不同连作方式对大豆生物固氮的影响

[目的]研究不同连作方式对大豆生物固氮的影响。[方法]在长期定位试验中设置正茬(大豆-小麦-玉米-大豆)、重茬(小麦-小麦-大豆-大豆)和迎茬(小麦-大豆-小麦-大豆)3种连作方式,研究不同连作方式对大豆根瘤形成和固氮量的影响。[结果]结荚期和鼓粒期正茬大豆体内含氮量较重茬、迎茬多。3种连作方式的大豆根系形成根瘤的数量表现为正茬>迎茬>重茬,迎茬、重茬的大豆根瘤数分别较正茬减少1.3~1.4、13.4~20.5个/株。大豆通过共生固氮作用固定的氮素表现为正茬>迎茬>重茬,重茬、迎茬大豆固氮量分别比正茬降低18.4%、6.5%。大豆产量表现为正茬>迎茬>重茬。[结论]大豆体内含氮量、根瘤数、固氮量和产量都表现为正茬>迎茬>重茬。     

重迎茬大豆植株氮磷钾含量与积累特征的研究

通过系统定位轮作试验，建立大豆正茬、迎茬、重茬的种植方式，在不同生育期，测定了大豆植株氮磷钾含量和积累。结果表明：在各个生育期大豆植株氮磷钾含量和积累总量均为正茬〉迎茬〉重茬。影响大豆植株氮磷钾的含量和积累的主要原因是：病虫危害大豆根部导致吸收和运输受阻以及受茬口影响，土壤中的氮磷钾活性变低。大豆固氮能力下降，氮磷钾的积累与产量相关。重茬大豆植株氮磷积累总量较正茬分别减少４１．８１％，４８．７８％     

减缓大豆重迎茬危害的技术措施

大豆是和平镇的主载作物,面积逐年增加,因此重迎茬现象愈来愈严重.据调查一般迎茬减产5％-10％,重茬一年减产10％-15％,重茬二年减产15％-20％,重茬三年以上减产20％-30％.重迎茬不但降低产量,而且也影响大豆的质量.重迎茬可导致灰斑病、霜霉病、食心虫、蚜虫、红蜘蛛、根腐病、菌核病等病虫害大面积发生.一般迎茬病粒率、虫食率分别较正茬增加0.7％、1.0％,重茬病粒率、虫食率分别较正茬增加1.7％、2.5％.     

大豆重迎茬减产的原因与防治要点

<正>1.大豆重迎茬减产的原因种大豆不宜重茬和迎茬,也不宜种在其他豆类之后。"油见油、三年愁",大豆重迎茬减产的主要原因是根部病虫害的严重危害,根系分泌物、根茬腐解物、根际微生物的变化,破坏了共生固氮系统,抑制了根的吸收能力,使植株代谢减弱,植株生育缓慢,产量降低。2.重迎茬对大豆产量的影响2.1重迎茬影响大豆植株干物质的生产积累正茬大豆的干物质积累量显着高于迎茬、重茬1a、重茬2a、重茬3a大豆的干物质积累量,而重茬大豆又低于迎     

连作对大豆根际可培养微生物及土壤理化性状的影响

【目的】探讨大豆重迎茬对根际可培养微生物及土壤理化性状的影响.【方法】以正茬和重迎茬大豆根际土壤为研究对象,在不同生育时期取根际土进行土壤微生物区系、微生物生理类群和土壤理化性状等指标的测定.【结果和结论】大豆重迎茬对土壤可培养微生物及微生物生理类群有较大影响.重迎茬使大豆全生育期细菌、放线菌、氨化细菌、硝化细菌、好气性自生固氮菌和纤维素分解菌总量减少,真菌数量显著增加.各处理土壤平均碱解氮和速效钾含量顺序为:正茬迎茬重茬1年重茬2年重茬3年;而土壤速效磷含量为正茬迎茬重茬1年重茬3年重茬2年.轮作正茬大豆土壤团聚体的平均质量直径(MMD)和几何平均直径(GMD)均高于迎茬和重茬各处理,其中以GMD差异更显著.     

大豆重迎茬问题研究进展

<正>根据连续栽培观察考证,大豆在重迎茬栽培过程中平均株高比正茬要降低5～21.8cm,单株荚数减少3.2～7.2个,单株粒数减少8～13.1个,百粒重下降1～2g。而且重茬大豆减产幅度要大于迎茬大豆,重茬较迎茬减产幅度5～12%。土壤病虫草害随重茬较种植年限逐年加重。重迎茬超过3年,大豆的蛋白质含量明显降低。大豆在重迎茬栽培同时也大大降低了土地的利用效率,综合来     

浅谈大豆重迎茬减产的原因及对策

一、重迎茬减产的原因 大豆由于受市场价格调控的影响，面积逐年增加，使重迎茬面积急剧扩大，据调查1993年大豆重茬面积为3．1％，1999年时发展到7．8％，已到非重即迎的地步，2006年发展到61．1％，正茬播种寥寥无己。调查大豆重迎茬减产规律如下：     

大豆连作对植株形态和生理指标的影响

由于大豆连作造成许多土壤障碍因素,使其大豆根系、根瘤发育不良,从而影响根系对养分的吸收和根瘤菌的固氮能力,导致植株体各项形态指标和生理指标的明显下降.随着连作年限的增加,植株体各项形态指标和生理指标下降显著,表现为正茬＞迎茬＞连作.     

重迎茬对大豆生长发育的影响

一、大豆重迎茬对产量和品质的影响 1、对产量的影响：重迎茬大豆均较正茬大豆减产,减产幅度随着重茬年限的增加而增大。试验表明,一般重茬大豆减产30%-50%;迎茬大豆减产10%-15%。 2、对品质的影响：重迎茬大豆百粒重下降,病粒率、虫食率增加,商品质量显著降低。另外,迎茬和短期重茬对大豆蛋白质和脂肪含量没有明显的影响,但三年以上的长期重茬,大豆的蛋白质含量明显增加,脂肪含量明显减少。     

重茬大豆减产原因及控制对策

<正>1.重茬对大豆产量和品质的影响1.1重茬对产量因子的影响大豆重茬栽培株高降低7～25cm,单株荚数减少2.5～2.6个,单株粒数减少8.5～10.8个,百粒重下降0.5～1.8g。1.2重茬对产量和品质的影响重茬较正茬平均减产20.5%,虫食率增加0.9%～2.0%,灰斑病病粒率重茬是正茬的7倍。重茬超过3年,大豆的蛋白质含量明显降低。由此可见,重茬大豆的食用品质和商品品质都有下降。     

重迎茬大豆施用促根剂效果分析

促根剂的田间小区试验和大面积推广示范试验结果表明：促根剂显著促进了重迎茬大豆苗期和花荚期植株地上部和根系的生长发育，其株高、根长、地上部和根系鲜重及根瘤重都较对照增加，特别是对根系生长的影响尤为显著，增加幅度在10％以上；促根剂提高了大豆叶片的光合作用，使干物质积累增加，表现在大豆叶面积比对照增大；在不同茬口的土壤上，促根剂的效果表现不尽一致，总体趋势为重1＞迎茬＞重2＞正茬；促根剂显著增加了大豆植株的总粒数，使重迎茬大豆产量比对照提高，增产幅度在10％以上。     

不同种植方式对苗期大豆、玉米根际土壤酶活性及微生物量碳、氮的影响

通过盆栽试验的方法,研究不同种植方式对苗期大豆、玉米根际土壤脲酶、过氧化氢酶、多酚氧化酶和蔗糖酶活性和微生物量碳、氮的影响,试验共设9个处理,分别在前茬作物为大豆、玉米和大豆-玉米混作的土壤上种植大豆、玉米和大豆-玉米混作。结果表明,①与大豆-玉米轮作相比,大豆连作降低了根际土壤多酚氧化酶和脲酶活性,玉米连作降低了脲酶活性而提高了过氧化氢酶活性,三种种植方式下蔗糖酶活性无显著差异。②与大豆-玉米混作相比,大豆连作和玉米连作都降低了根际土壤脲酶活性,提高了根际土壤蔗糖酶的活性,根际土壤多酚氧化酶的活性变化不明显。在前茬为玉米的土壤处理中,大豆-玉米混作的根际土壤过氧化氢酶活性显著低于单作大豆和单作玉米的处理。③大豆连作和玉米连作的土壤微生物量碳、氮均高于大豆-玉米轮作。在前茬为玉米的土壤处理中,大豆-玉米混作的土壤微生物量氮显著高于单作大豆和单作玉米的处理。④土壤微生物量碳与微生物量氮及其碳氮比都与土壤过氧化氢酶活性和多酚氧化酶活性呈显著相关或极显著相关。因此,不同的种植方式能够影响大豆和玉米的根际土壤酶活性和土壤微生物量碳、氮,但变化规律不尽相同。     

茬口对大豆苗期生物学性状及根部病虫害的影响

通过盆栽试验，对大豆正茬土、重茬土、迎茬土及连茬土施入有机肥，测定其土壤有机质含量变化对大豆苗期生物学性状及根部病虫害的影响。试验表明，正茬土的土壤环境优于其他3种茬口土壤，重茬土是最不利于大豆生长的土壤环境。施入有机肥后，4种茬口土壤有机质含量均有明显提高，提高幅度为14．8％～36．9％，对土壤酸碱度的影响不大。大豆根部病虫害的发生在正茬土中较轻，在其他3种茬口土壤中发生较重。施有机肥后能加重大豆根部病虫害的发生。     

A comprehensive analysis of the response of the fungal community structure to long-term continuous cropping in three typical upland crops

Certain agricultural management practices are known to affect the soil microbial community structure; however, knowledge of the response of the fungal community structure to the long-term continuous cropping and rotation of soybean, maize and wheat in the same agroecosystem is limited. We assessed the fungal abundance, composition and diversity among soybean rotation, maize rotation and wheat rotation systems and among long-term continuous cropping systems of soybean, maize and wheat as the effect of crop types on fungal community structure. We compared these fungal parameters of same crop between long-term crop rotation and continuous cropping systems as the effect of cropping systems on fungal community structure. The fungal abundance and composition were measured by quantitative real-time PCR and Illumina MiSeq sequencing. The results revealed that long-term continuous soybean cropping increased the soil fungal abundance compared with soybean rotation, and the fungal abundance was decreased in long-term continuous maize cropping compared with maize rotation. The long-term continuous soybean cropping also exhibited increased soil fungal diversity. The variation in the fungal community structure among the three crops was greater than that between long-term continuous cropping and rotation cropping. Mortierella, Guehomyces and Alternaria were the most important contributors to the dissimilarity of the fungal communities between the continuous cropping and rotation cropping of soybean, maize and wheat. There were 11 potential pathogen and 11 potential biocontrol fungi identified, and the relative abundance of most of the potential pathogenic fungi increased during the long-term continuous cropping of all three crops. The relative abundance of most biocontrol fungi increased in long-term continuous soybean cropping but decreased in long-term continuous maize and wheat cropping. Our results indicate that the response of the soil fungal community structure to long-term continuous cropping varies based upon crop types.     

大豆专用复混肥对轮作、连作大豆增产机理的研究

采用盆栽试验、田间试验及室内分析相结合的方法 ,研究了含有沸石、腐殖酸、稀土的大豆专用复混肥对轮作、连作大豆的增产机理。结果表明 ,施用大豆专用复混肥对轮作、连作大豆具有明显的改土、增加肥效、抗逆、提高光合效率和促进大豆生长的作用 ,最终表现出明显的增产效果。大豆专用复混肥的综合施用效果以连作大豆好于轮作大豆     

填闲大豆秸秆还田对黄瓜连作土壤化学指标的影响

以连作黄瓜土壤为研究对象,夏季休闲期设定接种与非接种根瘤菌还田处理,主栽作物时期设定传统施肥、75%施肥、50%施肥裂区试验,系统研究不同处理对土壤速效养分的影响。结果表明,夏季填闲大豆显著增加不同土层pH,降低土壤可溶性盐浓度和速效氮质量分数,且接种优于非接种处理;接种还田50%施肥处理增加秋冬茬土壤pH,降低电导率效果显著;接种还田50%施肥处理黄瓜拉秧期显著增加速效钾质量分数;黄瓜结瓜初期接种还田75%、50%施肥以及非接种还田50%施肥显著增加速效氮质量分数。0~20cm土壤速效磷质量分数显著高于其他土层,填闲非接种大豆增加显著,黄瓜初瓜期和拉秧期接种大豆还田下传统施肥显著增加0~20cm土壤速效磷质量分数。总之,填闲大豆可有效降低夏季休闲期土壤电导率和表层速效氮累积,增加土壤pH,接种根瘤菌大豆还田75%、50%施肥可提供秋冬茬作物较高的速效氮养分。     

不同施肥处理对大豆植株根系及产量的影响

试验采用营养极度缺乏的生土土壤,研究了施肥种类对大豆根系及产量的影响,结果表明:NPK+Org(有机肥)、Org、K、N四种施肥处理,根系总吸收面积较大;Org和P肥对大豆苗期根瘤的产生有促进作用,但P肥处理根瘤衰亡的速度过快;NPK+Org、Org处理的经济产量显著高于其他各处理,且NPK+Org处理的经济产量也显著高于单施Org处理。研究对人工造地、矿区复垦当年增产具有重要应用价值。     

Maize–legume intercropping promote N uptake through changing the root spatial distribution,legume nodulation capacity,and soil N availability

Legume cultivars affect N uptake, component crop growth, and soil physical and chemical characteristics in maize–legume intercropping systems. However, how belowground interactions mediate root growth, N fixation, and nodulation of different legumes to affect N uptake is still unclear. Hence, a two-year experiment was conducted with five planting patterns, i.e., maize–soybean strip intercropping (IMS), maize–peanut strip intercropping (IMP), and corresponding monocultures (monoculture maize (MM), monoculture soybean (MS), and monoculture peanut (MP)), and two N application rates, i.e., no N fertilizer (N–) and conventional N fertilizer (N+), to examine relationships between N uptake and root distribution of crops, legume nodulation and soil N availability. Results showed that the averaged N uptake per unit area of intercrops was significantly lower than the corresponding monocultures. Compared with the monoculture system, the N uptake of the intercropping systems increased by 31.7–45.4% in IMS and by 7.4–12.2% in IMP, respectively. The N uptake per plant of intercropped maize and soybean significantly increased by 61.6 and 31.8%, and that of intercropped peanuts significantly decreased by 46.6% compared with the corresponding monocultures. Maize and soybean showed asymmetrical distribution of roots in strip intercropping systems. The root length density (RLD) and root surface area density (RSAD) of intercropped maize and soybean were significantly greater than that of the corresponding monocultures. The roots of intercropped peanuts were confined, which resulted in decreased RLD and RSAD compared with the monoculture. The nodule number and nodule fresh weight of soybean were significantly greater in IMS than in MS, and those of peanut were significantly lower in IMP than in MP. The soil protease, urease, and nitrate reductase activities of maize and soybean were significantly greater in IMS and IMP than in the corresponding monoculture, while the enzyme activities of peanut were significantly lower in IMP than in MP. The soil available N of maize and soybean was significantly greater increased in IMS and IMP than in the corresponding monocultures, while that of IMP was significantly lower than in MP. In summary, the IMS system was more beneficial to N uptake than the IMP system. The intercropping of maize and legumes can promote the N uptake of maize, thus reducing the need for N application and improving agricultural sustainability.     

重茬对大豆株型影响的研究

试验研究重茬对大豆株型的影响。结果表明:重茬对大豆株高、分枝数和主茎节数的影响与正茬相比均不显著,重茬能显著增加大豆的结荚高度。重茬使大豆的叶面积指数降低,叶面积指数的减小幅度与结荚习性有关,亚有限性结荚习性大豆的减小幅度较大,有限结荚习性大豆则相对较小。重茬较正茬大豆的叶绿素含量降低,苗期和鼓粒期降低较明显,光合速率重茬较正茬也有降低的趋势。