,1,*, 马瑞丽1,3, 王琦2, 刘青林1, 崔佳佳11 2
3
Effects of Planting Years on the Root System and Soil Environment of Lycium barbarum L.
XU Sheng-Rong1,3, ZHANG En-He,1,*, MA Rui-Li1,3, WANG Qi2, LIU Qing-Lin1, CUI Jia-Jia112
3
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收稿日期:2017-10-16接受日期:2018-08-20网络出版日期:2018-09-06
| 基金资助: |
Received:2017-10-16Accepted:2018-08-20Online:2018-09-06
| Fund supported: |
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胥生荣, 张恩和, 马瑞丽, 王琦, 刘青林, 崔佳佳. 不同种植年限对枸杞根系及土壤环境的影响[J]. 作物学报, 2018, 44(11): 1725-1732. doi:10.3724/SP.J.1006.2018.01725
XU Sheng-Rong, ZHANG En-He, MA Rui-Li, WANG Qi, LIU Qing-Lin, CUI Jia-Jia.
根系是土壤水分和营养物质进入植物体的主要途径, 根系生理状况对土壤-植物-大气(SPAC)循环系统中物质和能量交换起着关键作用[1]。有研究表明, 随着蔬菜连作年限增加致使植株矮小, 根系活力和生长量降低, 产量下降, 品质变劣[2]。土壤是影响生态农业发展和限制农作物生长发育的主要因素。多年生植物随着种植年限的增加, 植株根系分泌物含量显著增加, 土壤有机质缺乏, 根际土壤微生物逐渐单一, 使根际微生物群落结构失调及病原菌数量增加, 成为影响树体生长及降低产量和品质的重要因素之一[3]。
土壤多种理化特性都与植株生长和微环境变化有直接或间接的关系。微生物与土壤生态功能相辅相成, 根际土壤微生物参与根际生态系统的物质转化和循环, 微生物群落的组成及其多样性是衡量土壤性质和功能的一个重要指标[4], 在维持土壤健康方面扮演着重要的角色[5]。土壤活性有机碳是植物碳循环中的主要来源, 与土壤肥力和农业可持续发展有密切联系[6,7]。土壤酶能加速土壤中有机物质的化学反应, 参与许多重要的生物化学过程[8], 可以表征土壤肥力水平和土壤生物活性。根际土壤的理化环境是根系生理活动的重要影响因子, 直接影响植株地上部分的生长发育。因此, 进一步了解根系生理状况和土壤微环境变化, 对探究植物生长与土壤环境间的内在联系具有重要作用。
宁夏枸杞(Lycium barbarum L.)属于茄科(Solanaceae)多年生落叶灌木, 具有改良土壤结构、提高土壤肥力、降低盐碱危害的作用, 是治理荒漠化土地的优良树种, 在西北干旱半干旱地区大面积种植。随着枸杞种植年限的不断增加, 植株根际土壤微生态环境对枸杞植株生长势的影响越来越严重, 加速其生长势衰弱和病虫害发生。本试验将不同种植年限枸杞根际土壤微环境与植株根系生理变化相联系, 分析其相互之间的关系, 旨在系统了解不同种植年限枸杞根际土壤微环境和根系生理状态的变化趋势, 为解决西北干旱半干旱地区枸杞早衰问题提供重要科学依据。
1 材料与方法
1.1 试验区概况
甘肃省古浪县枸杞示范园地处北纬37°30′, 东经103°29′, 海拔1760 m, 属温带大陆性干旱气候, 年平均气温5.6℃, 年均降水量300 mm, 无霜期140 d, 土壤类型以沙壤土为主。园区地势平坦, 果园行间清耕休闲, 果园追肥以尿素、磷酸二铵和氮磷钾复合肥为主, 春季施基肥时以有机肥为主。1.2 试验材料
试材为1 年生、3 年生、5 年生、7 年生和 10年生‘宁杞1号’地块和苗木。在枸杞营养生长旺盛期7月至9月份, 每月上旬随机取各处理3株以上, 在距离植株主干四周20~30 cm处随机选择4个点, 挖取深20~40 cm处部分土壤和根系, 抖落非根际土壤, 用毛刷将根际土壤装入自封袋中, 同时将根系装入自封袋中, 重复3次。将土样分为2份, 1份鲜样, 1份风干, 去杂, 过1 mm (20目)筛。同时取样测定根围土壤含水量和孔隙度, 在灌水后10~15 d, 于非施肥点采样, 尽量减少人为因素干扰。1.3 指标测定
1.3.1 导水率 使用高压流速仪(high pressure flow meter, HPFM, 美国Dynamax公司)于田间测定绝对导水率(hydraulic conductivity, Kh); 比导率(the special conductivity, Ks)为绝对导水率(Kh)除以茎干木质部横截面积(Sstem)所得的比率(Ks = Kh/Sstem); 用精密数字游标卡尺(0~150 mm digital caliper, NMT-150, 上海美耐特公司)测量茎干直径。1.3.2 根系活力和相对电导率 采用TTC染色法测定根系活力, 在7月至9月份生长旺盛季节, 采集距树干20~30 cm, 深10~20 cm处须根, 用单位鲜重根在单位时间内还原的 TTC毫克数来表示[9]。将根系用蒸馏水冲洗干净, 滤纸吸干表面水分, 将根尖部分剪成约1 cm长段, 称取1 g放入试管中, 加30 mL蒸馏水, 放入真空干燥器中抽气10 min, 缓慢放入气体后搅拌, 静止20 min后用DDS-307A测得电导率R1, 然后沸水浴中煮沸20 min, 冷却至室温后测出电导率R2, 相对电导率 = R1/R2 ×100%。
1.3.3 土壤孔隙度测定和含水量 将0~100 cm土壤分为10层, 每10 cm为一层, 土壤孔隙度测定采用环刀法测定。将0~150 cm土壤分为15层, 每10 cm为一层, 混匀后用烘干法测定土壤含水量。
1.3.4 土壤微生物的计数和多样性 采用平板计数法计数根区土壤细菌、真菌、放线菌, 采用牛肉膏蛋白胨琼脂培养基分离细菌, 采用高氏1号培养基分离放线菌, 采用PDA培养基分离真菌[10]。在采样后48 h内用BIOLOG生态测试板(ECO MicroPlate, Matrix Technologies Corporation, USA)测定土壤微生物群落功能多样性[11]。
平均颜色变化率[12] (AWCD) = (Ci-R)/n。式中, Ci为第i个非对照孔的吸光值, R为对照孔的吸光值, n为碳源种类数(n = 31)。
Shannon指数[13]H = -∑Pi-ln P。式中Pi表示第i个非对照孔中的吸光值与所有非对照孔吸光值总和的比值, 即Pi = (Ci-R) / ∑(Ci-R)。
丰富度指数[14](R), 指被利用的碳源总数目, 本研究中为每孔中(Ci-R)的值大于0.25的孔数。
1.3.5 土壤酶活性 利用苯酚钠比色法测定脲酶活性; 高锰酸钾滴定法测定过氧化氢酶活性; 邻苯三酚比色法测定多酚氧化酶活性; 三苯基四氮唑氯化物(TTC)还原法测定脱氢酶活性; 磷酸苯二钠法测定土壤磷酸酶活性; 3,5-二硝基水杨酸比色法测定土壤蔗糖酶活性。
1.3.6 土壤有机碳 参照张林森等[11]的方法测定土壤活性有机碳(LFOC)、土壤颗粒有机碳(POC)、微生物量碳(MBC)、易氧化有机碳(ROC)、可溶性有机碳(DOC)和土壤总有机碳(TOC)。
1.4 数据分析及处理
采用SPSS 17.0统计分析软件处理所得数据, 首先对不同处理间进行方差分析, 若差异显著, 再进一步进行LSD多重比较, 采用Microsoft Excel 2003作图。2 结果与分析
2.1 种植年限对枸杞根系生理特性的影响
根系作为植株与土壤之间相互作用的主要场所, 对于植株水分、营养物质的吸收和利用起到重要作用, 其根系导水率、活力和电导率将直接影响根系对土壤水分和营养物质的吸收能力。由表1可以看出, 随着种植年限的增加, 枸杞根系比导率在种植前3年内逐渐增大, 在种植第3年时达到最大, 然后逐年开始减小, 种植第10年时已减小到最大时的77.9%, 平均每年减小3.2%; 根系活力从种植1年生开始逐渐减小, 10年生减小到1年生的86.9%, 平均每年减小1.3%; 根系相对电导率随着种植年限的增大而增大, 7年生植株相对电导率最大, 达到1年生的125.5%, 平均每年增大3.6%, 其中, 在种植前3年内增大较快, 平均每年增大6.2%, 种植3年后变化相对较小, 平均每年增大1.4%, 7年生和10年生根系相对电导率略有减小, 但减小程度不显著。Table 1
表1
表1种植年限对根系理化性质的影响
Table 1
| 种植年限 Planting year | 根系比导率 Specific conductivity of root (Ks,root) (kg MPa-1 m-2 s-1) | 根系活力 Activity of root (μg g-1 h-1) | 根系相对电导率 Relative electric conductivity of root (%) |
|---|---|---|---|
| 1年 One year | 1.32±0.125 b | 482.3±34.5 a | 29.4±1.39 d |
| 3年 Three years | 1.49±0.201 a | 451.7±19.1 b | 34.9±2.56 c |
| 5年 Five years | 1.40±0.093 ab | 449.2±27.3 b | 35.7±2.62 bc |
| 7年 Seven years | 1.25±0.119 b | 426.9±20.5 c | 36.9±3.29 a |
| 10年 Ten years | 1.16±0.241 c | 419.3±14.4 c | 36.6±2.84 a |
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2.2 种植年限对土壤孔隙度和含水量的影响
土壤状况影响土壤水分的存在状态, 是植株根系生长和物质能量交换的主要影响因素; 土壤水分是植株体内水分的主要来源, 土壤水分状况直接影响植株对土壤水分的吸收, 对土壤水分向根系周围运输具有重要意义。从图1-A可以看出, 枸杞根围土壤孔隙度随着种植年限的增加不断减小。植株生长对土壤孔隙度的影响主要在土壤深0~60 cm之间, 而对70~100 cm处影响较小, 在土壤0~60 cm深处, 平均土壤孔隙度逐渐减小至种植1年地块的93.1%; 在土壤70~100 cm深处, 种植3年地块的平均土壤孔隙度最大, 随后逐年减小, 种植10年地块平均土壤孔隙度最小, 为最大值的97.8%。从图1-B可以看出, 不同种植年限枸杞根围土壤在0~150 cm土壤水分含量的垂直分布情况不同, 种植前5年枸杞地块土壤含水量逐渐增大, 种植第5年地块土壤含水量最大, 从种植第5年后逐年降低。植株生长对土壤水分含量的影响主要在土壤0~60 cm之间, 对70~150 cm处影响较小, 种植5年地块土壤含水量分别增大至种植1年地块的112.2%和102.9%; 种植10年地块土壤含水量分别降低到最大时的86.9%和93.9%。图1
新窗口打开|下载原图ZIP|生成PPT图1不同种植年限对0~100 cm孔隙度(A)及0~150 cm土壤含水量(B)的影响
Fig. 1Space distribution of soil porosity (A) and soil moisture content (B) under different planting years
2.3 种植年限对根际土壤微生物数量和多样性的影响
农田耕作方式和植物生长状况能够影响土壤温度、水分、有机质含量和存在状态等土壤理化性质,可以影响土壤微生物的生存环境, 从而影响土壤微生物的数量和多样性。由表2可知, 土壤细菌数量在种植前5年内逐渐增多, 第5年达到最多, 年平均增长率为4.7%, 5年后土壤细菌数量开始减少, 年平均下降率为2.8%; 土壤真菌数量在种植前7年内逐渐增大, 第7年达到最多, 年平均增长率为9.8%, 第10年地块真菌数量有所下降, 但减小差异不显著; 土壤放线菌数量随种植年限的增加没有明显变化, 基本趋于同一水平。土壤微生物总量先上升后下降, 在种植前5年内微生物总量不断升高, 年平均增长率为4.8%, 从第5年后逐渐减少, 种植10年地块土壤微生物总量减少至数量最大时的90.8%, 年平均下降率为1.8%。土壤微生物群落多样性是土壤微生物群落状态与功能的指标, 反映土壤中微生物的生态特征。土壤微生物平均颜色变化率(AWCD)逐年降低, 种植10年地块降低至最大时的83.3%, 年均下降率为1.7%, 在种植前5年内下降速率较大, 变化差异显著, 种植第5年后变化不显著; Shannon指数(H)和丰富度指数(S)总体变化趋势为逐年减小, 种植5年地块多样性指数显著减小, 但各种植年限之间差异不显著。Table 2
表2
表2种植年限对根际土壤微生物数量和多样性的影响
Table 2
| 种植年限 Planting year | 细菌 Bacterium (×106 CFU g-1) | 真菌 Fungi (×106 CFU g-1) | 放线菌Actinomyces (×106 CFU g-1) | 微生物总量Total (×106 CFU g-1) | 平均颜色 变化率 AWCD | 香浓指数Shannon index (H) | 丰富度指数 Richness index (S) |
|---|---|---|---|---|---|---|---|
| 1年 One year | 28.37±1.31 d | 3.99±0.19 d | 5.27±0.26 b | 37.63±1.47 c | 0.78 a | 3.13 a | 27 a |
| 3年 Three years | 30.95±0.93 c | 4.83±0.23 c | 4.73±0.16 c | 40.51±1.14 b | 0.73 ab | 3.11 a | 26 a |
| 5年 Five years | 35.16±2.09 a | 5.26±0.11 b | 5.98±0.24 a | 46.40±2.31 a | 0.68 b | 2.96 b | 21 b |
| 7年 Seven years | 32.81±1.52 b | 6.72±0.21 a | 5.16±0.15 b | 44.69±1.80 a | 0.66 b | 3.05 ab | 24 a |
| 10年 Ten years | 30.19±0.45 c | 6.53±0.25 a | 5.62±0.17 ab | 42.14±0.99 b | 0.65 b | 3.03 ab | 23 ab |
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2.4 种植年限对枸杞根际土壤有机碳的影响
土壤有机碳是农田碳循环的重要组成部分, 其累积和分解使含量的变化直接影响着整个系统内部的碳平衡, 对植株生长发育和土壤水分利用也有重要作用。由图2可知, TOC含量与其余5种活性有机碳含量的变化趋势一致, 随着年限的增长有机碳含量逐渐下降, 虽然种植5年地块的LFOC活性和种植7年地块的DOC活性有小幅上升, 但总体趋势一致。从种植第1年开始至第10年, TOC含量从9.19 g kg-1下降至2.92 g kg-1, 平均年下降率为3.18%, 其中下降率最大的为LFOC, 年平均下降率达到9.3%, 下降率最小的为DOC, 年平均下降率为6.9%, 其余3种活性有机碳的年平均下降率为8.2%~8.5%。图2
新窗口打开|下载原图ZIP|生成PPT图2种植年限对根际土壤TOC、POC、LFOC、ROC、DOC和MBC含量的影响
Fig. 2Total organic carbon (TOC), particulate organic carbon (POC), readily oxidizable organic carbon (ROC), light fraction organic carbon (LFOC), dissolved organic carbon (DOC), and microbial biomass organic carbon (MBC) content under different planting years
2.5 种植年限对根际土壤酶活性的影响
土壤酶活性可以在一定程度上用来反映土壤中各种生物化学过程的强度, 参与土壤与植物体之间多种物质能量交换, 是反映土壤生物学活性的指标。由图3可以看出, 随着种植年限的增加, 土壤脱氢酶活性相对稳定, 没有出现显著的增大或降低趋势, 保持在0.15~0.23 mg g-1之间; 土壤磷酸酶一直处于增大趋势, 平均年增长率为4.0%; 土壤脲酶、过氧化氢酶、多酚氧化酶以及土壤蔗糖酶活性变化趋势相对一致, 均呈现出先减小后增大, 其中, 土壤多酚氧化酶和蔗糖酶活性在种植3年地块最小, 土壤脲酶和过氧化氢酶在种植5年地块最小。图3
新窗口打开|下载原图ZIP|生成PPT图3种植年限对根际土壤酶活性的影响
Fig. 3Effect of planting years on rhizosphere soil enzyme activity in Lycium barbarum L.
3 讨论
根系作为植物与土壤之间相互物质联系的主要途径, 对于植株水分、营养物质的吸收和利用起到重要作用, 根系导水率可以表示根系对土壤水分的吸收能力, 植株中对导水率影响最大的部分发生在根系, 是根系对土壤环境变化响应的直接生理特性指标之一[15,16]。本研究发现, 随着种植年限的增加, 枸杞根系比导率先逐渐增大, 然后逐年减小。根系导水能力与树体木质部结构和土壤环境有直接的关系, 随着植株的生长, 根系木质部逐渐分化, 根系导水系统不断完善, 有利于根系水分运输, 由于树体对土壤环境影响不大, 土壤含水量变化小, 对根系导水率的影响不明显, 从而使根系导水率不断增大; 当枸杞植株生长到一定水平, 对土壤水分的需求量增大, 土壤含水量不断下降, 影响根系导水率, 由于部分根系老化, 导管运输能力降低, 导致根系导水率减小。根系活力和相对电导率是根系生物学活性的主要表现, 对根系吸收土壤水分和营养物质有直接的影响。根系活力受到植株自身生长势、土壤微生物活性、化感物质、土壤酶等根际土壤环境因子的影响。本研究发现, 随着种植年限的增大, 枸杞根系活力逐渐减小, 使土壤水分的吸收能力降低, 根系水势下降, 导致根系木质部导管更容易形成栓塞, 影响根系木质部导水率。植物细胞膜对维持细胞的正常代谢作用和微环境起着重要的作用, 细胞膜对物质具有选择透过性, 当细胞膜受到破坏或环境发生变化后, 可使电解质外渗, 以至于相对电导率增大。枸杞根系相对电导率随着种植年限的增加而增大, 虽然在种植7年后有所减小, 但减小程度不显著。相对电导率增大使根系木质部细胞结构和功能发生变化, 对木质部导管的水分运输作用也有一定的影响。随着种植年限的增大, 根系化感物质在根围土壤不断分泌累积, 对根系产生毒害作用, 加之土壤微生物种类和多样性的变化, 也可以使根系活力降低和相对电导率升高。
当植株受到土壤环境胁迫时, 根系首先发出信号, 土壤含水量[17]和通气状况[18]都能够影响到根系生理状况。土壤通气状况直接影响根系呼吸作用对O2的吸收和CO2的排放, 当根系周围空气O2含量降低, CO2含量升高时, 影响根系的呼吸作用和物质能量转化, 从而影响根系对土壤水分的吸收能力。由于目前枸杞行间操作主要以浅耕为主, 对30 cm以下土壤扰动较小, 施肥和采摘等行间作业使土壤孔隙度逐年减小, 从而影响土壤空气含量和根系活性。本研究发现, 土壤深0~150 cm处平均含水量在种植前5年内逐渐增大, 5年后开始逐渐降低, 尤其对60 cm以上浅层土壤水分影响显著。在种植前5年, 由于植株生物量小, 对水分的需求量少, 灌水和降雨能够补给土壤水分; 随着植株的不断生长, 在种植5年后, 由于长期农事操作破坏了表层土壤结构, 使土壤孔隙度减小, 导致表层土壤持水能力减弱, 可利用水分含量降低, 加之根系在土壤深层次分布量增大, 提高了深层土壤水分贡献率, 加快了深层次土壤水分的耗散。
农田生态系统中, 土壤微生物是主要组成部分, 可以作为反映土壤生态系统功能的主要指标[19], 在土壤营养循环管理[20]、能量转换[21]、有机物分解转化[22]以及土壤养分的形成[23]等方面具有重要的作用。有研究发现, 植物连作会引起土壤微生物区系发生变化, 部分真菌种群数量增加, 细菌和放线菌种群数量减少, 根际微生物群落结构失衡, 导致根围土壤理化性状变化, 微生物区系由“细菌型”向“真菌型”转化[24,25]。土壤微生物种群数量变化可以反映土壤生物活性水平, 土壤细菌和放线菌种群数量越高, 土壤的生物活性就高, 而土壤真菌种群数量上升, 则会使土壤地力衰竭。本研究发现, 随着枸杞种植年限的增长土壤微生物总量趋于上升, 其中, 土壤细菌和真菌数量趋于上升, 而放线菌数量变化不显著, 与前人对土壤微生物的研究结果一致[26,27,28]; 土壤微生物平均颜色变化率(AWCD)逐年降低, Shannon指数(H)和丰富度指数(S)变化趋势相对一致, 为先下降后上升。土壤微生物生存环境受到植物种类、生长状况, 根系分泌物以及土壤理化特性等多种因素的影响。植物根系分泌物数量和种类随着植物生长状况的不同而变化, 对部分微生物具有毒害作用, 导致微生物群落数量变化, 使单一种群微生物数量增多, 微生物多样性降低。
农田土壤有机碳是农田生态系统中碳循环的重要组成部分, 受土壤水分、温度、微生物、耕作制度和方式等许多土壤因素的影响, 其累积和分解的变化直接影响系统内碳平衡。本研究发现, 枸杞地块土壤TOC含量与其余5种活性有机碳含量的变化趋势一致, 随着种植年限的增长有机碳含量逐渐下降, 虽然种植5年地块的LFOC活性和种植7年地块的DOC活性有小幅上升, 但总体趋势一致。土壤活性有机碳主要来源于植物残体、土壤有机质水解、根系分泌物、土壤微生物代谢产物和自身残体以及有机肥的施用。随着种植年限的增长, 植物逐年对土壤有机物质利用, 使土壤肥力较低, 同时较高的收获指数和树体修剪导致土壤有机碳大量消耗, 系统内部碳总量逐年减少[29]。农田耕作措施也会导致土壤活性有机碳的分解, 与株内未干扰区相比, 行间土壤有机碳含量显著降低[30]。枸杞地块行间深翻、除草、果实采摘等作业使土壤物理条件变化, 破坏了土壤团聚体结构, 加速了土壤有机碳的分解, 导致土壤有机碳分解和减少。
土壤酶活性可以反映不同栽植条件和模式下土壤的质量, 在评价土壤肥力时部分土壤酶可以作为评价土壤生化过程的指标。土壤酶主要来自于土壤微生物, 定植植物和种植年限都会影响土壤微生物数量和种群多样性[31], 从而使土壤酶活性变化[32]。随种植年限的增加, 枸杞地块土壤脱氢酶活性相对稳定, 没有出现显著的变化趋势; 土壤磷酸酶一直处于增大趋势; 土壤脲酶、过氧化氢酶、多酚氧化酶以及土壤蔗糖酶活性变化趋势相对一致, 均呈现出先减小后增大。本研究枸杞地块过氧化氢酶活性虽先降低后升高, 但总体变化趋势与前人的研究相对一致[33]。
4 结论
随着枸杞种植年限的增加, 枸杞根系比导率先逐渐增大, 然后随着树体老化开始减小; 根系相对电导率种植前7年逐渐增大, 在种植7年后有所减小, 但减小程度不显著; 根系活力逐年减小, 对土壤水分的吸收能力降低。土壤平均含水量在种植前5年内逐渐增大, 5年后开始逐渐降低, 尤其对60 cm以上浅层土壤水分影响显著; 土壤细菌和真菌数量逐年增加, 放线菌数量变化不显著, 使土壤微生物总量趋于增加, 但土壤微生物多样性却逐年降低; 土壤活性有机碳含量逐渐降低, LFOC和DOC活性在种植5年和7年后有小幅上升, 但总体趋势一致; 不同土壤酶活性呈现不同变化趋势, 脱氢酶活性相对稳定, 没有出现显著的变化; 土壤磷酸酶逐渐增大; 脲酶、过氧化氢酶、多酚氧化酶和土壤蔗糖酶活性均为先减小后增大。随着土壤环境因子和根系生理特征变化, 枸杞农田系统物质和能量的内循环发生变化, 影响了植株对土壤营养物质和水分的吸收运输。参考文献 原文顺序
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被引期刊影响因子
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DOI:10.5846/stxb201606071097URL [本文引用: 1]
以不同连作年限怀牛膝根际土壤为材料，采用土壤农化分析技术和磷脂脂肪酸生物标记法，对土壤理化性质以及根际微生物群落结构进行分析。结果表明：怀牛膝连作会使大部分大量元素（全磷、碱解氮、速效磷和速效钾）含量上升，而全氮、全钾的变化并无明显趋势。全量钙、全量镁、全量锰和有效锌的含量也会随着连作年限的增加而增加。研究发现，怀牛膝连作1a的土壤与对照相比，根际土壤微生物群落结构差别不大，但是与连作10a和30a的土壤相比微生物多样性却发生了明显变化。土壤中总PLFAs、细菌、革兰氏阴性菌Gram（-）及真菌含量都随连作年限增加而明显上升，微生物多样性增加，且革兰氏阳性菌Gram（＋）/革兰氏阴性菌Gram（-）的比值随着连作年限的增加而下降。此外，土壤中一些嗜热解氢杆菌和真菌等参与土壤物质循环和木质素降解的微生物类群数量明显增加，假单胞菌等有益微生物类群也显著增多，这是牛膝连作促进作用的生物学基础。研究用药用植物怀牛膝证明了植物根际微生物结构和功能多样性对植物连作促进或连作抑制作用的产生与控制的生态学意义。
DOI:10.5846/stxb201606071097URL [本文引用: 1]
以不同连作年限怀牛膝根际土壤为材料，采用土壤农化分析技术和磷脂脂肪酸生物标记法，对土壤理化性质以及根际微生物群落结构进行分析。结果表明：怀牛膝连作会使大部分大量元素（全磷、碱解氮、速效磷和速效钾）含量上升，而全氮、全钾的变化并无明显趋势。全量钙、全量镁、全量锰和有效锌的含量也会随着连作年限的增加而增加。研究发现，怀牛膝连作1a的土壤与对照相比，根际土壤微生物群落结构差别不大，但是与连作10a和30a的土壤相比微生物多样性却发生了明显变化。土壤中总PLFAs、细菌、革兰氏阴性菌Gram（-）及真菌含量都随连作年限增加而明显上升，微生物多样性增加，且革兰氏阳性菌Gram（＋）/革兰氏阴性菌Gram（-）的比值随着连作年限的增加而下降。此外，土壤中一些嗜热解氢杆菌和真菌等参与土壤物质循环和木质素降解的微生物类群数量明显增加，假单胞菌等有益微生物类群也显著增多，这是牛膝连作促进作用的生物学基础。研究用药用植物怀牛膝证明了植物根际微生物结构和功能多样性对植物连作促进或连作抑制作用的产生与控制的生态学意义。
DOI:10.1016/j.copbio.2013.09.003URLPMID:24863892 [本文引用: 1]
Pesticide effects on microbial community structure and activity in soil are reviewed, showing that methodological developments within the past few years have generated new possibilities for assessing pesticide effects. The first example is the use of mRNA quantification showing that nitrification processes are indeed very susceptible to some pesticides, and that there is correlation between the mRNA transcript quantity and the nitrification rate. The second example is devoted to pesticides influencing microbial community structures. The emergence of high throughput sequencing techniques now allows a more detailed analysis of which bacterial species are influenced.
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DOI:10.3864/j.issn.0578-1752.2009.10.0018URL [本文引用: 1]
【Objective】This paper described the response of seedling growth and root cell viability of Brassica napus L. (rapeseed) to various concentrations of ZJ0273 treatments at germination stage to define the mechanism of this novel herbicide.【Method】Effects of different ZJ0273 treatments on dry matter, morphological characters, root oxidizability and cell membrane permeability of rapeseed seedlings were investigated by various physiological measurements. Root cell viability and mitosis as affected by herbicide treatments were also studied based on FDA-PI double staining and root-tip squashing method. 【Result】The results indicated that the inhibitive effects of ZJ0273 treatments on rapeseed dry matter and morphological characters were enhanced along with the increase of treatment concentrations and durations. Both of 10 and 100 mg?L-1 ZJ0273 treatments inhibited root development significantly. There were no distinct difference among 0, 0.1 and 1 mg?L-1 ZJ0273 treatments on root oxidizability and membrane permeability, compared with treatments at 10 and 100 mg?L-1 which obviously inhibited root cell viability and induced cell membrane disintegration. Furthermore, mitotic index of root-tip cells was declined and cell division was stopped at metaphase after being treated by 100 mg?L-1 ZJ0273. 【Conclusion】Rapeseed seedlings are very sensitive to herbicide ZJ0273 at germination stage. Treatment at 10 mg?L-1 ZJ0273 can significantly inhibit rapeseed growth and root viability, and the inhibitive effect is intensified with the increase of treatment concentrations and durations. The application of 1 mg?L-1 (critical concentration) is safe for rapeseed seedling growth.
DOI:10.3864/j.issn.0578-1752.2009.10.0018URL [本文引用: 1]
【Objective】This paper described the response of seedling growth and root cell viability of Brassica napus L. (rapeseed) to various concentrations of ZJ0273 treatments at germination stage to define the mechanism of this novel herbicide.【Method】Effects of different ZJ0273 treatments on dry matter, morphological characters, root oxidizability and cell membrane permeability of rapeseed seedlings were investigated by various physiological measurements. Root cell viability and mitosis as affected by herbicide treatments were also studied based on FDA-PI double staining and root-tip squashing method. 【Result】The results indicated that the inhibitive effects of ZJ0273 treatments on rapeseed dry matter and morphological characters were enhanced along with the increase of treatment concentrations and durations. Both of 10 and 100 mg?L-1 ZJ0273 treatments inhibited root development significantly. There were no distinct difference among 0, 0.1 and 1 mg?L-1 ZJ0273 treatments on root oxidizability and membrane permeability, compared with treatments at 10 and 100 mg?L-1 which obviously inhibited root cell viability and induced cell membrane disintegration. Furthermore, mitotic index of root-tip cells was declined and cell division was stopped at metaphase after being treated by 100 mg?L-1 ZJ0273. 【Conclusion】Rapeseed seedlings are very sensitive to herbicide ZJ0273 at germination stage. Treatment at 10 mg?L-1 ZJ0273 can significantly inhibit rapeseed growth and root viability, and the inhibitive effect is intensified with the increase of treatment concentrations and durations. The application of 1 mg?L-1 (critical concentration) is safe for rapeseed seedling growth.
DOI:10.3321/j.issn:0513-353X.2008.07.014URL [本文引用: 1]
在自然生长条件下，研究了不同品种百合在不同生育期根际土壤微生物种类、数量和土壤酶（过氧化氢酶、脲酶、碱性磷酸酶）活性的变化规律。结果表明：在百合生育期内，土壤微生物以细菌最多，对百合的根际效应也最敏感；其次为真菌，再次为放线菌。不同生育阶段以显蕾期根际土壤细菌和放线菌的数量最多，但显蕾期以后二者根际效应方向相反；根际土壤真菌的数量和根际效应在鳞茎充实期均达到最大。土壤脲酶活性和碱性磷酸酶活性在百合生育期内表现为先降、后升、再降的趋势，即在显蕾期形成峰值，根际效应显著，随生殖生长的推进其活性及根际效应均逐渐减弱；而过氧化氢酶活性则先上升后下降，根际效应不明显。在百合--土壤--微生物相互作用的体系中，根际土壤微生物的种类、数量和酶活性明显受到百合生长发育的影响。
DOI:10.3321/j.issn:0513-353X.2008.07.014URL [本文引用: 1]
在自然生长条件下，研究了不同品种百合在不同生育期根际土壤微生物种类、数量和土壤酶（过氧化氢酶、脲酶、碱性磷酸酶）活性的变化规律。结果表明：在百合生育期内，土壤微生物以细菌最多，对百合的根际效应也最敏感；其次为真菌，再次为放线菌。不同生育阶段以显蕾期根际土壤细菌和放线菌的数量最多，但显蕾期以后二者根际效应方向相反；根际土壤真菌的数量和根际效应在鳞茎充实期均达到最大。土壤脲酶活性和碱性磷酸酶活性在百合生育期内表现为先降、后升、再降的趋势，即在显蕾期形成峰值，根际效应显著，随生殖生长的推进其活性及根际效应均逐渐减弱；而过氧化氢酶活性则先上升后下降，根际效应不明显。在百合--土壤--微生物相互作用的体系中，根际土壤微生物的种类、数量和酶活性明显受到百合生长发育的影响。
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In: Eyal de Lara, eds. ACM SIGMOBILE Mobile Computing and Communications Review (MC2R).
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DOI:10.1016/S0038-0717(01)00044-XURL [本文引用: 1]
The stability and function of a soil ecosystem depends on the cycling of nutrients by the soil microbial community. To evaluate native variability in the functional soil microbial community, temporal changes in microbial community size, activity and metabolic diversity were measured by bacterial population densities, microbial biomass, dehydrogenase activity and metabolic diversity (BIOLOG) assays in native New Jersey Pineland soils. Native soils were sampled and assessed seasonally for five consecutive seasons along a toposequence with an O horizon that varied in organic matter (1.0 91.7%) and a water content that ranged from well-drained to poorly drained (0.21 4.30 g water g 1 dry wt soil). Significant differences ( P<0.05) were found in bacterial population densities, microbial biomass, and dehydrogenase activity between soil types in each sampling period. Seasonal variability was found in bacterial populations and dehydrogenase activity, but not in microbial biomass. Principal component analysis (PCA) revealed consistent differences in the metabolic diversity patterns of the A horizon of the low organic, xeric upland microbial community as compared to the transitional and lowland soil microbial communities. When the upland O and A soil horizons were compared, the two horizons showed different metabolic diversity patterns. Metabolic diversity patterns varied little over time, indicating a stable functional heterotrophic microbial community. The various indicators of microbial community dynamics used in this study demonstrated general seasonal microbial activity differences associated with a reasonably stable microbial biomass and metabolic diversity. Factors affecting metabolic diversity appeared to be linked closely with variation in the composition of the vegetation in the aboveground community along the toposequence.
DOI:10.1093/jxb/erm281URLPMID:18182426 [本文引用: 1]
Abstract Dwarfing of fruit trees is often achieved through the use of dwarfing rootstocks. Dwarf trees are characterized by sustained reductions in vegetative growth during the lifetime of the tree. The dwarfing mechanism is not well understood, but it has been hypothesized that hydraulic properties of the rootstock and the graft union are involved. It is hypothesized here that leaf- or stem-specific resistance of at least one hydraulic component of the water transport system would be negatively correlated with rootstock 'vigour', and this could be useful for selection of rootstocks. Hydraulic resistance (R) of fully grown apple trees on a variety of rootstocks of different 'vigours' was measured. Most measurements were with the evaporative flux (EF) method, where water uptake measured with sap flow sensors was related to the pressure gradient from soil (taken as pre-dawn leaf) and midday root (taken as covered root-sucker), stem (from covered leaf), and exposed and shaded leaf water potentials (Psi(l)). R of trees on dwarfing M9 rootstock was compared with that of more vigorous MM106 and MM111 rootstocks in Israel and Vermont, USA. In Israel, M9 consistently had higher leaf-specific hydraulic resistance (R(l)) in the soil to scion stem pathway, but this difference was only significant for one summer. R was larger in M9 between the root and stem, implicating the graft union as the site of increased resistance. In Vermont, R(l) of 9- and 10-year-old trees on six rootstocks of various vigours was not consistently related to vigour, and stem-specific resistance (R(s)) increased with increasing vigour. High pressure flow meter (HPFM) measurements gave a lower R than the EF method in all but one case, perhaps indicating a significant amount of xylem dysfunction in these trees, and demonstrated the increased resistivity of stem sections that included dwarf graft unions as compared with non-graft stem sections. It is concluded that stem- and leaf-specific R are not consistently positively correlated with dwarfing, although the increased resistivity of the graft union in dwarfing rootstocks may influence the transport of water and other elements across the graft union, and therefore be involved in the dwarfing mechanism.
DOI:10.3969/j.issn.1002-6819.2014.22.010URLMagsci [本文引用: 1]
局部根区灌溉可以刺激灌水区根系吸水的补偿效应。为了揭示局部灌溉条件下玉米根系补偿效应的动态变化及其影响因素，以聚乙二醇6000（polyethylene glycol 6000，PEG-6000）营养液的渗透势模拟水分胁迫，采用分根技术，通过水培试验模拟局部根区水分胁迫，设置3个水分胁迫程度处理（?0.2、?0.4、?0.6 MPa）和1个对照处理（无营养液），于处理后0、0.25、0.5、1、3、5、7、9 d连续动态监测各根区根系的生长及导水率。结果表明，局部根区受中度及其以下（≥?0.6 MPa）经水分胁迫0.25 d内，所有处理胁迫区根系总导水率和单位根长导水率均与非胁迫区和对照无显著差异（P＞0.05）。胁迫持续时间超过0.25 d，胁迫区根系总导水率和单位根长导水率均显著小于非胁迫区（P＜0.05），降低程度随水分胁迫程度而增大，各处理间胁迫区根系总导水率的差异随胁迫持续时间延长也逐渐增大。对于非胁迫区，轻度胁迫（?0.2 MPa）持续0.5 d，单位根长导水率较对照高10.11%（P＜0.05），1～9 d与对照持平；?0.4 MPa胁迫持续9 d，单位根长导水率为25.08×10-11 m2/(MPa·s)，显著高于对照（P＜0.05）；中度胁迫（?0.6 MPa）持续0.5～3 d单位根长导水率显著小于对照（P＜0.05），较对照低19.05%～40.11%，5 d后与对照持平。说明局部根区水分胁迫能有效刺激非胁迫区根系吸水的补偿效应，这种补偿作用在局部水分胁迫0.5 d时就已发生，受到局部水分胁迫程度和持续时间的影响，且根系吸水补偿效应的临界胁迫程度为≥?0.4 MPa。该研究可为更好的发挥局部灌溉在农业节水中的作用提供理论依据。
DOI:10.3969/j.issn.1002-6819.2014.22.010URLMagsci [本文引用: 1]
局部根区灌溉可以刺激灌水区根系吸水的补偿效应。为了揭示局部灌溉条件下玉米根系补偿效应的动态变化及其影响因素，以聚乙二醇6000（polyethylene glycol 6000，PEG-6000）营养液的渗透势模拟水分胁迫，采用分根技术，通过水培试验模拟局部根区水分胁迫，设置3个水分胁迫程度处理（?0.2、?0.4、?0.6 MPa）和1个对照处理（无营养液），于处理后0、0.25、0.5、1、3、5、7、9 d连续动态监测各根区根系的生长及导水率。结果表明，局部根区受中度及其以下（≥?0.6 MPa）经水分胁迫0.25 d内，所有处理胁迫区根系总导水率和单位根长导水率均与非胁迫区和对照无显著差异（P＞0.05）。胁迫持续时间超过0.25 d，胁迫区根系总导水率和单位根长导水率均显著小于非胁迫区（P＜0.05），降低程度随水分胁迫程度而增大，各处理间胁迫区根系总导水率的差异随胁迫持续时间延长也逐渐增大。对于非胁迫区，轻度胁迫（?0.2 MPa）持续0.5 d，单位根长导水率较对照高10.11%（P＜0.05），1～9 d与对照持平；?0.4 MPa胁迫持续9 d，单位根长导水率为25.08×10-11 m2/(MPa·s)，显著高于对照（P＜0.05）；中度胁迫（?0.6 MPa）持续0.5～3 d单位根长导水率显著小于对照（P＜0.05），较对照低19.05%～40.11%，5 d后与对照持平。说明局部根区水分胁迫能有效刺激非胁迫区根系吸水的补偿效应，这种补偿作用在局部水分胁迫0.5 d时就已发生，受到局部水分胁迫程度和持续时间的影响，且根系吸水补偿效应的临界胁迫程度为≥?0.4 MPa。该研究可为更好的发挥局部灌溉在农业节水中的作用提供理论依据。
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DOI:10.1111/emi.2012.14.issue-4URL [本文引用: 1]
DOI:10.1073/pnas.1010981108URLPMID:21368116 [本文引用: 1]
Ammonia oxidation is an essential part of the global nitrogen cycling and was long thought to be driven only by bacteria. Recent findings expanded this pathway also to the archaea. However, most questions concerning the metabolism of ammonia-oxidizing archaea, such as ammonia oxidation and potential CO60 fixation, remain open, especially for terrestrial environments. Here, we investigated the activity of ammonia-oxidizing archaea and bacteria in an agricultural soil by comparison of RNA-and DNA-stable isotope probing (SIP). RNA-SIP demonstrated a highly dynamic and diverse community involved in CO60 fixation and carbon assimilation coupled to ammonia oxidation. DNA-SIP showed growth of the ammonia-oxidizing bacteria but not of archaea. Furthermore, the analysis of labeled RNA found transcripts of the archaeal acetyl-CoA/propionyl-CoA carboxylase (accA/pccB) to be expressed and labeled. These findings strongly suggest that ammoniaoxidizing archaeal groups in soil autotrophically fix CO60 using the 3-hydroxypropionate-4-hydroxybutyrate cycle, one of the two pathways recently identified for CO60 fixation in Crenarchaeota. Catalyzed reporter deposition (CARD)-FISH targeting the gene encoding subunit A of ammonia monooxygenase (amoA) mRNA and 16S rRNA of archaea also revealed ammonia-oxidizing archaea to be numerically relevant among the archaea in this soil. Our results demonstrate a diverse and dynamic contribution of ammonia-oxidizing archaea in soil to nitrification and CO60 assimilation and that their importance to the overall archaeal community might be larger than previously thought.
DOI:10.1016/j.cosust.2012.08.003URL [本文引用: 1]
DOI:10.1146/annurev-phyto-081211-172914URL [本文引用: 1]
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DOI:10.1016/S0929-1393(00)00068-8URL [本文引用: 1]
While soil quality encompasses physical and chemical besides biological characteristics, soil health is primarily an ecological characteristic. Ecosystem health has been defined in terms of ecosystem stability and resilience in response to a disturbance or stress. We therefore, suggest that indicators for soil health could be found by monitoring responses of the soil microbial community to the application of different stress factors at various intensities. The amplitude of a response and time to return to the current state before application of stress could serve as measures of soil health. Root pathogens are an integral part of soil microbial communities, and the occurrence of epiphytotics forms an indication of an ecosystem in distress. Disease suppression can be viewed as a manifestation of ecosystem stability and health. Thus, indicators for soil health could possibly also function as indicators for disease suppressiveness. Previously suggested indicators for soil health and disease suppression have mainly been lists of variables that were correlated to more or less disturbed soils (ranging from conventional to organic agricultural soils, grassland and forest soils) or to conduciveness to disease. We suggest a systematic ecological approach to the search for indicators for soil health and disease suppression, namely, measuring biological responses to various stress factors and the time needed to return to the current state.
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DOI:10.3864/j.issn.0578-1752.2009.02.044URL [本文引用: 1]
【Objective】 The objective of the experiment is to study the effect of long-term cotton continuous cropping on soil physical-chemical and biological characters. 【Method】 Both cotton micro-experiment and conventional chemical methods were adopted to study the changes of soil physical-chemical properties and soil enzyme activities under long-term continuous cropping. 【Result】 Results showed that compared with 1 year cropping, both soil organic matter content and soil salt content were increased by 10.56%, 18.09%, 37.34%, 55.64% and 122%, 132%, 124%, 146%, respectively, under 5-20 years continuous cropping, while soil bulk density began to decline. With the time of continuous cropping increasing, the soil alkali-hydrolyzable N content was remarkably raised, but the soil available K content was decreased by 60.4%, 35.9% and 39.8% under 5-20 years continuous cropping, the soil available P content was enhanced in 5-year continuous cropping and then stable in 10, 15 and 20 years continuous cropping. The activities of urase, catalase, protease, invertase and phosphatase decreased in 5-10 years continuous cropping, while those enzyme activities increased in 15-20 years, the soil peroxidase activity increased with the continuous cropping year increasing. 【Conclusion】 In the oasis area of Xinjiang, under long-term continuous cropping, stalk returning can ameliorate soil physical characters, increase soil salt content, but soil N, P, K proportion was imbalanced. The enzyme activity of soil decreased in a short period of time (from 1 to 10 years), the obstacles of continuous cropping were more obvious.
DOI:10.3864/j.issn.0578-1752.2009.02.044URL [本文引用: 1]
【Objective】 The objective of the experiment is to study the effect of long-term cotton continuous cropping on soil physical-chemical and biological characters. 【Method】 Both cotton micro-experiment and conventional chemical methods were adopted to study the changes of soil physical-chemical properties and soil enzyme activities under long-term continuous cropping. 【Result】 Results showed that compared with 1 year cropping, both soil organic matter content and soil salt content were increased by 10.56%, 18.09%, 37.34%, 55.64% and 122%, 132%, 124%, 146%, respectively, under 5-20 years continuous cropping, while soil bulk density began to decline. With the time of continuous cropping increasing, the soil alkali-hydrolyzable N content was remarkably raised, but the soil available K content was decreased by 60.4%, 35.9% and 39.8% under 5-20 years continuous cropping, the soil available P content was enhanced in 5-year continuous cropping and then stable in 10, 15 and 20 years continuous cropping. The activities of urase, catalase, protease, invertase and phosphatase decreased in 5-10 years continuous cropping, while those enzyme activities increased in 15-20 years, the soil peroxidase activity increased with the continuous cropping year increasing. 【Conclusion】 In the oasis area of Xinjiang, under long-term continuous cropping, stalk returning can ameliorate soil physical characters, increase soil salt content, but soil N, P, K proportion was imbalanced. The enzyme activity of soil decreased in a short period of time (from 1 to 10 years), the obstacles of continuous cropping were more obvious.
DOI:10.11838/sfsc.20130107URL [本文引用: 1]
以日光温室辣椒连作土壤为对象,研究不同连作年限土壤微生物数量、类群及酶活性的变化。结果表明,土壤微生物数量、酶活性表现出明显的温室连作效应,随着连作年限的增加,土壤微生物类群细菌/真菌、放线菌/真菌值呈下降趋势,微生物由＂细菌型＂向＂真菌型＂过渡,其中氨化细菌先增加后减少、硝化细菌呈减少的趋势;多数土壤酶活性随着连作年限的增加呈下降趋势,但过氧化氢酶活性呈增加趋势。
DOI:10.11838/sfsc.20130107URL [本文引用: 1]
以日光温室辣椒连作土壤为对象,研究不同连作年限土壤微生物数量、类群及酶活性的变化。结果表明,土壤微生物数量、酶活性表现出明显的温室连作效应,随着连作年限的增加,土壤微生物类群细菌/真菌、放线菌/真菌值呈下降趋势,微生物由＂细菌型＂向＂真菌型＂过渡,其中氨化细菌先增加后减少、硝化细菌呈减少的趋势;多数土壤酶活性随着连作年限的增加呈下降趋势,但过氧化氢酶活性呈增加趋势。
