牛角花齿蓟马为害对紫花苜蓿生长及氮代谢的影响

为了明确牛角花齿蓟马为害对紫花苜蓿生长及氮代谢的影响,测定了不同牛角花齿蓟马虫口密度下抗、感蓟马苜蓿无性系R-1、I-1的受害指数、单株生物量及氮代谢的变化。结果表明：（1）随着牛角花齿蓟马虫口密度的增加,R-1、I-1无性系各接虫处理的受害指数均升高、单株生物量均下降,在相同牛角花齿蓟马虫口密度下,R-1无性系的受害指数及产量损失率均低于I-1无性系。（2）受牛角花齿蓟马为害后,R-1无性系各接虫处理硝酸还原酶活性上升后趋于稳定,硝态氮含量呈先上升后下降的趋势,游离氨基酸含量呈持续上升的趋势; I-1无性系各接虫处理的硝酸还原酶活性呈先上升后下降的趋势,硝态氮含量呈先下降后上升的趋势,游离氨基酸含量上升后趋于稳定或下降。结果说明：硝酸还原酶活性的升高是R-1无性系对蓟马诱导抗性的一种表现,而I-1无性系氮代谢失调是其感蓟马的主要原因之一,因此R-1无性系的适应能力强,受害较轻,对牛角花齿蓟马为害的抗性和补偿生长能力高于I-1无性系。     

施磷对紫花苜蓿光合作用及抗蓟马的影响

为了明确施磷对苜蓿抗蓟马的影响及其相关的光合机制,本试验以西北广泛种植的感蓟马苜蓿品种‘甘农3号’和抗蓟马苜蓿品种‘甘农9号’为材料,在大田蓟马为害高峰期,调查评价了不同施磷水平下苜蓿的受害指数、生长指标和蓟马虫口数量,测定了不同施磷水平下苜蓿的光合气体交换参数、可溶性糖含量。结果表明:施磷后,‘甘农3号’和‘甘农9号’苜蓿的受害指数均显著降低,株高和产量显著增加,蓟马虫口数量无显著变化;净光合速率(Pn)和水分利用率(WUE)显著升高,蒸腾速率(Tr)和气孔导度(Gs)显著降低;苜蓿心叶可溶性糖含量显著升高,但可溶性糖含量与蓟马虫口密度间无相关性,而与受害指数之间存在极显著的负相关关系。施磷有效地增强了苜蓿的光合作用,进而增强了苜蓿对蓟马的耐害性。在大田条件下,通过增施磷肥来控制苜蓿蓟马的危害是一种经济有效的绿色防控措施。     

施氮对苜蓿根茎叶光合产物分配及抗蓟马的影响

为了探究施氮对苜蓿抗蓟马的影响, 本试验在大田网室盆栽条件下, 以‘甘农3号’和‘甘农9号’苜蓿品种为材料, 以牛角花齿蓟马Odontothrips loti为研究对象, 设4个施氮处理(N1, N2, N3, N4)和1个不施氮的对照, 评价不同施氮水平下苜蓿的受害程度, 并测定苜蓿根茎叶生物量和可溶性糖含量。结果表明:1)施氮后2个苜蓿品种的受害指数均升高; 受牛角花齿蓟马为害7 d后, 2个苜蓿品种的受害指数均在N2处理下最高, 分别比对照高39.93%和20.06%; 受害14 d后, ‘甘农3号’的受害指数在N3处理下最大, 比对照高28.51%, ‘甘农9号’的受害指数在N1处理下最大, 比对照高23.97%; 在同一施氮水平下, ‘甘农3号’的受害指数均明显高于‘甘农9号’。2)施氮后2个苜蓿品种根茎叶的生物量增加, 但叶茎比和根冠比降低, 生物量更多向茎秆中分配, 向叶片和根系中分配较少。3)苜蓿叶片中的可溶性糖含量随施氮量的增加而减少, 而茎秆和根系中的可溶性糖含量升高。施氮降低了苜蓿对牛角花齿蓟马的抗性, 促进了苜蓿根茎叶的生长, 但根冠比下降, 致使苜蓿的再生能力和耐虫性下降; 施氮后苜蓿叶片中的可溶性糖含量下降, 使叶片合成防御物质的碳源不足, 进而导致苜蓿对蓟马的抗性降低。     

牛角花齿蓟马为害对紫花苜蓿MDA含量及防御酶活性的影响

为了明确紫花苜蓿对牛角花齿蓟马为害的抗性机理,测定了不同牛角花齿蓟马虫口密度下抗、感蓟马苜蓿无性系R-1、I-1的丙二醛（MDA）含量及防御性酶POD、PPO和PAL活性的变化。结果表明：受牛角花齿蓟马为害后,R-1、I-1无性系的MDA含量均上升,为害第5天时,MDA含量的增加量均与虫口密度呈显著的正相关,且I-1无性系MDA含量的增加量显著高于R-1无性系。R-1无性系的POD、PPO和PAL活性在低虫口密度（1、3头/枝条）下均呈上升趋势,在高虫口密度（5、7头/枝条）下均呈先上升后下降的趋势;I-1无性系的POD和PPO活性均呈先上升后下降的趋势,低虫口密度下PAL活性在为害后期上升,高虫口密度下PAL活性先上升后下降。说明POD、PPO和PAL活性的升高可能是紫花苜蓿对牛角花齿蓟马诱导抗性的一种表现,但R-1无性系对牛角花齿蓟马的抗性高于I-1无性系,在牛角花齿蓟马为害后期其体内POD、PPO和PAL活性仍处于较高水平,所以I-1无性系膜脂过氧化程度也较R-1无性系高,表现为感蓟马。     

苜蓿斑蚜为害对5种苜蓿品种(系)PAL、POD、PPO酶活性的影响

在室内将苜蓿斑蚜人工接种在不同抗性级别的苜蓿品种（系）幼苗上,苜蓿斑蚜为害后的3、7、10 d分别测定了5个品种（系）叶片中苯丙氨酸解氨酶（PAL）、多酚氧化酶(PPO)、过氧化物酶（POD）3种酶活性。结果表明,在试验期内,所有品种（系）叶片中的PAL活性在接虫后随着时间的增加而升高; PPO活性随天数增加呈下降趋势; POD与PAL酶的情况相同,随着为害时间的延长不断升高。HA 3感蚜后3种酶活性明显高于其他品种。     

早秋蚕桑蓟马防治指标研究

在夏伐后的桑园,根据桑藓马虫口密度的不同,将桑叶受害水平发为个等级。利用没等级的桑叶饲有蚕,得出在桑藓马不同为害水平下桑叶和蚕茧的产量,建立了桑蓟马虫日指数（Ｘ）与桑叶产量损失率和茧层量损失率的关系式分别为Ｙｍ＝－０．００５３２＋０．００２９Ｘ,Ｙｓ＝－０．００１３９＿０．０００１１Ｘ根据当地桑树害虫防治与蚕茧产品价格的有关经济数据,得到桑叶早秋蚕期间的防治指标为３级受害水平,即桑叶受桑蓟马为害的     

蓟马危害苜蓿的产量损失及防治指标研究

采用人工接虫的方法,研究了蓟马的虫口密度与苜蓿产量损失之间的关系和防治指标。结果表明,苜蓿干草产量损失率(Y)与20枝条虫量(X)的关系为Y=0.1021X-2.2461,相关系数r为0.9874,两者相关性极显著。按照防治的直接收益与成本,确定了宁夏旱地苜蓿和水地苜蓿蓟马的防治指标,即旱地苜蓿蓟马第1茬的防治指标为560头/100枝条,水地苜蓿蓟马第2茬的防治指标为390头/100枝条,第3茬的防治指标为580头/100枝条。     

小麦品种慢条锈性因素的相关分析和聚类划分

对８２份小麦品种（系）进行大田成株慢锈性鉴定,并通过潜育期、病情指数和千粒重损失率等３个抗性组分的相关分析和品种聚类分析,将供试品种划分为５大类,即高度慢锈性品种、中度慢锈性品种、耐锈性品种、中度快锈笥品种和高度快锈性品种。划分结果与前人的经验划分结果符合率达９２．６８％,分别建立了５个判别函数。对３个抗性发的相关分析结果表明,潜育期与病情指数、千粒重损失率呈极显著负相关,且病情指数对千粒重损失率     

小麦品种（系）抗麦红吸浆虫鉴定技术研究

小麦抗麦红吸浆虫指标的制定是筛选抗虫品种,对麦红吸浆虫实行综合治理的基础工作。通过分析比较危害指数、粒被害率、估计损失率、抗性指数、相对指数及聚类分析等指标鉴定结果,发现以感虫品种为对照,以穗被害率、粒被害率、估计损失率和单穗虫数等多个指标为依据的聚类分析法的鉴定结果最符合客观实际,建议今后在麦红吸浆虫抗性鉴定中推广应用。     

不同葡萄品种对越冬代绿盲蝽的抗性分析

为明确不同葡萄品种对越冬代绿盲蝽Apolygus lucorum的抗性水平,于2012—2014年连续3年系统研究了不同葡萄品种上绿盲蝽的为害情况以及越冬卵量,并分析了绿盲蝽越冬卵量与葡萄受害指数之间的关系。结果显示,每年越冬代绿盲蝽对不同葡萄品种的为害情况均存在显著差异;不同葡萄品种对越冬代绿盲蝽的抗性不同,其中香悦对绿盲蝽抗性最强,抗性指数为5.00,金田美指抗性最弱,抗性指数为1.00;每年绿盲蝽在不同葡萄品种上的越冬卵量均存在显著差异;相关性分析表明,不同葡萄品种受害指数与绿盲蝽越冬卵量之间无显著相关性。研究表明,不同葡萄品种对越冬代绿盲蝽的抗性水平存在显著差异。     

水稻品种对稻瘟病菌慢瘟抗性的研究

1985—1987年,以HA-4、Ba-90-2、红突31、HA84494、1952、V/38、837及早选4号为供试品种,研究了水稻品种的慢瘟抗性。结果表明,病斑大小、单位病斑的产孢量、最终百分病叶面积及病害进展曲线下的面积是慢瘟抗性的4个有效组分。4个组分问彼此高度相关(r=0.8082-0.9741)。就4个慢瘟组分对8个品种作聚类分析,可将供试品种划为8类。HA-4、Ba-90-2、红突31、HA84494及1952为慢瘟品种,V/38为中慢品种,837及早选4号为速瘟品种。以ZC_(15)为代表菌研究的慢瘟品种,对ZC_(13)、ZE_3、ZF_1及ZG_1 4个生理小种呈类似的慢瘟反应,在田间自然诱发试验里,也皆表现为抗病。室内外慢瘟性研究结果高度相关(r=0.9972)。     

20个苜蓿品种对炭疽病(Colletotrichum truncatum)的抗性测定

以20个苜蓿(Medicago sativa L.)品种为材料,研究其对苜蓿炭疽病(Colletotrichum truncatum)的抗性。通过对不同苜蓿品种抗苜蓿炭疽病的室内鉴定,以苜蓿的病叶量作为测定指标并对数据进行聚类分析。结果表明,不同品种抗苜蓿炭疽病能力的强弱不同,通过聚类分析将供试品种划分为4个类群,以ProINTA Patricia和Victoria SPI对苜蓿炭疽病的抗性最好,Defi德福、Lobo路宝、Salado萨兰多、新疆大叶苜蓿和Travois的抗病性最差,其他品种呈中等抗性。     

锐顶镰孢致病性及苜蓿品种间的抗病性研究

 为了探明锐顶镰孢菌对接种后苜蓿种苗的致病性,本研究采用菌饼接种法,将分离自4个地点的15个锐顶镰孢菌株接种于14个紫花苜蓿品种的种子上,接种后14 d 测定相对根长、苗高、发芽率,并计算病情指数。结果表明,参试的15个菌株均显著降低了苜蓿种苗的根长(P<0.05)。总体来看,各菌株之间的致病性有所不同,从苜蓿品种WL-323HQ中分离出来的5号菌株的致病性最强,从WL-525HQ中分离出来的13号菌株的致病性最弱,从WL-525HQ、Legacy、Affinity和Millionaire中分离出来的12号、10号、8号和6号菌株的致病性较强,从Aohan、Farmers、WL-323ML和Dingdian中分离出来的1号、4号、7号和9号菌株的致病性较弱;参试的14个苜蓿品种之间的抗病性也各不相同,Amerimultileaf的抗病性最强,Amerileaf721、Victoria、Powerplant和Legacy的抗病性较强,Sandy、Phabulous、Hunter river和Alfaking的抗病性较弱,Vernal的抗病性最弱。     

Enhanced Resistance to Sclerotium rolfsii in Populations of Alfalfa Selected for Quantitative Resistance to Sclerotinia trifoliorum

ABSTRACT Sclerotinia trifoliorum and Sclerotium rolfsii are pathogens for which similar mechanisms of parasitism have been proposed. This suggested that resistance to these pathogens may be related in a common host plant. This study was undertaken to determine whether selection for quantitative resistance to Sclerotinia trifoliorum in alfalfa also increases resistance to Sclerotium rolfsii as expressed in excised leaf tissues and whole plants. Resistance in excised leaf tissues was evaluated according to the rate of necrosis induced by Sclerotium rolfsii following inoculation with mycelium. Resistance to Sclerotium rolfsii in whole plants was evaluated according to their survival following crown inoculations. Three alfalfa populations previously selected from cv. Delta for quantitative resistance to Sclerotinia trifoliorum exhibited enhanced resistance to Sclerotium rolfsii, in comparison with Delta or with susceptible populations, in excised leaf tissues. When whole plants of Delta and two of these populations, Sclerotinia trifoliorum resistant (STR) and Mississippi Sclerotinia resistant (MSR), were inoculated with Sclerotium rolfsii at 3 to 8 weeks of age, significant (P = 0.01) differences in survival were attributed to plant age at inoculation and alfalfa populations. Survival of both MSR and STR was significantly (P = 0.05) greater than for Delta; the best differential results were obtained by inoculating plants 5 to 7 weeks old. To evaluate relationships of resistance to Sclerotinia trifoliorum and Sclerotium rolfsii over a broader genetic background, additional populations were selected for resistance to Sclerotinia trifoliorum from four other alfalfa cultivars by leaf-inoculation techniques, and this resistance was confirmed by whole-plant inoculations. In excised leaf tissues, all four of these populations also expressed enhanced resistance to Sclerotium rolfsii in comparison with either parent cultivars or populations of comparable size selected at random. These results establish that selection for quantitative resistance to Sclerotinia trifoliorum in alfalfa also confers enhanced resistance to Sclerotium rolfsii as expressed in excised leaf tissues and whole plants. Results suggest, therefore, that genes for quantitative resistance to Sclerotinia trifoliorum and Sclerotium rolfsii in alfalfa are likely to be synonymous, overlapping, or closely linked.     

半裸镰孢致病性及苜蓿品种间的抗病性研究

 为探明半裸镰孢对接种后苜蓿种苗的致病性、筛选抗苜蓿根腐病的品种,本研究把4个来源地的9个半裸镰孢分离物接种于14个品种的紫花苜蓿种子,在接种后第14 d测定苜蓿幼苗的相对根长、相对苗高、相对发芽率和病情指数,评价不同苜蓿品种对半裸镰孢的抗病性及病原菌对苜蓿幼苗致病性的相互关系。结果表明:半裸镰孢菌株和苜蓿品种对相对根长、相对苗高、相对发芽率及病情指数均有显著的影响(P<0.05)。病原菌方面,从苜蓿品种THG-1中分离出来的半裸镰孢的致病性最强,从Aohan中分离出来的半裸镰孢的致病性最弱,从WL-323HQ、Sitel和Siriver中分离出来的半裸镰孢的致病性较强,从Reindeer、Legacy和LM400中分离出来的半裸镰孢的致病性较弱;苜蓿品种方面,Algonguin的抗病性最强,Phabulous的抗病性最弱,Verna、Victoria、Hunter river和Amerimultileaf的抗病性较强,WL-323HQ、Sanditi、Sandy和Amerilea721的抗病性较弱。     

Jasmonic acid induces resistance to economically important insect pests in winter wheat

BACKGROUND: Insect damage induces chemical changes in plants, and frequently these changes are part of a defensive response to the insect injury. Induced resistance was activated in winter wheat using a foliar application of synthetic jasmonic acid. Field trials were conducted to observe effects of jasmonic acid application on some wheat insects. Two wheat cultivars (Cubus and Tommi) were sprayed twice at growth stages (GS) 41 and 59 with two concentrations of jasmonic acid, along with control plots that were sprayed with water. RESULTS: There was a significant difference in the number of thrips and wheat blossom midges (WBM) among treatments in both cultivars. Plants in control plots had higher numbers of thrips and midges than in treated plots. There were higher numbers of thrips in the Tommi cultivar than in the Cubus cultivar, while the latter had higher numbers of WBM larvae than the Tommi cultivar. There was a positive correlation between WBM numbers and infested kernels in both cultivars. This study also indicated that jasmonic acid enhances the wheat yield in sprayed plots compared with control plots. CONCLUSIONS: The results indicate that jasmonic acid induced pest resistance in wheat plants and may act as a resistance mechanism of wheat against insect herbivores. Copyright © 2010 Society of Chemical Industry