十字花科根肿病研究进展

总结了十字花科作物根肿病病原菌的分化、生物学特征、侵染方式、侵染症状、检测技术以及根肿病病害发生规律、抗病育种和防治方法,并展望了我国十字花科作物根肿病的研究方向。     

芸薹根肿菌（Plasmodiophora brassicae）单孢分离接种及生理小种的鉴定

芸薹根肿菌(Plasmodiophora brassicae)单孢分离接种方法曾有报道,本试验改进了国外单孢分离技术.将休眠孢子悬浮液稀释到1个/0.5 μL,滴在一块消过毒的载玻片上,放置在显微镜下反复检查,以确保它精确只含有一个孢子.用微管将孢子吸入接种在2日龄白菜幼苗根毛上,营养液培养3周.为使其更接近田间发病环境条件,后期将疑似发病根在无菌土中继续进行病菌增繁.该方法能够有效地加快病菌繁殖感染,提高单孢分离接种成功率.对不同地区病菌进行大量单孢分离接种.本试验对3个地区的病菌单孢接种共950株,接种成功27株,使用Williams根肿病菌鉴别寄主鉴定,共9个生理小种.     

蜡蚧轮枝菌与农药混配防治甘蓝蚜的研究

利用蜡蚧轮枝菌MZ041024菌株不同浓度的孢子液,与吡虫啉、灭多威、阿维菌素、乐斯本4种不同浓度的化学农药混配对甘蓝蚜防治效果的试验研究,结果表明,蜡蚧轮枝菌MZ041024菌株孢子液在4 900～4.9亿个/ml浓度对甘蓝蚜具有一定的防治效果,随着浓度增加而防效提高,0.49亿个/ml和4.9亿个/ml浓度时效果最好,死亡率达64.69%.在分生孢子液为0.49亿个/ml与4种不同浓度的化学农药混用增效比较中,吡虫啉最高增效9%,与灭多威等混用则表现出拮抗作用.因此从生物防治和IPM等方面来看, 蜡蚧轮枝菌MZ041024菌株具有重要的研究价值和开发前景.     

甘蓝夜蛾赤眼蜂滞育研究

寄生在麦蛾(Sitotroga cerealella)卵内的甘蓝夜蛾赤眼蜂(Trichogramma brassicae)在河北衡水地区田间能进入滞育越冬。当日均温度从15℃降低到5℃,田间诱导滞育率降低,多数个体在进入滞育虫态前死亡。实验室,采用变温和恒温方法均能诱导甘蓝夜蛾赤眼蜂滞育,在11℃恒温诱导卵期和前期幼虫赤眼蜂30d滞育率分别达到84％和82.5％;10℃恒温诱导前期幼虫和中期幼虫赤眼蜂30d,滞育率达到92.5％。     

白菜黑斑病菌（Alternaria brassicae）毒素钝化物的初步研究

通过３０种化合物对白菜黑斑病菌Ａｌｔｅｒｎａｒｉａｂｒａｓｓｉｃａｅ毒素钝化作用的研究。结果表明：Ｎａ＋、碱性物质和ＫＭｎＯ４。对毒素具有很强的钝化作用，而且随着浓度的提高，钝化作用增强，钝化物在离休叶片上的防效为６３～１００％；２０００ｍｇ／Ｌ的化合物对白菜黑斑病分生孢子萌发有较强的抑制作用，但对菌丝生长没有影响。     

Tillage intensity effects on soil properties and crop yields in a long-term trial on morainic loam soil in southeast Norway

Many tillage studies focus primarily on grain crops, whereas other important agricultural crops receive little attention. This paper presents yield results for various crops grown in the tenth to sixteenth year of a long-term tillage trial on loam soil in southeast Norway. Traditional plough tillage was compared with deep and shallow tine cultivation and with minimum tillage, and the residual effects of tillage were measured in the seventeenth and eighteenth years. Soil bulk density, air permeability and other soil conditions were found to be favourable for crop growth on all treatments in the tenth year. The yield levels of cereals (Hordeum vulgare L., Triticum aestivum L. and Avena sativa L.) and potatoes (Solanum tuberosum L.) showed consistent increases of 2–8% with declining tillage intensity, whereas yields of fodder beet (Beta vulgaris L.) were highest after plough tillage. The latter result was thought to be due to lower soil temperatures under reduced tillage. Yields of brassica crops were greatly affected by tillage intensity, owing to a marked reduction of clubroot (Plasmodiophora brassicae Wor.) infection with reduced tillage. Average yields for these crops were 23%, 52% and 59% higher with deep tine cultivation, shallow tine cultivation and minimum tillage, respectively, than with plough tillage. The effects were particularly dramatic in the case of fodder rape (Brassica napus L. ssp. oleifera Sinsk. f. biennis Reichb.) and cabbage (Brassica oleracea L. var. capita L.). Liming raised the yields of some brassica crops but did not influence the effect of tillage.

Soil acidity was measured twice during the trial period and again in the second residual year, and showed values which were 0.1–0.3 pH units lower with reduced tillage than with plough tillage. This rules out the conclusion that the effect of tillage on clubroot was associated directly with acidity. Positive residual effects of reduced tillage systems were found on the yields of both brassicaceous and gramineous crops. Reduced tillage intensity may thus be recommended for all crops studied, with the exception of fodder beet, on morainic loam soils of southeast Norway.     

某些培养条件对甘蓝夜蛾核型多角体病毒离体增殖的影响

不同培养条件对甘蓝夜蛾核型多角体病毒 （ Ｍｂ Ｎ Ｐ Ｖ） 在同源寄主细胞系 Ｍｂ９３１１０４ 中增殖的研究。结果表明, 培养基种类、细胞密度和细胞龄期影响 Ｍ ｂ Ｎ Ｐ Ｖ 在细胞系中的增殖, 引起细胞感染率和多角体产量显著的差异。使用 Ｔ Ｃ—１００ 昆虫组织培养基, 细胞密度为３×１０５ｃｅｌｌｓ／ｍ Ｌ的对数生长期的细胞接毒最适于 Ｍ ｂ Ｎ Ｐ Ｖ 的增殖, 条件培养基对该病毒在细胞系中的增殖没有显著影响。     

甘蓝夜蛾核型多角体病毒杀虫剂的制备及田间防治试验

应用活体增殖病毒 ,制备甘蓝夜蛾核型多角体病毒杀虫剂乳剂 ,室内对 4龄甘蓝夜蛾幼虫的毒力测定 ,其LD₅₀为9.42×10³PIB/头。田间防治效果表明 ,采用1.0×10¹¹PIB/hm² 和3.0×10¹¹PIB/hm²的剂量防治甘蓝夜蛾的效果都在70%以上。乳液的稳定性较好 ,粘着性较强     

芸薹链格孢菌孢子萌发及附着胞形成的初步定量研究

采用常规流行学方法研究了芸薹链格孢菌的孢子萌发及附着胞形成.结果表明:一般浸入水中2h后就有少量孢子萌发,10 h孢子萌发率可达90％以上;孢子萌发时各个细胞均可萌发形成芽管,向不同方向伸长,形成附着胞,20 h附着胞形成率可达50％以上;花粉和叶面物质对孢子萌发有促进作用;孢子抗干燥能力较弱,萌发孢子只须经4h干燥即可完全丧失存活能力;芸薹链格孢菌孢子萌发及附着胞形成的温度范围均为10～25℃,15℃为孢子萌发及附着孢形成的最适温度,温度达40℃后孢子不再萌发.     

河南省大白菜根肿病菌生理小种鉴定

为了明确河南省大白菜根肿病菌的生理小种类型,从新野县十字花科蔬菜种植基地采集2份大白菜根肿病菌样品(XY-1为原始菌,XY-2为新引菌),采用菌液注射接种法,利用Williams和ECD 2套鉴别系统分别对其进行生理小种鉴定。结果显示,采用Williams鉴别系统鉴定的2份大白菜根肿病菌生理小种相同,均为4号生理小种;采用ECD鉴别系统鉴定的大白菜根肿病菌生理小种明显不同,原始菌XY-1为ECD16/15/31,新引菌XY-2为ECD21/31/31,后者较前者的致病性更强。以上结果表明,Willams鉴别系统有一定的局限性,当病原菌致病力强于4号生理小种时无法区分,而ECD鉴别系统由于所用寄主数量及种类较多,可以将4号生理小种进一步区分为不同的类型,鉴定结果更为精确。