Impact of wheat cultivation on microbial communities from replant soils and apple growth in greenhouse trials

ABSTRACT Studies were conducted to assess the impact of short-term rotations of wheat on microbial community composition and growth of apple in soils from replant orchard sites. Soils from two orchards were cultivated with three successive 28-day growth cycles of 'Eltan', 'Penewawa', or 'Rely' wheat in the greenhouse and subsequently planted to 'Gala' apple seedlings. Cultivation of orchard replant soils with any of the three wheat cultivars enhanced growth of apple relative to that achieved in untreated soils. Improved growth was associated with a marked reduction in apple root infection by species of Rhizoctonia and Pythium. Populations of plant-parasitic nematodes were below damage threshold levels in these orchard soils; however, apple seedlings grown in wheat-cultivated soils had significantly lower root populations of Pratylenchus spp. than did seedlings grown in untreated soils. Growth of apple in 'Penewawa'-cultivated soils often was superior to that observed in soils planted with 'Eltan' or 'Rely'. In untreated orchard soils, fluorescent pseudomonad populations isolated from soil and the apple rhizosphere were dominated by Pseudomonas fluorescens biotype C and Pseudomonas syringae. Cultivation of replant soils with wheat induced a characteristic transformation of the fluorescent pseudomonad population, and Pseudomonas putida dominated the population of this bacterial group recovered from wheat-cultivated replant orchard soils. Results from this study suggest that use of short-term wheat cropping sequences during orchard renovation could be useful in management of replant disease and that this disease-control option may operate, in part, through modification of the fluorescent pseudomonad community.     

复合微生物菌肥KMM减缓苹果再植病害机制

为揭示木美土里复合微生物菌肥（Kimidori microbial manure,KMM）促进再植苹果树的生长及减缓苹果再植病的作用机制,采用土壤常规农业化学分析法和Illumma MiSeq高通量测序技术比较分析KMM和常规有机肥（对照）处理后再植苹果树的生长指标、理化因子、根际土壤酶活性以及细菌群落结构和功能的变化。结果表明,施用KMM后,果树的株高增长率、干径增长率、叶绿素含量、分枝个数和分枝长度等生长指标均显著升高,有机质含量显著增加,中性磷酸酶、脲酶、蔗糖酶和过氧化氢酶活性均显著提高,同时增加了再植土壤细菌群落的丰富度和多样性。从采集土壤中分离得到51株细菌并进行盆栽试验,其中经KMM-15、KMM-37和KMM-50菌株处理后海棠苗叶绿素含量、株高、茎粗均显著提高,经鉴定这3株菌株为贝莱斯芽胞杆菌Bacillus velezensis。表明春秋2次施用KMM提高了土壤有机质含量和酶活性,并重塑了根际土壤中细菌群落结构,进而缓解苹果再植病害发生程度,促进果树生长。     

Transformation of soil microbial community structure and rhizoctonia-suppressive potential in response to apple roots

ABSTRACT Changes in the composition of soil microbial communities and relative disease-suppressive ability of resident microflora in response to apple cultivation were assessed in orchard soils from a site possessing trees established for 1 to 5 years. The fungal community from roots of apple seedlings grown in noncultivated orchard soil was dominated by isolates from genera commonly considered saprophytic. Plant-pathogenic fungi in the genera Phytophthora, Pythium, and Rhizoctonia constituted an increasing proportion of the fungal community isolated from seedling roots with increasing orchard block age. Bacillus megaterium and Burkholderia cepacia dominated the bacterial communities recovered from noncultivated soil and the rhizosphere of apple seedlings grown in orchard soil, respectively. Populations of the two bacteria in their respective habitats declined dramatically with increasing orchard block age. Lesion nematode populations did not differ among soil and root samples from orchard blocks of different ages. Similar changes in microbial communities were observed in response to planting noncultivated orchard soil to five successive cycles of 'Gala' apple seedlings. Pasteurization of soil had no effect on apple growth in noncultivated soil but significantly enhanced apple growth in third-year orchard block soil. Seedlings grown in pasteurized soil from the third-year orchard block were equal in size to those grown in noncultivated soil, demonstrating that suppression of plant growth resulted from changes in the composition of the soil microbial community. Rhizoctonia solani anastomosis group 5 (AG 5) had no effect on growth of apple trees in noncultivated soil but significantly reduced the growth of apple trees in soil from third-year orchard soil. Changes in the ability of the resident soil microflora to suppress R. solani AG 5 were associated with reductions in the relative populations of Burkholderia cepacia and Pseudomonas putida in the rhizosphere of apple.     

复合微生物菌肥对苹果再植病害调控及对根围土壤真菌群落结构的影响

 为研究复合微生物菌肥对再植苹果幼树的影响,从再植土壤酶活性、真菌群落结构和功能的方面分析,探究复合微生物菌肥的作用机理。本研究设置了KMM和对照CK两个处理,再植苹果树于春秋两次分别施用复合微生物菌肥(KMM)和有机肥(CK)。通过土壤常规农业化学分析法和Illumma MiSeq高通量测序技术,系统研究了两个处理再植苹果树的生长、根围土壤酶活性以及真菌群落结构和功能的变化。试验结果表明,施用复合微生物菌肥显著提高了再植苹果幼树株高、干径、叶绿素、分枝个数和分枝长度;提高再植土壤酶活性(中性磷酸酶、脲酶、蔗糖酶和过氧化氢酶);降低再植土壤真菌群落丰富度,改变真菌群落结构。相对丰度高于1%的优势真菌属中有21个菌属与再植果树的5项生长参数具有相关性,并且在不同分类水平上具有一定的差异,缝壳菌属(Lophiostoma)、织球壳菌属(Plectosphaerella)、赤壳菌属(Nectria)和维希尼克氏属(Vishniacozyma)显著增加,丝孢菌属(Anguillospora)和假丝酵母菌属(Pseudeurotium) 显著降低。通过对测序片段功能水平的分析,在二级功能水平上显著降低了真菌群落氨基酸、核苷和核苷酸的生物合成、电子转移、发酵、呼吸、CTP生物合成嘧啶脱氧核糖核酸功能序列的丰度值,共6种功能类群均与土壤酶活性呈负相关。施用复合微生物菌肥,改变了真菌群落结构,减弱真菌群落相关代谢的功能,提高土壤酶活性,促进再植苹果幼树的生长。     

Elucidation of the microbial complex having a causal role in the development of apple replant disease in washington

ABSTRACT Systematic studies were conducted to elucidate the role of different soil microbial groups in the development of apple replant disease. Populations of targeted microorganisms were reduced by the application of semiselective biocides and soil pasteurization. Bacteria were not implicated in the disease, because application of the antibiotic chloramphenicol reduced soil populations of bacteria but failed to improve growth of apple transplants, while enhanced growth was achieved at pasteurization temperatures that did not alter attributes of the bacterial community recovered from apple roots. Populations of Pratylenchus penetrans were below the damage threshold level in eight of nine orchards surveyed, and nematicide applications failed to enhance apple growth in four of five replant soils tested, indicating that plant parasitic nematodes have a minor role or no role in disease development. Application of the fungicide difenconazole or metalaxyl enhanced growth of apple in all five replant soils, as did fludioxinil in the two soils tested. Soil pasteurization enhanced growth of apple and resulted in specific changes in the composition of the fungal community isolated from the roots of apple seedlings grown in these treated soils. Cylindrocarpon destructans, Phytophthora cactorum, Pythium spp., and Rhizoctonia solani were consistently isolated from symptomatic trees in the field and were pathogenic to apple. However, the composition of the Pythium and Rhizoctonia component and the relative contribution of any one component of this fungal complex to disease development varied among the study orchards. These findings clearly demonstrate that fungi are the dominant causal agents of apple replant disease in Washington state.     

复合微生物菌剂对苹果再植病害的生防效果测定及拮抗菌株鉴定

为探究复合微生物菌剂对苹果再植病害的生防效果,以苹果砧木实生海棠幼苗为试材,通过盆栽试验测试了木美土里复合微生物菌剂对苹果再植病害的防治效果及对再植海棠的促生作用,然后对该菌剂的可分离微生物进行了分离纯化,并以尖孢镰刀菌Fusarium oxysporum菌株HS2为靶标菌,测试分离获得的10株菌株的拮抗效果,并对拮抗效果显著的1株真菌菌株和2株细菌菌株进行种类鉴定。结果表明,木美土里复合微生物菌剂对苹果再植病害的防治效果达87.78%;经该菌剂处理后,再植海棠苗的株高、茎粗、鲜重、干重及叶面积分别是对照处理的1.51、2.00、5.74、5.21和2.83倍,表明该菌剂有显著的促生作用。木美土里复合微生物菌剂对菌株HS2的抑制率达到68.59%,并从中分离到7株真菌菌株,3株细菌菌株。其中,拮抗效果高于80.00%的真菌菌株有1株,细菌菌株有2株。经鉴定,真菌菌株MMTL-1为哈茨木霉Trichoderma harzianum;细菌菌株BM-01和BM-03均为解淀粉芽胞杆菌Bacillus amyloliquefaciens。     

Distribution of methyl bromide in soils treated for nematode control in replant vineyards

Methyl bromide was applied with and without polyethylene covers at rates of 337, 449, 673 and 898 kg/ha to replant vineyard soils to control plant parasitic nematodes. Distribution of the gas in the soil atmosphere at different depths was measured by gas chromatography. Higher doses, low soil moisture and deeper placement of methyl bromide resulted in more rapid soil penetration and higher concentrations of the gas at the deeper soil levels. Placement of methyl bromide in the soil at 0.76-0.81 m without polyethylene cover resulted in gas distribution at concentrations sufficient for nematode kill as deep as 2.44 m.     

荧光假单胞菌SS101对苹果再植病害的生防效果

为明确荧光假单胞菌SS101对苹果再植病害的生防效果,采用平板对峙法和孢子萌发法研究了SS101菌株对9株来自不同苹果产区病原菌的抑制作用以及对盆栽海棠实生苗、海棠大苗和苹果树生长的影响,并测定了连续处理4年苹果树的产量。结果显示,SS101菌株对9株病原菌的菌丝生长抑制率为39.39%~72.00%,对孢子萌发抑制率为19.86%~51.77%;经SS101菌株处理后,海棠实生苗叶绿素含量、株高和鲜重均显著高于再植土处理,分别提高13.38%、19.39%和48.26%;经SS101菌株处理后,海棠大苗定植9个月后,茎粗净增长量为2.97 mm,增长率为214.05%,而再植土处理仅为114.02%;连续处理4年的苹果树平均单株产量比再植土处理提高139.46%,且消除了再植病害症状。研究表明,SS101菌株对苹果再植病害病原菌具有显著抑制作用,在田间对再植病害具有良好的防控效果。     

Soil microbial activity and community structure as affected by exposure to chloride and chloride-sulfate salts

Mixed or chloride salty ions dominate in saline soils, and exert wide-ranging adversely affect on soil biological processes and soil functions. The objectives of this study were to(1) explore the impacts of mixed(0, 3, 6, 10, 20 and 40 g Cl~–/SO_4~(2–)salt/kg dry soil) and chloride(0, 1.5, 3, 5, 8 and 15 g Cl~– salt/kg dry soil) salts on soil enzyme activities, soil physiological functional(Biolog) profiles and microbial community structure by using soil enzymatic, Biolog-Eco microplates as well as denaturing gradient gel electrophoresis(DEEG) methods, and(2) determine the threshold concentration of soil electronic conductivity(EC_(1:5)) on maintaining the functional and structural diversity of soil microbial community. The addition of either Cl~– or mixed Cl~–/SO_4~(2–)salt obviously increased soil EC, but adversely affected soil biological activities including soil invertase activity, soil microbial biomass carbon(MBC) and substrate-induced respiration(SIR). Cl~– salt showed a greater deleterious influence than mixed Cl~–/SO_4~(2–)salt on soil enzymes and MBC, e.g., the higher soil MBC consistently appeared with Cl~–/SO_4~(2–)instead of Cl– treated soil. Meanwhile, we found that SIR was more reliable than soil basal respiration(SBR) on explaining the changes of soil biological activity responsive to salt disturbance. In addition, microbial community structures of the soil bacteria, fungi, and Bacillus were obviously affected by both salt types and soil EC levels, and its diversity increased with increasing of mixed Cl~–/SO_4~(2–)salt rates, and then sharply declined down after it reached critical point. Moreover, the diversity of fungal community was more sensitive to the mixed salt addition than other groups. The response of soil physiological profiles(Biolog) followed a dose-response pattern with Cl~–(R~2=0.83) or mixed Cl~–/SO_4~(2–)(R~2=0.89) salt. The critical threshold concentrations of salts for soil physiological function were 0.45 d S/m for Cl~– and 1.26 d S/m for Cl~–/SO_4~(2–), and those for soil microbial community structural diversity were 0.70 d S/m for Cl~– and 1.75 d S/m for Cl~–/SO_4~(2–).     

Correction to: Molecular identification of Nectriaceae in infections of apple replant disease affected roots collected by Harris Uni-Core punching or laser microdissection

Journal of Plant Diseases and Protection -     

土壤干旱对两品种小麦根际土壤微生物群落组成和酶活性的影响

采用双因素随机试验,在小麦孕穗期、灌浆期和成熟期研究了土壤干旱对两品种小麦根际土壤微生物丰度、多样性及4种酶活性(蔗糖酶、碱性磷酸酶、脲酶和脱氢酶)的影响。试验设4个处理,即分别在土壤干旱和正常水分下种植小麦"矮抗58"(P1)和"泛麦8号"(P2)。结果表明:与正常水分处理(种植P1和P2)相比,孕穗期,土壤干旱处理下小麦P1和P2根际土中普通细菌、革兰氏阴性细菌的丰度显著降低了11.3%和6.9%、8.4%和8.2%;灌浆期,干旱处理下小麦P1和P2根际土中丛枝菌根真菌的丰度明显下降了34.3%和21.8%;成熟期,干旱处理下小麦P1和P2根际土中革兰氏阳性细菌、真菌的丰度显著降低30.9%和8.6%、34.1%和17.3%。土壤干旱对微生物多样性无显著影响,却显著降低了孕穗期和灌浆期的碱性磷酸酶、脱氢酶活性和灌浆期的蔗糖酶活性,提高了成熟期的蔗糖酶活性。"矮抗58"比"泛麦8号"根际微生物多样性更高,但孕穗期其蔗糖酶活性更低。干旱与品种的交互作用对微生物各类群的丰度、多样性和4种酶活性的影响均不显著。综上,土壤干旱主要抑制微生物丰度,而品种间根际微生物多样性差异明显,干旱和品种均...     

苹果经营代际传递意愿及其影响因素分析——基于山东和陕西1012个苹果户的调查数据

采用山东和陕西1012个苹果户调查数据,运用二元Logit模型分析影响苹果经营代际传递意愿的主要因素.结果 表明:苹果经营代际传递意愿总体较弱,18.68％的苹果户愿意代际传递;苹果种植决策者的年龄、苹果劳动力人数、苹果收入占比、苹果效益、苹果种植技术和果园装备投入对苹果经营代际传递意愿有显著正向影响;计划缩小苹果种植...     

Effects of long-term fencing on soil microbial community structure and function in the desert steppe,China

One of the goals of grazing management in the desert steppe is to improve its ecosystem. However, relatively little is known about soil microbe communities in the desert steppe ecosystem under grazing management. In this study, we investigated the diversity and aboveground biomass of Caragana korshinskii Kom. shrub communities in long-term fencing and grazing areas, combined with an analysis of soil physical-chemical properties and genomics, with the aim of understanding how fence management aff...     

Chemical versus microbial degradation of cyanazine and atrazine in soils

A laboratory study was performed to investigate the relationship between chemical (non-biological) and microbial degradation of cyanazine and atrazine in soils ranging in pH from 5.3 to 8.1. Atrazine degradation was dominated by chemical processes in both a moderately acidic and a neutral pH soil, but showed a significant microbial involvement in the neutral pH soil. The primary cyanazine degradative mechanism was dependent on soil properties. Cyanazine was short-lived in neutral to slightly basic soils, due to rapid microbial degradation. Cyanazine amide and cyanazine acid were the major metabolites formed. In a moderately acidic soil, microbial degradation was slowed and chemical processes were the primary means of cyanazine degradation.     

不同连作年限硒砂瓜土壤细菌群落结构特征

应用高通量测序技术对宁夏中卫地区不同连作年限硒砂瓜土壤细菌群落结构和多样性进行研究,旨在揭示不同连作年限对硒砂瓜土壤细菌群落结构的影响。结果表明:随着连作时间的增加,细菌多样性指数和丰富度指数逐渐增加。从5份不同连作年限硒砂瓜土壤样本中共获得39门、98纲和620属的细菌;优势门为放线菌门(Actinobacteria)、变形菌门(Proteobacteria)、绿弯菌门(Chloroflexi)、酸杆菌门(Acidobacteria);随着连作时间的增加,放线菌门、酸酐菌门丰度先增加后降低,变形菌门丰度逐渐降低,绿弯菌门丰度呈先降低后增加又降低现象;优势纲分别为放线菌纲(Actinobacteria)、酸杆菌纲(Acidobacteria)、α-变形菌纲(Alphaproteobacteria)、芽单胞菌纲(Gmmatimonadetes)、杆菌纲(Bacilli)、热原体纲(Themomicrobia)、γ-变形菌纲(Gammaproteobacteria)、β-变形菌纲(Betaproteobacteria);优势目为norank_cAc...     

The management type used in plum orchards alters the functional community structure of arthropod predators

Abstract

The management practices in agroecosystems can alter the community structure of pests’ natural enemies, which can consequently disturb their biocontrol function. Here, we investigated how organic or conventional farming influence the community structure of arthropod predators (spiders, coccinelids, anthocorids, ants) in orchards. The three conventional orchards studied were plum tree monocultures where mainly fungicides were applied. The three organic orchards studied were dominated by plum trees with admixture of apple trees and no agrochemical was applied. We found that management significantly affected only spiders that were less abundant in the conventional orchards than in the organic orchards. In addition, the conventional management resulted in reduced species density and altered the community composition of spiders. The conventional management reduced the functional dispersion of spider body size, which may narrow the size-spectrum of pests that could be reduced by spiders. The conventional management also reduced abundances of foliage hunters and space-web spiders. Since these spiders are effective against various insect pests, the conventional management of applying fungicides might result in increased crop damage via increased insect pests.     

苹果园病虫害系统管理规范刍议

1苹果病虫害发生特点分析在陕西省常见的苹果病虫害种类超过100种(类),在生产上造成重大经济损失的达20种(类)以上。病害常发种类有苹果树腐烂病、白粉病、早期落叶病、斑点落叶病、黑星病、炭疽病、轮纹病、根腐圆斑病、霉心病、病毒病、花腐病、水心病、日灼病等。害虫及害螨常发种类有山楂叶螨、二斑叶螨、苹果全爪螨、花期金龟子类、蚜虫类、桃小食心虫、金纹细蛾、卷叶蛾类、潜叶蛾类、介壳虫、椿象等。苹果园病虫害发生是一个复杂的体系,影响发生的主要因素是病、虫发生的基数,果园温度、湿度(包括降水和灌溉)、土壤含水量和采取的防…     

陕西省新老苹果产区果园土壤硝态氮累积特性研究

以陕西省新、老果区（分别为洛川及礼泉）为研究对象,调查了两县各15个成龄果园的施肥现状,计算了果园氮素表观平衡,并测定了这15个果园的0~200 cm土壤剖面硝态氮含量,分析了树龄、施氮量与土壤剖面硝态氮累积量的关系。结果表明：新、老果区苹果园均过量施用氮肥,平均施氮量分别高达1 287±244 kg·hm^-2（洛川）和1 193±300 kg·hm^-2（礼泉）,导致土壤中盈余了大量的氮素。新、老果区土壤0~200 cm硝态氮累积量分别达2 724 kg·hm^-2和5 226 kg·hm^-2, 老果区土壤剖面硝态氮累积量显著高于新果区。相关分析表明,果园土壤剖面累积的硝态氮与树龄和施氮量呈正相关,与树龄的相关系数为0.641,与洛川、礼泉果园施氮量的相关系数分别为0.402和0.306。因此,建议研究区域采取措施控制果园施氮量,减少果园土壤硝态氮累积带来的资源浪费及环境污染。     

苹果树体磷素动态规律与施肥管理

以"富士"苹果树为试材,对果树体生物量和各器官及其皮层、木质部的磷含量和累积动态进行了研究,以期探讨果树磷素吸收、转运和分配规律.结果表明,3月26日至9月21日,树体生物量呈直线增加,果实采收后,生长缓慢,7月30日后,根系快速生长,植株、地上部及根系中磷累积迅速增加;枝、干和根系皮层内磷含量与累积7月30日最低,休眠期最高,皮层磷含量枝＞干＞根系;而木质部磷含量与累积4月30日达最低,木质部磷含量根系＞枝＞干;一年内,果树吸磷总量为28.72 kg/hm2,果实和叶片共带走磷素7.94 kg/hm2,7月30日至9月21日,吸收磷素18.32 kg/hm2,占吸收总量的63.8%,9月21日至1月15日,吸收磷素10.40 kg/hm2,占36.2%;苹果树(苹果产量48 t/hm2)年推荐施纯磷47.86 kg/hm2,果实收获后秋季基施磷17.33 kg/hm2,果实膨大期前追施磷30.53 kg/hm2.