Interactions of some nematicides with Azospirillum lipoferum and the growth of Zea maize

The possible interaction of four nematicides (Terbufos, Carbofuran, Fenamiphos, and Aldicarb) with Azospirillum lipoferum and growth of two Zea maize cultivars was studied in a greenhouse experiment. Application of nematicides, Fenamiphos in particular, resulted in higher plant length, dry matter production and N yield over the nematicide-untreated plants. Azospirillum spp. inoculation stimulated the growth of nematicide-treated Z. maize. Among the nematicides used, Carbofuran and Aldicarb inhibited the nitrogenase activity on plant roots more seriously than Fenamiphos and Terbufos. Generally, the inhibition percentages in acetylene reducing activity in soil of inoculated treatments were lower (14.4 - 61.8%) than those reported for the uninoculated ones (21.4 - 73.9%). Soil, irrespective of treatment, regained a part of its normal N₂-ase activity with time. Field concentrations of all nematicides showed different inhibitory effects on N₂-ase activity of Azospirillum spp. in culture medium, such effects increased with increased doses (10- and 100- fold) and incubation periods (10 days). The contribution of Azospirillum spp. to the N economy of soil treated with nematicides is discussed.     

除草剂对不同玉米品种生长发育和产量的影响

化学除草为作物田间管理带来方便的同时,药害问题也越来越突出,特别是苗后除草剂对作物造成的药害频繁发生。为此,本文以我国玉米主栽品种‘郑单958’、‘先玉335’、‘京科968’和‘京农科728’为试验材料,采用2,4-D丁酯和烟嘧磺隆2种苗后除草剂,每种除草剂设置0倍(人工除草,CK)、1倍(最适浓度,T1)和2倍最适浓度(T2)共3个喷施浓度处理,于玉米幼苗4展叶期喷施。研究苗后除草剂对不同基因型玉米品种生育进程、形态特征、保护酶活性和产量等性状指标的影响,旨在为玉米安全生产提供参考和指导。研究结果表明:1)喷施除草剂后,参试玉米品种的生育期呈延长趋势,‘郑单958’和‘先玉335’的生育期延长程度大于‘京科968’和‘京农科728’;2,4-D丁酯对参试品种的生育期延长幅度大于烟嘧磺隆。喷施除草剂后,参试玉米品种的叶面积、根系长度、表面积和体积呈降低趋势,且随除草剂浓度增加,降低幅度加大;品种间的反应也存在较大差异,‘郑单958’和‘先玉335’降低程度大于‘京科968’和‘京农科728’。2)喷施苗后除草剂后,参试玉米品种的叶片SOD活性、CAT活性和MDA含量在品种、除草剂和剂量间均存在极显著差异;参试玉米品种的SOD和CAT活性呈降低趋势、MDA含量呈升高趋势,且随喷施浓度增加影响加剧;不同品种间,随喷施浓度增加,‘郑单958’和‘先玉335’的SOD和CAT活性降幅高于‘京科968’和‘京农科728’;不同除草剂间,2,4-D丁酯处理的影响程度大于烟嘧磺隆。3)苗后除草剂对参试品种的穗粒数、百粒重和产量影响显著,均呈降低趋势;随除草剂浓度增加降幅增大;不同品种间,‘郑单958’和‘先玉335’的降幅大于‘京科968’和‘京农科728’。由此可见,2种苗后除草剂对参试玉米品种的生长发育和产量存在显著影响,表现在延长了生育期,抑制了根系和叶片的生长,降低了保护酶活性,并且加重了叶片的膜质过氧化程度,从而导致玉米减产显著,且随除草剂浓度增加,影响进一步加大。不同品种间,‘京科968’和‘京农科728’对苗后除草剂的耐受性好于‘郑单958’和‘先玉335’。     

蚯蚓与菌根提高玉米生长和氮磷吸收的互补效应

【目的】蚯蚓和丛枝菌根真菌处于不同的营养级,但在促进植物生长和提高土壤肥力等方面却都发挥着积极作用。研究蚯蚓菌根互作及其对玉米吸收土壤中的氮、磷养分的影响,可为提升土壤生物肥力及促进农业的可持续发展提供理论依据。【方法】本研究采用田间盆栽方式,以玉米为供试作物,研究蚯蚓(Eisenia fetida)与丛枝菌根真菌(Glomus intraradices)互作及其对玉米养分吸收的影响。试验设置P 25和175 mg/kg两个水平。每个磷水平进行接种与不接种菌根真菌以及添加与不添加蚯蚓,共8个处理。调查了玉米生长、养分吸收以及真菌浸染和土壤养分的有效性。【结果】两个磷水平下,蚯蚓和菌根在增加玉米地上部和根系生物量方面有显著正交互作用(P0.05)。接种菌根真菌的各处理显著增加了玉米的侵染率及泡囊丰度、根内菌丝丰度等菌根指标。同时添加蚯蚓和接种菌根真菌的处理(AM+E)显著提高了菌根的侵染率、菌丝密度、丛枝丰度和根内菌丝丰度但是泡囊丰度有所下降。两种磷水平下,AM+E处理玉米地上部和地下部含氮量和含磷量均显著高于其他三个处理。在低磷条件下,地上部氮磷总量的增加分别是添加蚯蚓和接菌的作用;而地下部磷总量的增加主要是菌根真菌的作用。在高磷条件下,单加蚯蚓显著增加玉米氮磷的总量,而接种菌根真菌对玉米氮磷吸收的影响未达显著性水平。在高磷条件下,单加蚯蚓的处理显著提高玉米地上地下部生物量(P0.05),而单接菌的处理效应不显著,蚯蚓菌根互作通过提高土壤微生物量碳、氮实现对玉米生长和养分吸收的调控。在低磷条件下,单接菌显著提高了玉米的生物量(P0.05),单加蚯蚓的处理具有增加玉米生物量的趋势。菌根真菌主要促进玉米对磷的吸收,蚯蚓主要矿化秸秆和土壤中的氮磷养分增加土壤养分的有效性,蚯蚓菌根互作促进了玉米根系对土壤养分的吸收并形成氮磷互补效应。【结论】无论在高磷还是低磷水平下,蚯蚓菌根相互作用都提高了玉米地上地下部生物量、氮磷吸收量同时提高了土壤微生物量碳、氮。蚯蚓菌根相互作用对植物生长的影响取决于土壤养分条件。在高磷条件下(氮相对不足),蚯蚓菌根互作通过调控土壤微生物量碳、氮调控玉米生长和养分吸收。低磷条件下,菌根主要发挥解磷作用,蚯蚓主要矿化秸秆和土壤中的氮素,蚯蚓和菌根互补调控土壤中氮、磷,从而促进植物的生长和养分吸收。     

Effect of Azospirillum inoculants on arbuscular mycorrhiza establishment in wheat and maize plants

Plant growth-promoting rhizobacteria and arbuscular mycorrhizal (AM) fungi represent two main groups of beneficial microorganisms of the rhizosphere. The role of different strains of Azospirillum on AM fungi development was evaluated by measuring the percentage of AM colonisation of the root system in durum wheat and maize plants, grown under both greenhouse and field conditions. The effect of wild-type Azospirillum brasilense strain Sp245 and genetically modified (GM) derivatives overproducing indole-3-acetic acid was assessed at greenhouse level in (1) three different cultivars of durum wheat, in the presence of indigenous AM fungi and (2) maize plants artificially inoculated with Glomus mosseae and Glomus macrocarpum. In addition, the establishment of natural AM fungal symbiosis was evaluated using Azospirillum lipoferum CRT1 in maize plants at field level. Despite the stimulatory effect of the different Azospirillum inocula on root growth, no significant differences in AM colonisation were found, independently of the AM fungus involved, either in wheat or in maize plants. Similarly, GM A. brasilense, which strongly stimulates root development, did not affect AM formation. Although these results were obtained in conditions in which the mycorrhization rate was moderate (15–30%), overall considered they indicate that the use of wild-type or GM Azospirillum phytostimulators does not alter mycorrhization.     

Interaction of maize roots and rhizosphere microorganisms

The interaction between the roots of Zea mays L. and its rhizosphere microflora was studied in nutrient solution with respect to two exemplary aspects - water soluble vitamins and the four most frequent carbohydrates. The exudation of vitamins and sugars into the medium is increased in a solid substrate (glass-ballotini simulating soil structure) in comparison with nutrient solution only. The amounts of vitamins released (1 to 421 ng per plant) are high enough for a pronounced influence on the rhizosphere microflora to be expected. However, the microbial population feeding on the exudates has very simple nutritional demands. In spite of appreciable amounts of vitamins found in the inoculated nutrient solution, the growth of vitamin requiring species is not stimulated compared to the soil population. The roots are mostly inhabited by shorter rods and occasionally by actinomycete-like filaments. The percentage of the root area covered by its microflora, assuming a monolayer, is 4% in the root region where root hairs are just emerging, 7% in the root hair zone and 20% in the oldest part of the roots, 10 mm below the grain. In the presence of rhizosphere microorganisms, root dry weight is lower than that of axenically grown plants because the diameter of the primary root is diminished. In addition, the vitamin and sugar content of the root is affected by rhizosphere microorganisms. The results can be interpreted as an indication that phytohormones may participate in interactions between roots and bacteria.     

巴西固氮螺菌中杂合双组分蛋白Org35与NifA的相互作用

巴西固氮螺菌(Azospirillum brasilense)可以与玉米(Zea mays)、小麦(Triticum aestivum)等重要作物联合固氮,是重要的潜在生物肥料.NifA蛋白是所有固氮基因转录所必需的激活蛋白.本研究利用融合蛋白下拉分析,探讨了Org35蛋白与NifA蛋白的相互作用.研究表明二者存在互作.Org35蛋白由3个独立结构区域组成,即PAS结构域、组氨酸蛋白激酶结构域和应答调节蛋白区域.本研究采用融合蛋白下拉分析了Org35蛋白三个结构域与NifA的互作关系,结果表明Org35蛋白与NifA蛋白之间的相互作用是由PAS结构域介导的.     

Interaction of the vesicular-arbuscular mycorrhizae of maize with extractable soil phosphorus levels and nitrogen-potassium fertilizers

Summary A field experiment was conducted for 3 years to determine whether increasing extractable soil P levels would affect vesicular-arbuscular mycorrhizae (VAM) of maize (Zea mays L.) and the subsequent uptake of P and production of dry matter. Five levels of extractable soil P were established on an Aquic Dystrochrept soil with high and low NK fertilization. The results show that as extractable soil-P levels increase the vesicular-arbuscular mycorrhizae of maize decrease, but P concentrations in both leaf and root tissue increase. There was a significant interaction between the extractable soil-P levels and NK treatment. At the low soil-P level NK fertilization increased mycorrhizae, while at the high soil-P levels NK fertilization reduced mycorrhizae. Dry-matter production generally paralleled extractable soil-P levels from 1.0 mg P kg^–1 to a maximum at 10 mg P kg^–1 soil (by ammonium acetate, pH 4.8). The reduction in vesicular-arbuscular mycorrhizae at the highest levels of extractable soil P apparently was not critical to either P uptake or dry-matter production.Scientific contribution No. 1196 Storrs Agricultural Experiment Station     

Implications of Azospirillum brasilense inoculation and nutrient addition on maize in soils of the Brazilian Cerrado under greenhouse and field conditions

The combination of nitrogen and Azospirillum can ensure greater nutrient absorption and crop yield in agricultural areas using high technology. Thus, the objective was to evaluate maize response to Azopirillum brasilense (AZ) inoculation and nutrient (macronutrients and micronutrients) application under greenhouse and field conditions in clay and sandy soils of the Brazilian Cerrado. In the greenhouse assays, the following parameters were measured: shoot dry weight (SDW), root dry weight (RDW), and root volume (RV). In the field experiments, the maize yield was determined after drying the grains at 60 °C for 48 h. In clay soil, there was a significant increase in the SDW, RDW and RV in the treatment with AZ concentrated (10¹¹ cells ml⁻¹ of inoculum) when compared with the control treatment and the treatment with AZ diluted (10⁶ cells ml⁻¹ of inoculum). In this soil, adding micronutrients did not affect the maize response under greenhouse conditions. In sandy soil, there was no difference between the AZ treatment and the control, except for treatments where nutrients and AZ were both added leading to a significant increase in the maize response. In both soils, the RV:RDW ratio was higher in the treatment with AZ concentrated compared to that in the treatment with AZ diluted, but the yield response depended on the addition of nutrients. Inoculation with A. brasilense gave comparable yield to the nitrogen treatment. The grain production was increased by 29% in the treatment with A. brasilense and nitrogen compared to nitrogen fertilization alone. In this study, the yield response was affected significantly when maize was inoculated with A. brasilense, but this response was dependent on the soil type under greenhouse conditions.     

Potential for enhancement of root growth and nodulation of soybean co-inoculated with Azospirillum and Bradyrhizobium in laboratory systems

The potential enhancement of root growth and nodulation in vegetable soybean (AGS190) was studied with application of Azospirillum brasilense (Sp7) and A. lipoferum (CCM3863) co-inoculated with two Bradyrhizobium japonicum strains (TAL102 and UPMR48). Significant root growth stimulation and nodulation were observed in Azospirillum as well as during its co-inoculation with Bradyrhizobium. Nodule formation is linked with the initiation of new roots; nodules were almost absent even in Bradyrhizobium inoculated plant due to the absence of new roots development in clipped rooted seedlings. Total root length, root number, specific root length, root dry matter, root hair development and shoot dry matter were significantly increased by Azospirillum alone and its co-inoculum. Co-inoculated plants significantly influenced the number of nodules and its fresh weight. A. brasilense seemed to perform better in root growth and nodule development compared to A. lipoferum.     

苗期喷施尿囊素对玉米后期生长及产量的影响

以尿囊素( Allantoin,以下缩写为All.) 3 0 0 mg/L和70 0 mg/L于1叶1心期和4叶1心期喷淋玉米(超甜2 0号)幼苗,以喷水作CK。结果表明:( 1 )抽雄后各组根系生长基本停止,地上生长仍在继续,故根/冠比都有下降,但是All.处理组一直高于CK组;( 2 ) All.组伤流液流量、电导率及氨基酸含量均高于CK组,同时+ 1叶叶绿素和可溶性糖含量亦高于CK;( 3 ) All.组青苞产量比CK增产1 6%左右。t分析显示,在两个All.组之间上述各项指标差异不显著,但与CK组相比差异则都达到0 .0 5的显著水平。从而证明,苗期喷施All.能促进根系生长,有利于壮苗的形成,使植株后期生长受益,并最终使产量提高。建议All.使用浓度以5 0 0±2 0 0 mg/L为宜     

Effect of inoculation with wild type Azospirillum brasilense and A. irakense strains on development and nitrogen uptake of spring wheat and grain maize

Under the controlled conditions of the greenhouse and by varying some biotic and abiotic factors, we tried to identify some of the factors critical to obtain successful Azospirillum inoculation. Spring wheat and grain maize were inoculated with different concentrations of the wild type strains A. brasilense Sp245 and A. irakense KBC1, and grown in a substrate with varying concentrations of organic matter (OM) and N fertiliser. The inoculum concentration was one of the factors that influenced most the outcome of an inoculation experiment on wheat, with lower inoculum concentrations (10⁵-10⁶ cfu plant^-1) stimulating root development and plant dry weight and higher inoculum concentrations (10⁷-10⁸ cfu plant^-1) having no effect or sometimes even inhibiting root development. The effect of inoculation was most pronounced at low to intermediate N fertilisation levels, while the OM content of the substrate had no effect. Inoculation was found to affect early plant and root development, plant and root dry weight, grain yield and the N-uptake efficiency of plants. However, inoculation did not change the N concentration in plants or grains. In addition, a difference in the ability of both strains to stimulate plant growth and N uptake of wheat and maize was observed, with A. brasilense Sp245 having most effect on spring wheat and A. irakense KBC1 being more effective on grain maize. The significance of the obtained results for agriculture is discussed.     

基于红边参数的夏玉米长势监测及其营养诊断研究

分析了夏玉米各组分含量、红边参数以及两者间的相关性。结果表明,可利用FD-Max反演叶面积指数,利用Depth672反演茎秆全N含量,利用Lwidth反演叶片全N含量、叶片和茎秆的含水量以及可溶性糖含量。构建了以红边参数为自变量的各组分的反演模型,对反演模型预测性分析表明,利用上述红边参数预测农学组分是可行的。     

11种除草剂对秋播豌豆生长发育的影响及防效研究

化学除草剂已成为农田控制杂草的重要技术措施,但目前还没有针对豌豆田杂草的高效、安全除草剂。为此,本文以陕西省关中地区主栽品种‘西豌2号’为试验材料,采用6种苗前除草剂（48%氟乐灵乳油、50%乙草胺乳油、33%二甲戊灵乳油、96%精异丙甲草胺乳油、50%敌草胺水分散粒剂、40%扑草净可湿性粉剂）和5种苗后除草剂（15%精吡氟禾草灵乳油、10%精喹禾灵乳油、12.5%烯禾啶乳油、10.8%高效氟吡甲禾灵乳油、12%烯草酮乳油）处理,设清水喷施（CK1）和人工除草（CK2）为对照,调查秋豌豆田杂草种类,研究不同除草剂的防除效果,探讨各除草剂对秋豌豆生育进程、形态特征、经济效益等相关指标的影响。结果表明：1）研究区秋豌豆田杂草共7科13种,以阔叶类杂草为主,其中阔叶杂草9种。除草剂对杂草株数和鲜重均有不同程度的防效作用,苗前除草剂以33%二甲戊灵综合防效最佳,苗后除草剂以12%烯草酮综合防效最佳。2）自越冬期至开花期,各除草剂均对秋豌豆株高、叶绿素相对含量产生显著影响,但从始荚期开始,影响不再显著。不同种类的除草剂对秋豌豆根、茎、叶器官各时期干物质的积累量均有不同程度的抑制作用,各处理的秋豌豆茎、叶器官干物质的移动率及转运率均高于人工除草,叶器官干物质的移动率及转运率均高于茎器官。3）除草剂对百粒重、荚长等产量构成因素影响不显著,除10.8%高效氟吡甲禾灵导致产量略微下降之外,其他除草剂均表现出一定的增产作用,其中33%二甲戊灵、12%烯草酮可使秋豌豆增产25%以上。所有除草剂处理的净收入均有所增加,以33%二甲戊灵、12%烯草酮处理的净收入为同时期除草剂中最高。由此可见,除草剂的使用有助于种植者经济效益的提高,结合各除草剂的防除效果、安全性、经济效益,苗前除草剂33%二甲戊灵和苗后除草剂12%烯草酮在秋豌豆田的综合效应分别为同时期除草剂中最佳。本试验条件下,针对秋豌豆田,苗前除草剂推荐使用33%二甲戊灵,苗后除草剂推荐使用12%烯草酮。     

玉米营养体分析及其应用

根据1987～1999年玉米长期丰歉定位试验研究提出了玉米营养体(茎粗×株高)代替干物质量的分析方法,采用该方法可客观地揭示出玉米在不同环境条件下生长规律与产量形成的关系,且较干物质量与产量形成的关系规律完全相同,从而为研究玉米生态学增加了新的生态指标.     

基于优先分配的玉米单个籽粒生长模拟

精确预测作物产量对于作物生产、栽培措施优化等具有重要意义。玉米单个籽粒的质量差异对玉米产量有显著影响,并且雌穗不同位置的籽粒获取同化物的能力不同。当前的玉米模型中由于缺乏基于单个籽粒生长机制的模拟过程,从而限制了其在更广泛环境下对产量的模拟精度和预测能力。为了量化雌穗不同位置籽粒对于同化物的竞争能力,基于源库理论建立了玉米单个籽粒灌浆过程的模型,并引入“优先权”方程量化雌穗一列籽粒中每个籽粒获取同化物的“优先”能力,整合进入潜在籽粒生长需求计算新的籽粒库强。通过多年多源库水平的玉米田间试验数据对模型的有效性进行系统评估。结果表明,引入“优先权”后明显提高不同位置籽粒的干质量的模拟精度。这为理解单个籽粒的生长发育过程、玉米产量形成过程提供基础依据。     

外源钙与丛枝菌根真菌协同对玉米生长的影响与土壤改良效应

为了缓解煤炭开采对神东矿区农业生产和地表环境造成的破坏,试验模拟神东矿区干旱缺水特点,以煤炭开采塌陷区退化土壤为供试基质,玉米为供试植物,研究丛枝菌根真菌(每克干土中含63个孢子)和不同浓度的外源钙(5,10,20,40,80mmol/L)协同效应对中度干旱胁迫下苗期玉米生长的影响。结果表明,干旱胁迫下,20mmol/L外源钙与丛枝菌根真菌协同效应最优,玉米质量平均每株可达4.03g,组织含水率和叶色值分别达到91.68%和43.67,玉米植株内氮磷钾累积量显著高于其他处理;同时,玉米根际土壤球囊霉素相关蛋白增加最为明显,总球囊霉素和易提取球囊霉素分别达到4.3和1.6mg/g,根际土壤中有机质含量增加明显。丛枝菌根真菌与外源钙联合作用有利于玉米的生长,缓解了干旱胁迫对苗期玉米生长的影响,接种丛枝菌根真菌对矿区退化土壤具有显著改良效应。     

尿素浓度对喷灌夏玉米生长和产量的影响

喷灌施肥灌溉时叶片对尿素的直接吸收作用是提高氮肥利用率的潜在因素之一。以地面灌溉、尿素撒施处理为对照(CK),通过设置不同的尿素喷施浓度,研究夏玉米生理生态指标和产量的响应特征。结果表明,追施尿素后叶片相对叶绿素含量(SPAD)增加,但不同尿素喷施浓度处理的夏玉米株高、SPAD无显著差异(P>0.05)。尿素喷施浓度对叶面积指数(leaf area index,LAI)和产量的影响具有较大的年际变化,2017年不同尿素喷施浓度处理的产量差异达到了显著水平,尿素喷施浓度为0.146%处理的产量(12.5 t/hm^2)显著高于尿素喷施浓度≥0.178%处理的产量(11.3 t/hm^2),2018年尿素喷施浓度为0.188%处理的LAI在喷灌施肥后的一段时间内出现了显著降低。喷灌施肥后,叶片吸收尿素对光系统活性和光化学效率的影响与SPAD有关,2017年SPAD较高时,喷施尿素后光系统活性和光化学效率呈先减小后增大规律,且尿素喷施浓度≤0.146%处理的抑制作用仅发生在施肥后1 d,尿素喷施浓度≥0.178%处理的抑制作用持续至施肥后3~5 d;2018年SPAD较低时,与CK处理相同,喷施尿素后所有处理的光系统活性和光化学效率均呈先增大后稳定规律。与CK处理相比,施氮量小于等于CK的喷灌处理的产量和水分利用效率与CK处理无显著差异,但氮肥偏生产力显著高于CK处理,证明了喷灌施肥灌溉的可行性及其节肥、增产潜力。