不同玉米自交系耐深播能力的差异分析

以45个玉米自交系为材料,在播深10 cm和15 cm条件下,研究了出苗率、根数、根长、中胚轴长、胚芽鞘长、中胚轴和胚芽鞘之和、苗长与玉米耐深播性的关系。结果表明,随着播深的增加,根长、中胚轴长、胚芽鞘长、中胚轴和胚芽鞘之和大体呈增加趋势,而出苗率、根数、苗长呈下降趋势。不同播深条件下出苗率和胚芽鞘长度的变异系数较大;而根长、根数和中胚轴的变异系数较小。在10 cm播深条件下的出苗率与胚芽鞘长、根长和苗长显著相关,而15 cm条件下的出苗率与中胚轴长、中胚轴和胚芽鞘之和、根数、根长、苗长显著相关。15 cm播深条件下的鉴定结果可以反映不同品种的耐深播能力。因此,在15 cm条件下,用出苗率、根数、根长、中胚轴长、中胚轴和胚芽鞘之和以及苗长按耐深播性强弱将45份自交系分成3组;同时,将45份自交系划分为Lancaster、四平头、PA、PB、BSSS和旅大红骨共6个亚群,其中Lancaster（Lan）、四平头(SPT)、PA的出苗率、根数、根长、中胚轴长、中胚轴和胚芽鞘之和以及苗长较高,含有较多耐深播系和中等耐深播系,为重要的耐深播种质类群。     

外源赤霉素对不同耐深播性玉米自交系的深播缓解效应

为探讨不同浓度的外源赤霉素(GA)对深播胁迫下玉米种子萌发、幼苗生长的影响,综合评价GA对深播的缓解效果,以2份深播敏感自交系(‘吉853’和‘自330’)和2份耐深播自交系(‘N192’和‘Mo17’)为试材,于其苗期在2种不同深播(15、20 cm)胁迫下施加4种不同浓度外源GA。结果表明:(1)深播胁迫下出苗率、苗长、根长显著降低,中胚轴长、胚芽鞘长、中胚轴和胚芽鞘长之和,胚芽鞘中的SOD酶活性,中胚轴、胚芽鞘中POD、CAT酶活性及木质素含量显著升高,其变化率(RC)介于-75.86%～100.19%。施加外源GA后幼苗各性状增辐达4.25%～389.06%。(2)用2份深播敏感自交系对外源GA的最佳浓度进行筛选,15 cm和20 cm深播胁迫下分别施加4.0 mg·L~(-1)和6.0 mg·L~(-1)外源GA的缓解效果最佳,隶属函数值分别为0.602和0.598。(3)最佳浓度下比较分析2种耐深播性不同玉米自交系的生长参数和生理特性,表明外源GA可缓解深播对玉米幼苗的胁迫,外源GA对耐深播性不同玉米自交系的敏感程度不同,表现为吉853自330Mo17N192。(4)利用主成分与热图分析玉米萌发期深播性鉴定的三级评价指标,出苗率、中胚轴长、中胚轴和胚芽鞘长之和是主要的评价指标,中胚轴中SOD、POD、CAT活性及中胚轴、胚芽鞘中木质素含量可作为二级评价指标,根数和苗长可作为三级评价指标。     

玉米圆斑病防治研究

目前吉林省推广的玉米骨干自交系吉63果穗上发生的穗腐症状是由Hel-minthosporium carbonum Ullstrup侵染引起的圆斑病。从病斑形态和培养性状与小斑病菌迥然不同。经温室苗期和田间成株期人工接种证明,圆斑病菌除为害吉63和少数自交系外,不侵染T型、M型等不育系及多数正常系玉米的果穗。从果穗抽出到灌浆期是圆斑病菌侵染发病的关键时期。病菌主要在病株残体里以菌丝体越冬,已腐烂的病组织则丧失生活力。六年共鉴定655份自交系、品种及杂交种,有184份材料的果穗感病,以吉63及其选系后代发病最重。经测定吉63感染圆斑病是由隐性感病基因所控制。     

不同基因型玉米自交系苗期根系抗旱性向水性及解剖结构研究

试验旨在研究旱胁迫下不同基因型玉米自交系苗期根系形态、生理生化、解剖结构的差异变化,为玉米自交系抗旱种质的筛选提供可借鉴的指标、方法,为玉米自交系苗期根系抗旱遗传机理研究提供依据。试验选用了14份玉米自交系,采用PEG-6000胁迫处理,测定玉米自交系苗期13个与抗旱紧密相关的根系形态与生理生化指标,并通过方差分析、关联分析及聚类分析,对各自交系的抗旱性进行综合评价,并对其中两个抗旱性差异明显的自交系,通过石蜡切片-显微镜观察根系横切面结构的差异。结果表明:干旱胁迫下,不同玉米自交系苗期的单株根干质量、单株地上部干质量、根系长度、根直径、根伸长速率、根失水率、根系还原力均呈不同程度的下降趋势,根系可溶性糖、脯氨酸均呈不同程度的上升趋势,且不同自交系的变化幅度差异较大。随着诱导物倾斜角的增大,不同自交系根系的向水性弯曲增强,不同自交系间的差异较大,高湿度梯度条件下,自交系Mo17向水性弯曲较对照增加134%,增加幅度最大,WN897向水性弯曲增加20%,增加幅度较小。利用不同抗旱指标的加权抗旱指数,综合评价不同基因型玉米自交系的抗旱性,并将14个玉米自交系种质聚类划分为强抗旱型、中抗旱型和旱敏感型、高旱敏感型4个抗旱级别。石蜡切片结果显示,抗旱性差异明显的自交系根系解剖结构差异较大,抗旱性自交系昌7-2皮层占根系直径比例较低,不抗旱自交系WN897皮层占根系直径比例大于昌7-2,且WN897的导管直径较大。结论:采用方差分析、关联分析及聚类分析等相结合的方法对不同玉米自交系苗期抗旱性进行评估,可以较好地揭示根系性状与抗旱性的关系。根系还原力、根系可溶性糖、根系长度、根向水性对干旱胁迫的反应较其他指标敏感,可作为玉米苗期的抗旱能力和抗旱自交系选育时优先考虑的鉴定指标。旱胁迫下,抗旱性差异明显的玉米自交系根系解剖特征差异显著,强抗旱型自交系苗期根系皮层厚度较小,皮层占根系直径比例较低,根系导管直径也较高旱敏感型自交系小。     

玉米丁布对玉米丝黑穗病菌抗性关系的研究

本文首次探索了玉米植抗素丁布对玉米丝黑穗病菌的抗性作用。丁布从玉米苗中提取纯化后,并经薄层色谱分析,紫外和红外色谱鉴定。由分离所得并经回接证实的病菌菌株,在培养液中加丁布含量40微克/毫升时对病菌生长有显著抑制作用;病理学组织切片也获得证实。试验结果表明丁布是一种抑制玉米丝黑穗病菌生长的抗生物质,以抗、感比较稳定的玉米自交系测定接种40天的中胚轴丁布含量与发病率相关程度提高。测得玉米自交系室内萌发第四天的胚芽含丁布量与发病率有极显著负相关(r=-0.9425,p=0.01)。此法可作为一种快速鉴定玉米抗性的辅助手段,它可节约时间和空间,准确性好。     

八重樱不同器官除草活性研究

为了明确八重樱不同器官的除草活性,为进一步开展活性化合物的研究提供依据,以生菜、黄瓜、反枝苋、苘麻、小麦和稗草为受体植物,采用琼脂混粉法进行了室内活性测定。结果表明,八重樱的不同器官粉末在10 g/L的添加浓度下对各受体植物幼苗的生长均具有不同程度的抑制作用,且普遍对胚根(或种子根)生长的抑制效果高于对胚轴(或胚芽鞘)生长的抑制。其中,以根、叶和花器官表现出的抑制活性最强,而茎的抑制效果则相对较弱。6种受体植物幼苗的胚根对八重樱各器官所表现出的敏感性以生菜、反枝苋最高,黄瓜和苘麻次之,小麦及稗草相对较低。而它们的胚轴所表现出的敏感性以生菜和苘麻最高,小麦、黄瓜和反枝苋次之,稗草最低。说明八重樱各器官,特别是果实、叶和花中均含有高除草活性物质。     

小麦胚芽鞘与耐深播抗旱研究进展

根据作者多年试验观察,综述澳美欧亚非30多个国家相关研究可知,胚芽鞘长、细、硬、快的小麦品种耐深播、抗旱、立苗好.小麦的“地中茎”由上胚轴组织派生且位于胚芽鞘基之上.小麦无中胚轴、无“根茎”.实证双胚苗的第二胚芽鞘自然开裂,并图释深播地中“拨节”现象值得研究者关注.小麦品种间胚芽鞘遗传长度变幅在1.5～ 18.0 cm,胚芽鞘长度的生理变异及环境变异小于品种间变异.多数接秆基因都缩短鞘长,但鞘长基因加性遗传,有育成矮秆长鞘、出苗力强、苗期抗旱、长势壮的新品种的报道.长胚芽辅品种的胚较大,这涉及到小麦脂肪优质育种的问题.建议:(1)尽快摸清中国的小麦长鞘品种资源,协商制定中国小麦胚芽鞘长与鞘色的描述标准;(2)加大常规育种中F2代的播量并加大播深,以便早代汰除出苗力差的个体;(3)强制描述小麦品种的鞘长,鞘色及批售种子的鞘长.     

玉米矮花叶病毒对不同抗性玉米自交系侵染及其运转的研究

 本文以抗病自交系黄野四-3、感病自交系8112和Mo17、耐病自交系478为材料,采用直接组织斑免疫测定法(IDDTB)和酶联免疫吸附测定法(ELISA)结合生物学症状研究了玉米矮花叶病毒对玉米的侵染及其运转规律,试验表明玉米抗玉米矮花叶病毒主要是抗系统传导,其次抗病毒增殖和细胞间扩展,但不抗侵入。     

利用GFP荧光标记比较大丽轮枝菌对抗/感马铃薯品种的侵染过程

为了对马铃薯黄萎病菌的系统侵染进行研究，本研究首先建立了用于观察大丽轮枝菌侵染马铃薯过程的培养皿滤纸体系，在此基础上利用带有GFP标记的大丽轮枝菌对不同抗性水平马铃薯根系侵染过程进行了比较研究，结果表明：马铃薯根系在浓度为10⁷个·mL^-1的大丽轮枝菌分生孢子液中浸泡处理2 h后，分生孢子可附着在抗/感马铃薯根系的根毛上，单个视野中感病品种根系上分生孢子附着平均数量为65个，显著高于抗病品种根系上附着的分生孢子数量(23个);接种12 hpi,根系上附着的分生孢子开始萌发，但抗/感品种根系表面孢子的萌发率无显著差异；接种3 dpi后，菌丝体能够突破根系表皮，进入细胞间隙，但感病品种根系中菌丝的扩展速度更快，并在7 d后到达根系的维管束内部；而抗病品种则在接种9 dpi,在维管束内才能够观察到绿色荧光信号；接种10 dpi,感病品种根系中可见新的分生孢子梗和分生孢子形成，而抗病品种中未见有分生孢子的形成。接种30 dpi,感病品种地上部茎杆中定殖的病原菌量是抗病品种的5倍以上；同时，感病品种叶柄中的病原菌数量也显著高于抗病品种。     

黄瓜白粉病菌在不同抗性黄瓜材料上的侵染过程

白粉病是黄瓜生产中发生普遍,危害严重的主要病害之一。pm5.1和PM5.2是黄瓜上的2个白粉病抗性位点,本文对7份不同抗病基因型的黄瓜自交系进行了黄瓜白粉病抗性鉴定,并开展了黄瓜白粉病菌侵染过程的研究,对侵染后12、24、72 h的萌发率、菌丝形成率及菌落形成率等进行了分析。结果表明,当基因型为PM5.1PM5.1 pm5.2pm5.2时,黄瓜病情指数最高,表现为高感白粉病;当基因型为PM5.1PM5.1PM5.2 PM5.2和pm5.1pm5.1pm5.2pm5.2时,表现为中感白粉病;当基因型为pm5.1pm5.1PM5.2PM5.2时黄瓜自交系病情指数最低,表现为抗白粉病。分生孢子在抗、感黄瓜自交系植株叶片上均能萌发,但只能在感病黄瓜材料上完成整个无性生长周期,产生分生孢子。此外,黄瓜白粉病菌分生孢子在感病材料上的萌发率、菌丝形成率及菌落形成率均高于抗病材料。     

玉米丝黑穗病菌侵染的研究

 玉米丝黑穗菌,对玉米幼根、幼芽都能侵染,但以幼芽侵染较多。在幼芽的芽鞘和根茎部位,侵染程度没有明显差异。     

Systemic infection of sorghum and corn by conidia ofSclerospora Sorghi

Conidia ofSclerospora sorghi, obtained from either systemically-infected or local-lesion-infected leaves of sorghum (cv. Vidan), were capable of inducing typical downy mildew systemic infection, including oospore formation, in sorghum and corn hybrids. Very young inoculated seedlings displayed chlorotic systemic symptoms already on the first leaf, and often died at fourth-leaf stage. Systemic infection was induced by conidia on sorghum 1–14 days old at inoculation. Incidence of infection was much higher and symptoms less delayed when the shoot rather than coleorhizas of young sorghum and corn seedlings were inoculated; in two-week-old sorghum with three leaves, inoculation of the coleoptile or of the base of the second and third blades resulted in systemic infection; with coleoptile inoculation partial leaf chlorosis was delayed until the fourth-or fifth-leaf stage, showing that penetration without symptoms had occurred as far as the meristematic tissues of young leaves still within the leaf tube. Conidial inoculation of young sorghum tillers sprouting after cutting down healthy mother shoots resulted in systemic infection. Conidial inoculum is deemed to be the probable major means for systemic infection of corn and sorghum sown in fields in which oospores are not present; inoculation of new tillers of forage sorghum by conidia from infected plants in a neighboring field can explain the rise in numbers of plants systemically stricken. Two sweet corn hybrids — one considered resistant in the field, the other very susceptible — proved equally susceptible when inoculated with conidia at 5 days of age.     

Influence of RNA composition of beet necrotic yellow vein furovirus isolates and of the sugarbeet cultivar on the translocation of the virus in mechanically inoculated sugarbeet roots1

The roots of young sugarbeet seedlings (5-12 days old) were inoculated mechanically with beet necrotic yellow vein furovirus (BNYVV). Vortexing of the seedlings in virus-containing suspensions proved to be especially effective. Higher percentages of infected tap roots were observed with a highly susceptible than with a tolerant cultivar. In the susceptible cultivar, the virus spread more readily from the tap root to the newly formed lateral roots than in the tolerant cultivar, indicating that the latter had a partial resistance to the virus. The translocation of the virus also depended on its RNA composition. An isolate with intact RNA3 and RNA4 was much more efficiently translocated to the lateral roots than an isolate which lacked these two RNAs. So far we have been unable to infect hairy roots of sugarbeet with BNYVV. These hairy roots had been induced by infection with Agrobacterium rhizogenes and were propagated in liquid culture.     

A rapid reliable test for screening aryloxyphenoxy- propionic acid resistance within Alopecurus myosuroides and Lolium spp. populations

A reliable seedling bioassay was developed and tested for the rapid screening for resistance to aryloxyphenoxypropionic (APP) herbicides in Alopecurus myosuroides and Lolium spp. populations. It is based upon the difference in coleoptile length of resistant and susceptible A. myosuroides and Lolium seedlings, respectively, exposed to fenoxaprop-P acid and diclofop acid solution for 6 days in a plastic box. A 6 mg L⁻¹ fenoxaprop-P acid solution was selected as the best concentration for a reliable screening of resistant biotypes within A. myosuroides populations. At this concentration, coleoptile lengths of susceptible and resistant seedlings were shorter and longer than 10 mm respectively. Similarly, resistant seedlings within Lolium populations were easily detected at 10 mg L⁻¹ diclofop acid. At this concentration, coleoptile lengths of susceptible and resistant seedlings were shorter and longer than 20 mm respectively. For both populations, the coleoptile length distributions appear to discriminate between two kinds of APP-resistant biotypes (highly and slightly resistant).     

Colonization of roots of subterranean clover cultivars by virulent and avirulent races of Phytophthora clandestina

The colonization of the roots of four cultivars of subterranean clover by isolates representing four races of Phytophthora clandestina was studied. There was a highly significant race × cultivar interaction in the growth of inoculated tap roots and the degree of colonization of roots by the pathogen. While all races were able to infect the roots of all cultivars tested, roots of the susceptible cultivars were colonized more rapidly and extensively than those of the resistant cultivars. In compatible combinations, fungal colonization extended for a few centimetres in the tap root and lateral roots in the moderately susceptible cultivars Trikkala and Meteora, or throughout the whole root system leading to the death of the host in the very susceptible cultivar Woogenellup. In contrast, limited fungal colonization of the tap root and lack of extension of the fungus into lateral roots was typical of incompatible combinations. In all cultivars, lateral roots were as susceptible to infection as tap roots. The number of lateral roots of Woogenellup was significantly reduced by infection. However, neither the rate of lateral root formation nor the total number of lateral roots of Seaton Park, Meteora and Trikkala was reduced by infection with virulent or avirulent races of the pathogen.     

Etiology of a newly described root rot of guar (Cyamopsis tetragonoloba) in Australia caused by Phytophthora cryptogea

An isolate of Phytophthora obtained from diseased roots and stems of guar ( Cyamopsis tetragonoloba ) growing in waterlogged soil from Dalby. Queensland. was identified as Phytophothora cryptogea ( P. drechsleri ). Sex organs were not observed, Pathogenicity to guar seedlings was established under glasshouse conditions either by using a hypocotyl-wound inoculation technique, or adding motile zoospores to seedlings growing under saturated conditions. This appears to be the first report of this disease. Seven isolates of P. drechsleri from hosts other than guar were shown to be pathogenic to guar following hypocotyls-wound inoculation.
The host range of the guar isolate was studied using both hypocotyl-wound inoculation and zoospores. After hypocotyl inoculation, the following species were found to be susceptible^: cantaloupe. cowpea, cucumber, mungbean, pea. pigeon-pea, safflower. sunflower, tomato and watermelon. Slight symptoms were observed on bean and chickpea. When zoospores were used as the inoculum, only pea. pigeon-pea, sunflower and safflower were highly susceptible. A range of guar cultivars and breeding lines were screened for resistance using zoospore inoculum, and although no genotypes were highly resistant, there were significant differences between disease reactions.     

Tolerance of onions (Allium cepa L.) to the pink root disease caused byPyrenochaeta terrestris

The response of 11 onion cultivars (Allium cepa, L.) grown in flats containing soil infested withPyrenochaeta terrestris, the causal agent of pink root disease, was studied. In addition, four cultivars were tested in field trials. Pink roots were found on all the cultivars, including those considered to be resistant. The cultivars ‘Golden’ and ‘Yellow Creole’ were highly susceptible to pink root, whereas cvs. ‘Dessex’, ‘Granex’, ‘Laredo’, ‘Grano 502’ and ‘Grano’ (local) managed to grow and produce reasonable yields, despite having infected roots. Following infection, the growth period of early and intermediate maturing cultivars was shortened by 4–14 days, and that of late maturing cultivars by 18–45 days. A large percentage of small bulbs was produced by most of the susceptible cultivars, but no consistent results were obtained with the resistant cvs. ‘Granex’, ‘Dessex’, and ‘Laredo’. The resistant cultivars maintained an, extensive and viable root system which enabled them to tolerate the disease when grown in infested soils.     

Morphological observation on development of juvenile seedlings of Monochoria vaginalis establishing on a flooded paddy soil surface

The development of juvenile seedlings of Monochoria vaginalis (Burm.f.) Kunth var. vaginalis concerning its hypocotyl hairs was investigated morphologically at establishing on 1 mm flooded paddy soil surface and in distilled water. Prime germination of M. vaginalis seeds sown after breaking dormancy was found on a flooded paddy soil surface and in distilled water at 6 h after seeding (HAS). Elongation of cotyledons and hypocotyl hairs of juvenile seedlings appeared at 12 HAS on a paddy soil surface, while lengths of hypocotyl hairs were almost the same as longitudinal length of seeds and cotyledons formed arch on the soil surface at 18 HAS. Seminal roots began to emerge and seedlings adhered completely to the soil surface by hypocotyl hairs, which were longer in length than seminal roots at 24 HAS. At 36 HAS, seed chaffs completely separated from the soil surface, as cotyledons had elongated from standing up, and lengths of seminal roots became longer than those of hypocotyl hairs. Emergence of first leaves and crown roots was simultaneously observed at 48 HAS. Elongations of cotyledons, seminal roots and hypocotyl hairs were completely terminated at 96, 120 HAS and 120 HAS respectively, and the elongation of 2 to 4 crown roots was observed at 120 HAS. Almost half the number of hypocotyl hairs putrefied at 240 HAS. In distilled water, hypocotyl hairs elongated to their longest at 36 HAS earlier than those on a paddy soil surface. It was concluded that hypocotyl hairs supported a strongly physical mechanism in establishing M. vaginalis seedlings on a paddy soil surface.     

Susceptibility of European bread and durum wheat cultivars to Tilletia indica

Representative European wheat cultivars were tested under quarantine containment for their susceptibility to Tilletia indica, the cause of Karnal bunt of wheat. Fifteen winter and 15 spring wheat ( Triticum aestivum ) and 11 durum wheat ( Triticum durum ) cultivars were inoculated by boot injection just prior to ear emergence to test their physiological susceptibility. Selected cultivars were then re-tested by spray inoculation after ear emergence to determine their morphological susceptibility, which is a better predictor of field susceptibility. At maturity, the ears and seeds were assessed for incidence and severity of disease. For the physiological susceptibility tests, 13/15 winter wheat cultivars were infected and the percentage of infected seeds ranged from 1 to 32%. For spring cultivars, 13/15 cultivars were infected and the percentage of infected seeds ranged from 1 to 48%. For the durum cultivars, 9/11 were infected and the percentage of infected seeds ranged from 2 to 95%. Across all cultivars, 35/41 were infected. Based on historical Karnal bunt susceptibility categories using coefficients of infection, one cultivar was classed as highly susceptible, three as susceptible, 11 as moderately susceptible, 20 as resistant and only six as highly resistant. The spray-inoculation morphological susceptibility tests broadly confirmed the physiological susceptibility results, although lower levels of infection were observed. Overall, the range of susceptibility was similar to that found in cultivars grown in Karnal bunt affected countries. The results demonstrate that European wheat cultivars are susceptible to T. indica and thus could potentially support the establishment of T. indica if introduced into Europe.