Factors affecting seed dormancy and germination of Johnsongrass, Sorghum halepense (L.) Pers.

Seeds of Johnsongrass [Sorghum halepense (L.) Pers.] germinated to higher percentages (20–30% higher) when incubated at 28 and 35° C than at 10 or 22° C. After-ripening was accelerated by dry storage of these seeds at 50°C. Seeds pre-chilled at 6°C for 2–4 weeks followed by incubation at 28°C germinated 40–60%. Light effects on germination were related to incubation temperatures; inhibitory at 22°C; no response at 28°C; and stimulatory at 35°C. Effects of gibberellin A₃ (GA₃) also varied depending on incubation temperature, sodium hypochlorite (NaOCl) immersion and light conditions. Immersion of dry seeds in either 700 mM NaOCl, 900 mM H₂O₂ or concentrated H₂SO₄ before incubation in water was effective in breaking dormancy. This result suggests the modes of action of H₂SO₄ in the termination of dormancy may be similar to those of NaOCl and H₂SO₄ as previously suggested by Hsiao & Quick (1984), that is by modification or scarification of the hull or seed coat membranes, and also by the supply of additional oxygen to the seed.     

A蛋白斑点免疫金染色和双抗体夹心酶联检测齿兰环斑病毒的比较

A蛋白斑点免疫金染色检测齿兰环斑病毒提纯病毒的灵敏度为1.56 ng/μl,检测病汁液的稀释倍数为640倍.同时采用碱性磷酸酯酶标记抗体IgG.IgG包被酶联板的浓度为1 μg/ml,酶标抗体以1 /1000稀释使用.DAS-ELISA技术检测ORSV提纯病毒的灵敏度为0.048 ng/μl,检测病汁液的稀释倍数为20480倍.     

土壤药剂处理结合阳光消毒防治番茄根结线虫技术评价

为了筛选安全、高效、实用的化学防治技术,对国内外生产的5种杀线虫剂(棉隆、1,3 二氯丙烯·氯化苦、威百亩、噻唑磷、溴甲烷)土壤处理结合阳光消毒防治番茄根结线虫的效果进行了评价。结果表明,使用98%棉隆微粒剂450 kg/hm2或10%噻唑磷颗粒剂30 kg/hm2防治番茄根结线虫(Meloidogyne incognita),结合夏季高温进行阳光消毒,能有效地降低番茄根结线虫的数量,减轻根结线虫的危害程度,节省农户的生产成本,提高番茄的产量和农户的经济效益,是夏季防治番茄根结线虫的有效措施。     

7种长蠹科昆虫的线粒体DNA ND4基因序列比较分析

长蠹科昆虫严重危害林木和仓贮物品。该文应用非损伤性DNA测序技术测定了来自不同国家的长蠹科害虫的线粒体DNA ND4基因的部分序列。在获得的204bp的序列中，7种昆虫的序列变异丰富，多数变异发生在密码子的第3位点上。将实验结果与形态学特征比较分析，探讨7个种的形态差异与基因序列的差异；结果表明，7种昆虫不仅在外形特征上存在差异，而且在ND4基因序列上的差异程度也很显著，平均为21．94％。这为分类鉴定提供了充分的证据。     

利用MaxEnt预测橡胶南美叶疫病菌在全球的潜在地理分布

橡胶南美叶疫病菌在美洲地区引起橡胶树严重的落叶病害,是亚太地区国家重要的检疫性有害生物。本文在MaxEnt预测全球范围内气候条件适宜该菌存活区域的基础上,结合寄主分布推测该菌的潜在地理分布。预测结果显示,在54个天然橡胶种植国家或地区中,除了该菌目前分布国家或地区、几内亚比绍和马里,其余33个国家或地区气候适宜值大于10的区域为该菌的潜在地理分布区,加强这些区域的调查监测对保护当地橡胶种植有重要意义。     

添加有机硅表面活性剂对低容量喷雾防治小麦蚜虫的影响

室内试验表明,有机硅表面活性剂Silwet408、非离子表面活性剂OP-10和JFC可显著降低药液的表面张力,其中Silwet408在质量分数为0.05%时可使水的表面张力降到22.05 mN/m,表面活性最强。当药液中含有0.001%的有机硅表面活性剂Silwet408时,其在小麦叶片上的接触角即开始显著减小,且在小麦背面的接触角小于在正面的接触角。在10%吡虫啉可湿性粉剂稀释2500倍药液中添加Silwet408,药液的表面张力和其在小麦叶片上的接触角明显降低,雾滴在小麦叶片上扩展面积明显增大。进一步田间试验表明,使用手持离心式低容量喷雾机喷雾,在10%吡虫啉可湿性粉剂药液中添加质量分数为0.05%和0.1%的Silwet408,可显著增加对小麦蚜虫的防治效果。     

Biological Control of Sclerotinia Diseases of Rapeseed by Aerial Applications of the Mycoparasite Coniothyrium minitans

Indoor and field experiments were conducted to evaluate the efficacy of applying the mycoparasite Coniothyrium minitans to the aerial parts of rapeseed plants at the flowering stage to control sclerotinia diseases caused by Sclerotinia sclerotiorum. Under controlled conditions, a petal inoculation technique was used to determine the effect of conidial suspensions of C. minitans on suppression of sclerotinia leaf blight. Results showed that C. minitans was effective in inhibiting infection initiated by ascospores of S. sclerotiorum on flower petals by restricting mycelial growth of the pathogen. Suppression of lesion development was related to the conidial concentration of C. minitans, with larger lesions at low concentration (5×10³conidia ml⁻¹), but smaller lesions at high concentration (5×10⁴ conidia ml⁻¹ or higher). When C. minitans-treated rapeseed leaves were inoculated with mycelia of S. sclerotiorum, C. minitans failed to prevent infection of leaves, but caused a significant reduction in number of sclerotia produced on the diseased leaves. No significant difference in efficacy was detected between the two isolates of C. minitans, LRC 2137 and Chy-1, on the two rapeseed cultivars, Westar (spring type) and Zhongyou 821 (winter type). Results of field trials showed a significant reduction of stem rot of rapeseed in four (1997, 1999, 2003 and 2004) out of five years by aerial application of C. minitans, compared with controls. No significant difference in suppressive efficacy was observed between the treatments of C. minitans (10⁶ conidia ml⁻¹), C. minitans (10⁶ conidia ml⁻¹) + benomyl (50 μg ml⁻¹) and benomyl (100 μg ml⁻¹) in 2003, and between the treatments of C. minitans (10⁶ conidia ml⁻¹), C. minitans (10⁶ conidia ml⁻¹) + vinclozolin (100 μg ml⁻¹) and vinclozolin (500 μg ml⁻¹) in 2004. Sclerotia of S. sclerotiorum collected from diseased plants in plots treated with C. minitans in 1999, 2000 and 2003, or with C. minitans + benomyl in 2003 were infected by C. minitans at frequencies ranging from 21.3 to 54.5%. This study concludes that aerial spraying of C. minitans is an effective method for controlling sclerotinia diseases of rapeseed.     

深圳红火蚁蚁巢密度、社会型研究及防治效果评价

本文报道了深圳红火蚁生境类型与蚁巢密度的关系,社会型的鉴别以及应用茚虫威对多后型和单后型、多后型共存地区的防治效果。红火蚁的蚁巢密度（巢/100 m2）与生境类型密切相关,在所调查的5类生境中,待建地的蚁巢密度最高,为3.81巢/100 m2,公路边的次之,为2.95巢/100 m2,城市绿地的最低,为0.63巢/100 m2。应用多元PCR技术对6个行政区社会型进行鉴别的结果表明,福田、龙岗、南山区为多后型与单后型共存,单后型与多后型的比仅为1∶(3~4)。罗湖、宝安、盐田3区全部为多后型;多后型地区的蚁巢密度（2.2巢/100 m2）比单后型地区（1.9巢/100 m2）的为高,但没有显著差异;应用茚虫威进行防治60 d后的调查结果表明,多后型地区的防治效果（97.8%）比单后型地区（96.7%）的要好,但没有显著差异。最后,本文对这些结果产生的原因及应用价值进行了讨论。     

中国苜蓿品种对黄萎病抗病性鉴定

 黄萎病(Verticillium albo-atrum Reinke & Berthold)是苜蓿的毁灭性病害,在欧洲常于播种当年就有许多植株发病,第二年末或第三年会有大批植株死亡,使苜蓿地失去利用价值。1976年以后,本病在北美流行,并造成巨大经济损失。