苦楝种源幼林期生长性状地理变异的研究

【目的】了解苦楝Melia azedarach种源的生长性状地理变异及其规律,选择适宜在广东地区造林的优良种源,为苦楝造林种子调拨提供依据。【方法】采集苦楝分布区53个种源,在广州增城开展种源试验,观测了幼林期树高、地径、侧枝数、干型和冠幅等性状,分析其地理变异规律,并探讨种源地理变异的气候生态学基础。【结果】各种源在6个性状间均存在明显的差异,其中树高和地径在种源间的差异最大,变异幅度分别为5~280 cm和1.2~64.0 cm。方差分析结果显示,除干型在种源间的差异达显著(P0.05)水平,其余5个性状在种源间的差异均达到极显著(P0.01)水平。树高、东西冠幅和南北冠幅等性状的重复力达到40%以上,说明这些性状较其他3个性状在种源间的差异更为稳定,而地径重复力仅为29.92%,表明地径在种源间表现的差异稳定性较弱。苦楝苗期生长性状地理变异趋势为:采种点由南至北,苗期生长变慢,高海拔种源生长更快。各性状受纬度、经度和海拔多重控制,但各生长性状多以纬向变异为主。生长性状的地理变异存在明显的气候生态学特征。气温较高、降水丰富、气压低、平均最低气温高、日照丰富地区的种源苗期生长快,生物量大。根据种源幼林生长性状采用欧氏距离离差平方和进行聚类,可以将53个种源大致划分为6个类群,且分类群具有明显的地理格局。【结论】各种源存在明显的地理变异规律,初步挑选出生长快、生物量大、干型优良、适应性好的种源740、629、843和349作为适宜广东地区造林的优势种源。     

Attraction ofTrichogramma platneri to eggs of some lepidopterous pests of avocado

The attraction ofTrichogramma platneri Nagarkatti (Hymenoptera: Trichogrammatidae) to eggs of two lepidopterous avocado pests,Boarmia sel-enaria (Schiffermüller) (Geometridae) andCryptoblabes gnidiella (Millière) (Phycitidae), was evaluated in olfactometer tests. The mobility of the wasp as measured by a mobility index was 0.6 for males and 1.8 for females; the males had a lower mobility and a lower search capacity index than the females. Frozen and fresh youngB. selenaria eggs had the greatest attraction forT. platneri, which diminished with increasing age of the eggs. The eggs ofC. gnidiella were also attractive to the parasitoid. Contribution from the Agricultural Research Organization. No. 2704-E, 1989 series.     

漳平不同产地毛竹造林试验研究

收集7个不同产地的母竹,进行移栽母竹试验,经过5 a观察不同产地毛竹的物候期、发笋成竹规律,应用数量遗传学和统计学原理,综合评选出4个优良母竹产地。     

不同种源地北美鹅掌楸光合特性研究

以3个种源地北美鹅掌楸无性系为试验材料,利用LI-6400XT便携式光合测定系统,研究了净光合速率日变化及对有效光辐射和CO₂的响应等光合特性。结果表明,宾夕法尼亚种源和俄亥俄种源北美鹅掌楸的P_n日变化曲线呈双峰型,具有明显的午休现象,峰值出现在10:00和14:00,纽约种源北美鹅掌楸不具有明显的午休现象。光响应曲线和CO₂响应曲线数据分析表明,纽约种源北美鹅掌楸光饱和点（1 180.4 μmol·m^-2·s^-1）和光补偿点（10.27 μmol·m^-2·s^-1）均高于另外2个种源。这种趋势也同样适用于CO₂饱和点（1 595.0 μmol·m^-2·s^-1）和CO₂补偿点（107.5 μmol·m^-2·s^-1）。在北方低光照环境下,纽约种源较高的光补偿点和CO₂补偿点,不利于有机物的积累,宾夕法尼亚种源对光照和CO₂要求较低,更适合北方环境。     

闽南山地桉树种/种源选择试验研究

闽南山地引种的19个不同桉树种／种源对比试验研究表明，尾巨桉、巨尾桉及广西尾叶桉属高产型树种，年平均蓄积生长量达35．3－53．3m^.hm^-2，其山地造林后表现适应性强、树干圆满通直、林木分化程度低，林相整齐、生产力高、经示范推广收效显著，是闽南山地短周期工业原 造林的首选树种，值得大力推广引种。     

厚朴遗传改良策略的研究

在厚朴种源试验和主产区采样研究的基础上,分析了厚朴种内主要经济性状的层次变异和遗传;依据主要经济性状的相关和厚朴遗传改良的目标,确定了鄂西小凸尖型厚朴为优良种源区,浙、闽中间型为次优种源区。以树高、胸径、皮厚、树皮类型以及粉末颜色、油性、易磨性为主要选择性状,进行种源、单株二水平联合选择,提出了遗传改良的系统程序和方法。为厚朴中药材人工基地建设实现优质、高产提供了策略。     

Prevalence of campylobacter in pigs during fattening; an epidemiological study

Summary

Numerous epidemiological reports implicate foods of animal origin as vehicles of human campylobacteriosis. Pigs are probably an important reservoir of campylobacter and a potential source of human infection. In order to improve our knowledge of the epidemiology of campylobacter in pigs, the prevalence of campylobacter and its contamination of feed were monitored in eight pig farms. Faeces samples of pigs aged 11 and 22 weeks, and samples of rectal, ileal and gastric content at a slaughterhouse were collected for bacteriological examination. On 5 farms, subsequent groups of pigs housed in the same stalls was sampled, too. A selection of the campylobacter isolates was characterized with a genetic typing method (RFLP). More than 85% of the sampled porkers were shown to be intestinal carriers of campylobacter at all stages of fattening. Subsequent groups of pigs housed in the same stalls were all carriers, too. The level of campylobacters in the faeces tended to decrease as the pigs got older. There was no difference in the frequency and level of infection with campylobacter between porkers on different farms. The feeding system (wet feed versus dry pellets) did not seem to influence the prevalence of campylobacter although wet feed gave lower counts of Enterobacteriaceae in the faeces.

RFLP‐typing showed a high diversity of campylobacter strains at each sampling on the farm. Similarities were seen between strains isolated during two subsequent samplings of the same group of pigs, but not between strains isolated on the same farm from subsequent groups of pigs housed in the same stall. This suggests that the piglets were already infected at a young age on the breeding farm.     

Evaluation of success rate of laparoscopic castration without orchidectomy in 32 mature horses

The surgical success of laparoscopic castration without orchidectomy results from avascular necrosis of the testes. However, failures and subsequent production of testosterone and stallion‐like behaviour have been previously identified. Laparoscopic castration without removal of the testes was performed in 32 horses with 2 normal descended scrotal testes between July 2006 and October 2012. The objectives of our study were to evaluate the success rate of laparoscopic castration without orchidectomy on descended testes in our population and assess complications and recovery time. Endocrine tests were performed after surgery and owners also asked to report on their horse's behaviour and ability to resume exercise. Castration was deemed successful if endocrine test results were in accordance with gelding values. Failed horses were castrated using a conventional technique and histology performed when possible. Basal testosterone levels decreased below 3 nmol/l after surgery in 30/32 cases. However, in 2 horses, stallion behaviour persisted and histological evaluation after inguinal castration showed residual viable tissue. Two horses maintained high testosterone levels after surgery associated with stallion‐like behaviour. Based on these results, 12.5% of horses (4/32 horses) failed to be considered a gelding based on either endocrine tests and/or histology. All horses, with one exception, were able to resume exercise less than a week after the procedure. Laparoscopic castration without orchidectomy appears to be a safe procedure. When assessing the success of laparoscopic castration, our total failure rate was 12.5% (4/32 horses) which is significantly higher than previously reported.     

钢板弹簧疲劳分析

传统的钢板弹簧强度分析中,多是借助简化的力学模型,基于材料力学的小挠度梁的线弹性理论进行计算,计算中的假设条件和计算方法与钢板弹簧实际情况不尽相符,计算结果存在误差。在钢板弹簧的结构应力计算基础上,通过建立钢板弹簧装配及加载状态的精确有限元模型,并考虑片间的非线性接触,在交变载荷作用下,计算得到钢板弹簧接近实际工况的应力循环,然后利用其S N曲线,基于Miner线性累计损伤准则计算其疲劳寿命。通过钢板弹簧的实际疲劳试验,验证了模型计算结果的正确性。     

杨尺蠖核多角体病毒的研究——Ⅳ.病毒多角体的回收试验

本文就杨尺蠖核多角体病毒的几种回收方法进行了比较。回收试验表明,以丙酮—乳糖(7.4—8.4％)共沉法回收 AciNPV 的多角体(PIB)是可行的。制备物的最终含量为 4.96×10~(10)PIB/g,回收率平均达 80.5％。生物活性测定证明,回收的新鲜制备物,对3龄初幼虫的致病力是很好的。其 LC_(50) 及其95％的置信限分别为2.84×10~3PIB/ml和 1.70×10~3—4.96×10~3PIB/ml。 使用该程序,可省去昂贵的离心设备,在实验室一般设备的情况下,一次上样1500—3000 g病死虫,仅需 3小时即可获得最终产品。配制的病毒制剂,可用于防治杨尺蠖 30—65ha。大批量生产证明,该流程操作简便,省工省时,一次上样量较大,完全可以替代离心法,回收的成本也很便宜。