Penetration, Development and Emigration of Juveniles of the Nematode Meloidogyne arenaria in Myrobalan Plum (Prunus cerasifera) Clones Bearing the Ma Resistance Genes

Penetration, development and emigration of M. arenaria in the roots of three Myrobalan plum (Prunus cerasifera) clones genetically characterized for their resistance to root-knot nematodes (RKN) were studied during the 10 (penetration) and 15 (emigration) days following the date of inoculation (D) of 2500 juveniles (J2s) per plant into the soil. Miniaturized tests were conducted on the two resistant clones P.2175 (Ma1 gene) and P.1079 (Ma2 gene) and the susceptible clone P.2032 (recessive for both genes), obtained from micropropagated plantlets and grown in mini-containers under controlled conditions at 25°C in a growth chamber. For penetration and development studies, nematodes in the roots were recovered by the acid fuchsin-lactophenol staining technique. Equivalent numbers of J2s were recovered in all the clones at D+1 and D+2. Subsequently, the numbers increased rapidly in P.2032 and were significantly different from those in P.1079 and P.2175 that remained at a low level. No swollen larvae were observed in the resistant clones. In P.2032, the first swollen larvae were observed at D+4, the first females were observed at D+12, whereas the first females with attached egg sacs and the first new-generation J2s were obtained between D+21 and D+28. Our data suggest that the resistance phenomenon does not act on the very early nematode penetration but acts later by preventing feeding-site induction and development into the third-stage. For emigration studies, plants in which J2s had been allowed to penetrate for two days (from D to D+2) were washed free of soil, repotted and then, after various periods of growth, soil-free roots were placed under a mistifier to evaluate the numbers of emigrating individuals. Emigration of J2s from the roots occured mainly from D+2 to D+4 in all the genotypes and was very limited from D+4 to D+10. There was no significant differences in the number of emigrated juveniles between the resistant and susceptible clones, indicating that emigration cannot explain the difference in the numbers of nematodes recovered in the roots.     

南方、花生和爪哇根结线虫PCR检测方法

为快速、准确、稳定的鉴定南方、花生和爪哇根结线虫,利用已报道的南方和爪哇根结线虫的两对特异性引物,结合本研究设计的花生根结线虫特异性引物,通过优化PCR反应体系,建立了3种根结线虫的PCR检测方法。结果表明,该方法能够特异性扩增以上3种根结线虫,特征片段长度分别为399、335和670 bp,灵敏度达到单条2龄幼虫的水平。研究结果将为以上3种根结线虫的快速鉴定提供技术支持。     

沙漠水渠人工固沙区沙篙和沙拐枣灌丛的土壤水分特征对比

在古尔班通古特沙漠引水渠沿线建植5a的人工固沙区内,选择自然生长的沙蒿和沙拐枣灌丛,依据冠幅大小设置5个水平距离梯度和4个土层深度梯度.对比研究了二者的土壤水分特征.结果表明,随土层深度的增加,两种灌丛土壤含水量均呈增加趋.,中下部2层(20～40 cm和40～60 cm)土壤含水量显著(P<0.05)高于上部2层(0...     

花生根结线虫对节瓜苗期植株生长及主要生理特性的影响

对感染花生根结线虫的节瓜植株主要生理指标和生长量的变化进行测定。结果表明：花生根结线虫的侵染明显降低节瓜根系的活力,引起节瓜苗期植株的Ｎ,Ｐ,Ｋ和Ｍｇ含量显著下降,但对Ｃａ所吸收则有所增加;植株的叶绿素含量和光合速率均显著降低,但呼吸强度在线虫接种量为３０００和５０００条时则明显提高;植株生长的各项指标也发生不同程度的变化。     

花生对根结线虫病抗性温室快速鉴定方法

为了通过对花生抗线虫鉴定方法的比较,确定更加快速有效的抗性鉴定技术,作者于2002～2003年在佐治亚大学的Tifton试验站进行了温室盆栽试验.结果表明侵然期幼虫(2000～4000条/株)与虫卵(8000～16000粒/株)均可以用于花生抗线性鉴定的温室接种,但与使用虫卵接种相比,以侵染期幼虫作为接种体需要多花3～5d的时间收集幼虫;接种后14d,可以依据0～5级的虫瘿分级标准将供试的4份花生种质区分开来;接种后6～10周依据卵块数量或每克根中的虫卵数可以进一步确认花生的抗性水平.虫瘿级数、虫瘿数量、卵块数量及每克根中的卵量之间存在着极显著(P＜0.01)的正相关关系.根据研究结果提出了温室中花生抗线虫鉴定的程序方法以8000粒卵/株为适宜接种量,接种后14d依据0～5级的虫瘿分级标准进行初筛,对初筛入选的材料再在接种后6周根据卵块数量或卵量验证其抗性.     

薯蓣根结线虫病的初步研究

 山东省荷泽地区薯蓣上根结线虫病发生严重。分离鉴定结果表明,该病的病原线虫是花生根结线虫Meloidogyne arenaria。该病在每年4月末开始发生,线虫在一年内发生完整的4代,完成一代平均约需要40 d,有明显的世代重叠现象。线虫主要在地表以下20~40 cm的土层内分布和为害。当地种植的4个主要品种中,肿脖温发病最重,明豆子发病最轻。     

三尖杉枝叶粉末防治花生根结线虫病

采用盆栽及大田小区试验,研究了三尖杉Cephalotaxus fortunei枝叶干粉末对花生根结线虫病的防治效果.盆栽试验结果表明,每盆(2kg土)施用三尖杉枝叶干粉末10、15及20 g三种处理,与对照组相比,初侵染相应推迟4、6、10天,并能减少侵染量,降低根结增长率,显著减轻花生根结线虫病病情.大田小区试验结果与盆栽试验结果相似,每小区(5m2)沟施三尖杉枝叶干粉末120、80、50 g,处理后34及53天的2次平均防治效果分别为89%、82%及50%,施药对照10%益舒宝颗粒剂25g处理(相当于45kg/hm2)为74%.综合使用剂量及花生生长情况,建议沟施150kg/hm2三尖杉枝叶干粉为宜.     

万强对花生根结线虫发育的影响及防治效果

利用室内培养和盆栽试验的方法，研究了万强对花生根结线虫（Ｍｅｌｏｉｄｏｇｙｍｅａｒｅｎａｒｉａ）发育的影响，结果表明：万强对胚胎发育无明显影响，但能延缓孵化时间，减慢线虫胚后发育的速度，减低雌虫的比例。田间小区试验表明：万强有减少土中２龄幼虫数量的作用，并有显著的防病增产效果。增产幅度为１９．６６％～２４．８３％。     

蛇麻黄和沙蒿两种典型灌丛对藻类分布的影响

为了解生物结皮中藻类植物与维管植物的关系,通过野外采样和室内固体培养法,研究了古尔班通古特沙漠中蛇麻黄和沙蒿灌丛对藻类分布的影响。结果表明：在两种灌丛内外,藻类种类组成主要表现在优势物种和优势度的变化。藻类物种多样性在两种灌丛内外有一定的差异,蛇麻黄灌丛内藻类物种数及多样性指数显著低于灌丛外（P＜0.05）,而沙蒿内藻类物种数显著高于灌丛外,多样性指数无明显差异。在群落结构中,蛇麻黄灌丛内蓝藻和丝状藻类物种数及优势度显著低于灌丛外（P＜0.05）,但单细胞和球形种类的优势度变化趋势相反且变化极显著（P＜0.01）。沙蒿灌丛内蓝藻、单细胞和球形种类的物种数显著高于灌丛外;蓝藻和丝状藻类的优势度由灌丛内至灌丛外显著升高（P＜0.01）,而绿藻、单细胞和球形种类则相反。在两种灌丛内外,藻类不同类群优势度的变化主要由一些关键物种引起,藻类在这两种灌丛中的不同分布特征可能是由于调节机制不同所致。     

温室快速鉴定花生根结线虫病抗性新方法

为了通过对花生抗线虫鉴定方法的比较,确定更加快速有效的抗性鉴定技术,作者于2002～2003年在佐治亚大学的Tifton试验站进行了温室盆栽试验。结果表明,侵染期幼虫与虫卵均可用于花生抗线性鉴定的温室接种,但与使用虫卵接种相比,以侵染期幼虫作为接种体需要多花3～5d的时间收集幼虫;接种后14d,可以依据0～5级的虫瘿分级标准将供试的4份花生种质区分开来;接种后6～10周依据卵块数量或每克根中的虫卵数可以进一步确认花生的抗性水平。虫瘿级数、虫瘿数量、卵块数量及每克根中的卵量之间存在着极显著(P<0.01)的正相关关系。根据研究结果提出了温室中花生抗线虫鉴定的程序方法:以8000粒卵/株为适宜接种量,接种后14d依据0～5级的虫瘿分级标准进行初筛,对初筛入选的材料再在接种后6周根据卵块数量或卵量验证其抗性。