【作者】 祝英；

【导师】 熊友才；

【作者基本信息】 兰州大学 ， 生态学·生态学， 2016， 博士

【摘要】 在黄土高原雨养农业区,低水多变的土壤环境是春小麦生长的最大制约因子,地膜覆盖和施加化肥为主的旱作农业技术从一定程度上提高了作物产量和水分利用效率,但导致土壤质量下降,水生产力还有较大的提升空间,研发环境友好型的水土管理和生态修复技术成为目前人们关注的热点。丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)是一类植物专性营养共生微生物,前期研究表明AMF能提高植物根系水分和养分吸收和利用,有利于植株生长和土壤养分循环,具有显著的生产和生态效应。然而,AMF能否对旱地春小麦起到类似的促进作用?能否融合到地膜覆盖技术中发挥更佳效果?对土壤质量和作物产量是否有积极促进作用?其生理生态机理如何?对上述问题的回答需要系统的实验验证。本研究以从澳大利亚西部小麦带土壤中分离到的三种AMF菌种为接种源,包括光壁无梗囊霉(Acaulospora laevis,ID:Sunsex)、根内球囊霉(Glomus intraradices)和单孢球囊霉(Glomus monosporum,ID:WUM11),在甘肃省榆中县实验站从2011–2015年开展了盆栽和大田实验,进行系统性的观测和研究,以期回答以上问题。盆栽实验以六倍体栽培品种L8275、四倍体栽培品种DM31和二倍体栽培品种MO4为实验材料,通过设置不同水分梯度,揭示AMF接种条件下不同倍体小麦水分利用、产量差异、进化特征及根冠通讯机理。大田实验以六倍体栽培品种L8275为实验材料,开展如下三个相对独立但又紧密联系的实验:1)将三种AMF分别单一和混合接种条件下,研究春小麦水分利用、生长、生物量积累和产量形成、根际土养分和可培养微生物类群的变化;2)裸地和地膜覆盖条件下,探讨春小麦水分利用、生长、生物量积累和产量形成的特征。3)地膜覆盖条件下,研究接种三个不同AMF菌种(单一和混合接种)对春小麦水分利用、生长、生物量积累和产量形成及土壤养分和微生物多样性的影响。主要得出如下结论:1.接种三种AMF均能显著提高六倍体春小麦(L8275)的生长和籽粒产量,接种光壁无梗囊霉(AL)和根内球囊霉(Gi)能显著提高四倍体春小麦(DM31)的生长和籽粒产量,并提高二倍体春小麦(MO4)的千粒重,有利于提高不同基因型小麦对干旱的适应策略,表明本研究所选AMF适用于旱地春小麦。不同AMF对不同基因型小麦的生理生态和生长特征的影响存在一定的差异,综合分析,光壁无梗囊霉(AL)对提高不同基因型小麦的干旱适应策略优于根内球囊霉(Gi);三种AMF对六倍体春小麦(L8275)的抗旱促生增产效果为Gm>AL>Gi。2.不论干旱年份还是湿润年份,不论单接种还是混合接种AMF,均能改善不同时期小麦的生长、显著提高小麦菌根侵染率和籽粒产量。AMF通过改善产量形成因素(分蘖数、有效穗、穗粒数和穗粒重等),增加了繁殖分配,改善R-V指数,而显著提高收获指数和籽粒产量。表明从西澳引进的AMF对旱地田间春小麦(L8275)同样具有促生、增产效果。3.大田生产条件下,分别添加AMF对两个年份根际土养分和5类可培养微生物类群的影响结果显示,添加AMF处理显著影响了根际土微生物类群的数量,不同微生物类群与土壤养分存在显著的相关关系;接种AMF有利于土壤水分的吸收利用和恢复;AMF处理提高全氮和有效钾的含量,但整体上降低根际土有机质和有效磷的含量,不利于半干旱雨养农业区土壤的可持续性。主成分分析结果显示,2014湿润年份和2015干旱年份降雨量对根际土养分和微生物类群的影响效应高于AMF处理,表明水分是影响半干旱雨养农业区“根际养分–根际微生物–AMF–寄主植物之间相互作用”的主要限制因素,添加AMF对根际微生物、水分和养分发挥微调控效应。该研究有助于揭示根际养分–根际微生物–AMF–寄主植物之间相互作用的根际过程。4.地膜覆盖条件下添加外源AMF,在地膜覆盖的基础上,不论干旱年份还是湿润年份均进一步提高了净经济产出。2014年添加AMF与仅地膜覆盖处理相比,净收入显著提高了45%–125%,与裸地处理相比,净收入显著提高了90%–195%;2015年添加AMF与仅地膜覆盖处理相比,净收入显著提高了61%–96%,与裸地处理相比,净收入显著提高了453%–576%,表明干旱条件下,添加AMF更能保产增加收益。与此同时,添加AMF与仅地膜覆盖处理相比,2014年土壤有机碳含量提高了16.5%,2015年提高了1.9%,表明添加AMF还能提高土壤碳的周转和恢复的能力,有利于旱地农业生态系统的可持续性。5.地膜覆盖条件下添加外源AMF与地膜覆盖两种农艺措施均能提高旱地农田生产力,但两者的促生增产机制不同:与裸地接种AMF效果相同,两个年份接种地膜覆盖条件下添加外源AMF均使异速生长指数趋于0.9–1.0(0<k<1),有利于生物量的稳定分配,此时作物的繁殖输出随着个体大小的增加而增加;同时也促使R–V指数趋向1.0,更有利于稳定的繁殖输出。而地膜覆盖虽然也促使R–V指数趋向0.9–1.0,有利于稳定的繁殖输出;但是对小麦异速生长指数影响不大。地膜覆盖条件下添加外源AMF在地膜覆盖的基础上进一步提高小麦地上生物量,更有利于小麦籽粒形成和产量的提高。6.在裸地和地膜覆盖条件下,分别添加AMF对两个年份根际土养分影响的实验结果显示,两个年份裸地添加AMF,均降低根际土有机质含量;而两个年份地膜覆盖条件下添加AMF,均能提高根际土有机质含量。而且地膜覆盖条件下添加外源AMF均提高了根际土放线菌、座囊菌的群落组成和AMF的多样性,有利于根际土养分的周转和水分的吸收,同时还有利于改善土壤质量。而且通过丛枝菌根真菌多样性分析,进一步确认了添加的AMF已经在根际定殖并发挥作用。表明地膜覆盖条件下添加外源AMF这一农艺措施更有利于土壤的可持续发展。综上所述,本研究通过盆栽控水实验和大田实验,验证了从西澳大利亚小麦带土壤中分离到的三种AMF菌种对黄土高原雨养农业区的旱地春小麦均有促生增产效应。盆栽控水实验从AMF接种对小麦气体交换参数、膜损伤、渗透调节物质、氧化酶活性和激素(ABA)等方面的影响,揭示了干旱胁迫下AMF对不同倍体春小麦的促生增产机理。而大田实验回答了AMF接种在农业生产应用的促生增产机理和可行性,特别是AMF接种融合地膜覆盖技术,在地膜覆盖的基础上不但能进一步提高小麦产量和经济收益,而且增加了土壤有机碳含量、改善土壤微生物多样性和功能、提高土壤质量,有利于半干旱雨养农业区的可持续发展。更多还原

【Abstract】 Spring wheat is widely planted in the semi–arid region of Loess Plateau,northwest China.However,regional precipitation is usually low and variable at the critical stage of water demand,when wheat growth requires much water for seed germination and plant development.Therefore,it became a core issue to make full use of the soil deep water for wheat yield and water use.In this region,application of plastic film mulching(PFM)has improved yield and water use efficiency to a certain extent,yet soil quality proved to be decreasing,and there was still a huge space to enhance water productivity.In this case,to explore environment–friendly soil and water management technology is urgently needed.Arbuscular mycorrhizal fungal(AMF)is a kind of soil microorganism,which symbiosis with plant use plant photosynthetic products and helps plant absorb nitrogen,phosphorus and other mineral elements,and enhance plant respond to biotic or abiotic stresses.However,can AMF play a similar role in promoting stress resistance in dryland spring wheat? Can AMF inoculation under plastic film mulching play much better effects? Whether AMF noculation under plastic film mulching have a positive effect on soil quality and crop yield,and what is their physiological and ecological mechanism? The answer to these questions requires systematic experiment to verify.In this study,three AM fungal species,Acaulospora laevis(ID: Sunsex),Glomus monosporum(ID: WUM11)and Glomus intraradices were used.Spores of the three AMF species isolated from the wheat belt in Western Australia were pot–cultured with white clover(Trifolium repens)prior to the experiment.The study was performed to illustrate the effects of AMF on wheat growth,yield formation,water use and sustainability for dryland agriculture under potted water control,field,or intergreting with plastic film mulching in field at the Dryland Agricultural Ecological Experimental Station in Yuzhong County of Gansu from 2011 to 2015.Pot experiment was conducted to assess the inoculation effects of three AMF species on different ploidy wheat cultivars individual water use and yield,and their physiological and ecological mechanism under the condition of different water gradients.Three relatively independent but closely related field trials with spring wheat L8275 and three AM fungal species,were conducted to evaluate effects of AMF inoculation on grain yield,biomass accumulation,water use efficiency(WUE),soil organic carbon and economic profitability in with or without plastic film mulching.Trial 1 inoculated with three AMF species(Acaulospora laevis,Glomus monosporum,and Glomus intraradices)alone or in combination,or without inoculation as the control.Trial 2 included traditional flat planting and plastic film mulching,which was the control Trial of Trial 3.Hence Trial 3 consisted of PFM treatment inoculated with three AMF species(Acaulospora laevis,Glomus monosporum,and Glomus intraradices)alone or in combination,or without inoculation as the control.Major results and innovations were achieved as follows:1.The growth and grain yield of hexaploid spring wheat(L8275)were significantly increased with inoculation of three AMF species,the growth and grain yield of tetraploid spring wheat(DM31)and the 1000-grain weight of diploid spring wheat(MO4)were also significantly enhanced with inoculation of the Acaulospora laevis and Glomus intraradices under different water conditions,which were helpful to improve the adaptation strategy of different wheat genotypes to drought stress.There were different physiological and ecological characteristics due to different AMF that affected on different genotypes of wheat.The results showed that Acaulospora laevis improve host drought tolerance better than that of Glomus intraradices.The benefit effects on improving drought tolerance of hexaploid spring wheat(L8275)among three AMF were Gm > AL> Gi.2.The wheat growth,root colonization rate and grain yield were significantly improved no matter with single or mixed AMF inoculation and in dry or wet year.AMF inoculation not only improved the yield-forming factors such as tiller number,grain number and grain weight per spike,but also affected the R-V index to benefit for increasing the host plant harvest index and grain yield.The results indicated that AMF introduced from Western Australia could also promote the growth and grain yield of dryland spring wheat in the Loess Plateau of China.3.Rhizosphere soil nutrients and five kinds of cultural microbial populations were also measured in this study.The results showed that AMF inoculation significantly affected the number of microflora in rhizosphere soil,and there was close correlation between different microbial groups and soil nutrients.AMF inoculation also increased total nitrogen and available potassium contents,but decreased the content of organic matter and available phosphorus,which was disadvantageous to the soil sustainability in semi–arid rainfed agriculture area.The results further showed that the rainfall played more impacts on soil nutrients and cultural microbial populations than those of AMF inoculation,which indicated that water is the major factor to limit the rhizosphere processes,and AMF inoculation play a micro–regulation on rhizosphere microbes,water and nutrients in rhizosphere soil.4.Importantly,across all the species under PFM,the AMF inoculation increased grain yield and aboveground biomass by 46.6% and 56.5% in wet year 2014,and 16.6% and 27.4% in dry/warm year 2015,respectively,comparing with no AMF inoculation.AMF symbiosis also significantly enhanced harvest index and population fitness,and higher inoculation rates generally led to greater magnitudes of the increases in yield,biomass and WUE.We also quantitatively estimated the economic benefits among various treatments,and found that PFM significantly increased net economic income by 35.8% in 2014 and 245.0% in 2015 respectively,comparing with traditional flat planting,while AMF inoculation further promoted net income averagely by 72.9% in 2014 and 21.7% in 2015 respectively on the basis of CK–2.Meanwhile,the AMF inoculation further significantly increased the contents of SOC by 16.5% in 2014 and 1.9% in 2015,respectively.The results showed that integrated AMF–mulching farming system improved field productivity,economic benefit and soil organic carbon,which may act as an environment–friendly and high–yielding management to ensure wheat production and ecosystem sustainability under climate change.5.Although AMF coupled with plastic film mulching and without plastic film mulching,both agronomic measures could improve dryland farmland productivity,but the mechanism of promoting growth and yield was different.Allometric exponents under AMF coupled with plastic film mulching fall into the threshold range from 0.9 to 1,which means that biomass allocation was much stable while the R–V exponents were close to 1 in two growth years,which could be further maximized the reproductive output under AMF coupled with plastic film mulching.However,the allometric exponents unchanged and the R–V exponents were fall into the threshold range from 0.9 to 1(not close to 1)under plastic film mulching in two years.Whereas AMF not only increased host plant individual size,but also improved more reproductive output than vegetative biomass,which was beneficial to population fitness and yield improvement.6.Wheat aboveground biomass and yield have been improved in field inoculated with AMF and AMF inoculation coupled with PFM.However,soil organic matter content declined in two years under inoculated with AMF,which was not conductive to soil sustainability.AMF coupled with PFM improved soil organic matter,which benefited to soil sustainability,and was a promising farming strategy.The higher contents of Actinomycetes and Dothidemycetes were detected in bacterial and fungal OTUs under AMF coupled with PFM treatments,respectively.AM fungi diversity also improved as the introduced AMF had been colonized in wheat rhizosphere by AMF diversity analysis under AMF coupled with PFM treatments.The results indicated that inoculated with AMF could improve rhizosphere microbial diversity and soil quality to benefit with nutrients cycling and water uptake.In conclusion,in this study,wheat aboveground biomass and yield have been improved under potted water control,and field trials,which verified AMF inoculation,play a beneficial role in promoting dryland spring wheat.Gas exchange parameters,membrane damage,osmotic adjustment,oxidase activity and hormone(ABA)in three spring wheat,L8275,DM31 and MO4 were detected to reveal the main mechanism of AMF on improving wheat growth and yield under drought stress.Field Trials results answered the mechanism of AMF inoculation promoting wheat growth and yield and AMF inoculation technology is feasibility to use in agricultural practice,especially better effects of AMF inoculation coupled with PFM technology.AMF inoculation coupled with PFM technology not only further enhanced wheat yield and economic benefit than PFM,but also increased soil organic carbon content,improved soil microbial diversity and function to improve soil quality,which is beneficial to the sustainable development of semi–arid rain–fed agricultural areas.更多还原