温度对棉蚜生命参数影响的研究

本试验利用不同温度及代别组合共计12个处理研究了温度对棉蚜生命参数的影响。研究结果表明,温度对棉蚜的影响和棉蚜亲代素质有密切的关系。健壮个体子代在14～30℃温区随温度升高,发育速率呈幂函数曲线上升,棉蚜在14℃下若蚜死亡率高达70％,成蚜繁殖力极低,但在18～30℃温区内绝大多数棉蚜可以发育至成熟,以18～20℃棉蚜寿命最长,繁殖力最强,平均单蚜产仔蚜54.66～63.52头。温度升高发育历期缩短而导致内禀增长率呈对数曲线增加,至30℃r_m值达0.4486。但在高温下(26～30℃)连续饲养子代其r_m值则明显下降。不同温度下发育的个体大小差别明显,以18～20℃下成蚜较大。因此,作者认为棉蚜最适温区的划分不仅应考虑棉蚜的存活率、繁殖力及寿命,还应注意这些参数连续多代饲养的稳定性。根据亲代、子代棉蚜内禀增长率的差异程度,认为18～22℃为棉蚜发育的最适温区,处于最适温区的棉蚜个体健壮,体长宽积1mm~2以上。鉴于高温能导致短期内棉蚜种群剧增,因而从生物学意义上可以认为棉蚜具有在棉花蕾铃期猖獗的潜在能力。     

木槿上棉蚜种群动态的研究

对合肥地区木槿上棉蚜的种群动态进行了研究,结果表明,越冬前棉蚜成蚜和若蚜主要发生于10月下旬至12月上旬,发生高峰期为11月中、下旬,12月上旬以后以卵越冬。棉蚜种群在木槿上呈聚集分布,以植株中、南部分布量最大。二维排序结果表明,木槿上棉蚜种群动态可分为成蚜回迁期、成若蚜高峰期、成若蚜阶段向越冬卵阶段过渡期和越冬卵期4种主要动态类型。     

不同受害程度的棉株对棉蚜种群的影响

通过室内对不同密度棉蚜两次为害棉株的生态学参数测定，结果表明：棉株在受到棉蚜二次为害后，无论是棉株生长点或是不同生长期棉株受害，均可影响棉蚜种群数量下降，增长率降低，发育历期增大，扩散率提高，体色趋变黄色。可以证明受害棉株明显存有诱导抗性，且６片真叶以后的诱导抗性大于６片真叶以前。     

石河子棉区棉蚜消长动态及测报

石河子棉区蚜迁入棉田始见期一般５月上旬末－中旬末；棉蚜中心株多在５月中正旬发现；６月中下旬棉蚜进入全面迁飞扩散期；棉蚜种群的消长与５，６月份中旬气温级７，８月份气温，降水和天敌关系密切。棉蚜的测报着手从棉蚜迁入棉田期，天敌发生情况，高温天气，不同体色棉蚜发生数量，有蚜株率及有翅株率等几方面进行。     

棉蚜外寄生性天敌——卵形异绒螨研究进展

卵形异绒螨(Allothrombium ovatum)是棉蚜(Aphis gossypii)的一种外寄生性天敌.本文报道了该种天敌的生活史;卵、前幼螨、幼螨、若蛹、若螨、成蛹和成螨的发育历期和各种虫态的生活习性和生境;幼螨的寄主和寄主选择性;成、若螨的猎物和成螨的产卵量;棉田卵形异绒螨的来源、扩散及种群动态;棉蚜有翅成蚜携螨的最大负载量和向不同棉田的日迁移量;棉蚜-卵形异绒螨的生态位及其空间格局;卵形异绒螨对棉蚜的寄生作用及控蚜阈值;该种天敌种群密度与棉田海拔、水位、连作时间及栽培方式的关系;杀虫剂种子处理、喷雾和涂茎对棉蚜和卵形异绒螨的选择毒性.提出了卵形异绒螨的应用前景及其保护利用的方法.     

巧尽其用的虫足

<正>胸足的基本构造足是昆虫的运动器官。昆虫有3对足,在前胸、中胸和后胸各有一对,被相应地称为前足、中足和后足。每个足由基节、转节、腿节、胫节、跗节和前跗节几部分组成。基节是足最基部的一节,多粗短。转节常与腿节紧密相连而不活动。腿节是最长最粗的一节。第四节叫胫节,一般比较细长,长着成排的刺。第五节叫跗节,一般由2⁵个亚节组成,为的是便于行走。在最末节的端     

麦盖提垦区棉蚜暴发原因及其防冶

1棉蚜暴发的原因 1．1气候因素 棉蚜种群数量受棉蚜发生期间的天敌与气候的共同作用，棉蚜繁殖的适宜温度是23-27℃，适宜的温度是棉蚜种群数量剧增的主导因素。2004年5月中旬至6月上旬，卖盖提垦区平均气温在23．4℃，相对湿度49％，有利于棉蚜的发生。从系统调查看，棉蚜6月5日达到高峰，有蚜株率100％，百株三叶蚜量3045头，益害比1：1549。并且棉蚜和棉黑蚜在棉田同时并存。从随机调查来看，棉苗出现大面积油叶、卷叶现象，再加上此期麦盖提垦区降水少，雨量小，有翅蚜在棉田扩散速度快，迁飞数量大，也是棉蚜发生的重要条件之一。     

新疆棉蚜生物型的研究

在新疆主要棉蚜寄主植物之间进行了接种试验，确立了不同的棉蚜食物专化型—瓜蚜型和棉蚜型。二者各自在瓜类和棉花上独立存在，互相不能直接迁移定植；初步推断出棉蚜在新疆存在３种生活周期型：（１）异寄主全周期型，以石榴和黄金树等为越冬寄主，棉花为侨居寄主；（２）同寄主全周期型，初步观察棉蚜在黄金树上能完成生活周期；（３）不全周期型有两种情况，一是瓜蚜型夏季在田间瓜类作物上营孤雌生殖生活，秋季进入温室和大棚的黄瓜等寄主上继续营孤雌生殖生活；二是夏季在棉花上营孤雌生殖生活，秋季进入温室和大棚的扶桑等寄主上继续营孤雌生殖生活；并采用ＲＡＰＤ－ＰＣＲ技术对不同寄主植物上的棉蚜种群进行了检测。     

非生物胁迫对棉花次生代谢及棉蚜种群消长的影响

盐碱、干旱等非生物胁迫影响棉花的次生代谢,而次生代谢可能影响棉株上的害虫发生。为明确非生物胁迫与次生代谢及棉蚜种群消长三者间的关系,以不同浓度氯化钠(NaCl)和聚乙醇(PEG)溶液分别处理棉苗,测定了棉叶组织内棉酚和可溶性糖含量的变化,并观察了棉蚜在被处理棉苗上的生长发育及繁殖情况。结果发现,100和200 mmol·L~(-1) NaCl处理棉苗的棉酚含量分别比不含NaCl的对照提高20%和53.5%,可溶性糖含量分别提高15.7%和46%。盐胁迫显著延长棉蚜的发育历期并降低繁殖率,100和200 mmol·L~(-1) NaCl处理的棉蚜若蚜期分别比对照延长6.4%和9.9%,单雌产蚜量分别减少22.6%和52.3%。干旱胁迫也影响棉花叶片棉酚和可溶性糖含量,质量分数2.5%和5%的PEG处理棉株的棉酚含量分别比对照提高39.7%和61.5%,可溶性糖含量分别提高14.2%和47.1%,生长在PEG处理棉株上的棉蚜的若蚜期分别延长7.4%和16.5%,单雌产蚜量分别减少26.8%和55.8%。叶片内棉酚和可溶性糖含量均与棉蚜若蚜期呈显著正相关,与棉蚜的产蚜量呈显著负相关。由此推断,盐碱、干旱等非生物胁迫增强了棉苗的次生代谢,导致棉酚和可溶性糖等次生代谢产物大量积累,抑制了棉蚜种群的消长。     

中国北方棉区转基因抗虫棉对棉苗蚜及其两种天敌的影响(英文)

2 0 0 1年田间小区试验研究了转 Bt基因棉和转双价基因 ( Bt+ Cp TI)棉对棉苗蚜及其天敌种群动态的影响 ;室内研究了转基因抗虫棉对两种棉蚜天敌的生物学影响。结果表明 ,转基因抗虫棉对棉蚜种群数量的影响不明显 ,未达显著水平。单作转基因棉田棉蚜发生期比麦套棉田提前 5天左右 ,发生数量是麦套棉田的 1 .6倍 ,表明麦棉套作可有效的控制苗蚜的为害。室内研究表明 ,异色瓢虫对用 Bt棉处理的的棉蚜的捕食量比对照增加 2 2 .0 % ,棉蚜茧蜂对用 Bt棉处理的棉蚜的寄生率降低 2 3.5 %。     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

Pollen and pollination experiments. III. The viability of apple and pear pollen as affected by irradiation and storage

Summary Apple and pear pollen was irradiated with doses of 0, 50, 100, 250 and 500 krad (gamma rays) and stored at 4°C and 0–10% r.h. From the in-vitro germination percentages an average LD 50 dose of about 220 krad was estimated. For both irradiated and untreated pollen a close and corresponding lineair relationship existed between germination percentage and pollen tube growth.Irradiated pollen was much more sensitive to dry storage conditions than untreated pollen, resulting in less germination and more bursting. Apparently, irradiation caused the pollen cell membrane to lose its flexibility faster than normal. Rehydration of dry-stored, irradiated pollen in water-saturated air restored germination percentages up to their initial levels. The importance of this procedure in germination trials is stressed.     

Water Extraction Process of Chinese Herbal Compound Man Gan Ning

[Objectives]To optimize the water extraction process of Chinese Herbal Compound Man Gan Ning and establish a method for its extraction and content determination...     

Present status and future strategy in breeding faba beans (Vicia Faba L.) for resistance to biotic and abiotic stresses

Progress is being made, mainly by ICARDA but also elsewhere, in breeding for resistance to Botrytis, AScochyta, Uromyces, and Orobanche; and some lines have resistance to more than one pathogen. The strategy is to extend multiple resistance but also to seek new and durable forms of resistance. Internationally coordinated programs are needed to maintain the momentum of this work.Tolerance of abiotic stresses leads to types suited to dry or cold environments rather than broad adaptability, but in this cross-pollinated species, the more hybrid vigor expressed by a cultivar, the more it is likely to tolerate various stresses.     

Optimization of Extraction Technology and Determination of Content of Total Phenols of Leaves in Acanthopanax giraldii Harms

[Objectives] To determine the optimum extraction technology for total phenols of leaves in Acanthopanax giraldii Harms.[Methods]The single factor test and ortho...     

Cytoplasmic male sterility,resistance to gall mite and mildew,and season of leafing out in black currants

Summary Cytoplasmic male sterility (cms) is described in the F₁ hybrids Ribes × carrierei (R. glutinosum albidum × R. nigrum) and R. sanguineum × R. nigrum. In backcrosses to R. nigrum, progenies with R. glutinosum cytoplasm were either all male sterile, or segregated for full male fertility (F) and complete (S) and partial (I) male sterility. Ratios of F:I+S suggested that two linked genes controlled cms, F plants being dominant for one (Rf ₁) and recessive for the other (Rf ₂).Segregation for cms in relation to three linded genes, Ce (resistance to the gall mite, Cecidophyopsis ribes), Sph ₃(resistance to American gooseberry mildew, Sphaerotheca mors-uvae) and Lf ₁(one of two dominant additive genes controlling early season leafing out) indicated that Rf ₁and Rf ₂were in this linkage group. The gene order and approximate crossover values appeared to be: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqef0uAJj3BZ9Mz0bYu% H52CGmvzYLMzaerbd9wDYLwzYbItLDharqqr1ngBPrgifHhDYfgasa% acOqpw0xe9v8qqaqFD0xXdHaVhbbf9v8qqaqFr0xc9pk0xbba9q8Wq% Ffea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qqQ8frFve9Fve9Ff0dme% aabaqaciGacaGaamqadaabaeaafaaakeaacaWGdbGaamyzamaamaaa% baGaaiiiaiaacccacaGGWaGaaiOlaiaacgdacaGG0aGaaiiiaiaacc% caaaGaaiiiaiaacccacaGGGaGaamOuaiaadAgaliaaigdakmaamaaa% baGaaiiiaiaacccacaGGGaGaaiiiaiaaccdacaGGUaGaaiOmaiaacs% dacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaaaacaWGsbGaamOzaSGa% aGOmaOWaaWaaaeaacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaiaacc% cacaGGGaGaaiiiaiaacccaaaGaamitaiaadAgaliaaigdakmaamaaa% baGaaiiiaiaacccacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaiaacc% cacaGGGaGaaiiiaiaacccacaGGGaaaaiaadofacaWGWbGaamiAaSGa% aG4maaaa!6E4D!\[Ce\underline { 0.14 } Rf1\underline { 0.24 } Rf2\underline { } Lf1\underline { } Sph3\]. Crossover values of 0.36 for Ce-Lf ₁, and 0.15 for Lf ₁-Sph ₃were estimated from the relative mean differences in season of leafing out between seedlings dominant and recessive for Ce and Sph ₃.It is suggested that competitive disadvantage of lf ₁-carrying gametes and/or zygotes at low temperatures may be implicated in the almost invariable deficit of plants dominant for the closely linked mildew resistance allele Sph ₃. Poor performance of lf ₁- (and possibly lf ₂-) carrying gametes and young zygotes during periods of low temperature at flowering might also account for the liability of some late season cultivars and selections to premature fruit drop (running off).     

Screening techniques and sources of resistance to parasitic angiosperms

Parasitic angiosperms cause great losses in many important crops under different climatic conditions and soil types. The most widespread and important parasitic angiosperms belong to the genera Orobanche, Striga, and Cuscuta. The most important economical hosts belong to the Poaceae, Asteraceae, Solanaceae, Cucurbitaceae, and Fabaceae. Although some resistant cultivars have been identified in several crops, great gaps exist in our knowledge of the parasites and the genetic basis of the resistance, as well as the availability of in vitro screening techniques. Screening techniques are based on reactions of the host root or foliage. In vitro or greenhouse screening methods based on the reaction of root and/or foliar tissues are usually superior to field screenings and can be used with many species. To utilize them in plant breeding, it is necessary to demonstrate a strong correlation between in vitro and field data. The correlation should be calculated for every environment in which selection is practiced. Using biochemical analysis as a screening technique has had limited success. The reason seems to be the complex host-parasite interactions which lead to germination, rhizotropism, infection, and growth of the parasite. Germination results from chemicals produced by the host. Resistance is only available in a small group of crops. Resistance has been found in cultivated, primitive and wild forms, depending on the specific host-parasite system. An additional problem is the existence of pathotypes in the parasites. Inheritance of host resistance is usually polygenic and its transfer is slow and tedious. Molecular techniques have yet to be used to locate resistance to parasitic angiosperms. While intensifying the search for genes that control resistance to specific parasitic angiosperms, the best strategy to screen for resistance is to improve the already existing in vitro or greenhouse screening techniques.