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磷是植物生长和发育过程中的必需营养元素,也是制约作物生产的大量营养元素之一。磷供应不足会严重抑制作物生长,降低生物量和产量。在土壤中磷酸盐很容易和金属阳离子形成难溶化合物,导致土壤中生物可利用磷供应不足。在农业生产中,农民通常通过施用磷肥以保证作物产量[1],但仅有不到25%的磷肥能够被作物利用,大部分磷被土壤矿质颗粒固定,而一部分磷可能通过侵蚀和地表径流等过程流失,最终进入水体而导致水体富营养化[2]。农业生产中的磷肥主要来源于不可再生的磷矿,持续大量施用磷肥会造成世界范围内磷矿资源枯竭,最终导致全球粮食危机[3]。随着世界人口的快速增长,全球粮食需求仍在迅速增加,在磷矿资源有限的背景下,急需寻求有效的技术途径最大限度利用土壤磷库中的磷,减少磷肥施用并提高磷肥利用效率,从而维持可持续的农业生产[4]。
丛枝菌根真菌 (arbuscular mycorrhizal fungi,AMF) 能够与绝大多数陆生植物形成共生体系,帮助宿主植物获取土壤中的磷、微量元素等矿质养分,从而促进植物生长[5],增强植物抗逆性[6]。AMF庞大的根外菌丝网络可增加宿主植物对磷素的吸收面积[7],而且AMF能分泌有机酸活化土壤磷[8],在菌丝中磷的运输速率远比在根中快[9]。在土壤磷含量较低时,植物通过AMF吸收磷比直接通过根系吸收要更为高效[10]。AMF不仅帮助宿主植物高效吸收磷,还通过调节植物基因表达、代谢物质合成与分配,以及改善植物生长环境,促进植物的生长发育。Sawers等[11]发现,AMF可以提高植物中大多数磷转运蛋白基因的表达从而促进磷的吸收和传输,低磷条件下接种AMF的植物根中特异性磷酸酶活性比供磷处理时高[12],且磷胁迫下菌根植物分泌有机酸显著增多[13]。很多研究表明,在低磷土壤上接种AMF能够有效改善植物磷营养状况,促进植物生长,而且基本上能够达到和施用磷肥相似的效果[14-16]。
玉米作为主要的粮食作物,在全世界范围内被广泛种植,也是中国种植面积最大的粮食作物之一[17]。玉米植株个体生物量较大,生长较快,对磷的需求量比较高[18]。很多试验表明,玉米是菌根依赖性较强的作物,接种AMF对于改善玉米磷营养具有显著积极作用[19-20]。然而,有关AMF与玉米磷营养的研究大多基于盆栽试验[11, 19-21],且局限于玉米营养生长阶段,很少考虑玉米全生育期和籽粒产量。有限的田间试验由于复杂的自然环境条件、AMF与宿主植物种类、接种技术等诸多因素存在差异,使得试验结果很不一致,甚至有研究报道低磷土壤上接种AMF反而降低了玉米产量[22],因此如何适当应用菌根技术,充分发挥其在农业生产中的积极作用,仍非常有必要开展系统研究。
本研究基于玉米菌根化育苗移栽开展田间小区试验,在玉米拔节期和完熟期分别取样,考察不同施磷条件下接种AMF对玉米生长、磷营养状况,以及籽粒产量与品质的影响,旨在验证AMF在实际作物生产中的潜在作用,探索菌根技术的应用范围与条件,为推进菌根技术的实际应用奠定基础。
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试验地点位于北京市延庆区唐家堡村中国科学院生态环境研究中心野外实验与示范基地 (40°29′N,115°59′E)。试验区属大陆性季风气候,处于温带与中温带、半干旱与半湿润之间的过渡地带,年平均降水量为400~500毫米,气候四季分明,昼夜温差大。试验地土壤成土母质为洪积冲击物,黄土性沉积物。试验区0—20 cm土层土壤基本理化性质:pH 8.12,有机质15.0 g/kg,硝态氮64.1 mg/kg,铵态氮17.2 mg/kg,碱解氮75 mg/kg,全磷0.87 g/kg,速效磷8.48 mg/kg,速效钾204 mg/kg。
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试验于2018年5月至10月进行,玉米 (Zea mays L.) 采用自交品系B73,种子由吉林师范大学生命科学院提供。供试AMF为Rhizophagus irregularis Schenck& Smith BGC AH01,由北京农林科学院植物营养与资源研究所提供。试验采用施磷和接种AMF两因素随机区组设计,共设置4个试验处理,分别为:1) 不施磷不接种AMF (–P–M);2) 不施磷接种AMF (–P+M);3) 施磷不接种 AMF (+P-M);4) 施磷并接种AMF (+P+M)。每个处理3次重复。划分12个2.5 m × 2.8 m的小区,每个小区种植30株玉米,行距40 cm,株距50 cm。
玉米种子经10%过氧化氢浸泡5 min后用灭菌水冲洗数遍,放入装有3层湿润滤纸的培养皿中,25℃催芽3天。土壤经60Co辐照灭菌后分装到高12 cm直径8 cm的育苗袋中,将经催芽的玉米种子播入装有约250 g灭菌土壤的育苗袋中,接菌处理土壤中混入10 g AMF菌剂,不接菌处理加入AMF菌剂过滤液。接菌处理和不接菌处理分别育苗200株。在培养室培养两周后,挑选大小一致的玉米幼苗移栽到田间小区。
每个小区在玉米移栽前施加等量氮肥 (每小区42 g硫酸铵) 和钾肥 (每小区125 g 硫酸钾) 作为底肥。施磷处理每小区施加500 g过磷酸钙。在移栽玉米前施磷小区土壤有效磷含量为14.52 mg/kg,不施磷小区土壤有效磷含量为8.07 mg/kg。
玉米移栽前清除小区内杂草并翻土 (深度约为25 cm)。移栽前每小区使用自来水充分浇灌,移栽后再充分浇灌一次。玉米生长期间依靠自然降水,每隔两周人工清除小区内的杂草。
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试验于玉米拔节期 (2018年6月底) 采集植物样品,以分析玉米生长和养分吸收状况;在完熟期 (2018年9月底) 采收玉米果穗,测定玉米籽粒产量及元素含量。
拔节期采样时,各小区最外围玉米不进行采样以避免边际效应,每个小区选取5株玉米,采集整株地上部,以植株基部为圆心,采挖直径30 cm、深度25 cm的土体中的所有根系作为根系样本。根系样品带回实验室后,在水桶中浸泡,再用自来水冲洗,捞出漂根,并剔除可见草根,取2 g左右新鲜根系样品用于测定菌根侵染率。其余植物样品于烘箱中105℃杀青,70℃烘干至恒重,测地上部与根部干重,之后用振动混合球磨仪将样品研磨成粉后用于测定元素含量。
玉米完熟期每小区采集5株植株上的玉米果穗,于烘箱中60℃烘干。每小区果穗样品脱粒后称干重,折算小区籽粒产量,进而计算出不同处理单位面积籽粒产量。此外,取烘干后的籽粒样本,数100粒称重,重复三次,取平均值得籽粒百粒重;另取部分籽粒样品,经球磨仪研磨粉碎后用于测定元素含量。
两次采样均采集土壤样品,按照5点取样法使用土钻采集每个小区表层0—20 cm的土壤,每个小区的土壤充分混匀后作为一个土壤样品,用于测定土壤pH和有效磷含量。
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进行菌根侵染率测定时,根系染色过程依据Phillips和Hayman (1970) 的方法,但有所简化,具体如下:将约0.5 g根系放入10% KOH中,90℃水浴锅中煮10 min,用自来水冲洗干净后,加入0.05%的台盼蓝,90℃下染色5 min。乳酸甘油脱色处理后将染色根段置于载玻片上,然后盖上盖玻片观察,每个样品观测30条根段[23],然后使用MYCOCALC软件计算根段侵染频率[24]。
植物菌根依赖性计算公式:菌根依赖性 = (接种植株生物量/非接种植株生物量) × 100%[25]。
拔节期玉米使用便携式光合仪 (LI-6400XT,LI-COR Corp,USA) 测玉米光合速率与气孔导度。所有测量在晴天上午8: 30—11: 00期间进行,随机选择每个小区中心三株玉米,取玉米植株完全展开上部叶片进行测定。光合仪设定参数:光量子通量密度1200 μmol/(m2·s),CO2流量400 mg/kg,叶温28℃。
土壤基本理化性质 (如土壤pH、土壤有效磷、有机质和速效钾含量等) 根据《土壤农化分析》进行测定[26]。植株和籽粒样品磷含量及其他元素含量采用微波消煮—电感耦合等离子体发射光谱法测定。称取0.2 g粉碎样品加入微波消解管中,加入10 mL硝酸 (优级纯),并静置过夜后使用全自动微波消解系统 (Mars 6,CEM crop.) 进行样品消解。消解液以超纯水定容至50 mL,过滤后用电感耦合等离子体发射光谱测定。样品消解和测定过程加入国家标准物质灌木枝叶 (GBW 07602,GSV-2) 并采用空白对照进行质量控制。土壤全磷同样使用微波消解—电感耦合等离子体发射光谱法进行测定,称取0.10 g经球磨仪研磨粉碎的土壤样品,加入6 mL硝酸 (优级纯)、2 mL盐酸 (优级纯) 和2 mL氢氟酸 (优级纯),静置过夜后进行样品消解和分析测定。玉米籽粒经球磨仪研磨粉碎后,使用元素分析仪 (Vario MAX,Elementar,Germany) 测定籽粒氮含量。
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试验数据分别采用Origin 9.1 (OriginLab Corp.,Northampton,MA,USA) 与SPSS 18.0 (SPSS,Chicago,USA) 作图和进行统计分析。通过双因素方差分析 (two-way ANOVA) 检验施磷和接菌处理及其交互作用对测定指标是否有显著影响。分别使用Shapiro-Wilk测试和Levene测试检查所有数据的正态性和均匀性以确保数据满足ANOVA假设,不符合的数据进行数据转换[16]。采用Duncan’s多重检验法检验不同处理之间的差异显著性 (P < 0.05)。
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施磷条件下玉米植株地上部与根系干重均显著高于不施磷条件下 (表1)。不施磷条件下,接种AMF显著提高了玉米根系干重,玉米的菌根依赖性 (164%) 显著高于施磷情形 (124%)。接菌和施磷对玉米叶片的光合速率和气孔导度均有显著影响 (表1)。不施磷不接菌小区玉米叶片的光合速率和气孔导度明显低于其他三个处理。不施磷接菌条件下,玉米叶片的光合参数与施磷条件下无显著差异。
表 1 不同处理下拔节期玉米生长与光合参数
Table 1. The growth and photosyntheticparameters of maize plants at elongation stage with different treatments
处理
Treatment地上部干重
Shoot dry weight
(g/plant)根系干重
Root dry weight
(g/plant)根冠比
Root/shoot ratio光合速率
Photosynthetic rate
[μmol/(m2·s)]气孔导度
Stoma conductance
[μmol/(m2·s)]–P–M 9.24 ± 0.69 b 1.45 ± 0.15 c 0.157 ± 0.010 38.56 ± 0.71 b 0.250 ± 0.007 b –P+M 15.13 ± 1.92 b 2.37 ± 0.18 b 0.160 ± 0.012 45.29 ± 0.75 a 0.308 ± 0.010 a +P–M 23.71 ± 2.27 a 3.47 ± 0.27 a 0.147 ± 0.001 46.86 ± 0.39 a 0.302 ± 0.005 a +P+M 29.91 ± 2.37 a 3.83 ± 0.19 a 0.131 ± 0.016 46.33 ± 0.93 a 0.313 ± 0.006 a 显著性 Significance by ANOVA analysis AMF * * ns *** ** P *** *** ns *** ** AMF × P ns ns ns *** * 注(Note):*—P < 0.05; **—P < 0.01; ***—P < 0.001; ns—不显著 Not significant; 同列数值后不同小写字母表示不同处理间差异显著 Values followed by different small letters in the same column indicate significant differences among treatments (P < 0.05). -
不接菌条件下,不施磷小区玉米根系菌根侵染率和丛枝丰度显著高于施磷小区,接菌条件下施磷与不施磷小区无显著差异;无论施磷与否,接菌处理均显著提高了玉米菌根侵染强度和丛枝丰度;不施磷情况下,接菌处理显著提高了玉米地上部和根部磷含量,植株磷含量与施磷情形无显著差异 (表2)。
表 2 不同处理下拔节期玉米菌根侵染情况和植株磷含量
Table 2. Mycorrhizal colonization and P contentsin maize plants at jointing stage under different treatments
处理
Treatment菌根侵染强度 (%)
Mycorrhiza infection intensity丛枝丰度 (%)
Arbuscularabundance地上部磷含量 (mg/g)
Shoot P content根系磷含量 (mg/g)
Root P content–P–M 19.78 ± 0.39 b 18.43 ± 0.59 b 2.32 ± 0.25 b 1.20 ± 0.52 b –P+M 38.96 ± 2.75 a 34.52 ± 2.39 a 2.94 ± 0.06 a 1.41 ± 0.14 a +P–M 10.48 ± 0.87 c 8.66 ± 0.57 c 2.77 ± 0.11 ab 1.63 ± 0.05 ab +P+M 33.27 ± 0.68 a 30.51 ± 0.93 a 2.87 ± 0.11 a 1.68 ± 0.15 a 显著性 Significance by ANOVA analysis AMF *** *** * ns P *** *** ns * AMF × P ** *** ns ns 注(Note):*—P < 0.05; **—P < 0.01; ***—P < 0.001; ns—不显著Not significant; 同列数值后不同小写字母表示不同处理间差异显著 Values followed by different small letters in the same column indicate significant differences among treatments (P < 0.05). -
玉米拔节期土壤pH在施磷处理下显著较低,完熟期施磷小区土壤pH仍显著低于未施磷处理。玉米拔节期与完熟期时土壤有效磷含量均受施磷处理显著影响,完熟期施磷小区土壤有效磷含量总体上显著高于未施磷小区 (表3)。
表 3 不同处理土壤pH和土壤有效磷
Table 3. Soil pH and Olsen-P under different treatments
处理
Treatment土壤pH Soil pH 土壤有效磷Soil Olsen-P (mg/kg) 拔节期Jointing stage 完熟期Ripe stage 拔节期Jointing stage 完熟期Ripe stage –P–M 8.79 ± 0.01 a 8.48 ± 0.02 a 7.67 ± 0.39 ab 4.46 ± 0.67 bc –P+M 8.76 ± 0.05 a 8.51 ± 0.02 a 6.58 ± 0.75 b 3.61 ± 0.74 c +P–M 8.45 ± 0.02 b 8.39 ± 0.05 b 10.45 ± 1.13 ab 9.70 ± 1.51 a +P+M 8.37 ± 0.03 b 8.36 ± 0.03 b 14.14 ± 2.74 a 7.30 ± 0.93 ab 显著性Significance by ANOVA analysis AMF ns ns ns ns P *** ** * ** AMF × P ns ns ns ns 注(Note):*—P < 0.05; **—P < 0.01; ***—P < 0.001; ns—不显著 Not significant; 同列数值后不同小写字母表示不同处理间差异显著 Values followed by different small letters in the same column indicate significant differences among treatments (P < 0.05). -
不施磷不接菌条件下,玉米的籽粒产量和百粒重两个指标均显著低于其他三个处理,而不施磷条件下接菌处理的玉米百粒重和籽粒产量与施磷条件下的无显著差异 (图1)。
图 1 不同处理下玉米籽粒产量和百粒重
Figure 1. The grain yield and 100-grain weight of maize plants under different treatments
玉米籽粒中磷含量受到施磷处理显著影响,不施磷不接菌处理籽粒磷含量显著低于其他三个处理,不施磷接种AMF处理籽粒中磷含量与施磷处理无显著差异 (图2,表4)。不施磷接菌处理相比不接菌处理显著提高了籽粒中镁、锰和锌的含量,且与施磷情形无显著差异。接种和施磷处理对籽粒中氮、钾、钙、铜和锌含量无显著影响。
表 4 不同处理下玉米籽粒中元素含量的方差分析结果
Table 4. ANOVA outputs of elemental contents in maize grains under different treatments
处理Treatment 氮N 磷P 钾K 钙Ca 镁Mg 铁Fe 锰Mn 铜Cu 锌Zn AMF ns ns ns ns ns * ns ns ns P ns *** ns ns * *** * ns ns AMF × P ns ** ns * ** ns * ns * 注(Note):*—P < 0.05; **—P < 0.01; ***—P < 0.001; ns—不显著 Not significant. -
玉米作为重要的粮食作物,因其高产及工业应用价值较高而被广泛种植。很多研究表明,AMF对改善玉米矿质营养尤其磷营养具有重要作用,但大多数研究都集中在玉米的营养生长期[11, 20-21],只有少数研究考察了田间条件下接种AMF对玉米全生育期的影响[18, 27]。本研究在田间条件下考察了接种AMF对玉米营养生长、养分吸收、籽粒产量及品质的影响,试验结果表明,未施磷条件下接种AMF显著提高了玉米生物量和磷含量,增加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;不施磷时接种AMF和施磷条件下玉米生长及籽粒产量无显著差异。试验结果证实了接种AMF对于大田玉米生产具有潜在的重要作用。
土壤磷水平和植物自身磷营养状况会影响AMF对植物生长和磷吸收的积极作用[28]。研究表明,土壤供磷不足情况下AMF更容易与植物建立共生体系[10],植物对AMF的依赖性更强,而磷供应充足时,菌根共生体系对宿主植物的生长促进作用通常不明显[10-11]。本试验中未接菌情况下,玉米被土著菌根真菌侵染的强度在施磷处理下显著低于未施磷情形,表明施磷处理在一定程度上抑制了土著菌对玉米的侵染。一方面,施磷可能直接影响到植物根际的真菌多样性[29],供磷充足时菌根侵染和丛枝形成也会受到抑制[30-31],不利于菌根共生体系的建成和发育。另一方面,当土壤中有效磷含量较高时,植物通过自身根毛吸收磷的“成本”比通过AMF吸收的“成本”低[10],使得施磷情况下玉米菌根依赖性降低,土著菌对玉米的侵染强度也较低。接菌处理在施磷与不施磷情况下菌根侵染无显著差异,一个重要原因可能是接菌处理下玉米是先经菌根化育苗再移栽到田间,在施磷处理之前AMF对玉米根系已形成良好侵染,未受到田间施磷处理的显著影响。总体上接菌处理下玉米的菌根侵染率要显著高于不接菌处理,可能也得益于这种预先接种方式,避免了外源AMF和土著菌的直接竞争,保障了良好菌根侵染和共生效能。值得注意的是,虽然未接菌处理下土著菌对玉米形成了一定侵染,但其对玉米生长及养分吸收的作用可能非常有限,不如外源接种的AMF作用显著。有研究报道,特定情况下土著菌侵染可能对宿主植物生长表现出显著的负效应[32]。当然,要明确土著菌的共生效能,以及土著菌和外源AMF之间的相互作用,还需要进一步深入研究。
AMF能够通过根外菌丝扩大根系吸收养分的范围,获得植物根系无法直接获取的土壤磷素[33],这可以解释未施磷时接菌处理玉米磷含量显著高于未接种情形。在本试验中,未施磷条件下接种AMF的玉米在拔节期的生物量和植株磷含量与施磷情况下无显著差异,充分说明一定条件下接种AMF能够替代磷肥的功效,有效改善玉米磷营养并促进植株生长。此外,有研究表明AMF侵染提高了玉米侧根和细根百分比,增大了玉米与土壤的接触面积[29],从而促进了玉米对磷的吸收。AMF也可能特异性诱导相关磷转运蛋白基因的表达促进共生体对磷的吸收和转运[21, 34]。这些机制可能共同作用,使得接种AMF的玉米吸收积累更多的磷,从而提高玉米的产量潜力[35]。
本研究中玉米籽粒产量在未施磷接菌处理下与施磷情形无显著差异,而未施磷接种AMF的玉米产量显著高于未接种情形。接种AMF提高作物产量已有不少报道,如AMF接种可以提高洋葱[36]和马铃薯[37]产量,但是也有报道显示接种AMF并没有积极作用甚至导致减产[38]。不同的试验条件、不同作物品种及接种方式可能是导致不同试验结果的主要原因,同时AMF接种效应也受到AMF和宿主植物适合性的影响[39]。本试验中,施磷处理下接种与不接种玉米生长和磷吸收及产量均无显著差异,原因可能是土壤有效磷含量较高,可以满足玉米生长需求[40],AMF对玉米磷营养及生长没有明显积极作用。试验条件下,施磷小区土壤有效磷含量达到了14.52 mg/kg,而之前的研究发现,当土壤速效磷达到12.1 mg/kg时,施加磷肥对于玉米产量即无显著影响[41-42],同样在土壤速效磷含量较高时接种AMF对作物生长也很难表现出积极作用。从应用角度考虑,可能在肥力较低的农田才适合接种AMF,而田间接种AMF时也需要注意合理施肥,特别是不能再大量施用磷肥。
就作物生长和产量而言,菌根效应不仅取决于特定的植物与真菌组合[43],还取决于特定环境条件[44]。不同植物对菌根真菌的依赖性存在很大差异,其菌根效应可以是正的、中性的或负的[32]。本试验中未施磷小区土壤有效磷含量属于中磷水平[26],玉米B73通过菌根化育苗外源接种AMF在不施磷时籽粒产量与质量与施磷处理无显著差异,而有的研究发现低磷土壤上接种AMF反而降低了玉米产量[22],造成这种差异的原因可能是由于玉米品种的差异,以及外源AMF和土著菌相互作用的不同[11]。因此,菌根技术的田间应用要充分考虑土壤肥力水平、作物种类 (品种)、土著菌的作用等等,从而明确菌根技术是否适用以及应该采用什么样的接种技术。
玉米作为重要粮食作物,对籽粒品质的评估不可忽视[26]。本研究发现,接种AMF与施磷处理均提高了玉米籽粒百粒重与磷含量,同样显著增加了籽粒中锌、镁和锰的含量,也一定程度增加了籽粒铁含量。锌和铁是两种重要的营养元素,籽粒的营养质量评估即需要考虑锌和铁的含量[26]。本试验中接菌处理增加了籽粒中锌和铁的积累,对于提高籽粒品质具有重要意义。试验结果还显示施磷显著降低了土壤pH,随着土壤pH降低土壤溶液中可溶性金属阳离子会数量级增多[45],从而更有利于植物吸收,这可能是施磷处理下玉米籽粒中相关元素含量升高的主要原因。不过,本试验仅进行了一年,未能验证AMF提高玉米籽粒品质的继代效应,今后可考虑利用本试验所得玉米籽粒继续开展研究,为菌根技术在作物生产中的应用提供更有力的科学证据。
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本研究证实,不施磷条件下接种AMF可促进玉米吸收矿质养分 (尤其是磷),进而促进玉米生长,提高玉米籽粒产量和品质。不施磷条件下接种AMF的玉米在生长和籽粒产量与施磷条件下无显著差异。实际生产中,通过适当的接种方式 (如菌根化育苗) 确保AMF对作物的侵染,可以在不减产的前提下,减少磷肥施用,从而节约不可再生资源,保护生态环境,进而有利于可持续农业的发展。
菌根化育苗促进田间不施磷玉米生长和养分吸收
Seedling mycorrhization can promote the growth and nutrient uptake of maize without phosphorus application under field condition
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摘要:
【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、籽粒产量及品质的影响,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小区玉米叶片的光合速率和气孔导度显著低于其他三个处理。–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,提高籽粒产量和品质。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。 Abstract:【Objectives】Many environment-controlled experiments have demonstrated that mycorrhizal symbiosis formed between arbuscular mycorrhizal fungi (AMF) and plant roots can increase plant phosphorus uptake effectively. However, the practical field application of AMF varied greatly in results. In the present study, field trial was established with mycorrhized maize seedlings transplanted to field, to test the effectiveness of AMF inoculation on the maize growth, nutrient uptake, grain yield and quality, and also to explore the suitable conditions for field application of mycorrhizal technology. 【Methods】A field trial was carried out in Yanqing District, Beijing from May to October, 2018, with an inbred line maize strain Zea mays L. cv. B73 as tested plant. The plots were treated with and without P application (+P, –P). The seedling bags (containing 250 g of soil each) were added with or without AMF inoculum (+M, –M). The tested AMF strain was Rhizophagus irregularis Schenck& Smith BGC AH01, and added in rate of 10 g inoculum per bag for +M treatment. The germinated maize seeds were sowninto the bags and grew for two weeks before transplanted into field plots. At the elongation stage, the maize leaf photosynthetic rate and stoma conductance were measured by portable photosynthesis system, the plant dry weights, mycorrhizal infection rate, and the P contents of roots and shoots were determined. At the full ripening stage, the 100-grain weight,grain yield and nutrient contents were determined. 【Results】Whether in –P or +P plots,the AMF infection intensity and arbuscular abundance in roots ofmycorrhizal maize seedlings weresignificantly higher than those from non-mycorrhizal seedlings. In –P plots, the seedling mycorrhization treatment significantly increased the dry weight of maize roots. The growth dependence of maize on AMF in –P plotswas164% which was higher than that in +P plots (124.1%).The photosynthetic rate and stoma conductance of -P-M treatment were significantly lower than those of the other 3 treatments, whereas there was no significant difference among –P+M, +P-M and +P+M. In –P plots, seedling mycorrhization significantly increased P contents in shoots and roots, and the P contents were not significantly different from those in +P plots. Meanwhile, seedling mycorrhization also significantly increased plant biomass and P uptake, grain yield, 100-grain weight and grain zinc, manganese and magnesium contents. By contrast, in +P plots, seedling mycorrhization showed no significant effects on all the tested indexes. 【Conclusions】Seedling mycorrhization is capable of providing a steadily promoting effect of AMF on maize growth and nutrient uptake including P, Zn, Mn and Mg, which is almost equally efficient as P fertilization in improving maize yield and grain qualities. Therefore, seedling mycorrhization technology could be applied to save P fertilizer without loss of crop yield and serve as an alternative strategy for supporting sustainable agriculture. -
Key words:
- maize /
- arbuscular mycorrhizal fungi (AMF) /
- field trial /
- phosphorus /
- nutrient uptake /
- yield /
- quality
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表 1 不同处理下拔节期玉米生长与光合参数
Table 1. The growth and photosyntheticparameters of maize plants at elongation stage with different treatments
处理
Treatment地上部干重
Shoot dry weight
(g/plant)根系干重
Root dry weight
(g/plant)根冠比
Root/shoot ratio光合速率
Photosynthetic rate
[μmol/(m2·s)]气孔导度
Stoma conductance
[μmol/(m2·s)]–P–M 9.24 ± 0.69 b 1.45 ± 0.15 c 0.157 ± 0.010 38.56 ± 0.71 b 0.250 ± 0.007 b –P+M 15.13 ± 1.92 b 2.37 ± 0.18 b 0.160 ± 0.012 45.29 ± 0.75 a 0.308 ± 0.010 a +P–M 23.71 ± 2.27 a 3.47 ± 0.27 a 0.147 ± 0.001 46.86 ± 0.39 a 0.302 ± 0.005 a +P+M 29.91 ± 2.37 a 3.83 ± 0.19 a 0.131 ± 0.016 46.33 ± 0.93 a 0.313 ± 0.006 a 显著性 Significance by ANOVA analysis AMF * * ns *** ** P *** *** ns *** ** AMF × P ns ns ns *** * 注(Note):*—P < 0.05; **—P < 0.01; ***—P < 0.001; ns—不显著 Not significant; 同列数值后不同小写字母表示不同处理间差异显著 Values followed by different small letters in the same column indicate significant differences among treatments (P < 0.05). 表 2 不同处理下拔节期玉米菌根侵染情况和植株磷含量
Table 2. Mycorrhizal colonization and P contentsin maize plants at jointing stage under different treatments
处理
Treatment菌根侵染强度 (%)
Mycorrhiza infection intensity丛枝丰度 (%)
Arbuscularabundance地上部磷含量 (mg/g)
Shoot P content根系磷含量 (mg/g)
Root P content–P–M 19.78 ± 0.39 b 18.43 ± 0.59 b 2.32 ± 0.25 b 1.20 ± 0.52 b –P+M 38.96 ± 2.75 a 34.52 ± 2.39 a 2.94 ± 0.06 a 1.41 ± 0.14 a +P–M 10.48 ± 0.87 c 8.66 ± 0.57 c 2.77 ± 0.11 ab 1.63 ± 0.05 ab +P+M 33.27 ± 0.68 a 30.51 ± 0.93 a 2.87 ± 0.11 a 1.68 ± 0.15 a 显著性 Significance by ANOVA analysis AMF *** *** * ns P *** *** ns * AMF × P ** *** ns ns 注(Note):*—P < 0.05; **—P < 0.01; ***—P < 0.001; ns—不显著Not significant; 同列数值后不同小写字母表示不同处理间差异显著 Values followed by different small letters in the same column indicate significant differences among treatments (P < 0.05). 表 3 不同处理土壤pH和土壤有效磷
Table 3. Soil pH and Olsen-P under different treatments
处理
Treatment土壤pH Soil pH 土壤有效磷Soil Olsen-P (mg/kg) 拔节期Jointing stage 完熟期Ripe stage 拔节期Jointing stage 完熟期Ripe stage –P–M 8.79 ± 0.01 a 8.48 ± 0.02 a 7.67 ± 0.39 ab 4.46 ± 0.67 bc –P+M 8.76 ± 0.05 a 8.51 ± 0.02 a 6.58 ± 0.75 b 3.61 ± 0.74 c +P–M 8.45 ± 0.02 b 8.39 ± 0.05 b 10.45 ± 1.13 ab 9.70 ± 1.51 a +P+M 8.37 ± 0.03 b 8.36 ± 0.03 b 14.14 ± 2.74 a 7.30 ± 0.93 ab 显著性Significance by ANOVA analysis AMF ns ns ns ns P *** ** * ** AMF × P ns ns ns ns 注(Note):*—P < 0.05; **—P < 0.01; ***—P < 0.001; ns—不显著 Not significant; 同列数值后不同小写字母表示不同处理间差异显著 Values followed by different small letters in the same column indicate significant differences among treatments (P < 0.05). 表 4 不同处理下玉米籽粒中元素含量的方差分析结果
Table 4. ANOVA outputs of elemental contents in maize grains under different treatments
处理Treatment 氮N 磷P 钾K 钙Ca 镁Mg 铁Fe 锰Mn 铜Cu 锌Zn AMF ns ns ns ns ns * ns ns ns P ns *** ns ns * *** * ns ns AMF × P ns ** ns * ** ns * ns * 注(Note):*—P < 0.05; **—P < 0.01; ***—P < 0.001; ns—不显著 Not significant. -
[1] Abdelrahman M, El-Sayed M A, Hashem A, et al. Metabolomics and transcriptomics in legumes under phosphate deficiency in relation to nitrogen fixation by root nodules[J]. Frontiers in Plant Science, 2018, 9: 922. doi: 10.3389/fpls.2018.00922 [2] Aulakh M S, Garg A K, Kabba B S. Phosphorus accumulation, leaching and residual effects on crop yields from long-term applications in the subtropics[J]. Soil Use and Management, 2007, 23(4): 417–427. doi: 10.1111/j.1475-2743.2007.00124.x [3] Gilbert N. Environment: The disappearing nutrient[J]. Nature, 2009, 461(7265): 716–718. doi: 10.1038/461716a [4] Bargaz A, Lyamlouli K, Chtouki M, et al. Soil microbial resources for improving fertilizers efficiency in an integrated plant nutrient management system[J]. Frontiers in Microbiology, 2018, 9: 1606. doi: 10.3389/fmicb.2018.01606 [5] Adesemoye A O, Kloepper J W. Plant-microbes interactions in enhanced fertilizer-use efficiency[J]. Applied Microbiology and Biotechnology, 2009, 85(1): 1–12. doi: 10.1007/s00253-009-2196-0 [6] Li T, Sun Y Q, Ruan Y, et al. Potential role of D-myo-inositol-3-phosphate synthase and 14-3-3 genes in the crosstalk between Zeamays and Rhizophagusintraradices under drought stress[J]. Mycorrhiza, 2016, 26(8): 879–893. doi: 10.1007/s00572-016-0723-2 [7] 姚青, 赵紫娟, 冯固, 等. VA菌根真菌外生菌丝对难溶性无机磷酸盐的活化及利用[J]. 核农学报, 2000, 14(3): 145–150. Yao Q, Zhao Z J, Feng G, et al. Mobilization and utilization of sparingly soluble phosphates by VA mycorrhizal fungus external hyphae[J]. Journal of Nuclear Agricultural Sciences, 2000, 14(3): 145–150. doi: 10.3969/j.issn.1000-8551.2000.03.004
[8] 张玉凤, 冯固, 李晓林. 丛枝菌根真菌对三叶草根系分泌的有机酸组分和含量的影响[J]. 生态学报, 2003, 23(1): 30–37. Zhang Y F, Feng G, Li X L. The effect of arbuscular mycorrhizal fungi on the components and concentrations of organic acids in the exudates of mycorrhizal red clover[J]. Acta Ecologica Sinica, 2003, 23(1): 30–37. doi: 10.3321/j.issn:1000-0933.2003.01.005
[9] Smith S E, Gianinazzi P V, Koide R, et al. Nutrient transport in mycorrhizas: structure, physiology and consequences for efficiency of the symbiosis[J]. Plant and Soil, 1994, 159(1): 1573–5036. [10] Raven J A, Lambers H, Smith S E, et al. Costs of acquiring phosphorus by vascular land plants: patterns and implications for plant coexistence[J]. New Phytologist, 2018, 217(4): 1420–1427. doi: 10.1111/nph.14967 [11] Sawers R J H, Svane S F, Quan C, et al. Phosphorus acquisition efficiency in arbuscular mycorrhizal maize is correlated with the abundance of root-external hyphae and the accumulation of transcripts encoding PHT1 phosphate transporters[J]. New Phytologist, 2017, 214(2): 632–643. doi: 10.1111/nph.14403 [12] Ezawa T, Yoshida T. Characterization of phosphatase in marigold roots infected with vesicular-arbuscular mycorrhizal fungi AU - Ezawa, Tatsuhiro[J]. Soil Science and Plant Nutrition, 1994, 40(2): 255–64. doi: 10.1080/00380768.1994.10413299 [13] 刘进法, 王鹏, 罗园, 等. 低磷胁迫下AM真菌对枳实生苗吸磷效应及根系分泌有机酸的影响[J]. 亚热带植物科学, 2010, 39(1): 9–13. Liu J F, Wang P, Luo Y, et al. Effects of arbuscular mycorrhizal fungus on absorbing phosphorus and excreting organic acids of Poncirus trifoliata seedlings under low-phosphorus stress[J]. Subtropical Plant Science, 2010, 39(1): 9–13.
[14] Urcoviche R C, Gazim Z C, Dragunski D C, et al. Plant growth and essential oil content of Mentha crispa inoculated with arbuscular mycorrhizal fungi under different levels of phosphorus[J]. Industrial Crops and Products, 2015, 67: 103–107. doi: 10.1016/j.indcrop.2015.01.016 [15] Schweiger R, Mueller C. Leaf metabolome in arbuscular mycorrhizal symbiosis[J]. Current opinion in plant biology, 2015, 26: 120–126. doi: 10.1016/j.pbi.2015.06.009 [16] Xie W, Hao Z, Yu M, et al. Improved phosphorus nutrition by arbuscular mycorrhizal symbiosis as a key factor facilitating glycyrrhizin and liquiritin accumulation in Glycyrrhiza uralensis[J]. Plant and Soil, 2018: 1–15. [17] 仇焕广, 张世煌, 杨军, 等. 中国玉米产业的发展趋势、面临的挑战与政策建议[J]. 中国农业科技导报, 2013, 15(1): 20–24. Chou H G, Zhang S H, Yang J, et al. Development of China's maize industry, challenges in the future and policy suggestions[J]. Journal of Agricultural Science and Technology, 2013, 15(1): 20–24.
[18] Gómez-Muñoz B, Jensen L S, de Neergaard A, et al. Effects of Penicillium bilaii on maize growth are mediated by available phosphorus[J]. Plant and Soil, 2018, 431(1–2): 159–173. doi: 10.1007/s11104-018-3756-9 [19] Willmann M, Gerlach N, Buer B, et al. Mycorrhizal phosphate uptake pathway in maize: vital for growth and cob development on nutrient poor agricultural and greenhouse soils[J]. Frontiers in Plant Science, 2013, 4: 533. [20] Gerlach N, Schmitz J, Polatajko A, et al. An integrated functional approach to dissect systemic responses in maize to arbuscular mycorrhizal symbiosis[J]. Plant, Cell & Environment, 2015, 38(8): 1591–1612. [21] Tian H, Drijber R A, Li X, et al. Arbuscular mycorrhizal fungi differ in their ability to regulate the expression of phosphate transporters in maize (Zea mays L.)[J]. Mycorrhiza, 2013, 23(6): 507–514. doi: 10.1007/s00572-013-0491-1 [22] 李腾腾, 傅智峰, 李侠. 低磷土壤接种菌根真菌和解磷细菌对大田玉米生长和磷吸收的影响[J]. 土壤通报, 2017, 48(4): 922–929. Li T T, Fu Z F, Li X. Effects of inoculation of arbuscular mycorrhizal fungi and phosphate-solubilizing bacteria on maize growth and phosphorous nutrient uptake in low phosphorous field[J]. Chinese Journal of Soil Science, 2017, 48(4): 922–929.
[23] 徐丽娇, 姜雪莲, 郝志鹏, 等. 丛枝菌根通过调节碳磷代谢相关基因的表达增强植物对低磷胁迫的适应性[J]. 植物生态学报, 2017, 41(8): 815–825. Xu L J, Jiang X L, Hao Z P, et al. Arbuscular mycorrhiza improves plant adaptation to phosphorus deficiency through regulating the expression of genes relevant to carbon and phosphorus metabolism[J]. Chinese Journal of Plant Ecology, 2017, 41(8): 815–825. doi: 10.17521/cjpe.2017.0018
[24] Trouvelot A, Kough, J L, Gianinazzi-Pearson V. Mesure du taux de mycorhization VA d'un système radiculaire. Recherche de méthodes d'estimation ayant une signification fonctionnelle[A]. Gianinazzi-Pearson V, Gianinazzi S. Physiological and genetical aspects of mycorrhizae[M], Paris: INRA, 1986. 217–221. [25] 林先贵, 郝英文. 不同植物对VA菌根菌的依赖性[J]. 植物学报, 1989, 31(9): 721–725. Lin X G, Hao Y W. Mycorrhizal dependency of various kinds of plants[J]. Acta Botanica Sinica, 1989, 31(9): 721–725.
[26] 鲍士旦. 土壤农化分析[M]. 北京: 中国农业出版社, 1998.
Bao S D. Soil agro-chemistrical analysis[M]. Beijing: China Agriculture Press, 1998.[27] Berta G, Copetta A, Gamalero E, et al. Maize development and grain quality are differentially affected by mycorrhizal fungi and a growth-promoting pseudomonad in the field[J]. Mycorrhiza, 2014, 24(3): 161–170. doi: 10.1007/s00572-013-0523-x [28] Carbonnel S, Gutjahr C. Control of arbuscular mycorrhiza development by nutrient signals[J]. Frontiers in Plant Science, 2014, 5: 462. [29] Yu P, Wang C, Baldauf J A, et al. Root type and soil phosphate determine the taxonomic landscape of colonizing fungi and the transcriptome of field-grown maize roots[J]. New Phytologist, 2018, 217(3): 1240–1253. doi: 10.1111/nph.14893 [30] Liu W, Zhang Y L, Jiang S S, et al. Arbuscular mycorrhizal fungi in soil and roots respond differently to phosphorus inputs in an intensively managed calcareous agricultural soil[J]. Scientific Reports, 2016, 6: 24902. doi: 10.1038/srep24902 [31] Sugimura Y, Saito K. Transcriptional profiling of arbuscular mycorrhizal roots exposed to high levels of phosphate reveals the repression of cell cycle-related genes and secreted protein genes in Rhizophagus irregularis[J]. Mycorrhiza, 2017, 27(2): 139–146. doi: 10.1007/s00572-016-0735-y [32] 雷垚, 郝志鹏, 陈保冬. 土著菌根真菌和混生植物对羊草生长和磷营养的影响[J]. 生态学报, 2013, 33(4): 1071–1079. Lei Y, Hao Z P, Chen B D. Effects of indigenous AM fungi and neighboring plants on the growth and phosphorus nutrition of Leymus chinensis[J]. ActaEcologicaSinica, 2013, 33(4): 1071–1079.
[33] Cavagnaro T R. Impacts of compost application on the formation and functioning of arbuscular mycorrhizas[J]. Soil Biology and Biochemistry, 2014, 78: 38–44. doi: 10.1016/j.soilbio.2014.07.007 [34] Nagy R, Karandashov V, Chague V, et al. The characterization of novel mycorrhiza-specific phosphate transporters from Lycopersicon esculentum and Solanum tuberosum uncovers functional redundancy in symbiotic phosphate transport in solanaceous species[J]. The Plant Journal, 2005, 42(2): 236–250. doi: 10.1111/j.1365-313X.2005.02364.x [35] Sabia E, Claps S, Morone G, et al. Field inoculation of arbuscular mycorrhiza on maize (Zea mays L.) under low inputs: preliminary study on quantitative and qualitative aspects[J]. Italian Journal of Agronomy, 2015: 30–33. [36] Gosling P, Jones J, Bending G D. Evidence for functional redundancy in arbuscular mycorrhizal fungi and implications for agroecosystem management[J]. Mycorrhiza, 2016, 26(1): 77–83. doi: 10.1007/s00572-015-0651-6 [37] Hijri M. Analysis of a large dataset of mycorrhiza inoculation field trials on potato shows highly significant increases in yield[J]. Mycorrhiza, 2016, 26(3): 209–214. doi: 10.1007/s00572-015-0661-4 [38] Dai M, Hamel C, Bainard L D, et al. Negative and positive contributions of arbuscular mycorrhizal fungal taxa to wheat production and nutrient uptake efficiency in organic and conventional systems in the Canadian prairie[J]. Soil Biology and Biochemistry, 2014, 74: 156–166. doi: 10.1016/j.soilbio.2014.03.016 [39] Thirkell T J, Charters M D, Elliott A J, et al. Are mycorrhizal fungi our sustainable saviours? Considerations for achieving food security[J]. Journal of Ecology, 2017, 105(4): 921–929. doi: 10.1111/1365-2745.12788 [40] 姚姗, 张东杰, Javkhlan B, 等. 冬小麦-夏玉米体系磷效率对鴥土磷素肥力的响应[J]. 植物营养与肥料学报, 2018, 24(6): 1640–1650. Yao S, Zhang D J, Javkhlan B, et al. Responses of phosphorus use efficiency to soil phosphorus fertility under winter wheat?summer maize cropping in loess soil[J]. Journal of Plant Nutrition and Fertilizers, 2018, 24(6): 1640–1650. doi: 10.11674/zwyf.18262
[41] Tang X, Ma Y B, Hao X Y, et al. Determining critical values of soil Olsen-P for maize and winter wheat from long-term experiments in China[J]. Plant and Soil, 2009, 323(1): 143–151. [42] Bai Z H, Li H G, Yang X Y, et al. The critical soil P levels for crop yield, soil fertility and environmental safety in different soil types[J]. Plant and Soil, 2013, 372(1): 27–37. [43] Liu Y, Shi G, Mao L, et al. Direct and indirect influences of 8 yr of nitrogen and phosphorus fertilization on Glomeromycota in an alpine meadow ecosystem[J]. New Phytologist, 2012, 194(2): 523–535. doi: 10.1111/j.1469-8137.2012.04050.x [44] Janos D P. Plant responsiveness to mycorrhizas differs from dependence upon mycorrhizas[J]. Mycorrhiza, 2007, 17(2): 75–91. doi: 10.1007/s00572-006-0094-1 [45] Tipping E, Smith E J, Lawlor A J, et al. Predicting the release of metals from ombrotrophic peat due to drought-induced acidification[J]. Environmental Pollution, 2003, 123(2): 239–253. doi: 10.1016/S0269-7491(02)00375-5 -