水稻品种苗期阶段对白叶枯病的抗性研究

 根据水稻品种各叶期对白叶枯病的抗性表现和强弱程度可分为四类:(1)全期抗病型;(2)全期中抗型;(3)苗感成株抗病型;和(4)全期感病型。可以看出,水稻品种除少数苗感成抗型外,其余三种抗性类型苗期与成株期的抗性反应是一致的。由于中抗、成抗和感病品种各叶期的抗性有随着叶位的升高而抗性增强的趋势,不同抗性品种在苗期阶段抗感对比均较成株期明显。因此,水稻品种对白叶枯病的抗性鉴定采用苗期鉴定方法是可行的。影响水稻品种苗期抗性的因素是:苗龄(叶期)、观察时期、品种与菌株的组合等。     

西南地区小麦品种(系)抗条锈病基因多样性调查

为调查西南地区小麦条锈病抗性、抗病基因位点及其组合多样性,于2013—2014年对以西南地区为主的140份小麦品种(系)进行了成株期、苗期抗病性鉴定和抗病基因标记扫描。成株期鉴定结果显示,2013年贵阳、赫章试验点和2014年贵阳、绵阳试验点都表现为抗病的品种(系)共有50份,其中表现为全生育期抗性的有37份,表现为成株期抗性的有13份;5个抗病基因Yr9、Yr10、Yr15、Yr18、Yr26的分子标记检测结果显示,西南地区小麦Yr26的使用频率最高,为41.4%,Yr9次之为37.9%,Yr10、Yr15、Yr18使用频率较低;抗条锈病基因的组合分析显示,共出现16份基因聚合品种、7种组合类型,其中组合Yr9+Yr26出现频率较高,为5%。表明西南地区的小麦品种(系)以利用全生育期抗性为主,且抗条锈病基因利用较为单一,应发掘和利用新抗条锈病基因及重视多基因的聚合。     

番茄幼苗和成株对寄生疫霉抗性的比较

番茄十一个基因型的幼苗在第一片真叶期于控制条件下接种以寄生疫霉的游动孢子后,按幼苗的死亡情况评价其抗性。各基因型幼苗也移栽于染有寄生疫霉的两处地块,种植至成熟,按植株死亡情况及叶冠萎枯情况评价其成株抗性。商用品种(系)和野生的樱桃番茄11个基因型有10个在苗期和成株期反映出相关的抗性或感性,另一基因型苗期感病,但成株期似为抗病。苗期、成株期的抗性表现均受环境影响。     

关中棉花枯萎病及其防治研究

棉花枯萎病在陕西关中,近几年由局部地区发展到点面发生,蔓延速度和面积已超过黄萎病。一般发病和死苗在30—50%,严重的棉田在90%以上。一些黄萎病区逐渐转为枯、黄萎混合发生区,枯黄萎同株型极为普遍。此病在棉花苗期即表现症状,潛育期为10—20天。1—2片真叶发病率达10—15%;5—6片真叶(蕾期)即会引起大量枯死和萎蔫。土壤致病温度平均在20°—25℃,维持10天以上,发病最烈;28℃以上病势减轻。土壤含水量在60—75%之间,枯萎病发病率最高。每年枯萎病发生消长与5、6月份的温、湿度及降雨量有一定关系。以4—6片真叶期,枯死植株发展较快,开花后期枯死率显著下降,到吐絮期尚有高峯出现。各品种间的枯死规律基本相同;仅有枯死程度上的差异。防治棉花枯萎病主要途径以抗病品种为主。由1956—1961年已鉴定出抗病品种(系)有52-128、鸭棚、147-Φ、57-50、南通二号、F96,F80等。其中确定能在病区生产应用的有52-128,鸭棚,平均降低发病率在30—70%,增产15—40%左右。并发现抗病免疫类型有中棉“嘉定硬子”。远缘杂交材料(353×G 1472)×芙蓉葵353 F_2可作杂交原始亲本材料。在病区增施氮、磷无机肥料,有降低苗期枯萎病的作用。轮作防病在关中采取二年小(?)、玉米轮作倒茬,发病率由原来的85%降低到38%,死苗率由50%下降到20%,有一定防病增产效果。     

黄淮冬麦区区试品种的抗条锈鉴定

对34个黄淮冬麦区区试品种和4个生产对照品种进行了苗期分小种鉴定和成株期混合小种鉴定。结果表明,苗期有44．74％的品种抗条中29号小种,26．32％的品种抗条中31号小种．10．53％的品种抗条中32号小种,仅有1个品种对3个小种均表现抗病。成株期有10个品种表现抗病,其中大部分可能为慢锈型或高温抗锈性品种。     

持久抗条锈小麦品种抗病性特点分析

利用我国１５个小麦条锈菌主要流行小种和致病类型，测定了国内外７个持久抗条锈小麦品种的抗病性。结果表明，尽管不同持久抗病品种苗期抗病谱有很大差异，但成株期对许多供试菌系均表现有效抗性。抗病温度敏感性试验显示，随着培养温度由低温、常温向高温提高，持久抗性品种抗性逐渐增强，表现为反应型和严重度降低。抗病基因分析表明，持久抗病品种不仅含有温敏型微效抗病基因，而且含有成株抗病基因，它们共同对品种持久抗条锈性起作用     

甘薯品种对蔓割病抗性的研究

1984—1987年采用盆苗接种法鉴定890个甘薯品种(系),结果表明:属于高抗和抗病型的41个;中抗型的71个;中感型的261个;感病型和高感型的517个。不同抗性型品种用不不同菌株和不同菌量测定,或在不同气候下重复鉴定,虽会发生不同幅度的抗性变化,但都保持相对稳定的抗病性。同时,用不同抗性型的10个品种分别在盆栽苗期和田间成株期进行抗性鉴定,结果证实了两者间抗性呈极显著正相关。     

水稻抗纹枯病苗期快速鉴定技术研究

 以抗感反应不同的5个水稻品种为试验材料,在人工气候箱、控温室中进行水稻苗期抗纹枯病接种试验,并与田间相应的成株期抗性试验进行比较,研究水稻苗期快速鉴定技术。结果表明:85%的相对湿度为纹枯病菌侵染危害水稻苗期植株的适宜湿度;苗期5个水稻品种对纹枯病抗性差异极显著,可将其分为相对感病(Lemont、武育粳3号)和相对抗病(YSBR1、Jasmine85、特青)2大类;接种叶龄对发病程度有显著的影响,5个品种在四叶期接种时的平均病级显著高于五叶期接种的平均病级;苗期水稻品种间抗感差异小于田间鉴定试验结果,但两者间品种抗感趋势基本一致。苗期快速鉴定技术可用于大规模水稻品种(组合)的抗性筛选或初步鉴定。     

远缘杂交衍生后代中筛选小麦抗条锈病新抗源

 针对小麦远缘杂交的一系列衍生系,在陕西杨凌人工条锈病圃(CYR32和CYR33混合小种)选择压力下,兼顾抗病性与农艺性状,经过连续6年系统选择,筛选了106份远缘杂交衍生后代选系。在此基础上,通过杨凌人工混合小种接种鉴定圃和甘肃天水自然诱发鉴定圃,对其进行成株期抗条锈病鉴定;利用当前流行小种CYR32、CYR33和G22-9进行苗期分小种鉴定;结合Yr26的分子标记检测评估抗源价值。建立基于成株期与苗期抗病性鉴定相结合,异地抗病表型鉴定与分子标记筛查的抗源筛选和评价体系。结果表明:106份远缘杂交后代衍生系中,筛选出54个能够抵抗包括G22-9在内的多个流行小种的选系;结合标记筛查结果,筛选到36份不含Yr26的抗病材料,其中4份为全生育期抗条锈病性类型(ASR),32份为成株期抗性(APR)类型。推测这些抗性选系可能具有抗条锈病新基因。     

小麦品种(系)对叶枯病的抗病性鉴定研究

1989-1991年连续两年对62个小麦品种(系)进行抗叶枯病鉴定,供试各品种(系)间抗病性有明显差异,但无免疫类型,且中抗、中感类型较多,抗病类型较少;综合评定结果表明,尉氏132、鲁215953、郑州83203等5个品种(系)为抗病类型,占8.07％;豫麦2号、陕农7859、西安8号等31个品种(系)为中抗类型,占50％;豫麦17号、冀麦5418等21个品种(系)为中感类型,占33.87％;感病和高感类型,占8.6％。在研究品种(系)抗性与生物学特性的关系中,发现品种(系)抗性与植株形态,如株高、单茎叶面积等有一定相关性。     

东北春小麦根腐病防治研究

东北春小麦根腐病Bipolaris sorokiniana(Sacc.ex Sorokin)shoem.是推广抗锈良种后出现的问题。苗期引起根腐,成株期发生叶斑、穗腐和黑胚粒。病菌有两种类型定名为H_1和H_2型,田间前者占优势。病种子和病株残体是田间发病的初侵染源,种子消毒和轮作可减轻苗期根腐并提高种子出苗率。根腐病菌寄主范围很广,来自29种禾本科杂草和作物上的菌株均能侵染小麦。温室和田间试验结果,小麦灌浆乳熟期发病对产量影响最大,也是形成黑胚粒时期。目前尚无免疫品种,农家种和半冬性品种比国外品种和硬粒小麦抗病,Triticum timopheevii表现高抗。采取种植抗病品种结合种子消毒、轮作、增施氮肥等综合防治技术是防治小麦根腐病的有效措施。     

Differential expression of resistance to powdery mildew incited by race 1 or 2 ofsphaerotheca fuliginea inCucumis melo genotypes at various stages of plant development

Thirty-nine genotypes ofCucumis melo (plant introduction entries, open-pollinated cultivars and F₁ hybrids) were evaluated for resistance to powdery mildew under either natural field conditions or artificial inoculation in growth chambers at the cotyledonary stage and the 2-true-leaf stage. Results confirmed that susceptibility in cotyledons was not necessarily associated with susceptibility in either true leaves in growth chambers or adult plants in the field. However, resistance at the 2-true-leaf stage in growth chambers was highly correlated with resistance of field-grown plants. Results also showed that 20 muskmelon genotypes resistant to race 1 at the cotyledonary stage were also resistant at the 2-leaf-stage and as adult plants in the field. The same was true for ten genotypes with race 2 inoculations. Because muskmelon genotypes expressing resistance in cotyledons were also resistant in true leaves in growth chambers or the field, the use of plants at the cotyledonary stage is recommended for screening for powdery mildew resistance caused by race 1 or race 2 ofS. fuliginea. When cotyledons are susceptible, screening should be done at the 2-true-leaf stage.     

Development of Fusarium Wilt-resistant Genotypes in Safflower (Carthamus tinctorius)

Screening of 51 promising safflower germplasm lines in Fusarium wilt-infested plots resulted in identification of highly wilt-resistant selections viz., 86-93-36A, 237550, VI-92-4-2 and II-13-2A, with some moderate resistance in HUS-305. Progenies from crosses made using these resistant lines were tested for their reaction to wilt. F₁ progenies from 86-93-36A × 237550 and 86-93-36A × II-13-2A recorded zero wilt incidence, while 237550 × 86-93-36A was highly resistant to the Rajendranagar geographical isolate. The reaction for the three progenies showed stability for wilt resistance with no segregation until the F₇ generation. Geographical isolates of Fusarium oxysporum f. sp. carthami (Foc) were collected from different safflower growing regions and tested for their pathogenic variability on six host differentials under glasshouse conditions. Based on the reaction of the differentials, the Foc isolates were grouped into four biotypes. The three resistant progenies were tested for their reaction to the four biotypes. The progeny of cross 86-93-36A × 237550 showed an immune reaction to all the biotypes, except for a highly resistant reaction to biotype 3. The progenies of the two other crosses (86-93-36A × II-13-2A and 237550 × 86-93-36A) exhibited immune reactions to biotypes 2,3 and 1,3, respectively, and were highly to moderately resistant to biotypes 1,4 and 2,4, respectively.     

棉花抗枯萎病品种抗性稳定性初步研究

病原学研究证明新疆哈密瓜花叶病主要由西瓜花叶病毒2号(WMV-2)、黄瓜花叶病毒(CMV)、南瓜花叶病毒(SqMV)引起,大田发病以 WMV-2为主。研究证明 WMV-2的介体主要为麦二叉蚜、苜蓿蚜、桃蚜、伞形蚜,其次是麦长管蚜、叶虫甲。CMV 的介体有桃蚜、苜蓿蚜、伞形蚜。SqMV 的介体为叶(虫甲)。哈密瓜在田间感染病毒的时间与上述蚜虫开始迁飞的时间有相关性。有翅蚜的发生、消长与田间发病成正相关。6月份降雨量与病害发生,有翅蚜消长成反相关。据五家渠、昌吉等地区调查,WMV-2的自然寄主有蚕豆、豌豆、西葫芦,它们的发病时间比甜瓜早。     

玉米丝黑穗病防治研究

玉米丝黑穗病是白城地区的重要病害,一般发病率为3—5%,重者高达30%以上,是生产上急待解决的问题。其症状以正常型为主,有时出现矮化型、矮化丛生型和多分蘖型等特异症状。病株以雌穗为黑穗、雄穗为健穗及雌雄穗皆为黑穗者居多。病穗上自然脱落的厚垣孢子萌发率高,病穗内的萌发率明显降低。此病为系统侵染病害,种子及土壤均可带菌传病,以土壤带菌为主,属土传病害。厚垣孢子在土壤里能存活三年,土壤带菌量越多,菌土覆盖种子越厚,发病率越高。丝黑穗病菌侵染玉米幼苗时间较长,从种子萌芽到四叶期最易侵染,五叶期后,侵染明显下降,八叶期后不再侵染。在幼苗叶片上接菌不能侵染致病。玉米丝黑穗病菌不能侵染高梁。高梁丝黑穗病菌能侵染玉米,但侵染率甚低。侵染玉米后的病菌,不再侵染高梁,只侵染玉米,且致病力明显增强。两菌是同一菌种的不同生理型。用来自九个省、市的丝黑穗病菌接种于不同抗性的自交系鉴定寄主,其致病力不同,陕西和新疆的致病力弱,辽宁和吉林的致病力强。在田间人工接种条件下,鉴定了二百余份自交系和杂交种的抗病性,品种间有明显差异,高抗的近于免疫,高感的发病率在90%以上。抗病性遗传规律表现为双亲高抗的,其后代亦抗,以母本的抗病性起主导作用。选百余种农药处理种子,筛选结果:个别药剂防效有高达70%以上者,但年度间效果不稳定,多数药效稳定在50%左右。     

Identification and characterization of the <Emphasis Type="Italic">Enterobacter</Emphasis> complex causing mulberry (<Emphasis Type="Italic">Morus alba</Emphasis>) wilt disease in China

Mulberry wilt disease (MWD) was recently identified in Hangzhou, Zhejiang province, China. Typical symptoms of the disease are browning of vascular tissues, leaf wilt, defoliation, and tree decline. Unlike the symptoms of bacterial wilt disease caused by Ralstonia solanacearum, symptoms of MWD generally started from the bottom of the plants and moved upward. In inoculation experiments, four selected MWD strains caused mulberry shoot leaf wilt, discoloration, and defoliation. They also induced whole plant leaf wilt, defoliation and dark brown discoloration of vascular tissue. Based on Biolog metabolic profiles, fatty acid methyl ester analysis (FAME) and sequence analysis of the partial 16S rDNA and rpoB genes four MWD strains were identified as members of the genus Enterobacter. The 16S rDNA and rpoB gene sequences revealed a close relationship among two isolates, R2-2 and R6-2, and the E. asburiae type strain JCM6051. The isolates showed >98% similarity to E. asburiae JCM6051 in their rpoB gene. These results indicated that isolates R2-2 and R6-2 belonged to E. asburiae. No similarity in 16S rDNA sequences above 97% was found between either of the remaining isolates, R11-2 or R18-2, and any recognized Enterobacter species, suggesting that the two isolates may represent novel Enterobacter species. rpoB gene similarity values between the isolates and Enterobacter spp. type strains were <98%, providing further evidence that the two isolates may represent a novel species within the Enterobacter. The causal agent for MWD was previously reported to be E. cloacae, however, this study found that other Enterobacter spp. (E. asburiae and Enterobacter sp.) also cause MWD.     

烟草不同发育阶段对赤星病的抗性表现与综合防治技术

人工接种结果表明，随着烟叶自下而上逐渐成熟、衰老，抗病性下降。不同抗性类型的品种，其绿色叶片对病害均表现免疫或近免疫，近成熟叶片高抗，成熟衰老叶片表现为感病，与品种田间抗病性结果一致。田间结果表明，采用增施钾肥、适时打顶和下部叶片近成熟期摘除1～3片底脚叶等措施，提高烟草品种抗病性、配合有效的农药品种综合防治烟草赤星病，在重病区布局抗病品种能有效地推迟病害的发生时期，减慢病情的发展速度，且能减少农药施用量和施用次数，减少环境污染。     

Recovery of Young Olive Trees from <Emphasis Type="Italic">Verticillium dahliae</Emphasis>

Natural recovery from wilt disease symptoms was evaluated in young olive trees root dip inoculated with Verticillium dahliae in a growth chamber over a 12 week period and, later on, when the trees were transplanted in a V. dahliae-free soil in a lathhouse during a period of 127 weeks. Recovery in an individual tree was considered when a plant showed symptom remission after having reached a maximum value of symptom severity. Recovery accounted for 53% of 464 trees that showed wilt symptoms during observations in the two environments. The remaining trees died. Recurrent wilt symptoms were not observed in recovered trees, and recovery was usually accompanied by the production of new green tissues. Recovery was clearly higher in trees inoculated with a non-defoliating (ND) isolate (86.4%) of the pathogen than in those inoculated with a defoliating (D) isolate (23.9%). The percentage of recovery and the level of resistance were significantly correlated. Recovery accounted for 92.1% of the cases in resistant and moderately susceptible cultivars, reaching 100% in plants inoculated with the ND isolate (Table 2); meanwhile it was three times lower (30.1% of the plants) in susceptible and extremely susceptible diseased trees. In the lathhouse, periodical tissue isolations for monitoring the progress of infections over a period of 127 weeks in recovered trees, showed that the pathogen could only be isolated from trees 19 weeks after inoculation. Pathogen isolation was significantly higher from susceptible and extremely susceptible cultivars (84.6%) than from resistant and moderately susceptible ones (33.3%). Results showed that if a tree overcomes infection by pathogen from a single inoculation, and it is able to begin a recovery process, it will not express wilt symptoms again in a pathogen-free environment. The pathogen remained inactive or dead over time in recovered trees. Thus, new infections from rootlets would be necessary for new symptom expression. Recovery from Verticillium wilt is an important natural mechanism that occurs in a high percentage of infected olive trees, and can complement the resistance of the cultivar, particularly in conditions of low inoculum densities of low virulence isolates of the pathogen in the soil.     

棉苗黑斑病的发生条件及其防治途径

棉苗黑斑病的致病菌在关中棉区初步认为是 Alternaria tenuis Nees 与棉成株期叶片上的致病菌不同。病菌孢子借气流传布。种子带菌率虽然很高,但诱发苗病率却很低,因此,种子消毒或采用轮栽来控制这个病害,是不能达到预期效果的。病害发生与棉苗受冻、强风对棉苗的伤害以及棉苗阶段发育有密切的关系。各年发病期有早有晚,但以真叶出现时为易感阶段。本文阐述了棉苗生育阶段、气候条件与发病的关系,为预测病害发生的物候与气象参考条件提供了资料。棉株伤害与发病有关系,建议在生产上适当降低播种量,提高播种质量,适期早疏苗、早间苗;以减轻由于伤损而导致病害侵染。品种与病害发生的关系不显著。试验证明,使用波尔多液加1059于降温前喷射效果较好。     

Variation in susceptibility of lettuce cultivars to fusarium wilt caused by Fusarium oxysporum f.sp. lactucae

Lettuce cultivars adapted to Californian growing conditions were screened for resistance to fusarium wilt caused by Fusarium oxysporum f.sp. lactucae in order to determine if differences in susceptibility among currently grown cultivars might contribute to management of this disease. Based on a preliminary evaluation of 46 cultivars, eight that were among the most resistant of their horticultural type (iceberg, romaine or leaf) were selected for further testing. The relative susceptibility of these cultivars was assessed by: (i) root-dip inoculation, (ii) sowing seeds into infested potting mix and (iii) transplanting seedlings into an infested field. Evaluations of disease severity showed that both methods (i) and (ii) produced cultivar rankings that were significantly correlated with rankings from field trials [method (iii)]. Two romaine and two leaf cultivars were highly resistant to fusarium wilt (mean disease severity rating of ≤1·3 on a 1–4 scale) under all test conditions. Other romaine and leaf cultivars, however, were highly susceptible in root–dip tests, so there was no consistent association between cultivar type and susceptibility to fusarium wilt. Likewise, there was considerable variation in susceptibility to wilt among iceberg cultivars, but all were significantly more susceptible than the most resistant romaine and leaf cultivars.