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1.
The endoparasitic nematophagous fungusHirsutella rhossiliensis was tested for its ability to suppress root penetration and cyst formation by the potato cyst nematode speciesGlobodera pallida. Isolates ofH. rhossiliensis were obtained from infected potato cyst nematode juveniles from different starch potato fields in The Netherlands. The isolates showed no difference in spore adhesion to juveniles on agar plates (adhesion rate: ±90%). The most rapid growing isolate, CBS 108.94, was used for experiments. Vegetative mycelial colonies ofH. rhossiliensis CBS 108.94, grown in potato dextrose broth, were used as soil inoculum. During submerged cultivation the mycelial colonies produced phialides (spore-bearing cells) but no spores. Exposed to the air, however, spores were rapidly formed. The effect of different soil inoculum densities of mycelial colonies on root penetration byGlobodera pallida was examined in an experiment in 250-ml pots. Up to a mycelial colony concentration representing a potential spore density of 104 g–1 soil no suppression occurred. At approximated densities of 2.5×104 and 105 spores g–1 soil the numbers of juveniles which penetrated roots were reduced by 30% and 34%, respectively. The distribution of the inoculum could be improved by fragmentation of the mycelial colonies before soil inoculation. Using mycelial fragments, again no suppression of root penetration was observed up to a potential spore density of 104 g–1 soil, but at densities of 105 and 106 g–1 a suppression of 54% and 88%, respectively, was measured. In a greenhouse experiment, soil inoculation with mycelial colonies with a potential spore production of 2.5×105 g–1 soil resulted in a suppression of root penetration of 37% and 51% after 5 and 6 weeks, respectively, but the number of newly formed cysts after 18 weeks in soil was not different for control and inoculated pots. It is concluded thatH. rhossiliensis may be useful for the reduction of root damage caused by juveniles of potato cyst nematodes, but the usefulness for population control is doubtful.  相似文献   

2.
Potatoes were grown under a permanent rain shelter in mobile containers in soil with and without potato cyst nematodes (Globodera pallida). The plants were either subjected to an early drought stress period from planting until 43 days after planting, to a late drought stress period during tuber bulking or to a drought control. Leaf water potentials, stomatal diffusion resistances for water vapour, transpiration rates, dry matter accumulation and water use efficiencies of the plants were determined periodically. Both drought and nematodes decreased leaf water potential and increased stomatal resistance.Drought led to a higher water use efficiency, cyst nematode infection, however, reduced the water use efficiency at early stages of growth, and increased it at later stages. It is concluded that at least two main growth reducing mechanisms exist of which the relative importance varies with time. Firstly, reduced apparent assimilation rates, which are unrelated to a change in the water balance caused by the initial attack by the cyst nematodes. Secondly, a reduced dry matter accumulation resulting from a decrease of water uptake. Effects of drought and cyst nematode infection on plant growth and water relations were not always additive mainly because infected plants used up less water leading to less drought stress.  相似文献   

3.
Potatoes were grown under a permanent rain shelter in mobile containers in soil with or without potato cyst nematodes (Globodera pallida). The plants were subjected to an early drought stress period starting at planting until 43 days after planting, to a late drought stress period starting at 43 days until senescence at 92 days and to a drought control. Dry matter weight and characteristics of leaves, stems, stolons and roots were determined at periodic harvests. The early drought stress and nematode infection affected many plant organ characteristics in similar ways. Numbers of leaves, specific leaf area, plant height, specific stem weight, leaf area ratio, mean tuber weight and harvest index were reduced by both stress factors at early stages of growth.Later on, interactions between both stress factors which influence the development rate of the plants led to more diverse plant reactions. Plants of all treatments rapidly senesced at about 90 days after planting. Uninfected plants had then depleted the soil nutrient supply whereas the plants grown in the inoculated soil senesced as a result of the potato cyst nematode infection.  相似文献   

4.
山东省烟草孢囊线虫的群体动态和世代发生特点   总被引:1,自引:1,他引:1  
为探究烟草孢囊线虫Heterodera glycines的田间侵染循环特点,2012年从山东省诸城市某烟田定点定期取样,对土壤和根组织中的线虫进行分离和染色后镜检并计数。结果显示,4月29日至9月9日在土壤中均检出烟草孢囊线虫2龄幼虫(J2),有4个发生高峰,最大密度在7月9日,为7.3条/100 g土壤。5月13日至8月13日在根组织中出现J2,有3个明显高峰,最大密度在7月15日,为30条/10 g根;年轻雌虫在5月21日至8月30日形成,有3个明显高峰,最大密度在7月2日,为54条/10 g根。研究表明,烟草孢囊线虫 1年发生4代,平均世代历期27 d;后两代存在明显世代重叠现象;第4代线虫侵染量很少,且根内线虫发育不良。  相似文献   

5.
为探究河南省主要禾谷类作物孢囊线虫的发生分布,明确孢囊线虫对不同作物的危害情况,于2017—2020年对河南省18个市50个县(区)的小麦、玉米和水稻作物的孢囊线虫种类和发生分布进行随机取样调查,采用形态学特征、分子生物学鉴定和rDNA-ITS序列进化树分析技术鉴定不同作物孢囊线虫的种类,并根据土壤中孢囊基数和单孢囊卵数明确不同作物孢囊线虫的发病严重度。结果显示,共采集土壤样品308份,其中224份样品检测到孢囊,孢囊检出率为72.7%。小麦孢囊线虫发生分布范围覆盖40个县(区),其中15个县(区)为禾谷孢囊线虫Heterodera avenae侵染,23个县(区)为菲利普孢囊线虫H. filipjevi侵染,南阳市西峡县西坪镇和开封市尉氏县张市镇为禾谷孢囊线虫和菲利普孢囊线虫混合侵染发生区;玉米孢囊线虫H. zeae在濮阳市清丰县韩村镇、许昌市长葛市董村镇和禹州市范坡镇检测点首次被发现;旱稻孢囊线虫H. elachista在信阳市潢川县魏岗乡、来龙乡和新乡市获嘉县亢村镇检测点首次被发现。孢囊线虫发病严重度数据表明,小麦田平均孢囊含量高达17.3个/100 mL;玉米田平均孢囊量为11.0个/100 mL;水稻田平均孢囊量为4.4个/100 mL。表明河南省孢囊线虫高发地块主要集中在豫北、豫东和豫中平原区。  相似文献   

6.
在塔里木河下游枣树生态经济林进行根灌试验,研究了直插式根灌条件下的土壤水分时空分布和节水效率。结果表明:(1)灌水过程中直插式根灌的土壤水分分布在0~100 cm土壤层,随灌溉时间增加,土壤含水量,0~20 cm土层呈波动变化,80~100 cm土层基本稳定,其余各土层呈S型增加;(2)不同时期1 m深土层平均土壤体积含水量最大值及达到最大值的时间,枣树生长初期为44.62%、7.5 h,花期为43.26%、12.5 h,幼果期为46.3%、15 h;(3)根灌过程中,各土层土壤含水量变异系数大小次序为80 cm20 cm40 cm60 cm100 cm;灌后土壤平均含水量,80、100 cm土层与其余各层之间差异显著,20、40、60 cm土层之间差异不显著,80 cm土层土壤含水量空间异质性最高;(4)三次试验后20 d内,0~100 cm土层的平均土壤体积含水量消退速率分别为0.21%·d~(-1)、0.19%·d~(-1)和0.17%·d~(-1),土壤体积含水量60 cm和100 cm土层消退速率稳定,40 cm土层呈先消退后增加的趋势,20 cm土层0~10 d迅速消退,80 cm土层11~20 d迅速消退;(5)直插式根灌的节水效率比地表滴灌高27.78%,水分利用效率分别比地表滴灌和漫灌高8.12%、52.46%。  相似文献   

7.
In field trials during three years respectively 18, 22 and 57 potato genotypes were grown on soils moderately or heavily infested with potato cyst nematodes (Globodera pallida) after soils were fumigated or not. Nematode infection increased leaf calcium contents but genotypes that were relatively tolerant of potato cyst nematodes (Globodera pallida) had lower leaf calcium concentrations on a particular sampling date. Tolerance of potato cyst nematodes was closely linked to genotype lateness and may be related to tolerance of drought. When using the method in plant breeding and screening for genotypes with tolerance, plants may be planted in infected or in uninfected soils, without influencing the outcome. The relationship between tolerance and calcium contents was clearest when sampling took place towards the end of the growing season when the variability was at it highest with a good distinction between newly formed leaves in late maturing genotypes and aged leaves in early maturing cultivars.  相似文献   

8.
为了探索干旱胁迫下不同抗旱性油菜品种的地上、地下部生长特征与抗旱性的关系,通过土柱栽培试验,对油菜品种DR1、DR2和DR3在不同水分处理条件下不同土层根量、地上部生物量、冠层覆盖面积及抗旱性之间的关系进行研究。结果表明:3个品种在水分胁迫和正常供水条件下产量和根系生物量在品种间均达到显著性差异,3个品种的抗旱能力大小依次为:DR1>DR3>DR2;不同水分处理下油菜的根系主要分布于0~30 cm土层,占根系总量的70%以上;在干旱胁迫下,3个品种DR1、DR2和DR3的总根量分别减少了22.53%、24.17%和24.53%,但仍表现出抗旱性强的品种DR1的根系总量最大,达到12.07 g,其次为品种DR3和DR2;在大于30cm的土层中,DR1的根系量占到总根量的31.5%,这表明根系垂直分布量的多少对抗旱性的影响较大,同时植株冠层面积、总生物量、根系干重与抗旱性的直接通径系数分别为0.5861、0.4514、0.5715,说明除了根系外,大的冠层面积可减少地表蒸发有利于作物抗旱。  相似文献   

9.
研究了西辽河平原灌区3种主要灌溉方式(浅埋滴灌、膜下滴灌和传统畦灌)对玉米根系形态特征和生理生化特性的影响.采用大田对比试验,以农华101为供试品种,大小垄种植(小垄行距40 cm,大垄行距80 cm),种植密度7.5万株·hm-2,在设定的灌溉定额下(膜下滴灌和浅埋滴灌为3150 m3·hm-2、传统畦灌为4500 ...  相似文献   

10.
玉米膜孔灌农田土壤水氮分布特性   总被引:1,自引:1,他引:0  
通过大田玉米灌水试验,研究了畦灌和膜孔灌条件下农田土壤水氮运移特性。结果表明:在相同灌水定额条件下,膜孔灌土壤剖面含水率比畦灌土壤剖面含水率变化均匀,0~30 cm土层灌水后1天和灌水后5天膜孔灌土壤含水率比畦灌土壤含水率高19.2%和18.3%;在相同灌水定额条件下,土壤铵态氮含量受土壤水分运动的影响较小,主要分布在30 cm以上土壤层,膜孔灌条件下土壤铵态氮含量随时间分布比畦灌均匀,其含量最大值为41.6 mg/kg,同畦灌相比铵态氮含量增加了4.3%;硝态氮含量受灌水方式的影响较大,在相同灌水定额条件下,10~50 cm各土层硝态氮含量膜孔灌比畦灌分别增加了41.3%、96.3%、55.3%、50.7%和46.5%,膜孔灌土壤硝态氮含量随时间和垂直土壤剖面分布均匀,其硝态氮含量主要集中在0~50 cm土层,有利于作物对氮素的吸收,提高氮素利用率。  相似文献   

11.
Potato-cyst nematodes (Globodera pallida) cause severe yield losses in potato. Plants infected with potato-cyst nematodes generally have reduced concentrations of nitrogen, phosphorus and potassium in the foliage. This study investigated whether reduced growth of nematode-infected potato is caused by nutrient limitation.Experiments in the field and in containers showed that phosphorus concentration correlated best with total crop biomass at early stages of growth. The role of phosphorus in nematode damage was further investigated in the field and in the Wageningen Rhizolab. The experimental field was infested with potato-cyst nematodes and two levels of nematode density were established by fumigation with a nematicide. Prior applications of calcium carbonate resulted in pHKCl levels of 4.8 and 6.1. Two levels of phosphorus fertiliser were applied: either 0 or 225kgPha–1. In the Wageningen Rhizolab, soil of both pH levels from the field was used after treatment with 1MRad gamma irradiation to kill the nematodes. Subsequently, half of the soil was inoculated with cysts to give a nematode density of 30 viable juveniles per gram of soil.In the field, nine weeks after planting, the total crop biomass ranged from 107gm–2 for the treatment with nematodes at pHKCl 6.1 without phosphorus fertiliser to 289gm–2 for the fumigated treatment at pHKCl 4.8 with phosphorus fertiliser. The differences in total biomass for the various treatments were explained by differences in foliar phosphorus concentration. Nematodes induced or aggravated P deficiency and reduced total biomass. This was not the only damage mechanism as at high, non-limiting levels of foliar phosphorus concentration, nematodes still reduced total biomass.In the Wageningen Rhizolab, directly after planting, the number of roots visible against minirhizotrons was reduced by nematodes. However, the increase of root number in the nematode treatment continued longer than in the control, until root number was higher than that of the control. The compensary root growth of the nematode treatment was restricted to the top 30cm and nematodes reduced rooting depth.High soil pH reduced growth, mainly by reducing the availability of phosphate. Both nematodes and high soil pH reduced nutrient uptake per unit root length. Our results lead us to suggest an interaction between nematodes and soil pH, with nematode damage being higher at pHKCl 6.1 than at pHKCl 4.8.  相似文献   

12.
The nematicidal effect of soil amendments with dry top and root material from Medicago sativa and/or Medicago arborea was evaluated on the root-knot nematode Meloidogyne incognita and on the cyst nematode Globodera rostochiensis in potting mixes. All amendments suppressed root and soil population densities of both nematode species compared to non-treated and chemical controls. The suppressiveness of M. sativa differed between top and root material and among the amendment rates. In field conditions soil amendments with 20 or 40 t ha−1 of a pelleted M. sativa meal increased tomato crop yield and reduced soil population densities and root galling by M. incognita. It is suggested that saponins were at least partly responsible for the nematicidal activity.  相似文献   

13.
为明确土壤干旱对麦田燕麦孢囊线虫Heterodera avenae(Ha)发生动态的影响,于2014年分别对灌溉和非灌溉小区定期取样,通过对土壤中线虫的分离和小麦根组织中线虫的镜检,确定灌溉和非灌溉小区中Ha各虫态的发生密度。结果表明,与非灌溉小区相比,灌溉小区土壤中2龄幼虫和白色雌虫以及根组织中2、3或4龄幼虫的群体密度在4—5月均明显较高;尤其在4月,灌溉小区2龄幼虫平均孵出量和侵入量分别为3.0条/100 g土壤和19.0条/10 g根,而非灌溉小区的分别仅为0.6条/100 g土壤和1.0条/10 g根。在小麦生长期,灌溉小区的Ha群体密度略有增长,繁殖系数为1.04,而非灌溉小区的显著下降,繁殖系数仅为0.09。研究表明,土壤严重干旱能抑制Ha 2龄幼虫的孵出和侵入,减少3、4龄幼虫和白色雌虫发生数量,导致繁殖系数显著下降。  相似文献   

14.
滴灌条件下核桃园土壤水分动态变化的数值模拟研究   总被引:1,自引:0,他引:1  
为探究滴灌条件下核桃根系对土壤含水量的影响,试验以8 a生核桃树为研究对象,使用分层分段挖掘法分析核桃根系的空间形态分布,通过构建HYDRUS-2D模型,对有根系吸水下的土壤水分变化进行求解,并利用实测点数据校验2D模型的可用性。经过实际计算与理论分析,得出如下结论:在垂直二维剖面中,水平距树0~30 cm、垂直40~60 cm土层的细根根长密度分布最大,为1 618.216 m·m~(-3)。对比实测数据与模拟数据,结果显示RMSE均小于0.0186 cm~3·cm~(-3),ME绝对值小于0.0108 cm~3·cm~(-3),证明数值模拟效果较好,HYDRUS模型可应用于实际试验研究。将根系模块纳入模型模拟,并比照单独水流模块作用,结果显示根系对土壤含水量产生影响,使体积含水率曲线整体低于单独水作用下的含水率曲线,且两者关系差异性显著。模拟核桃生育前期土壤含水量变化,结果表明灌水后6 d至7 d内,土壤含水量存在明显减小现象,故可将生育前期灌水周期设定为6 d或7 d。  相似文献   

15.
喷灌冬小麦农田土壤NO-3-N分布特征及作物吸氮规律   总被引:1,自引:0,他引:1       下载免费PDF全文
以传统地面灌溉(畦灌)为对照,2002~2003和2003~2004两个生产年度田间试验分析喷灌对冬小麦农田土壤NO3^-—N分布和作物吸氮的影响。试验结果表明:喷灌与地面灌溉相比,土壤NO3^-—N含量蜂值迁移较浅,土壤NO3^--N主要分布在冬小麦主要根系分布层0~40cm土层内。与喷灌相比,在冬小麦根系层下部,地面灌溉土壤NO3^-N存在不同程度的累积。试验期间地面灌溉土壤NO3^-—N累积淋失量分别为8.68kg/hm^2和7.70kg/hm^2,喷灌条件下没有明显的土壤NO3^-—N淋失,最大累积淋失量只有地面灌溉条件下的3%。2003和2004年喷灌冬小麦地上部分吸氮量分别为235.7kg/hm^2和161,7kg/hm^2,分别比地面灌溉高7.0kg/hm^2和34.7kg/hm^2。与地面灌溉相比,喷灌有利于冬小麦后期吸收氮素,喷灌不同生育期冬小麦吸氮量年际之间的差异都小于地面灌溉。  相似文献   

16.
Findings from 2 years of field experiments investigating the relationship between Globodera rostochiensis and Rhizoctonia solani on unique field sites are reported. In 2000, a field experiment was positioned on land that had previously been used for experimental work investigating integrated potato cyst nematode (PCN) management methods. This study had produced an ‘untypical’ mosaic of PCN population densities ranging from 5 to 221 eggs g−1 soil. In 2001, the field experiment was conducted on a different field site and overlaid on a focus of G. rostochiensis population densities ranging from 11 to 108 eggs g−1 soil. In each experiment, potatoes (cv. Désirée) were grown in plots with similar population densities of G. rostochiensis that were either uninoculated or inoculated with R. solani. A series of potato plant harvests were undertaken to investigate the effects of nematode infestation on the incidence and severity of R. solani diseases and the associated development of plants. In both experiments, a clear relationship was found between the density of G. rostochiensis juveniles present in potato roots and the incidence of stolons infected by R. solani, 6 weeks after planting. For the first time this interaction has been determined under field conditions. The results of the study suggest that the interaction between nematode and fungus is indirect and possible mechanisms are discussed.  相似文献   

17.
"环状毛细芯渗灌"是利用毛细现象的原理,在已有的毛细直芯基础上增加一个毛细环,通过毛细芯浸润方式给植物根部供水的节水渗灌方法。试验在宁夏自治区永宁县玉泉营农场的红地球(Vitis vinifera L.cv.red globe)葡萄园内进行,灌溉方式为环状毛细芯渗灌与常规沟灌(CK);毛细芯渗灌的灌水次数分为一次和两次,每次灌满一桶水(100L),水由毛细芯慢慢渗出,常规沟灌的灌水次数为两次;环状毛细芯的埋藏深度分为两种:30cm深和土壤表面(0cm深)。试验结果表明,处理0*1(环状毛细芯表面渗灌、一次灌水)下副稍增长量最大,与常规沟灌存在显著差异(P0.05)。在相同灌水量下,处理0*1副稍增长量高于处理30*1(地下30cm深的环状毛细芯渗灌、一次灌水)。处理0*2(表面渗灌、两次灌水)叶中脉长势最好。处理0*2、0*1相比于其它处理果实粒径增长量最大,处理0*1横径增长速度比CK提高了55.6%,这说明环状毛细芯渗灌有效促进了葡萄果实的增长。在相同灌水量下,表面渗灌下葡萄粒径的长势明显好于30cm深的渗灌。处理30*2(地下30cm深的环状毛细芯渗灌、两次灌水)百粒重比相同灌水量下的CK提高了30%。常规沟灌下脯氨酸含量最高,处理30*2脯氨酸含量最低;在相同灌水量下,表面渗灌下脯氨酸含量高于30cm深的渗灌,这说明30cm深的毛细芯渗灌能较好地减轻植物的水分胁迫。处理30*2与30*1的可溶性固形物较高,处理30*1的糖酸比最高;在相同灌水量下,30cm深的渗灌下葡萄糖酸比高于表面渗灌。从最终产量和果实品质的角度看,处理30*2是旱区葡萄着色期~成熟期最好的组合。  相似文献   

18.
为揭示不同滴灌技术参数及施肥周期对苹果根区土壤硝态氮动态及分布的影响,探究适于渭北地区矮化密植苹果园的技术参数,以4 a生苹果树为试验对象,开展田间滴灌施肥试验。设置毛管布置方式(一行一管,P1;一行两管,P2)、滴头间距(30 cm, D1;50 cm, D2)、施肥周期(15 d, T1;30 d, T2)3个试验因素,监测根区土壤硝态氮在生育期内的时空分布特征。试验年份为平水年且土壤含水率相对较高,在此条件下研究表明,T1和T2处理硝态氮含量变化分别为7.06~168.36 mg·kg-1和9.73~248.86 mg·kg-1。延长施肥周期使0~40 cm和80~100 cm土层硝态氮变化幅度加大,并加剧硝态氮向深层移动,减少了0~60 cm土层(根系层)中硝态氮含量。与P1相比,P2处理使垂直树行方向硝态氮的扩散范围...  相似文献   

19.
种子处理诱导大豆抗胞囊线虫病的生防细菌筛选与鉴定   总被引:1,自引:0,他引:1  
国内研究了简单芽孢杆菌Bacillussimplex包衣处理大豆种子,诱导大豆植株抗胞囊线虫的侵染。采用温室盆栽试验,对研究室通过2年田间试验筛选出的3株生防细菌进行复筛,获得最优菌株Sneb545;为了阐明其作用方式,设计了裂根试验验证菌株Sneb545诱导大豆产生抗胞囊线虫的能力,并对菌株Sneb545进行种水平鉴定。结果表明,菌株Sneb545处理种子后可以诱导苗期大豆对第一代胞囊线虫产生明显的抗性,线虫入侵总数显著降低,较对照降低72.63%,胞囊抑制率达70.63%;裂根试验结果证明,菌株Sneb545能够诱导大豆对胞囊线虫产生很强的抗性,菌株Sneb545在挑战根系中接种后,应答根系中胞囊线虫入侵量降低51.27%,土壤中胞囊减少65.82%;经形态学特征、生理生化试验测定及16SrDNA序列同源性分析,确定该菌株为简单芽孢杆菌。  相似文献   

20.
Root growth and spatial and temporal distribution in the 0-100 cm soil profiles of three common annual halophytes Salsola subcrassa, Suaeda acuminate and Petrosimonia sibirica distributed in a saline desert in northern Xinjiang, China were studied in 2009 and 2010. The results showed that the root systems of the three halophytes were of the taproot type, vertically distributed in the 90-cm soil profile, and were deepest in late July. Their taproots reached maximum depth rapidly, early in the growth period, but with rare lateral roots. They were then dug out in an orderly way, from bottom to top, exhibiting vertical development first and then horizontal development. The distribution of specific root length, which reflects the characteristics of the feeder root, was gradually increased from top to bottom, whereas root weight displayed an opposite distribution pattern. The root length distribution of the three halophytes was concentrated (62% to 76%) in the middle soil profile (20-60 cm), with less distribution in the surface (0-20 cm) and bottom (60-90 cm) soil profiles. The results indicated that the roots of the three annual halophytes grew rapidly into the deeper soil layer after germination, which ensured the plant survival and uptake of water and nutrition, and thus built up a strong tolerance to an arid, high-salt environment.  相似文献   

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