在土壤有效磷含量较高的条件下,研究了接种丛枝菌根真菌（arbuscular mycorrhizal fungus, AMF）对不同水分处理梯度（田间最大持水量的70%、 45%和20%）条件下玉米生长和抗旱性的影响。结果表明,在三种不同水分处理条件下,接种AMF显著提高了玉米植株地上部的生物量,且对玉米地上部、 地下部全磷含量有显著提高作用。水分胁迫显著降低了玉米叶片水势,增加了玉米叶片脯氨酸、 丙二醛、 过氧化物酶和过氧化氢酶含量,而不同水分梯度条件下接种AMF均显著提高了植株叶片水势,降低了脯氨酸含量,提高了叶片保护酶（过氧化物酶和过氧化氢酶）活性从而减少丙二醛的积累,减轻植物叶片膜脂过氧化的伤害。由此说明,接种AMF在土壤有效磷含量较高的条件下能够与玉米根系形成良好的共生关系,提高玉米的抗旱性。     

牛粪堆肥方式对温室气体和氨气排放的影响

为明确堆肥过程中温室气体和氨气排放规律以及产生的总温室效应,在云南省大理州开展堆肥试验,并以奶牛粪便为试验材料,研究了农民堆肥(FC)、覆盖堆肥(CC)、覆盖-翻堆堆肥(CTC)和覆盖通风-翻堆堆肥(CATC)4种堆肥方式对温室气体和氨气排放的影响。结果表明:覆盖通风-翻堆堆肥(CATC)可提高堆肥腐熟度,有效降低CH4和N_2O排放,但并没降低CO2和NH_3排放;与农民堆肥(FC)相比,覆盖堆肥(CC)的CH4排放量增加了48.7%,而N2_O和NH3排放量与农民堆肥(FC)基本一致;覆盖-翻堆堆肥(CTC)虽然提高了腐熟度,但CH_4、CO_2和NH_3排放量较大;堆肥结束时,4个处理的总温室效应分别为25.6、32.9、38.1及18.0 kg/t;温度与CH_4、CO_2、N_2O和NH_3排放速率均极显著相关,pH值显著影响N_2O和NH_3的排放。因此,覆盖通风-翻堆堆肥(CATC)不仅能够满足堆肥产品的腐熟度要求,而且能够减少总温室效应,再加上其操作简便,能够在生产中推广应用。     

碳中和目标下畜牧业低碳发展路径

推动实现碳中和是可持续发展的关键,减少温室气体排放是推动实现碳中和的根本。作为国际低碳行动的引领者和开拓者,中国承诺将力争于2030年前实现二氧化碳排放达峰,努力争取2060年前实现碳中和。农业生产活动是中国温室气体的第三大排放源,其中畜牧业贡献了农业非二氧化碳温室气体排放的80%,是农业主要温室气体排放源。因此,畜牧业的低碳减排对实现碳中和至关重要。该研究从动物呼吸、动物胃肠道发酵、粪污处理等直接排放源和饲料生产加工、设备设施能源消耗、动物产品加工及运输等间接排放源系统综述了畜牧业的温室气体排放,从源头、过程和末端全方位阐述了畜牧业的低碳减排途径。源头减排包括动物的肠道发酵管控、饲料成分升级、粗粮与精粮比例的调整、使用添加剂以及选育优质畜禽品种,过程减排包括畜舍环境及设备能耗调控、畜禽管理方式优化以及精准畜牧业的应用,末端减排包括粪污处理以及畜产品供应链的优化。该研究对碳中和目标下的畜牧业低碳发展路径进行了综述,以期为推动实现碳中和,促进畜牧业绿色可持续发展提供参考。     

Meta分析生物质炭对中国主粮作物痕量温室气体排放的影响

该文采用Meta分析方法定量分析生物质炭输入对中国主粮作物痕量温室气体的影响,研究可为农田痕量温室气体减排提供有效的途径.结果表明相对于不施加生物质炭,生物质炭输入对甲烷吸收/排放并无显著影响,而甲烷排放在不同耕作和施氮情况下发生显著变化.旋耕和不施氮情况下施加生物质炭分别显著提高稻田甲烷排放达30%和46%,而在翻耕和施氮的情况下施加生物质炭可减少稻田甲烷排放达9%和10%.生物质炭输入分别可显著减少主粮作物氧化亚氮、全球增温潜势(global warming potential,GWP)及温室气体排放强度(greenhouse gas intensity,GHGI)达41%、18%及25%.不同土地利用类型、耕作类型、生物质炭施用量及生物质炭类型均可显著影响农田氧化亚氮、GWP和GWPI.合理的管理主粮作物生物质输入可为减少温室气体排放做出贡献,建议生物质炭与施氮和翻耕2种农作措施相结合,施加小于10 t/hm2及碳氮比(C/N)低于80的生物质炭,以利于主粮作物综合温室效应的减排.     

Water status and stomatal behaviour of cowpea,Vigna unguiculata (L.) Walp,plants inoculated with two Glomus species at low soil moisture levels

The effects of arbuscular mycorrhizal (AM) fungi on water status and stomatal behaviour of cowpea, Vigna unguiculata (L.) Walp. cv. B89-504, under water-stressed conditions in the greenhouse were studied. The 3 × 2 experimental design included two levels of mycorrhizal colonisation (Glomus mosseae, Glomus versiforme) and non-mycorrhizal control treatment and two soil moisture levels (well-watered pots and pots allowed to dry). Relative water content and leaf water potential values were higher in well-watered mycorrhizal and non-mycorrhizal plants than in water-stressed mycorrhizal and non-mycorrhizal plants. AM species had no significant effect on leaf osmotic potential, stomatal conductance and leaf transpiration in both well watered and water-stressed plants. The values of stomatal conductance and leaf transpiration were high during the vegetative stage and low during the flowering stage. These responses which can be related to the age of the plant suggest that mycorrhizal colonisation did not affect stomatal closure of cowpea plants during water stress. The decrease in plant growth and dry matter production in both mycorrhizal and non-mycorrhizal plants shows that drought resistance in cowpea was unaffected by mycorrhiza in the vegetative phase.     

冻融交替对土壤CO2及N2O释放效应的研究进展

在秋冬交替和冬春交替时期高纬度地区和高海拔生态系统表层土壤常有冻融交替频繁发生。由于冻融交替作用通过改变土壤水热性质而对土壤物理、化学、生物学特性产生效应。冻结通常导致土壤团聚体破裂、微生物细胞及细根死亡,释放出活性较高的有机物,增强随后融解的土壤的反硝化和呼吸活性,从而影响土壤生物、生物化学过程以及生物地化循环。已有对苔原、泰加林等北极和亚北极生态系统的研究表明,土壤冻融交替次数、冻融极端温度、土壤水分、土壤团聚体结构变化等对CO2和N2O的释放通量影响较为显著,一般在冻融的最初几个循环温室气体排放会增加,随后会降至一个较为稳定的水平。目前,冻融循环变化背景下的温室气体排放研究主要是针对北方高纬度地区,而且对冻融交替影响土壤温室气体排放的机理研究也不够。我国面积广大的青藏高原高海拔地带在全球增温背景下,轻微增温会导致季节性冻土表层冻融交替次数增加,甚至冻土季节消失,加强全球增温背景下我国高山亚高山季节性冻土生态系统效应和过程研究,特别是土壤暖化导致的温室气体排放变化通量和变化机理的研究,对揭示全球变化的区域效应以及高海拔生态系统的管理都具有重要作用。     

秸秆还田对免耕稻田温室气体排放及土壤有机碳固定的影响

秸秆还田影响免耕稻田土壤固碳潜力,相应地改变了温室气体的排放,从而影响秸秆还田后稻田土壤固碳减排对减缓全球变暖的贡献。通过研究不同油菜秸秆还田量（0、3000、4000kg·hm-2和6000kg·hm-2）对免耕稻田温室气体（CO2、CH4和N2O）排放和土壤碳固定的影响,评估秸秆还田后温室气体增排的综合增温潜势对稻田固碳减缓全球变暖的贡献的抵消作用。结果表明,秸秆还田显著提高CO2和N2O排放,降低CH4排放,显著提高土壤有机碳含量,有效地提高土壤碳固定,从而有效地提高稻田土壤碳固定对温室气体增排的温室效应抵消作用。随着秸秆还田量的增加,稻田土壤固碳减缓全球变暖的贡献相应增加,因此必须考虑免耕稻田秸秆还田量的问题,以有效发挥免耕稻田秸秆还田的固碳潜力和降低温室气体的排放。     

Influence of bacteria on growth and phosphorus nutrition of mycorrhizal corn

Com plants were grown in a non‐sterile soil in a greenhouse or in hydroponic culture in a growth chamber. We studied the influence of chitinolytic, pectinolytic, P‐solubilizing bacterial isolates, and a collection of bacterial strains on the development of native vesicular‐arbuscular mycorrhizal (VAM) populations, colonization of roots by the VAM fungus Glomus fasciculatum and their influence on the phosphorus (P) nutrition and growth of plants. As compared with VAM native control, the most potent stimulants for root colonization of soil‐grown plants by the VAM native population was a strain of Agrobacterium radiobacter and isolate H30. All bacteria used significantly supressed shoot fresh weight of mycorrhizal plants (‐13% up to ‐37%), with the exception of Agrobacterium. Under hydroponic conditions, the P‐solubilizing isolate F27 significantly stimulated the intensity of mycorrhiza, the number of arbuscules in roots, and increased both the P concentration and P content in corn shoots (+30% and +35%), than did the VAM fungus alone. Isolate F27 significantly increased shoot dry weight as compared with the mycorrhizal control. The other bacteria did not influence biomass production of corn.     

Effect of three vesicular‐arbuscular mycorrhizae species and phosphorus on reproductive and vegetative growth of three strawberry cultivars 1

A study was undertaken to evaluate the yield, fruit size, and vegetative growth of three strawberry cultivars inoculated with three vesicular‐arbuscular mycorrhizal (VAM) species at three phosphorus (P) fertility levels. Vesicular‐arbuscular mycorrhiza inoculation and P fertility had no effect on inflorescence or flower number, total yield, fruit weight, or crown number. Higher levels of P did not increased total dry shoot weight, total fresh shoot, weight leaf area, total dry root weight, and leaf number in the present of VAM. However, the cultivars responded differently to VAM inoculation. Vesicular‐ arbuscular mycorrhiza inoculation in combination with P at all levels increased total dry and fresh shoot weight, leaf area, and leaf number compared to application of P alone. The results indicated that it may be possible to increase strawberry stolon production by inoculating the strawberry plants with VAM, a technique which might be useful in nurseries to produce certified strawberry plants.