盐城药用菊花连作障碍形成原因初步研究

以连作1年、3年、7年、15年的菊花田土壤和菊花为研究对象,考察各处理组菊花产量、发病率、土壤及菊花样品中的元素含量、土壤中可培养微生物数量及酚酸类化感物质的含量,进一步探讨不同浓度对羟基苯甲酸、香草酸、香豆酸、香豆素等化感物质对菊花组培苗生长的影响.结果表明:随着连作年限的增加,菊花的产量逐渐降低,发病率逐渐增加,连作15年的菊花产量仅为初茬菊花产量的19.80％,种植15年菊花的发病率达到100％.土壤中硼元素含量随连作年限的增加而逐渐减少.连作15年的菊花植株中的氮、磷、钾、铁、锰、铜、锌、硼8种元素含量,与其他组相比均有较大程度的降低.随着连作年限的增加,土壤真菌化严重,细菌和放线菌数量在3年达到最大,15年显著降低.土壤中香豆酸含量随着种植年限的增加而逐渐增加,连作7年后土壤中检测出香豆素残留.低浓度对羟基苯甲酸、香草酸及香豆酸对菊花组培苗生长发育影响不大,但香豆素、混合酚酸及高浓度的香豆酸显著抑制菊花组培苗生长和根的发育.酚酸物质积累、微生物区系的改变、土壤微量元素硼的减少可能是菊花连作障碍的主要原因.     

连作植烟土壤酚酸类物质变化特征及其与主要环境因子的Mantel Test分析

为明确酚酸类物质在连作植烟土壤中的变化特征,探讨土壤主要环境因子对酚酸类物质的影响,以不同连作年限（4 a,6 a,8 a,14 a和16 a）植烟土壤为对象,研究了不同连作年限植烟土壤酚酸类物质、理化性状、酶活性和细菌多样性的变化特征,并利用Mantel Test分析了酚酸类物质与土壤主要环境因子的相关性。结果表明,随连作年限增加,土壤酚酸类物质和速效钾含量升高,pH、有机质含量、细菌菌群丰度和多样性降低,水解性氮和有效磷含量呈先降低后升高趋势,酶活性呈先升高后降低趋势。Mantel Test分析表明,土壤酚酸类物质含量与理化性状、酶活性和细菌丰度显著相关,且与理化性状相关性最高;不同酚酸类物质含量与土壤主要环境因子相关性存在差异,其中,对羟基苯甲酸和阔马酸与植烟土壤理化性状、酶活性以及细菌丰度的相关性最高。因此,在本试验条件下,连作植烟土壤酚酸类物质具有明显积累特征,植烟土壤环境恶化;酚酸类物质积累受理化性状、酶活性和细菌多样性影响,且理化性状影响最大;不同酚酸类物质受主要土壤环境因子的影响存在差异,其中对羟基苯甲酸和阔马酸积累所受影响最大。     

连作对花生土壤酶活性、养分含量和植株产量的影响

通过盆栽试验,设置4个不同连作年限处理,研究连作对花生栽培种桂花17和野生种A.correntina土壤酶活性、养分含量和植株干物质产量影响的差异。结果表明:与对照相比,两个花生品种不同连作年限土壤有效养分含量和植株干物质产量均降低,A.correntina相比桂花17下降幅度小。桂花17各连作年限处理土壤的脲酶、转化酶、酸性磷酸酶活性随连作年限的增加有下降的趋势,处理间变幅大。而A.correntina各生育期土壤的脲酶、转化酶、酸性磷酸酶活性总体表现无一致性上升或下降的规律,处理间变幅小。两个花生品种在不同的连作年限间的过氧化氢酶活性的变化无规律性。连作条件下,花生野生种A.correntina的土壤理化和生物学性状的变化幅度更小。     

设施辣椒连作对土壤理化性状、酶活性及微生物区系的影响

以青海省尖扎县设施辣椒连作土壤为对象，研究不同连作年限土壤理化性状、酶活性及微生物区系的变化。结果表明，土壤理化性状、酶活性、微生物数量及微生物量均表现出明显的连作效应。随着连作年限的增加，土壤容重和电导率呈上升趋势，pH呈下降趋势，有机质、全氮、有效磷和速效钾呈先上升后下降趋势。土壤碱性磷酸酶、蔗糖酶、淀粉酶和过氧化氢酶随连作年限的增加均呈下降趋势，脲酶和碱性蛋白酶呈先上升后下降趋势。与对照相比，连作导致土壤细菌与真菌数量的比值降低，土壤微生物量碳与微生物量氮比值升高，土壤微生物群落结构由“细菌型”转变为“真菌型”。     

不同连作年限不同生长时期对大蒜土壤性质的影响

选取中国出口大蒜主产区山东省济宁市嘉祥县连作5年大蒜田、金乡县连作25年大蒜田和连作40年大蒜田进行大蒜鳞茎产量及各生长时期根际土壤、非根际土壤理化性质研究。结果显示:大蒜随着连作年限的增加,产量出现先下降后回升的现象;随着大蒜连作年限的增加,根际土壤全磷、速效钾含量呈现富集趋势,而有机质含量随着连作年限增加而逐渐降低;全氮、全磷、有效磷、有机质含量受生长时期的影响大于连作年限,而速效钾含量受连作年限的影响大于生长时期;连作年限与全氮、有机质含量呈极显著的负相关关系。     

大棚辣椒连作土壤微生物数量、酶活性与土壤肥力的关系

选取不同连作年限的辣椒大棚土壤和相邻露地小麦-辣椒轮作土壤(对照),研究了大棚辣椒连作土壤微生物数量、酶活性与土壤肥力的关系。结果表明,连作土壤养分含量显著高于对照,而pH值显著低于对照;土壤细菌,放线菌数量随连作年限延长呈先增加后降低的趋势并高于对照,而真菌数量不断增加;连作土壤酶活性含量均显著高于对照。土壤细菌数量与土壤有机质、全磷呈显著相关性,真菌数量与土壤养分无显著相关性,放线菌数量、过氧化氢酶、蔗糖酶、脲酶活性与pH值呈显著负相关性,与养分呈显著相关性。土壤全磷、全氮、pH值对微生物数量的影响较大,而全氮、pH值对土壤酶活性的影响较大。     

番茄连作对日光温室土壤微生物及土壤理化性状的影响

对大庆地区具有代表性的温室进行调查研究,了解不同种植年限对番茄温室土壤微生物及土壤理化性状的影响,为解决温室土壤连作障碍问题奠定理论依据。结果表明,随着种植年限增加,细菌、真菌的数量及土壤速效钾、有效磷、碱解氮、有机质、盐分的含量呈增加趋势,种植年限为10年分别是对照(露地菜田)的2.14、1.33、2.18、2.09、1.96、2.86、9.5倍,土壤p H值相反,种植年限为10年比对照下降了0.64,但放线菌数量与B/F值[(细菌+放线菌)/真菌]在第5年与第7年达到最高,呈现先增高再降低的趋势,分别比对照增加了34.12%、44.26%;随着土壤深度的增加,土壤微生物数量及土壤速效钾、有效磷、碱解氮、有机质、盐分含量降低,土壤含水量、p H值增加。综合分析番茄连作对土壤微生物和土壤理化性状的影响,番茄连作6年后出现一定程度的连作障碍问题。     

连作对大棚辣椒生长发育及品质的影响

选取连续种植辣椒3、7、10、15 a的大棚土壤,以种植黄瓜的邻棚土壤为对照进行盆栽试验,研究了连作对辣椒植株株高、茎粗、叶面积、产量、叶片中光合色素质量分数和果实品质的影响。结果表明,随着连作年限增加,辣椒植株的株高、茎粗及产量都明显低于对照;光合色素质量分数降低,其中叶绿素a质量分数和总叶绿素质量分数显著低于对照。连作条件下辣椒果实品质显著下降,其中可溶性固形物质量分数和可溶性蛋白质量分数均显著低于对照。     

轮作油葵对马铃薯生长发育及抗性生理指标的影响

为了探究轮作油葵对连作马铃薯生长发育及抗性生理的影响,选取马铃薯连作4年、连作4年后轮作油葵1年、连作6年、连作6年后轮作油葵1年的同一块试验田,以该试验田前两年分别种植藜麦、玉米的地块为对照,测定土壤理化性质、土壤酶活性及土壤微生物数量变化,测评土壤环境。再在该试验田种植马铃薯,对其幼苗光合作用、抗氧化酶活性以及马铃薯生长发育指标进行测定。结果表明,随连作年限增加,马铃薯根际土壤pH总体升高,偏碱性,有机质和有效磷含量逐渐减少,碱解氮含量上升;土壤酶活性与连作年限呈负相关;随连作年限增加,土壤中细菌数量、放线菌数量和细菌与真菌比(B/F)呈下降趋势,真菌数量呈增加趋势;土壤环境的恶化导致马铃薯植株生长量减少,叶绿素相对含量降低,叶片光合速率下降,超氧化物酶(SOD)活性下降,O_2~-.产生速率加快,丙二醛(MDA含量上升。轮作油葵明显降低了土壤pH,提高了土壤有机质、有效磷和碱解氮含量,增加了土壤酶活性、细菌数量和B/F值,降低了真菌数量,改善了根际土壤微环境,对植株生长发育起到促进作用;增加了马铃薯叶片相对叶绿素含量、光合速率,SOD活性增强,而O_2~-.水平和MDA含量下降,可见轮作油葵减轻了马铃薯叶片膜脂过氧化作用和自由基伤害,促进了马铃薯生长发育,且整体效果以连作4年后轮作油葵较好。     

新疆绿洲连作棉田土壤微量元素含量的时空变化研究

为了解棉花长期单一种植对土壤微量元素含量的影响,明确连作棉田土壤质量变化规律,在南疆棉区分别选择新开垦1a和连续植棉5、15、20、30 a的棉田,研究了不同时间尺度上棉田0~100cm土壤剖面Mo、Cu、Zn、Mn、Fe等5种微量元素全量的变化规律,分析了棉田微量元素含量与连作年限之间的关系。结果表明,棉花长期连作后,土壤0~20cm耕作层全钼含量随连作年限的增加持续下降,与连作年限呈一元负线性关系;全铜、全锌、全锰含量随年限的增加先升后降,与年限呈二次函数关系,分别在连作7~10、10~12、17~18 a达到最高累积量,之后持续下降,分别在14~17、20~22、32~34 a降回到开垦初期的水平。土壤剖面中部30~50cm土层各元素全量均随连作年限增加剧烈下降,与连作年限呈一元负线性关系,长期连作易导致该层微量元素缺乏。剖面下层50~90cm土层各元素全量在长期连作后表现出一定的累积趋势,然而与连作年限之间没有明显的函数关系。随连作年限延长,0~60cm土层中含量水平越低的元素,含量下降越明显,Mo表现最明显,其次为Zn和Cu,而Mn和Fe下降较少。在长期连作棉田,棉花种植应注重Mo、Zn、Cu等微量元素肥料的补充施用,并结合土壤深度翻耕,提高中部土层微量养分含量。     

Physical changes and compaction sensitivity of a fine-textured, poorly drained soil (Typic Endoaquept) under varying durations of cropping, Manawatu Region, New Zealand

The physical deterioration of soil under continuous cropping is a problem in many humid, temperate areas. While soils of the Kairanga Series (Typic Endoaquept), Manawatu Region, North Island, New Zealand, are widely used for continuous cereal production, there is concern over the long-term sustainability of this land use. We report the results of a field experiment conducted on a sequence of sites on Kairanga soils, with cropping durations of 0, 4 and 28 years. Study objectives were to quantify physical differences between these soils and to assess a field method for measuring sensitivity to further compaction. Significant changes in key soil physical properties were recorded between the pasture and cropped sites in the 0–30 cm depth range. Most changes had occurred within the first 4 years of cropping. Physical properties that changed significantly included macropore volume (>60 μm), air capacity volume (>30 μm), air permeability, saturated hydraulic conductivity, unsaturated hydraulic conductivity (−0.4 kPa), and shear strength. Bulk density increased significantly only after a long cropping period, and penetration resistance measurements did not significantly differentiate sites of increasing cropping duration. Hence, bulk density and penetration resistance measurements on their own may not be adequate to assess cropping impact. Agricultural tractors were used under moist spring conditions to impose wheel traffic at an intensity of 273–305 Mg km ha⁻¹ on the study sites. The wheel traffic experiment confirmed the trends revealed by the initial site sampling, and also indicated that both soil deformation and soil compaction were the operational forms of soil disturbance at a soil water matric potential of −10 kPa. Soil physical conditions at the long-term cropped site (28 years) had stabilised and were in equilibrium with the soil’s biological and physical environments, while the short-term cropped site (4 years) was still in a transition state, with the likelihood of further increases in bulk density and shear strength. To start appropriate amelioration, it is important to identify when soils are in transition between pasture and long-term cropped states.     

滩涂围垦区不同连作年限蔬菜大棚土壤质量特征

通过区域调查、采样和分析,系统研究了苏北滨海围垦滩涂设施农业土壤的连作障碍特征。研究表明,随着大棚青椒和韭菜连作年限的增加,大棚土壤呈不同程度的板结趋势,0~20、20~60 cm的表、根层土壤逐渐呈轻中度的盐渍化趋势,土壤有机质、全氮、碱解氮、速效钾等养分含量呈显著降低趋势,土壤全磷、有效磷、全钾含量则无显著变化,土壤微生物数量呈显著降低趋势。滩涂青椒和韭菜连作大棚土壤基本不缺磷肥,但有补充氮肥、钾肥和有机肥的必要性。滩涂地区大棚青椒和韭菜连作3年后,土壤呈现较为严重的连作障碍特征,主要表现为严重的次生盐渍化、养分失衡和微生物环境恶化风险,全年棚期的青椒连作障碍风险尤为显著,因此提出滩涂大棚青椒和韭菜的连作年限应不超过2年。     

Changes in soil properties and the availability of soil micronutrients after 18 years of cropping and fertilization

Micronutrient deficiencies are common in many parts of China's Loess Plateau. The objective of this experiment was to study the effects of long-term cropping and fertilization practices on soil properties and micronutrient availability in this region. The field plot experiment began in 1984. It included five cropping systems and four fertilizer treatments. In September 2002, soil samples were collected and soil pH, organic matter content, available P, and CaCO₃ were measured. Total and available Zn, Cu, Mn, and Fe were also determined. The relationship between soil properties and available micronutrients was determined by correlation and path analysis. After 18 years, soil pH and CaCO₃ levels were lower in the cropped and fertilized treatments compared to the fallow treatment. In contrast, soil organic matter and available P levels were higher in cropped compared to fallow treatments. A comparison of unfertilized treatments indicated that available Zn and Cu levels in cropped treatments were lower compared to the fallow treatment, probably due to the removal of these micronutrients from the system through crop uptake and harvest. In contrast, available Mn and Fe levels were higher in cropped treatments compared to the fallow treatment. The impacts of fertilization on available micronutrients varied with cropping systems. Generally, available Zn and Fe were higher in fertilized compared to unfertilized treatments, but available Cu was not significantly influenced by fertilization. Fertilization tended to increase available Mn in continuous wheat and maize, but reduced available Mn in continuous clover and the crop–legume rotation. The total (plant available + unavailable) micronutrient contents were lower in the four cropped-treatments compared to the fallow treatment. The addition of manure or P fertilizer increased total Zn, Fe, and Mn, but had no significant effect on total Cu. The results of correlation analysis and path analysis indicated that soil organic matter exerts a significant and direct effect on the availability of Zn, Mn, and Fe, but has little influence on available Cu. The effects of available P, CaCO₃, and pH on micronutrient availability were indirect, passing through soil organic matter. The results of this study suggest that long-term cropping and fertilization altered several important soil properties and increased the plant available micronutrient content of this loess-derived soil.     

生物有机肥提高设施土壤生产力减缓黄瓜连作障碍的机制

【目的】针对土壤连作障碍问题，探索高强度连作条件下生物有机肥在减缓土壤连作障碍发生、平衡土壤养分、调控土壤酶活性等方面的作用机制，为生物有机肥在改良土壤、防控黄瓜连作障碍、促进农业可持续发展等方面的应用奠定基础。【方法】以如皋市农业科学研究所设施蔬菜种植基地为试验平台，采用田间定位试验的方法，设置CK (空白对照)、B10 (生物有机肥施用量为10 t/hm2)、B20 (生物有机肥施用量为20 t/hm2) 3个处理，于第一季黄瓜种植前将生物有机肥一次性施入试验小区，于2016年12月5日、2017年6月28日和2017年11月26日，连续三季，在黄瓜成熟采集0—20 cm土壤样品。将土壤样品分成两份，一份放于4℃冰箱冷藏保存，用于测定土壤生物学性质；另一份风干后过筛处理，以供土壤理化性状分析。同时，调查黄瓜产量。【结果】随着黄瓜连续种植季数增加，CK处理中土壤容重和电导率呈增加趋势，土壤各肥力指标、酶活性、微生物量碳氮含量及黄瓜产量呈下降趋势；在同一季黄瓜成熟期，与CK相比，施用生物有机肥可降低土壤容重和电导率，增加土壤总孔隙度、pH、有机质、全氮、硝态氮和速效磷含量，其中连续种植3季黄瓜过程中，土壤有机质、速效磷和硝态氮含量分别增加了39.3%～83.9%、5.98～14.2%和10.0～22.0%，而土壤电导率降低了8.57%～12.7%。同一季黄瓜成熟期，不同处理中土壤脲酶、过氧化氢酶、蔗糖酶和磷酸酶活性由大到小排列均表现为B20 > B10 > CK，且连续种植3季黄瓜后B10和B20处理中4种土壤酶活性均高于第一季黄瓜成熟期CK处理；连续种植3季黄瓜期间，施用生物有机肥处理中土壤微生物量碳、氮含量均明显高于CK，B10和B20处理中微生物量碳、氮含量较CK分别增加了4.26%～23.2%和21.8%～56.2%。与CK相比，第一季、第二季、第三季B10处理黄瓜产量分别提高了3.93%、9.73%、10.6%，B20处理分别提高了12.9%、18.8%、20.2%。黄瓜连作过程中，土壤容重、有机质、硝态氮和速效磷与生物学指标和黄瓜产量相关显著，且土壤pH和电导率与土壤过氧化氢酶活性、蔗糖酶活性、微生物量氮含量和黄瓜产量呈显著相关关系。【结论】生物有机肥可改善黄瓜连作过程中土壤耕性变差、养分失衡和酸化等理化性质变劣的现象，缓解黄瓜连作土壤的次生盐渍化状况，还能提高土壤酶活性、微生物量碳氮含量和黄瓜产量，且黄瓜连作过程中土壤理化性质和生物学特性指标无明显变化，从而减缓黄瓜连作障碍的发生。     

生物炭和AM真菌配施对连作辣椒生长和土壤养分的影响

研究生物炭和丛枝菌根(arbuscularmycorrhizal,AM)真菌对连作辣椒生长和土壤养分的影响,可为辣椒连作土壤改良和新型肥料的开发提供理论依据。采用温室盆栽试验,设置4个生物炭添加水平(0、1%、2%、3%), 2个接菌水平[接菌(+AM)和不接菌(-AM)]。辣椒生长60 d后收获并测定其生理指标、土壤酶活性及土壤养分含量。结果表明,施加生物炭和接种AM真菌处理促进了连作辣椒的生长,提高了辣椒叶片净光合速率、蒸腾速率、气孔导度和叶绿素含量。接种AM真菌对辣椒的促生效果弱于生物炭,而生物炭和AM真菌配施的促生效果最佳。接种AM真菌促进辣椒对P吸收的效果优于生物炭;但对于K吸收来说,施加生物炭的效果优于接菌。生物炭(3%)和AM真菌配施条件下,辣椒根部N、P、K含量分别较对照(0生物炭和-AM处理)显著提高74.04%、106.42%和78.82%。生物炭(3%)与AM真菌配施处理菌根侵染效果最佳,侵染率高达58.96%,较0生物炭+AM处理提高41.59%。土壤pH随生物炭添加量的增加呈增加趋势,但差异不显著。土壤脲酶、蔗糖酶活性随生物炭添加量的增加呈增加趋势,且差异显著,接种AM真菌处理对其影响不显著。土壤速效钾、有效磷、有机质含量随生物炭添加量的增加而增加,接种AM真菌对土壤有机质含量、阳离子交换量(CEC)无显著影响。土壤速效钾、有效磷、碱解氮含量均在生物炭(3%)和AM真菌配施条件下达最大。与单一处理相比,生物炭和AM真菌配施在促进连作辣椒生长、改善连作土壤养分方面具有显著的协同增效作用,尤其是3%生物炭与AM真菌配施条件下效果最佳。     

Sustainability of soil structure quality in rice paddy— soya-bean cropping systems in South Sulawesi, Indonesia

In South Sulawesi, paddy rice (Oryza sativa L.) is generally double cropped with soya-bean (Glycine max L.) in the dry season. Decline in soya-bean yield and response to fertilisers after some years indicates that these cropping systems may not be sustainable in terms of soil strucural properties. We investigated the deterioration of soil structure by measuring penetration resistance, air-filled porosity, bulk density and plant available water content in rice paddy-soya-bean rotations of 10, 16 and 21 years duration. These results were compared with those from a 21 year rotation in which rice was followed by grass fallow. The non-limiting available water range was used to assess cropping system differences.

Rice-soya-bean cropping systems were detrimental to soil physical conditions in the long term. Bulk density and soil strength increased and air-filled porosity decreased significantly over a period of 21 years. At this time, aeration porosity at the upper drained limit was below the critical value for adequate aeration, soil penetration resistance exceeded the limits for root growth within the plant available water content range, and the non-limiting range of plant avaiable water was narrowed. These results indicate that double cropping is unsustainable in terms of soil structure quality. Shorter periods (10 years) of double cropping did not cause the same level of deterioration and the grass fallow system had no discerible limitation to available water as a result of poor alteration or high soil strength. We conclude that grass fallow cropping systems appear to be more sustainable and in long-term double cropped systems, a period of grass fallow is probably required to restore soil structure to a favourable state.     

加工番茄连作对土壤理化性状及微生物量的影响

通过在石河子大学农学院试验站开展加工番茄连作定点微区试验,研究了不同连作处理(种植1 a、连作3 a、5 a和7 a)对新疆加工番茄土壤理化性状、微生物生物量和酶活性的影响。结果表明,随着连作年限的延长,土壤p H升高,全磷、速效磷及全钾含量呈先升后降的趋势,土壤容重无明显变化。连作7 a时土壤有机质、全氮及速效钾含量较对照分别下降了8%、21%和29%(p0.05)。土壤微生物量碳(SMBC)、微生物量氮(SMBN)和微生物商(q MB)呈显著下降趋势,与对照相比分别降低了52.3%、78.8%和48.2%(p0.01);微生物量磷(SMBP)呈先升后降趋势,连作3a时,SMBP含量达到最大值,是对照的1.65倍(p0.01)。土壤过氧化氢酶活性呈显著升高趋势,而脲酶、蔗糖酶、多酚氧化酶及磷酸酶活性的变化则相反。连作导致加工番茄产量显著下降,连作7 a时产量下降达34%(p0.01)。相关分析表明,p H、微生物量、q MB、酶活性及养分之间相关性极为密切,说明土壤微生物量和酶活性相结合,可以反映土壤质量的变化。加工番茄连作导致土壤p H和电导率升高,显著抑制了土壤微生物活性,降低了土壤肥力,最终造成产量下降,连作障碍明显。     

水稻连续免耕抛栽对土壤理化和生物学性状的影响

于2005~2007年在双季稻田以翻耕处理为对照,研究了水稻连续免耕抛栽对土壤理化和生物学性质的影响。结果表明,稻田免耕1年(2季),有利于土壤物理性状的改善,随着免耕时间(3年6季)的延长,土壤物理性质变差。但免耕2年后,采用紫云英和稻草还田能降低免耕稻田的土壤容重,提高总孔隙度和非毛管孔隙度。免耕有利于土壤养分在表层土壤富集。土壤中三大类微生物总量免耕处理小于翻耕处理,免耕土壤细菌的数量增加,而放线菌和真菌的数量减少。土壤中脲酶活性增加,而过氧化氢酶和过氧化物酶的活性均降低。脲酶、过氧化氢酶和多酚氧化酶的活性均与土壤有机质、全氮含量呈极显著相关,而过氧化物酶活性则与土壤全氮和速效钾含量呈极显著相关。该结果有水稻免耕抛秧栽培技术的推广应用的参考意义。