蚯蚓粪对作物连作障碍抑制作用研究进展

随着集约化生产的进一步发展,连作障碍已成为制约我国一些地区种植业可持续发展的瓶颈问题。蚯蚓粪是一种优质的有机肥,目前已成功应用于连作障碍防治,并取得了一定的研究成果。本文简要介绍了蚯蚓粪的理化性质和生物学性质,综述概括了其在抑制连作障碍方面的研究进展,并对以后的研究提出了展望,以期能为作物连作障碍综合防治提供一定的参考。     

不同浓度有机物料发酵流体对连作苹果幼树生物量及土壤环境的影响

在老果园的更新中,连作障碍是制约果树持续发展的重要因素,施用获得国家专利的不同有机物料发酵液可有效缓解连作果树再植病。本试验以富士/八棱海棠二年生嫁接苗为试材,设计了六个不同有机物料发酵液灌溉浓度:(CK)、 1%(T1)、 3%(T2)、 5%(T3)、 7%(T4)、 9%(T5),利用盆栽方法,在春、 夏、 秋季三个季节研究了重茬土上利用该技术制备的有机物料发酵液对连作土壤条件下苹果幼树生物量及土壤环境的影响。结果表明, 1）春、 夏、 秋三个季节,浇灌不同浓度的有机物料发酵液均不同程度地提高连作土的有机质、 铵态氮、 硝态氮、 速效磷、 速效钾含量,以添加 9% 的发酵液（T5）的土壤养分含量最高。2）浇灌有机物料发酵液对苹果幼树生长发育的作用表现为低促高抑的效应,浇灌浓度小于5%（T3）,可促进苹果幼树的生长,且以浇灌浓度为3%（T2）增长最显著。浇灌浓度在7%（T4）和 9%（T5）时,对苹果幼树的生长有抑制作用。3）浇灌不同浓度的有机物料发酵液均可提高连作土壤酶的活性,且以T2处理土壤过氧化氢酶活性、 土壤脲酶、 蔗糖酶和中性磷酸酶的活性最高。4）浇灌有机物料发酵液可增加土壤微生物的数量,以细菌数量增长最显著,放线菌次之,真菌最小。     

发酵时间对有机物料发酵流体成分含量变化及对连作苹果生物量的影响

为探明不同季节不同发酵时间有机物料发酵流体成分含量变化及其对连作苹果生物量的影响,本研究选择富士/八棱海棠二年生嫁接苗为试材,设置季节（春、 夏、 秋）和发酵时间（30 d、 45 d、 60 d）两个因素,共9个处理,盆栽条件下对发酵流体成分含量与连作苹果幼树生长间的关联进行了研究。结果表明,有机物料发酵流体可以减轻苹果连作障碍,与对照相比,施入春、 夏、 秋分别发酵60 d、 45 d、 45 d的发酵流体的植株干重分别增加了22.42%、 22.82%和19.63%。从总体上看,测定范围内夏、 秋季处理发酵流体相关成分平均含量大于春季处理,同时随着发酵时间的延长发酵流体相关成分含量有增大的趋势。其中春季发酵60 d、 夏季和秋季发酵45 d发酵流体相关成分含量最高,且对促进连作苹果幼树株高、 地茎、 鲜重及干重增加的影响最大。在发酵流体相关成分中与苹果幼树生长相关性最大的为细胞分裂素（6BA）、 维生素B12（VB12）、 苹果酸、 氨基酸和乙酸,与植株干重的相关系数分别为0.65、 0.81、 0.53、 0.51和-0.5。     

蚓粪减轻苹果砧木平邑甜茶幼苗连作障碍的土壤生物学机制

【目的】有害真菌数量的增加是造成苹果连作障碍的主要原因。本文探讨了蚓粪对苹果连作障碍的防控效果以及作用机理。【方法】以苹果常用砧木平邑甜茶 (Malus hupeheusis Rehd.) 为试材进行了盆栽试验,供试土壤为棕壤,取自山东省泰安市25年的红富士老果园。以连作土壤为对照 (CK),设灭菌连作土壤 (TM)、连作土壤施用蚓粪 (YF)、连作土壤施用灭菌蚓粪 (MYF) 共4个处理。幼苗生长一年后,测定平邑甜茶生物量、根系相关指标,分析土壤可培养微生物类群及土壤酶活性。【结果】与连作土壤CK相比,蚓粪(YF)和灭菌蚓粪 (MYF) 处理的平邑甜茶植株干重显著提高了351.1%和348.2%;蚓粪处理 (YF) 和灭菌蚓粪 (MYF) 处理都显著促进了平邑甜茶植株根系的生长,提高了植株根系的抗氧化酶活性和根系呼吸速率,两个处理间无明显差异;YF处理土壤细菌、放线菌数量分别增加了107.8%和97.7%,真菌数量减少了17.1%。实时荧光定量PCR结果显示,施入蚓粪后 (YF) 连作土壤中尖孢镰刀菌的数量下降了51.0%,MYF处理的尖孢镰刀菌数量降低了57.6%,YF和MYF两个处理间无显著差异;YF处理的土壤磷酸酶、脲酶、蔗糖酶和过氧化氢酶活性分别比CK提高了97.9%、540.9%、213.1%和109.4%。【结论】在连作土壤上添加蚓粪或灭菌蚓粪,均可显著增加土壤中细菌和放线菌数量,降低真菌特别是尖孢镰刀菌数量,改善连作土壤微生物环境,进而减轻苹果连作障碍带来的危害,提高土壤酶活性,促进植株根系健康生长,提高平邑甜茶幼苗的生物量。     

蚯蚓粪缓解草莓连作土壤障碍的作用

【目的】土壤灭菌处理已成为草莓生产中土传病害综合管理的重要措施,但是土壤灭菌明显抑制了土壤微生物的活性,影响草莓植株的生长。有机肥中含有大量的生物活性物质,尤其是蚯蚓粪。本研究通过观测连作土壤灭菌后施用不同有机肥对草莓植株地上部和地下部的影响,为减缓草莓植株生长的连作障碍提供有机肥选择。【方法】采用温室盆栽草莓模拟试验,首先在去除土壤化感效应影响基础上设置土壤灭菌和正常土壤栽培两个处理,探讨土壤灭菌对草莓植株不同阶段地上部叶片及地下部根系生长影响,在此基础上以相同连作土壤进行另一个盆栽试验,设置不灭菌土壤加无机肥料(LW)、 加牛粪(LN)、 加蚯蚓粪(LQ)处理,灭菌土壤加无机肥料(LMW)、 加牛粪(LMN)、 加蚯蚓粪(LMQ)共6个处理。调查了不同处理开花前苗期草莓植株地上部叶片及地下部根系的生长状况。【结果】土壤灭菌处理较相应未灭菌处理显著抑制了草莓花前幼苗阶段植株地下部的生长(P＜0.05),在果实成熟期、 盛果期及盛果末期植株生长均存在补长效应。土壤灭菌改变了草莓植株地上部和地下部正常的生长发育进程,植株不同发育阶段根冠比发生变化。无论连作土壤灭菌与否,施用无机肥料处理较施用有机肥处理显著抑制了根系生长(P＜0.05)。在不灭菌土壤上,施用蚯蚓粪处理草莓植株根系总长、 根系总表面积、 根尖数及根叉数与施用牛粪处理差异不显著,但灭菌土壤上,施加蚯蚓粪与施加牛粪相比,显著增加了草莓植株根系总长、 根系表面积及根叉数(P＜0.05)。【结论】蚯蚓粪与牛粪和无机肥料相比具有显著的生物活性。在草莓连作土壤灭菌后施用具有生物活性的蚯蚓粪,可以促进根系生长,缓解土壤灭菌对草莓植株生长发育的影响,是值得推荐的有效措施。     

大豆连作障碍的研究进展

从生物学、微生物学和植物营养生理学的角度及诸多障碍因子等方面,综合评述和分析了国内外大豆连作研究的现状,阐述了目前国内外学者提出的各种应对连作问题的策略和技术措施,提出大豆连作障碍研究仍有待解决的问题和研究方向。     

蚯蚓原位堆肥提升番茄连作土壤质量研究

[目的]连作障碍引起的土壤质量劣变是制约种植业可持续发展的瓶颈问题之一.已有研究表明蚯蚓腐熟粪肥能有效提升连作障碍土壤质量.本研究比较了蚯蚓原位腐熟粪肥和使用异地腐熟粪肥对提高土壤理化和生物学性状的效果,以提出高效可行的蚯蚓堆肥施用模式.[方法]田间试验在宁夏连续种植5年番茄的温室内进行,供试番茄品种为'粉宴1号'.试...     

设施蔬菜连作障碍原因综合分析与防治措施

  目的  为了探索种养模式下,不同品种蚯蚓对连作土壤微生态及西瓜长势的影响,阐释蚯蚓防控西瓜连作障碍机制。  方法  基于连作6 a的西瓜设施大棚,以连作障碍成因为切入点,设置不投放蚯蚓（CK）、投放0.6 kg m⁻²赤子爱胜蚓（T1）、投放0.6 kg m⁻²威廉环毛蚓（T2）3个处理,监测不同时期土壤微生态、西瓜长势的变化动态,并分析它们之间的相关性。  结果  与CK相比,西瓜移栽前,T1、T2增加了土壤总养分（23.92% ~ 31.90%）、有效养分（10.67% ~ 13.70%）的含量;西瓜种植季,T1、T2显著降低土壤的pH（2.03% ~ 8.25%）、总酚酸（23.98% ~ 60.80%）、容重（3.79% ~ 5.39%）、西瓜枯萎病病原菌的数量（22.93% ~ 59.18%）,显著提高了细菌数量、土壤细菌/真菌比值,显著降低了西瓜枯萎病的发病率（10.00%以上）,促进了主蔓生长（增加了71.43%以上）。而与T1相比,T2能更好的改善土壤微生态环境,降低连作障碍的发生。  结论  蚯蚓能显著改善土壤微生态,促进西瓜生长,从而缓解连作障碍,而且土壤微生态、西瓜长势均与土壤微生物密切相关。     

连作障碍发生机制研究进展

连作障碍是农业生产中经常发生的一种病害,各种作物或轻或重都会发生,已成为世界性难题,给农业生产造成了严重损失。近年来,国内外学者从多方面、多角度对连作障碍进行分析。本文从土壤生物学环境的恶化、化感作用和土壤理化性状改变等角度阐述了连作障碍发生机制的研究进展。     

花生连作土壤障碍机制研究进展

花生是我国主要经济作物和油料作物,连作障碍问题严重影响花生的产量与品质,制约着我国花生产业可持续发展。已有研究认为自毒物质积累、病菌增加、土壤微生物群落失衡及土壤理化性质恶化是花生连作障碍的主要因子,但大多停留在单因子水平上,有的认识缺乏直接的证据。本文简要综述了花生连作障碍的危害、机制及调控措施,结合作者近几年来相关研究,主要从花生根系分泌物效应、化感物质存留特征、土壤生物群落演变等方面介绍了花生连作障碍机制研究进展,最后对花生连作障碍的进一步研究及防控技术发展方向提出展望。     

复合生物制剂防治西瓜连作病害的研究

T42木霉与枯草芽孢杆菌Bs-6对尖孢镰刀菌FUS3有明显的拮抗作用。田间试验表明，由T42木霉与枯草芽孢杆菌Bs-6组成的复合生物制剂能显著增加连作西瓜的茎长和茎粗，经济产量、生物产量分别增加50．9％、66．7％，对连作病害的防效可达75％。     

Microbial community development in the rhizosphere of apple trees at a replant disease site

Apple replant disease (ARD) is a complex syndrome that affects young trees in replanted orchard sites causing necrotic lesions on feeder roots, stunted tree growth and reduced cumulative yields. Use of ARD-tolerant rootstocks is an emerging control strategy. We studied the bacterial, fungal, and oomycetes populations in the rhizosphere of five rootstock cultivars (M.7, M.26, G.16, G.30 and CG.6210) planted into the old tree row or grass lanes of a previous orchard in Ithaca, NY, to better understand the role of rhizosphere microbial communities in the prevalence and control of ARD. The possible involvement of antagonistic Pseudomonas species, Pythium spp., Phytophthora spp. and rhizosphere cyanide concentrations in ARD were also examined. The rootstocks M.7, M.26 and G.16 were susceptible to ARD, while G.30 and CG.6210 were more tolerant. Tree growth on the rootstocks M.7, M.26 and G.16 was reduced by 10% when planted in the old tree rows, but this did not significantly reduce yields in the first fruiting year. The susceptible rootstocks, M.7 and M.26, supported higher densities of culturable rhizosphere fungi and bacteria than G.16, G.30 and CG.6210. Over 2 years, microbial densities were highest in July, lower in May and lowest in September. The composition of bacterial and fungal communities in the rhizosphere was highly variable and changed over seasons and years, as assessed by terminal restriction fragment length polymorphism (T-RFLP) analyses. Initial differences in fungal rhizosphere communities between the two planting positions converged 2 years after the trees were replanted. In contrast, the bacterial rhizosphere community composition still differed significantly between the two planting positions 3 years after the orchard was replanted. The bacterial and fungal rhizosphere community compositions of susceptible rootstocks, M.7 and M.26, differed from those of the tolerant rootstocks, G.30 and CG.6210; G.16, differed from all the other rootstocks. The observed effects of rootstocks, planting positions and time on microbial community composition were small relative to the high variability observed overall. Pythium spp. and Phytophthora spp. infestations were high and similar for all rootstocks and planting positions. Neither potentially antagonistic Pseudomonas nor rhizosphere cyanide concentrations appeared to be involved in the ARD-complex at the studied site. Avoiding replanting into the old tree rows coupled with use of tolerant rootstocks appear to be the best strategies for reducing ARD in replanted orchards. Changes in rhizosphere microbial communities are among the many factors that contribute to improved tree growth when these management strategies are used.     

A multi-phasic approach reveals that apple replant disease is caused by multiple biological agents, with some agents acting synergistically

Apple replant disease (ARD) has been reported from all major fruit-growing regions of the world, and is often caused by a consortium of biological agents. The aim of this study was to investigate the etiology of ARD in South Africa in six orchard soils, using a multiphasic approach under glasshouse conditions. This approach first involved determining the ARD status of the soils by monitoring apple seedling growth responses in non-treated soil versus growth in pasteurized soil, as well as in 15% non-treated soil that was diluted into pasteurized soil. Subsequently, the potential for specific organisms to function as causal agents of ARD was investigated using (i) biocide applications, (ii) quantitative real-time PCR (qPCR) analyses of ARD ‘marker’ microbes (Pythium irregulare, Pythium sylvaticum, Pythium ultimum, Pythium vexans, Rhizoctonia solani AG-5 and the genera Cylindrocarpon and Phytophthora), (iii) nematode analyses, (iv) isolation of actinomycetes and (v) pathogenicity testing of actinomycetes individually, and when co-inoculated with P. irregulare or Cylindrocarpon macrodidymum. The analyses showed that the soils could be grouped into low, moderate and severe ARD soils, with each group containing two soils. Several lines of evidence suggested that actinomycetes are not involved in ARD in South Africa. Multiple biological agents were determined to contribute to ARD including (i) oomycetes (Phytophthora and Pythium) that are important based upon their widespread occurrence, and the fact that metalaxyl application improved seedling growth in four soils (ii) the genus Cylindrocarpon that was also widespread, and for which a synergistic interaction with P. irregulare was demonstrated and (iii) occasionally parasitic nematodes, mainly Pratylenchus penetrans, Pratylenchus scribneri and Pratylenchus delattrei, since fenamiphos application improved seedling growth in two orchards. qPCR analyses of the ARD marker microbes showed that R. solani AG-5 is absent from South African orchards, and that P. ultimum is widespread, even though the latter species could not be detected in previous isolation studies. The other marker microbes were also widespread, with the exception of P. sylvaticum. qPCR quantification of the marker microbes could not be correlated with the severity of ARD in any manner. qPCR analyses did, however, show that possible root pruning pathogens such as P. irregulare, P. sylvaticum and P. ultimum had much lower DNA concentrations in seedling roots than P. vexans and the genera Cylindrocarpon and Phytophthora.     

不同氮形态对连作平邑甜茶幼苗生长及土壤尖孢镰孢菌数量的影响

【目的】研究盆栽条件下不同形态氮对苹果砧木—平邑甜茶幼苗生长以及对连作土壤微生物的影响,为连作建园时科学施肥、减轻苹果连作障碍提供依据。 【方法】试验于 2015 年露地进行,以平邑甜茶幼苗为试材,以连作土为对照1 (CK1) 和溴甲烷熏蒸为对照2 (CK2),设置施入铵态氮 (T1)、硝态氮 (T2) 和酰胺态氮 (T3) 3 个不同形态氮处理 (N 180 mg/L),于 2015 年 8 月测定平邑甜茶生物量、光合参数和土壤微生物等相关指标。 【结果】铵态氮 (T1) 和酰胺态氮 (T3) 处理均能明显提高连作条件下‘平邑甜茶’苹果幼苗的生物量,其中 T1 处理的株高、地径、鲜重、干重与 CK1 相比分别提高了 35.3%、24.4%、42.0%、57.7%。添加 3 种形态氮素均可不同程度地提高平邑甜茶幼苗叶片的净光合速率 (Pn)、气孔导度 (Gs) 和根系呼吸速率,其中 T1 处理的 Pn、Gs 和根系呼吸速率分别比 CK1 提高了 27.6%、35.6%、43.3%,却并未达到 CK2 的效果。实时荧光定量 PCR 结果表明,CK2 尖孢镰孢菌的基因拷贝数降低最为明显,比 CK1 降低了 52.6%,T1 也有效地降低了尖孢镰孢菌的基因拷贝数,而 T2 和 T3 处理尖孢镰孢菌的基因拷贝数与 CK1 没有显著性差异。T-RFLP 结果表明,T1 和 T3 处理的真菌群落结构与 CK1 有明显差异,T1 处理与 CK2 的真菌群落结构较为相似,T2 处理的真菌群落结构与 CK1 较为相似。 【结论】铵态氮处理可更好地提高连作平邑甜茶幼苗的生物量、净光合速率以及根系呼吸速率,降低土壤尖孢镰孢菌的基因拷贝数,明显改变连作土壤的真菌群落结构,可作为减轻苹果连作障碍的措施。     

添加残次苹果发酵物对稻草青贮品质及其微生物数量的影响

为了探讨添加残次苹果发酵物改善稻草的青贮品质及其适宜添加比例,该研究按残次苹果发酵物和稻草质量比为全部为稻草（Ⅰ）、1∶9（Ⅱ）、3∶7（Ⅲ）、5∶5（Ⅳ）、7∶3（Ⅴ）、9∶1（Ⅵ）混合进行青贮。青贮90 d 后开封,测定青贮前后的营养成分,鉴定青贮饲料的感官品质、发酵品质以及有氧暴露情况下pH值和微生物数量的变化。结果表明,添加残次苹果发酵物显著提高青贮原料的粗蛋白（Crude Protein,CP）和可溶性碳水化合物（Water Soluble Carbohydrate,WSC）的含量（P<0.05）,降低了原料的中性洗涤纤维（Neutral Detergent Fiber,NDF）和酸性洗涤纤维（Acid Detergent Fiber,ADF）的含量（P<0.05）;青贮90 d天后,混合青贮饲料的乳酸（Lactate Acid,LA）、乙酸（Acetic Acid,AA）含量随着残次苹果发酵物添加量的增加而增加;处理Ⅰ的LA（0.17%）、AA（0.09%）含量显著低于其他5个处理（P<0.05）,而丁酸（Butyric Acid,BA）含量、AN/TN（Ammonia Nitrogen Total Nitrogen）的比值显著高于其他5个处理（P<0.05）;有氧暴露后,随着有氧暴露时间的延长,各处理的pH值、酵母菌数量、霉菌数量逐渐增多,乳酸菌数量逐渐减少;处理Ⅰ的乳酸菌数量始终显著低于其他各处理（P<0.05）,酵母菌和霉菌数量始终显著高于其他各处理（P<0.05）;而处理Ⅲ、Ⅳ的乳酸菌数量始终显著高于其他处理（P<0.05）,酵母菌和霉菌数量始终保持较低水平。未添加残次苹果发酵物处理Ⅰ的感官评分和综合评分均为劣等,添加残次苹果发酵物的稻草青贮处理Ⅲ和处理Ⅳ的感官评分和综合评分均为优等;同时添加残次苹果发酵物增加了混贮的营养价值,改善了混贮的发酵品质。综合分析,在试验中添加残次苹果发酵物能改善稻草的青贮品质,其添比例在3∶7～5∶5之间适宜。     

生物炭介导下磷水平对连作苹果幼苗及土壤环境的影响

苹果连作障碍是制约苹果产业可持续发展的重要因素之一。研究生物炭介导下不同施磷水平对连作条件下平邑甜茶幼苗生物量、根系呼吸速率和土壤环境的影响,探讨生物炭配施磷肥这种措施对苹果连作障碍的防控效果,并筛选出合适磷肥用量,为生产中老果园改造提供理论依据。盆栽条件下,以苹果常用砧木-平邑甜茶为试材,设计了连作土壤(CK)、连作土用溴甲烷熏蒸处理(F)、连作土+2%生物炭(B)、连作土+2%生物炭+0.5‰磷肥(BP0.5)、连作土+2%生物炭+1‰磷肥(BP1)和连作土+2%生物炭+2‰磷肥(BP2)6个处理。采用常规方法测定了不同处理对平邑甜茶幼苗生物量、根系呼吸速率、土壤养分和土壤酶活性的影响。结果表明:溴甲烷灭菌后,幼苗的株高、地径、鲜重和干重均远远高于连作土,分别是连作土中幼苗的1.6,1.5,2.9,2.5倍,幼苗的根系呼吸速率及保护酶也远远高于对照和其他处理。生物炭、或者生物炭配施磷肥,均可提高平邑甜茶幼苗的生物量,幼苗的株高、地径、鲜重和干重分别是连作土中幼苗的1.2,1.1,1.6,1.4倍和1.4,1.2,2.2,1.9倍,2种处理的根系呼吸速率也有大幅度提高;生物炭配施0.5‰磷肥可明显提高幼苗根系SOD、POD和CAT酶活性,同时降低MDA含量;与对照相比,生物炭配施0.5‰磷肥能明显提高土壤中有机质含量,增加硝态氮和速效磷的含量,促进土壤中脲酶、蔗糖酶和磷酸酶的活性。综合分析比较,生物炭配施0.5‰磷肥相比于单施生物炭,能更好的提高连作条件下平邑甜茶幼苗的生长发育,增加土壤有机质含量,增强土壤酶活性。因此,生物炭配施磷肥这一综合措施能更好的防控苹果连作障碍。     

The role of root exudates in specific apple (Malus × domestica Borkh.) replant disease (SARD)

In an effort to improve our understanding of the specific apple replant disease (SARD), direct and indirect effects of phytohormones and related compounds (abscisic acid, 6‐benzyladenine, indole‐3‐acetic acid, 1‐naphthaleneacetic acid, and gibberellins GA₃ or GA₄) on root exudates of apple seedlings were evaluated as a potential mediating factor in the infection process. In the first type of experiments, radioactively labeled hormonal substances were applied to the stumps of decapitated apple‐seedlings and the occurrence of radioactivity in root exudates and their qualitative characterization were examined (direct influence). In another set of experiments, the effects of leaf‐applied plant growth regulators on the amount and composition of the predominant organic acids, carbohydrates, and amino acids/amides were studied. Cherry seedlings resistant to SARD and apple seedlings with dormant apical buds and, thus, not susceptible to infection were used for comparison. The results showed no differences in exudation of applied plant growth regulators between growing cherry and apple seedlings. Thus, a direct effect of plant hormones on the infection process is unlikely. However, leaf treatments with growth regulators, in particular with auxin‐type compounds and abscisic acid, increased exudation of alditols. This may indicate that plant hormones are, to some degree, indirectly involved in the infection process.     

Soil fumigation and compost amendment alter soil microbial community composition but do not improve tree growth or yield in an apple replant site

Apple replant disease (ARD) is a disease complex that reduces survival, growth and yield of replanted trees, and is often encountered in establishing new orchards on old sites. Methyl bromide (MB) has been the fumigant used most widely to control ARD, but alternatives to MB and cultural methods of control are needed. In this experiment, we evaluated the response of soil microbial communities and tree growth and yield to three pre-plant soil treatments (compost amendment, soil treatment with a broad-spectrum fumigant, and untreated controls), and use of five clonal rootstock genotypes (M.7, M.26, CG.6210, G.30 and G.16), in an apple replant site in Ithaca, New York. Polymerase chain reaction (PCR)—denaturing gradient gel electrophoresis (DGGE) analysis was used to assess changes in the community composition of bacteria and fungi in the bulk soil 8, 10, 18 and 22 months after trees were replanted. PCR-DGGE was also used to compare the community composition of bacteria, fungi and pseudomonads in untreated rhizosphere soil of the five rootstock genotypes 31 months after planting. Tree caliper and extension growth were measured annually in November from 2002 to 2004. Apple yield data were recorded in 2004, the first fruiting year after planting. Trees on CG.6210 rootstocks had the most growth and highest yield, while trees on M.26 rootstocks had the least growth and lowest yield. Tree growth and yield were not affected by pre-plant soil treatment except for lateral extension growth, which was longer in trees growing in compost-treated soil in 2003 as compared to those in the fumigation treatment. Bulk soil bacterial PCR-DGGE fingerprints differed strongly among the different soil treatments 1 year after their application, with the fingerprints derived from each pre-plant soil treatment clustering separately in a hierarchical cluster analysis. However, the differences in bacterial communities between the soil treatments diminished during the second year after planting. Soil fungal communities converged more rapidly than bacterial communities, with no discernable pattern related to pre-plant soil treatments 10 months after replanting. Changes in bulk soil bacterial and fungal communities in response to soil treatments had no obvious correlation with tree performance. On the other hand, rootstock genotypes modified their rhizosphere environments which differed significantly in their bacterial, pseudomonad, fungal and oomycete communities. Cluster analysis of PCR-DGGE fingerprints of fungal and pseudomonad rhizosphere community DNA revealed two distinct clusters. For both analyses, soil sampled from the rhizosphere of the two higher yielding rootstock genotypes clustered together, while the lower yielding rootstock genotypes also clustered together. These results suggest that the fungal and pseudomonad communities that have developed in the rhizosphere of the different rootstock genotypes may be one factor influencing tree growth and yield at this apple replant site.     

豆腐渣混合苹果渣固态发酵改善纤维适口性

为了改善豆腐渣发酵后膳食纤维的适口性,适量混合部分苹果渣,利用其糖分提高酿酒酵母的发酵效率,并对其固态发酵工艺条件进行优化。采用单因素和正交试验方法优化的较佳发酵条件为pH值为8、发酵温度22℃、豆腐渣与苹果渣质量比2∶1、酿酒酵母接种量8%、发酵时间48 h。在优化发酵条件下,豆腐渣和苹果渣混合物中粗纤维的质量分数由发酵前的107.8 mg/g下降到发酵后的64.2 mg/g,降解率为40.45%。混合苹果渣的固态发酵极大地改善了膳食纤维的适口性,可以作为健康食品原料广泛使用。