高温干旱共胁迫下外源甜菜碱和CaCl2对烟草生理响应的影响

以烤烟品种云烟85为材料,采用盆栽试验研究了对高温干旱共胁迫的反应,以及外源甜菜碱（GB）和CaCl2对烟草抗高温干旱共胁迫方面的作用。结果表明,叶面喷施GB和CaCl2能显著提高烟草植株生物量。在高温干旱共胁迫下,叶面喷施GB较蒸馏水处理能极显著提高烟草叶片叶绿素含量、SOD和POD活性,维持较高的脯氨酸含量及较低的丙二醛（MDA）含量和质膜相对透性;叶面喷施CaCl2较蒸馏水处理能极显著提高烟草叶片叶绿素含量、SOD和POD活性,极显著降低质膜相对透性,显著降低丙二醛（MDA）含量,维持较高的脯氨酸含量。高温干旱共胁迫恢复生长后,GB、CaCl2和蒸馏水处理的烟草其叶绿素含量、SOD和POD活性均有不同程度回升,丙二醛含量、脯氨酸含量、细胞质膜透性都有所下降。因此,GB和CaCl2对有效减轻双逆境胁迫引起的伤害,提高烟草的抗高温干旱胁迫能力具有积极的作用。     

铅胁迫下小花南芥与玉米间作对根系分泌物 有机酸的影响

为了揭示Pb胁迫对间作和单作的超累积植物和作物根系分泌低分子有机酸的影响,研究设置400 mg·L?1Pb胁迫,采用水培曝气法试验,以玉米和小花南芥单作为对照处理,研究Pb胁迫下玉米和小花南芥间作对植物根系形态、根系分泌有机酸及Pb吸收的影响。结果表明:与单作相比,间作小花南芥情况下,玉米根系分泌物检测到乳酸;玉米分根条数、根表面积和根密度与单作相比分别增加60%、15%和42%,地下部和地上部干重生物量分别增加108%和75%,玉米地下部Pb含量下降44%;与单作相比,间作玉米条件下,小花南芥根系分泌物检测到乙酸和乳酸,小花南芥根系分泌物量与单作相比增加103%~1 700%,小花南芥地下部和地上部Pb累积量分别比单作增加49%和75%,转运系数增加22%。相关分析结果表明,单作小花南芥只有地上部Pb累积量与草酸显著相关,而间作小花南芥地下部和地上部Pb累积量与草酸、柠檬酸和苹果酸显著相关。研究表明超富集植物小花南芥与玉米间作体系,根系分泌的有机酸改变了Pb在小花南芥和玉米体内的累积特征,促进超累积植物小花南芥累积Pb,减少农作物玉米植株体内Pb含量。Pb胁迫下超累积植物小花南芥与玉米间作是一种可行的修复模式。     

麦茬处理方式对机播夏玉米的生态生理效应

为探求适合黄淮海平原机播夏玉米的最佳麦茬处理方式,采用大田试验,研究了麦茬处理方式(平茬、立茬、除茬)对机播夏玉米的生态生理效应.结果表明,平茬有利于提高土壤含水率、平衡和改善耕层土壤温度,较好地满足玉米生长对土壤温度和水分的需求.3展叶时,玉米叶面积、干物质重等指标都以除茬处理最好;6展叶时,平茬处理玉米的株高、单株干重、叶面积、光合速率均表现最优,产量也最高.所以平茬处理为机播夏玉米的生长提供了较好的生态条件,促进了夏玉米的生长发育和产量的提高,有很大的推广价值.     

华北地区采用无机氮测试和植株速测进行夏玉米氮肥推荐

A field experiment with a split-plot design was carried out at Dongbeiwang Farm in Beijing Municipality to establish reliable N fertilizer recommendation indices for summer maize (Zea mays L.) in northern China using the soil Nmin(mineral N) test as well as the plant nitrate and SPAD (portable chlorophyll meter readings) tests. The results showed that Nrnin sollwert (NS) 60 kg N ha^-1 at the third leaf stage and N rate of 40 to 120 kg N ha^-1 at the tenth leaf stage could meet the N requirement of summer maize with a target yield of 5.5-6 t ha^-1. Sap nitrate concentrations and SPAD chlorophyll meter readings in the latest expanded maize leaves at the tenth leaf stage were positively correlated with NS levels, indicating that plant nitrate and SPAD tests reflected the N nutritional status of maize well. Considering that winter wheat subsequently utilized N after the summer maize harvest, the 0-90 cm soil Nmin (74 kg N ha^-1) and apparent N loss (12 kg N ha^-1) in the NS60＋40 treatment were controlled at environmentally acceptable levels. Therefore NS60＋40, giving a total N supply of 100 kg N ha^-1, was considered the optimal N fertilizer input for summer maize under these experimental conditions.     

磷胁迫下蔗糖对水稻苗期根适应性和磷酸转运蛋白基因表达的影响

磷是植物生长和发育中最重要的必须元素之一。尽管土壤中磷资源很丰富,但大部分磷是以植物不能吸收利用的固定态和有机态存在,特别是以酸性土壤为主的南方稻田,水稻缺磷现象非常严重。理解和掌握水稻对低磷的适应机制有助于利用分子手段培育磷高效利用水稻品种。为阐明蔗糖提高水稻耐低磷的机制,本研究对水稻幼苗进行不同磷、糖处理,分析水稻幼苗在不同磷糖配比培养基中的根系结构、无机磷、酸性磷酸酶活性的变化,并利用定量RT-PCR技术分析水稻磷酸转运蛋白基因(OsPT)和酸性磷酸酶基因(OsSAP1)的表达。试验设2个磷浓度:无磷和85 mg·L?1KH2PO4,2个蔗糖浓度:无糖和3%蔗糖,正交设计。结果表明,在低磷胁迫时添加蔗糖,能使水稻幼苗的根总长度、总根数、根冠比显著增加,根分泌的酸性磷酸酶活性降低,但水稻体内的磷酸转运酶活性提高。11个与磷具有高度亲和力的磷酸转运酶的表达发生了改变,其中根优势表达的4个基因OsPT2、OsPT3、OsPT4、OsPT6对磷、糖的影响最为敏感,暗示了蔗糖是通过调节磷转运蛋白维持磷的吸收和平衡。增加根系的蔗糖分配能够提高水稻幼苗对磷胁迫的耐受性。     

负压控水下不同株型玉米水分利用效率和产量的盆栽试验

干旱胁迫研究中的难点之一在于减少土壤水分波动对试验结果的影响。该研究采用负压供水盆栽装置,通过调节供水负压值精确控制土壤含水率,模拟土壤干旱胁迫,研究比较3种胁迫程度(无胁迫CK、轻度和重度胁迫)、2个胁迫时期(苗期、吐丝期)对不同株型玉米(小株型CF1002和大株型CF3330)的水分利用效率、生物量和产量的影响,旨在分析2种株型夏玉米对不同时期、程度干旱胁迫的响应差异。结果表明:随着苗期胁迫程度加重,CF1002的水分利用效率(water use efficiency,WUE)从3.24增至3.43,而CF3330的WUE从3.70降至3.25。吐丝期轻度干旱胁迫后CF1002和CF3330的WUE较CK分别降低2.7%和24.4%,吐丝期重度胁迫后,CF1002和CF3330的WUE较CK分别降低17.4%和57.1%。与CK相比,吐丝期轻度和重度干旱胁迫使小株型和大株型玉米胁迫期耗水量下降61.3%和62.5%,灌浆中期光合速率下降22.9%和54.3%,成熟期地上部干物质质量减少24.8%和38.0%,最终减产47.9%和71.5%,以上指标大株型玉米的降幅大于小株型玉米。在生育中后期,大株型玉米光合生产和蒸腾作用更易受干旱胁迫抑制,使物质生产和积累减少,水分消耗大幅下降。针对不同株型玉米在生育后期采用不同的水分管理策略有助于降低干旱造成的损失。     

转碱蓬SsNHX1基因烟草的耐盐抗旱性研究

烟草是重要的模式植物和经济作物,盐害和干旱两种环境因子对其生长发育、产量和品质都危害很大。为了提高烟草的耐盐抗旱性,本研究利用农杆菌介导的遗传转化法在烟草中过量表达了碱蓬液泡膜Na~+/H~+逆向转运基因SsNHX1,对转基因烟草的耐盐及抗旱性进行表型鉴定和各项生化指标的检测,以期得到耐盐抗旱表性良好的SsNHX1转基因烟草。表型分析发现,SsNHX1基因过表达株系L1和L5的抗盐能力比野生型显著提高,表现为盐胁迫条件下仍能保持旺盛的生长且根系的伸长未受抑制。SsNHX1过表达株系在叶片和根系中积累了更多的Na~+和K~+,同时Na~+含量增长速率较快,而K~+含量降低速率较缓,并可维持较高的叶片相对含水量和叶绿素含量,及较低的丙二醛含量和相对电导率。干旱胁迫发现,过表达株系受干旱胁迫程度更小,并在复水后迅速恢复正常生长。同时,过表达株系的丙二醛含量和相对电导率显著低于野生型,且维持了较高的叶片相对含水量及叶绿素含量。这些结果说明SsNHX1基因在烟草中过量表达后,降低了盐胁迫和干旱胁迫对烟草根系及细胞膜的损伤,并通过调节离子含量、降低细胞的渗透势,维持了叶片较高的相对含水量和叶绿素含量,最终提高了烟草的抗盐和抗旱性。     

Soil pH changes during legume growth and application of plant material

During cultivation of legumes soil is acidified due to proton release from roots. As a consequence of proton release, plants accumulate organic anions which may, if returned and decomposed in the soil, neutralize the soil acids. Until now the detailed processes responsible for the change in soil pH after incorporation of plant material have not been completely understood. Using a pot experiment we studied the changes in acid and base in soil during growth of field beans (Vicia faba L. cv. Alfred) and after incorporation of the plant material into the soil. Soil pH was significantly decreased by field beans from 6.00 to 5.64 in a cultivation period of 45 days. Proton release amounted to 32.7 mmol H⁺ pot^-1, which was approximately equivalent to the accumulated alkalinity in the plant shoots (34.4 mmol). Return of field bean shoots caused a significant soil pH increase from 5.64 to 6.29. Within 7 days more than 90% of the added alkalinity was released. After 307 days incubation, soil pH decreased to 5.86 due to nitrification. In a second experiment, maize leaves (Zea mays L.), containing various concentrations of nitrogen and at various alkalinities, were incorporated into the soil. Soil pH change was positively correlated to alkalinity and malate concentration and negatively correlated to total nitrogen and water-soluble organic nitrogen of incorporated leaves. It is concluded that the soil acidification caused by legume cultivation can be partly compensated for if crop residues are returned to the soil. Addition of plant material may initially cause an increase in soil pH due to decomposition of organic anions and organic nitrogen. Soil pH may decrease if nitrification is involved. The concentrations of nitrogen and alkalinity of added plant material are decisive factors controlling soil pH change after incorporation of plant material.Dedicted to Professor J.C.G. Ottow on the occasion of his 60th birthday     

Diversity and versatile functions of metallothioneins produced by plants: A review

Metal ions are essential for plant growth and development,but in excess,these compounds can become highly toxic.Plants have adopted numerous ways to maintain metal homeostasis while mitigating adverse effects of excess metal ions,including phytochelatin and the metal-chelating proteins metallothioneins(MTs).A family of cysteine(Cys)-rich,intracellular,and low-molecular-weight(4–8 kDa) MTs are proteins found in nearly all phyla including plants,animals,and fungi,and they have the potential to scavenge reactive oxygen species and detoxify toxic metals including copper,cadmium,and zinc.Based on their Cys numbers and residues,MTs have been categorized into three major classes.Class I MTs,which have highly conserved Cys residues,are found in animals,while class II MTs,with less conserved Cys residues,are present in plants and are classified further into four groups.Class III MTs include phytochelatins,a group of enzymatically synthesized Cys-rich proteins.The MTs have been an area of interest for five decades with extensive studies,which have been facilitated by advancements in instrumental techniques,protein science,and molecular biology tools.Here,we reviewed current advances in our understanding of the regulation of MT biosynthesis,their expression,and their potential roles in the alleviation of abiotic stresses(i.e.,drought,salinity,and oxidative stresses) and heavy metal detoxification and homeostasis.     

铝胁迫下磷对水稻苗期生长的影响及水稻耐铝性与磷效率的关系

选用两个耐铝性差异较大的水稻品种武运粳7号(耐铝品种)和扬稻6号(铝敏感品种)作为实验材料,利用水培铝-磷交替处理试验研究了磷对水稻铝胁迫下苗期生长的影响及水稻耐铝性与磷效率之间的关系。结果表明,从水稻铝-磷交替处理下的生物量和根系形态等指标来看,P缓解了Al对两个水稻品种的毒害作用,且对敏感品种扬稻6号的缓解作用更加明显。铝-磷交替处理下,武运粳7号的体内磷含量显著高于扬稻6号的,而根部铝含量显著低于扬稻6号,因此武运粳7号体内的P/Al显著高于扬稻6号;同时,虽然两个品种间根表及根自由空间中Al浓度没有差别,而武运粳7号根表及根自由空间中P浓度显著高于扬稻6号,表现出耐铝品种更强的质外体解铝毒能力,这可能与武运粳7号较强的磷吸收效率有关。此外,与耐铝品种武运粳7号相比,铝敏感品种扬稻6号虽然磷吸收效率低,但利用效率高,即两个水稻品种的耐铝性与水稻的磷吸收效率和利用效率不一致,这为酸性土壤水稻育种提供了理论基础,即选育适应酸性土壤的水稻基因型不仅要关注其耐铝性还要关注其磷利用效率。     

干旱胁迫对黄土高原不同质地土壤长柄扁桃和沙柳幼苗生理生态特征的影响

通过盆栽控水试验,研究了干旱胁迫对黄土高原不同质地土壤(砂土、壤土)长柄扁桃和沙柳幼苗光合特性(净光合速率P_n、气孔导度G_s、胞间CO_2浓度C_i、内禀水分利用效率WUE)、蒸腾速率T_r及叶片水势Ψ_w的影响。结果表明:干旱胁迫下不同质地土壤长柄扁桃和沙柳P_n、G_s、WUE及T_r均呈现先上升后下降的趋势,而C_i和Ψ_w分别表现为上升和下降趋势。土壤质地显著影响长柄扁桃和沙柳对水分亏缺的敏感性,在相同干旱程度下,壤土中长柄扁桃P_n和G_s均显著高于砂土,而沙柳P_n和G_s表现为砂土显著高于壤土(p0.05)(重度干旱除外)。当土壤含水量降至中度和重度干旱时,长柄扁桃和沙柳WUE在不同质地土壤间具有显著差异(p0.05)。壤土中长柄扁桃生长优于砂土,而沙柳则相反。因此,黄土高原植被恢复与生态建设过程中不仅应根据土壤水分状况选择造林树种,还应考虑植物在不同质地土壤上对干旱胁迫的不同响应。     

Fitting plants to soil through mycorrhizal fungi: Mycorrhiza effects on plant growth and soil organic matter

Summary Vesicular-arbuscular mycorrhizal (VAM) fungi affect diverse aspects of plant form and function. Since mycorrhiza-mediated changes in host-plant responses to root colonization by different VAM fungi vary widely, it is important to assess each endophyte for each specific effect it can elicit from its host as part of the screening process for effectiveness. Three species of VAM fungi and a mixture of species were compared with non-VAM controls for their effects on soil organic matter contents and on nutrition and morphology in two varieties (native and hybrid) of corn (Zea mays L.) and one of sunflower (Helianthus annuus L.) in P-sufficient and N-deficient soil in pot cultures. Differences in soil organic matter due to the fungal applications were highly significant with all host plants. Native corn responded more to VAM colonization than the hybrid did; differences in treatments were significant in leaf area, plant biomass, and root: shoot ratio in the former, but not in the latter. Responses in the sunflower were similar to those in the native corn. Significant VAM treatment-related differences in shoot N and P contents were not reflected in shoot biomass, which was invariant. Correlations between plant or soil parameters and the intensity of VAM colonization were found only in soil organic matter with the native corn, in specific leaf area in the hybrid corn, and in plant biomass in the sunflower. The presence of the different endophytes and not the intensity of colonization apparently elicited different host responses.     

分室磷添加下菌根对滇池流域红壤间作玉米生长及磷素利用的影响

随着全球范围内磷矿资源短缺问题的日益严重,间作或菌根技术强化作物对土壤磷(P)的利用及增产增收的效应受到越来越多的关注。通过三室隔网盆栽模拟试验研究了分室磷处理[不添加磷(P0)、添加有机磷(OP50)、添加无机磷(IOP50)]和根室不接种(NM)、根室接种丛枝菌根真菌Glomus mosseae(GM)对与大豆间作的玉米的生长及磷素利用的影响。研究结果表明:所有复合处理中,以间作?GM?IOP50组合处理下的玉米根系最短和地上部生物量最高;OP50处理下,间作玉米的菌根侵染率显著高于单作处理。间作条件下,无论分室磷添加与否,接种GM处理的玉米地上部生物量明显高于NM处理;接种GM处理的玉米根系生物量和株高均显著高于NM处理,且根系生物量以间作?GM?OP50组合处理下最高。接种GM条件下,P0、IOP50、OP50处理下的间作植株生物量较单作处理分别提高45.98%、111.33%、33.56%。单作条件下,无论分室磷添加与否,接种GM处理的玉米地上部磷含量均显著高于NM处理;无论何种种植模式及分室磷添加与否,接种GM处理的植物根系磷含量均显著高于NM处理。无论磷添加与否,间作?GM组合条件下的玉米地上部磷吸收量均显著较高,其中IOP50处理下的地上部磷吸收量显著高于OP50处理。间作?GM组合条件下,IOP50处理玉米根系的磷吸收效率均显著高于OP50处理。可见,接种GM、分室磷添加和间作各自在一定程度上促进了玉米的生长。综合菌根侵染、生物量及磷含量与吸收量、磷吸收效率等指标,所有复合处理中以间作?GM?IOP50组合对玉米地上部的促生作用最好,玉米磷素吸收最多,可望有效强化滇池流域红壤坡耕地磷素的利用。     

Characterization of a flint maize (Zea mays var. indurata) Italian landrace, II. Genetic diversity and relatedness assessed by SSR and Inter-SSR molecular markers

A comparative characterization of 10 field populations of the maize (Zea mays var. indurata) landrace Nostrano di Storo was carried out using different types of PCR-based markers. The inbred line B73 and three synthetics (VA143, VA154 and VA157) selected from as many landraces were also used. Genetic diversity and relatedness were evaluated over 84 SSR and 53 I-SSR marker alleles using a total of 253 individual DNAs. Up to 23 alleles per SSR locus were scored while the average effective number of alleles per population was 6.99. Nei's total genetic diversity as assessed with SSR markers was H_T = 0.851 while the average diversity within populations was H_S = 0.795. The overall Wright's fixation index F_ST was as low as 0.066. Thus, more than 93% of the total variation was within population. Unique alleles over all SSR loci were found for six populations. An average of 17.7 marker alleles per I-SSR primer were scored with an effective number of marker alleles per locus of 1.34. The Shannon's diversity information index over all populations and I-SSR loci was 0.332, varying from 0.286 to 0.391. The extent of differentiation between populations was as low as G_ST = 0.091. Dice's genetic similarity matrices were estimated for both SSR and I-SSR markers. The mean genetic similarity coefficients within and between populations were respectively 0.269 and 0.217, for SSR markers, and 0.591 and 0.564, for I-SSR markers. UPGMA dendrograms displayed all field populations but one clustered into a distinct group, in which the synthetic VA154, selected from the Marano Vicentino landrace, was also included. One field population and the other two synthetics were clustered separately as well B73. The matrix correlation assayed by the Mantel's correspondence test was as high as 0.908. Findings suggest that, although a high variability can be found among plants, most plant genotypes belong to the same landrace called Nostrano di Storo. Although gene flow from commercial hybrids might have occurred, the large number of polymorphisms and the presence of both unique alleles and alleles unshared with B73 and synthetics are the main factors underlying the value of this flint maize landrace as a source of genetic variation and peculiar germplasm traits. Because of its exclusive utilization for human consumption, such a molecular marker characterization will be a key step for obtaining the IGP mark and so promote the in situ conservation and protection of the landrace Nostrano di Storo.     

灌浆结实期高温干旱复合胁迫对稻米直链淀粉及蛋白质含量的影响

灌浆结实期是水稻产量与品质形成的关键时期,近年来,由于受全球气候变化和局部地形地貌的影响,我国南方稻区在水稻灌浆结实期频频遭遇高温和伏旱的混合影响,造成水稻产量与品质的同步下降。本研究选用导入空心莲子草基因组DNA构建的籼稻耐旱变异品系H5,在灌浆结实期于人工温室进行高温干旱复合胁迫试验,测定了不同处理稻米直链淀粉与蛋白质含量,旨在深入研究高温干旱复合逆境对稻米品质的影响。试验设6个处理,分别是适温中度干旱(OT-MD)、适温严重干旱(OT-SD)、高温正常供水(HT-WW)、高温中度干旱(HT-MD)、高温严重干旱(HT-SD)和适温正常供水(OT-WW,CK)。除对照外,其余各处理的胁迫时间设10 d、20 d、30 d和40 d。结果表明:灌浆结实期高温胁迫会导致稻米直链淀粉含量下降和蛋白质含量增加,高温胁迫10~40 d的稻米直链淀粉含量比CK降低了1.783~5.987个百分点,稻米蛋白质含量比CK增加了1.178~2.741个百分点;灌浆结实期干旱胁迫同样会导致稻米直链淀粉含量下降和蛋白质含量增加,在中度干旱条件下,胁迫10~40 d处理的稻米直链淀粉含量比CK降低了1.956~6.270个百分点,稻米蛋白质含量比CK增加了1.153~2.944个百分点,在严重干旱条件下,胁迫10~40 d处理的稻米直链淀粉含量和蛋白质含量相对于CK的变异幅度比中度干旱胁迫下的更大;灌浆结实期高温干旱复合胁迫引起稻米直链淀粉含量下降和蛋白质含量增加的幅度均超过单一高温胁迫或干旱胁迫,且其变化幅度随胁迫因子的增加、胁迫强度的增强和胁迫时间的延长而增大;灌浆结实期的前20 d遭遇高温干旱复合胁迫是稻米品质变差的主要原因;在相同胁迫时间内,各处理对稻米直链淀粉和蛋白质含量的胁迫效应按升序排列依次为:高温正常供水(HT-WW)、适温中度干旱(OT-MD)、适温严重干旱(OT-SD)、高温中度干旱(HT-MD)、高温严重干旱(HT-SD)。本研究结论可为水稻的抗旱与抗高温育种与栽培提供参考依据。     

施肥对干旱胁迫下幼龄期小粒咖啡光合 特性及生长的影响

为明确氮、磷肥对幼龄期小粒咖啡抗旱性的影响,采用盆栽试验,研究了干旱胁迫下3种施氮水平[N0(0 g·株-1)、N1(2.5 g·株-1)、N2(7.5 g·株-1)]和3种施磷水平[P0(0 g·株-1)、P1(2.5 g·株-1)、P2(7.5 g·株-1)]的完全处理组合对幼龄期小粒咖啡光合及生长的影响。结果表明:干旱胁迫下小粒咖啡的叶片相对含水量(LRWC)、最大净光合速率、气孔导度、蒸腾速率、叶绿素含量、比叶面积及生物量均较正常供水时低。干旱胁迫时,施氮、磷肥均能减缓咖啡LRWC的下降速度,其中中氮(N1)和磷肥(P1、P2)单施及其配施处理下的LRWC均在72%以上,显著大于N0P0处理的LRWC。施氮、磷肥有利于改善干旱胁迫下咖啡的光合特性,其中N0P1、N0P2和N1P2处理的最大净光合速率和水分利用效率显著大于其他处理,分别是N0P0处理的2.09倍、2.09倍、2.40倍和1.37倍、1.46倍、1.58倍。施氮、磷肥皆可增加叶绿素含量,还能缓解干旱下叶绿素的降解速度,且氮磷配施的效应优于氮磷单施。施氮、磷肥有利于小粒咖啡各器官生物量的积累,而干旱胁迫能促进光合产物向地下部的分配,各处理的根重比(RMF)和根冠比(R/S)都大于正常供水时的对应值,其中N0P1和N0P2处理的RMF和R/S最大,其次是N1P2处理,且N1P2处理的根干重大于正常供水时的对应值。因此得出,氮肥和磷肥在改善幼龄期小粒咖啡抗旱性方面发挥着重要作用,而磷肥的效果优于氮肥,增强小粒咖啡抗旱性的最佳施肥处理为N1P2。     

干旱胁迫对花生生育中后期根系生长特征的影响

花生是较耐旱的经济和油料作物, 长期少雨或季节性干旱是限制花生产量提高的重要环境因子, 也是花生收获前黄曲霉素感染的重要因素。根系是植物吸水的主要器官, 不同土壤水分状况下植物的根系构型可能会表现出显著差异, 进而影响植物根系吸收养分和水分的能力。研究不同土壤水分状况下花生根系形态的发育特征与抗旱性的关系对进一步理解花生的水分吸收、运输、利用和散失机制以及培育抗旱性花生具有非常重要的作用。为明确不同抗旱性花生品种的根系形态发育特征, 探讨其根系形态发育特征对不同土壤水分状况的响应机制, 在防雨棚旱池内进行土柱栽培试验, 研究抗旱型花生品种"花育22号"和干旱敏感型花生品种"花育23号"生育中后期根系生长特征及其对干旱胁迫的响应。设置正常供水和中度干旱胁迫(分别控制土壤含水量为田间持水量的80%~85%和45%~50%)2个水分处理, 分别在花针期、结荚期和饱果期进行取样,根长、根表面积和体积扫描后通过WinRhizo Pro Vision 5.0a程序进行分析; 收获时测定产量和抗旱系数(干旱胁迫处理与正常供水处理下产量之比)。结果表明, "花育22号"具有较高的产量和抗旱系数, "花育23号"对干旱胁迫的适应性小于"花育22号"。抗旱型品种"花育22号"具有较大的根系生物量、总根长和根系表面积, 且深层土壤内根系表面积和体积大于"花育23号"。与正常供水处理相比, 干旱胁迫显著降低2个品种花针期的根系总根长、根系总表面积和总体积, 对结荚期和饱果期根系性状无显著影响; 干旱胁迫增加2个品种生育中后期40 cm以下土层内的根长密度分布比例、根系表面积和体积, 但"花育23号"各根系性状增加幅度小于"花育22号"。干旱胁迫处理下20~40 cm和40 cm以下土层内根系表面积和体积分别与总根长、总表面积和总体积呈显著或极显著正相关, 而正常供水处理下0~20 cm土层内根系表面积和体积与整体根系性状表现极显著正相关。总体而言, 具有较大根系和深层土壤内较多的根系分布是抗旱型花生的主要根系分布特征; 土壤水分亏缺条件下, 花生主要通过增加深层土壤内根长、根系表面积和体积等形态特性调节植株对水分的利用。     

干旱胁迫下丛枝菌根对大豆抗氧化代谢及根围微生物的影响

丛枝菌根真菌(AMF)可促进作物营养吸收和提高抗逆性,成为寄主抵御干旱胁迫的有效途径。为探明AMF提高大豆抗旱性的机制,以‘桂春豆103’为材料接种幼套近明囊霉(Claroideoglomus etunicatum,简写为C.e),研究干旱条件下C.e对田间大豆叶抗氧化酶及根围土中C/N/P循环相关酶活性等的影响,并用变性梯度凝胶电泳等方法探索土壤微生物群落结构的变化。结果表明:干旱处理前,接种C.e(+AM)处理大豆SOD、POD活性及游离脯氨酸(FP)含量,磷酸酶、蔗糖酶和脲酶活性,土壤细菌、真菌和放线菌数量及物种多样性、丰富度和群落均匀度指数,大豆生物量和株高均显著高于(-AM)处理(P0.05),MDA含量显著降低(P0.05)。干旱(D)处理后,+AM+D处理的上述各项指标,除MDA含量比-AM+D或+AM处理分别显著降低或升高(P0.05),FP含量比两处理显著提高(P0.05)外,其余指标值及细菌和真菌r DNA条带数均比-AM+D处理显著升高,比+AM处理显著下降(P0.05)。-AM+D与-AM处理的细菌和真菌群落均分别聚类于两不同分支,+AM与+AM+D处理聚于同一分支。可见,+AM+D处理能显著促进大豆抗氧化酶系统活性,维持较强的活性氧清除和渗透调节能力,缓解干旱对土壤酶活性的抑制,保持较高的细胞膜稳定性、土壤微生物数量和群落多样性,有利于C/N/P循环转化,提高抗旱性,最终促进大豆生长。本研究可为促进农业生态系统可持续发展奠定基础。