防浸渍处理后马铃薯癌肿病休眠孢子囊的大小变化

从采集的样本中发现马铃薯癌肿病的休眠孢子囊超过子已报道的形态大小，防腐浸渍液处理后休眠孢子囊平均大小缩小５０％以上。     

马铃薯抗癌肿病品种比较试验

马铃薯癌肿病(Potato wart)又名黑瘤病、黑痂病,群众俗称"疙瘩洋芋".病菌(属鞭毛菌亚门真菌)以休眠孢子囊在病组织内或随病残体遗落在土壤中越冬.休眠孢子囊抗逆性很强,可在土壤中存活25 a左右,遇适宜的条件,萌发产生游动孢子和合子,从寄主表皮细胞侵入.     

马铃薯癌肿病游动孢子囊活性的测定方法

在马铃薯癌肿病病原菌的发育史中,形成休眠孢子囊是由于不利因子(变动的气候条件、缺乏寄主、应用化学药品等)影响的一种保护性反应。休眠孢子囊按照生理学的成熟等级分为一年的、二年的和多年的。当条件最适宜而无寄主时,个别孢子囊在土壤中达10—30年而不失去活性(M.Pratt,1976)。实验室测定病原体活性多半采用质壁分离法,该方法由苏联的研究家们提出,其依据是:活的原生质比较易于渗水而对溶质有阻留作用(克·耶·沙利阔夫,1951,1954;     

不同寄主来源的葡萄霜霉病菌致病力测定及孢子囊大小比较

对采自我国不同地区、不同主栽葡萄品种‘红地球’、‘巨峰’及‘赤霞珠’上的12份葡萄霜霉病菌的致病力及孢子囊大小进行了比较和分析,结果表明:采自不同葡萄品种的病原菌对感病葡萄品种‘奥迪亚无核’叶片的致病力具有明显差异,其中‘巨峰’及‘红地球’来源的病原菌致病性较强,明显大于‘赤霞珠’来源的病原菌致病力;采自不同葡萄品种的霜霉病菌孢子囊大小存在一定的差异,‘赤霞珠’来源的病原菌孢子囊明显大于‘巨峰’及‘红地球’来源的霜霉病菌孢子囊。上述结果表明,采自不同寄主的葡萄霜霉病菌的致病力及孢子囊大小均存在一定程度的分化。     

蚕豆油壶菌疱疱病及其防治的初步研究

 蚕豆疱疱病是川西北高原春蚕豆的主要病害之一,发病面积约6万亩。罹病茎、叶起疱,一般因病减产20%左右。病原为巢豆油壶菌(Olpidium viciae)。巢豆油壶菌及其所致病害发生于日本,我国尚属初次发现。该菌寄主范围广,易见的自然寄主为蚕豆、豌豆和歪头菜。在人工接种下,除可侵染大豆、菜豆、箭舌豌豆、兵豆等多种豆科作物外,也能侵染油菜、结球甘蓝、大白菜、萝卜、黄瓜、南瓜、莴苣、菠菜、荞麦等作物。以病株残体内的休眠孢子囊在土内越冬,翌春萌发侵入寄主,在寄主细胞内形成游动孢子囊,通过出管释放单鞭毛游动孢子进行再侵染,潜育期13~18天。游动孢子亦起配子作用,结合形成双鞭毛游动合子,以合子侵入。后期在寄主细胞内形成休眠孢子囊。     

马铃薯癌肿病生物学特性及检测方法

进一步较系统地研究了马铃薯癌肿病的生物学特性、宏观与微观危害特征及在我国的病害发展。对马铃薯块茎休眠芽癌肿病的早期(潜伏期)诊断、土壤休眠孢子囊及其活力测定等快速检测方法与技术进行了研究并取得预期结果。     

甜菜多粘菌传带甜菜坏死黄脉病毒的细胞定位研究

 利用砂培体系继代培养不同病区甜菜多粘菌(Polymyxa betae),经酶联检测,分离得到2个带毒率高的分离株N,HR₁₂。应用甜菜坏死黄脉病毒(BNYVV)抗血清和免疫金标记技术分析了甜菜根中P.betae不同发育阶段与病毒的关系。在初生原质体、游动孢子囊以及未成熟的游动孢子中观察到被金颗粒标记的病毒粒子,在休眠孢子外围也观察到金标记的病毒粒子,但在休眠孢子内未直接观察到病毒粒子,只是在其内壁及液泡中常见有标记上的金颗粒。     

云南马铃薯粉痂病病原研究

马铃薯粉痂菌(Spongospora subterranea f.sp.subterranea)是引起马铃薯粉痂病的病原。本试验对云南省马铃薯产区的马铃薯粉痂菌进行了研究,通过光学和扫描电子显微镜对病原菌进行了描述。光学显微镜观察到了典型的海绵状蜂窝结构;扫描电子显微镜观察到的休眠孢子囊结构与国外观察的一致,证明了马铃薯粉痂菌在云南省马铃薯主产区的存在。     

百合疫病病原菌的鉴定及培养基的筛选

从具典型症状的新鲜百合疫病植株茎基部病组织中分离到百合疫霉菌,根据其病原菌菌丝的形态、菌落特征,厚垣孢子、游动孢子囊和卵孢子的形态和大小,以及病原菌致病性测定,该病原菌鉴定为烟草疫霉Phytophthora nicotianae van Brede de Haan.供试的16种培养基中,病原菌在胡萝卜琼脂培养基(CaA)和辣椒琼脂培养基(PeA)上生长最好,生长速率分别为1.771和1.770mm/h.在常规培养条件下,病原菌不易产生厚垣孢子、游动孢子囊和卵孢子,在低温、皮氏溶液和土壤浸出液中分别诱导产生出大量厚垣孢子、游动孢子囊和卵孢子.     

土壤pH对芸薹根肿菌侵染及病害发生的影响

通过设置不同pH梯度,研究土壤pH对根肿菌侵染及病害发生的影响。结果表明:土壤酸性时病菌侵染速度快,碱性时慢,而强酸性和碱性土壤条件则抑制孢子萌发;pH为6.0时最有利于根肿菌休眠孢子萌发,萌发率最高,为53.96%;碱性条件可使初级原生质团变形凝结成球状,不能正常分裂或延迟形成游动孢子囊,从而不利于根肿菌侵染。白菜发病率与病情指数随pH升高,呈先上升后下降趋势。其中,pH为5.0时,发病率和病情指数最高,pH 7.0~8.0时发病轻。因此,适宜的偏酸性环境条件下,通过作用于病菌休眠孢子萌发和侵染,提高病害危害程度,而中性或碱性条件干扰该过程并降低病害发生。     

麻竖毛天牛幼虫大小对松褐天牛肿腿蜂产卵决策的影响

为探讨寄主大小对松褐天牛肿腿蜂产卵决策的影响，进而为其人工繁育和林间应用提供科学依据。本研究选取重量0.10～0.15、0.15～0.20、0.20～0.25、0.25～0.30、0.30～0.35 g的麻竖毛天牛幼虫为寄主，接入已交配的雌性松褐天牛肿腿蜂，观察并记录其寄生和产卵行为，统计子代数量和子代性比（雄性占比）。结果表明寄主大小对松褐天牛肿腿蜂的寄生率影响不明显，但可影响子代适合度；子代数量与寄主大小呈正相关关系；雄性占比随寄主个体增大而降低，但子代发育历期不受寄主大小影响。研究结果证实，寄主大小可影响松褐天牛肿腿蜂的寄生决策。     

山西省城市规模分布研究

选取1996年,2000—2003年山西省11个地级市建成区用地规模的资料,把运用在城市人口规模上的位序—规模法则,首位比,不平衡指数法移植到城市用地上,分析了山西省地级市建成区土地利用规模的变化规律,然后运用分形理论,阐释了位序—规模曲线。得出结论:(1)山西省地级市用地规模分布的均衡程度不断增强;(2)山西省地级市用地规模的总量不断增加;(3)对城市用地规模进行分类,发现小城市的数量在逐渐减少,中等城市的数量在逐渐增加;(4)首位城市太原市的用地规模已基本稳定,中等城市和小城市的用地规模将会扩大,其速度是前者大于后者。     

颗粒粒径和粒谱对悬浮剂贮存物理稳定性影响研究

通过颗粒粒径和粒谱对悬浮剂贮存物理稳定性影响研究 ,明确了悬浮剂剂型加工中研磨时间与制剂悬浮颗粒粒径和粒谱分布的关系。结果表明 ,在选定了适当助剂、确定了加工工艺的条件下 ,通过调整研磨时间、降低悬浮颗粒粒径和粒谱分布 ,可以改善悬浮体系的物理稳定性。另外 ,由于研磨时间的延长、粒径变小所带来的悬浮体系粘度的增加 ,对制剂物理稳定性也是非常有利的。     

Fetch effect on the developmental process of aeolian sand transport in a wind tunnel

As the sand mass flux increases from zero at the leading edge of a saltating surface to the equilibrium mass flux at the critical fetch length, the wind flow is modified and then the relative contribution of aerodynamic and bombardment entrainment is changed. In the end the velocity, trajectory and mass flux profile will vary simultaneously. But how the transportation of different sand size groups varies with fetch distance is still unclear. Wind tunnel experiments were conducted to investigate the fetch effect on mass flux and its distribution with height of the total sand and each size group in transportation. The mass flux was measured at six fetch length locations(0.5, 1.2, 1.9, 2.6, 3.4 and 4.1 m) and at three free-stream wind velocities(8.8, 12.2 and 14.5 m/s). The results reveal that the total mass flux and the mass flux of each size group with height can be expressed by q=aexp(–bh), where q is the sand mass flux at height h, and a and b are regression coefficients. The coefficient b represents the relative decay rate. Both the relative decay rates of total mass flux and each size group are independent of fetch length after a quick decay over a short fetch. This is much shorter than that of mass flux. The equilibrium of the relative decay rate cannot be regarded as an equilibrium mass flux profile for aeolian sand transport. The mass fluxes of 176.0, 209.3 and 148.0 μm size groups increase more quickly than that of other size groups, which indicates strong size-selection of grains exists along the fetch length. The maximal size group in mass flux(176.0 μm) is smaller than the maximal size group of the bed grains(209.3 μm). The relative contribution of each size group to the total mass flux is not monotonically decreasing with grain size due to the lift-off of some small grains being reduced due to the protection by large grains. The results indicate that there are complex interactions among different size groups in the developmental process of aeolian sand transport and more attention should be focused on the fetch effect because it has different influences on the total mass flux, the mass flux profile and its relative decay rate.     

Grain size distribution at four developmental stages of crescent dunes in the hinterland of the Taklimakan Desert,China

Although scientists have performed many studies on crescent (barchan) dunes in the Taklimakan Desert,few studies reported the changes in grain size at different development stages of crescent dunes.In order to evaluate the changing trends of surface sediment grain size with dune development,we investigated the grain size characteristics at four developmental stages (oval sand pile,shield dune,incipient crescent dune and mature crescent dune) of crescent dunes by measuring the morphology of sand dune and observing the near-surface wind regime.The dunes have developed in a wide inter-dune corridor between high compound longitudinal ridges in China's Taklimakan Desert.The surface sediments at four developmental stages of the crescent dunes were primarily composed of fine sands,followed by very fine and medium sands.Mean grain sizes ranged from 2.8 to 3.1 φ,with a unimodal distribution.The sands were moderately well-sorted,their distribution varied from platykurtic to very platykurtic,and symmetrical or skewed towards the fine particles.From oval sand piles through shield and incipient crescent dunes to mature crescent dunes,incipient grain size gradually increased,particles became finer,sorting became better,kurtosis and skewness increased.Grain sizes on the surface layer became coarser upwards from the toe of the windward slope and then became finer towards the bottom of the leeward slope.We found that the coarsest particles at different positions at the four developmental stages were different.The coarsest particles were distributed at the top of the oval sand piles and shield dunes,versus at the middle of the windward slope of the incipient and mature crescent dunes.Correlations between the mean grain size and other grain size parameters showed that as mean grain size became finer,sorting became better and kurtosis became wider,but skewness changed only slightly.In addition,grain size variation in the surface sediments correlated with the movement speed of the dunes in the study area.In the open ground among tall-complex longitudinal ridges in the hinterland of the Taklimakan Desert where aeolian environment is characterized by comparatively strong wind and unsaturated sand flow,faster dune movement corresponded to coarser grain size.     

Assessment of the sample size to estimate the weed seedbank in soil

It was found that, in order to estimate the number of weed seeds in soil with a desirable degree of accuracy and confidence level. the sample size depends to large extent on the spatial distribution pattern of the seeds in the soil. The seeds of most weeds found in cultivated soils are distributed according to one of two statistical distributions: Poisson or Negative Binomial. For an acceptable degree of accuracy in estimating the number of seeds in the soil, the sample size must be large, Taking this into account, in this study a practical solution based on a theoretical approach is proposed for the problem of establishing the sample size for a species distributed according to either statistical pattern. In addition, given the sample size, it was possible to determine the estimation error to be expected. This theoretical approach is compared with that proposed in previous studies. Two abaci, based on simple expressions, are provided to determine the sample size, according to the Poisson or the Negative Binormal distribution of the weed species. For Poisson distribution, the sample size is determined (given the desired maximum relative error estimation and the confidence level) as a function of only one parameter: the expected number of seeds per sampling unit m (estimaied by the sample mean). For Negative Binomial distribution, the sample size is determined as a function of two parameters: m and p (estimated according to the relationship between the sample mean and the sample variance). A sample size n nol very different from those given in previous studies is obtained, but the lower limit found for the n -values is lower than that found in these studies.     

青海湖布哈河口沉积物粒度特征及其环境意义

以青海湖西北部布哈河口湖泊沉积物为研究对象,用激光粒度仪对其进行粒度分析,并用137Cs定年法测定了该区沉积速率。结果表明:沉积物的粒度特征随着水动力条件的波动呈有规律的变化。QH06和QH08的深度堆积速率分别是0.137 cm·a~(-1)、0.078 cm·a~(-1),质量堆积速率分别是0.105 g·cm~(-2)·a~(-1)、0.030 g·cm~(-2)·a~(-1)。靠近湖岸,137Cs通量较大,沉积速率较大,分选性也较好。结合粒度特征分析得出,青海湖西北部布哈河口气候变化分为3个阶段:1853—1886年,该区气候向干旱方向发展;1886—1940年向湿润方向发展;1940—2013年向干旱方向发展。其中,1978年和1989年粒度特征的明显变化和布哈河水文资料相对应,说明了粒度特征指示该区气候干湿变化的可靠性。布哈河口环境受人类活动的影响较大。     

Effect of the rust fungus Puccinia chondrillina TU 788 on plant size and plant size variability in Chondrilla juncea

Chondrilla juncea is one of the most serious introduced weed species in Australia. Successful biological control has been achieved by the release of the rust fungus Puccinia chondrillina. Although P. chondrillina is thought to reduce the competitive ability of C. juncea by reducing plant size, the precise mechanism by which the pathogen controls its host is poorly understood. In this experiment, we examined the effect of P. chondrillina TU 788 infection on individual plant size, and size variability, in two genotypes (one resistant, one susceptible) of C. juncea. Exposure to P. chondrillina significantly reduced the average size of susceptible C. juncea plants, a reduction apparent in both roots and shoots. Plant size variability of the susceptible C. juncea genotype was also reduced by P. chondrillina. Plant size, and plant size variability of the resistant genotype were unaffected by exposure to rust, or association with rust‐affected plants. The effect of P. chondrillina on plant size in rust‐susceptible C. juncea plants shows how effective bio‐control of this weed may occur in field populations.     

粘粒含量——夏季风的良好替代指标

通过对位于东亚季风区尾闾部位的沙沟剖面、东部半湿润区王官剖面、东部湿润区扣马剖面的气候代用指标的分析发现 ,黄土地层中 <5 μm的粘粒含量指标对各剖面中黄土-古土壤序列指示得比较清晰 ,可以较好地反映东亚夏季风的变化。对黄土地层中粘粒含量的测试及其环境意义分析以及与经典的东亚夏季风的替代指标———磁化率、红度指标 (a )的对比分析发现 ,粘粒含量指标的意义比较明确 ,适应范围更广 ,灵敏性也较高 ,是一比较可靠的、新的东亚夏季风的良好替代指标。     

河北邯郸HZ-S孔第四纪沉积物粒度特征分析

对河北邯郸HZ-S孔第四纪沉积物样品采用MS-2000型激光粒度分析仪进行测试和系统的粒度分析,研究结果表明:沉积物总体形成于水动力平稳低能的河湖相沉积环境。与典型的古洪水平流沉积物粒度特征进行对比,显示具有古洪水平流沉积特征。物质来源主要是以洪水为介质动力的河流冲积物(或洪积物),沉积物组成总体以粉砂为主,主要由悬移质构成,沉积物分选较好,粒度分布多为单峰型。其次是以地表径流为介质动力的陆源碎屑物质,由于短距离搬运,造成沉积物分选较差,跃移组分较多,粒度分布多为双峰型。纵向上沉积物平均粒径与<32μm细颗粒级百分含量呈同步正相变化,其大小主要受<4μm的粘土含量变化所控制。