Morphological Basis of Resistance in Cotton to the WhiteflyBemisia Tabaci     

N. S. Butter  B. K. Vir 《Phytoparasitica》1989,17(4):251-261

The morphological basis of resistance to the whiteflyBemisia tabaci Genn. (Aleyrodidae: Hemiptera) was studied. The plant characters examined were leaf area, thickness of leaf lamina, hair density, hair length, angle of insertion of leaf hair, and density of gossypol glands. Hair density and leaf thickness were positively correlated with the population ofB. tabaci, and a positive correlation was obtained between the adult whitefly population and gossypol glands on stem internodes. Cotton genotype USA-22 (sparsely hairy) was found to be more tolerant toB. tabaci than was genotype USA-13 (velvety hairy). The use of thinner and glabrous leaved cotton varieties is suggested to minimize the whitefly menace in cotton.  相似文献   

哈纳斯自然保护区植被特点及植物区系形成的探讨   总被引：10，自引：4，他引：10  

潘晓玲  张宏达 《干旱区研究》1994,11(4):1-7

哈纳斯自然保护区的植被充分反映了欧洲－西伯利亚区系成分的特色。山地针叶林带与天山相比显著下降，为阴暗泰加林类型。植被类型丰富多样，与天山的植被特点迥然不同。本区植物区系形成于第四纪。其区系组成以温带成分为主，并含有少量的古地中海成分。以本土发生的安哥拉区系成分米体；发源于华夏地区的亚洲温带成分渗透至本区；残存的古地中海成分有小部分通过相邻地区向本区渗放。  相似文献   

Phenotypes Including Immunocompetence in Scavenging Local Chicken Ecotypes in Tanzania     

Msoffe PL  Minga UM  Olsen JE  Yongolo MG  Juul-Madsen HR  Gwakisa PS  Mtambo MM 《Tropical animal health and production》2001,33(4):341-354

A study was conducted to determine the variations in physical characters and immunocompetence among scavenging local chicken ecotypes in Tanzania. Eighty-four adult scavenging local chickens from four eco-climatic regions of Tanzania were studied. Measurements of adult body weight, body length, shank length and egg weight and observations of plumage colour and pattern, earlobe colour, skin colour and the shape of the comb were conducted. The antibody response to sheep red blood cells, serum haemolytic complement and the cutaneous response to phytohaemagglutinin-P were assessed. Five ecotypes were identified and named Mbeya, Morogoro-medium, Ching'wekwe, Kuchi and Singamagazi. Singamagazi and Kuchi were significantly heavier, with longer shanks and heavier eggs than the other ecotypes. The average adult body weight for males ranged from 1621 g (Mbeya) to 2915 g (Singamagazi). Average female weights ranged from 1108 g (Morogoro-medium) to 2020 g (Singamagazi). Mean egg weights ranged from 37.65 g (Ching'wekwe) to 45.61 (Singamagazi). The Kuchi had mostly rose and walnut combs, while the other ecotypes were mostly single combed. In each ecotype there were chickens with a high or low antibody response to red blood cells, but there was a significant difference between the ecotypes.  相似文献   

禾谷镰孢菌对多菌灵的敏感性基线及抗药性菌株生物学性质研究   总被引：48，自引：5，他引：48  

周明国  王建新 《植物病理学报》2001,31(4):365-370

 引起小麦赤霉病的禾谷镰孢菌(Fusarium graminearum)在华东地区对多菌灵已出现了高水平抗药性。本文报道了F.graminearum对多菌灵的敏感性基线及其抗药性菌株生物学特性。离体条件下多菌灵对100个野生敏感型菌株的平均EC₅₀和MIC值分别为0.5748±0.0133 μg/ml和 < 1.4μg/ml。而对50个抗药性菌株的平均EC₅₀和MIC值则分别为9.2375μg/ml和 > 100 μg/ml。在麦穗上多菌灵对50个敏感菌株和抗药性菌株防效的平均EC₅₀分别为282.6 μg/ml和 > 2 000μg/ml。从田间获得的抗多菌灵菌株对苯菌灵、噻菌灵、甲基托布津表现交互抗药性,但不同于室内突变菌株,对乙霉威不表现负交互抗药性。抗药性菌株的无性和有性繁殖后代以及在无药培养基上菌丝体转代培养后,抗药水平保持不变。抗药性菌株的菌丝生长速率、产孢能力及致病力等与敏感菌株相比没有差异。  相似文献   

麦茎谷蛾生物学特性及防治     

宁焕庚  白莉  史忠良 《植物保护》1995,21(4):10-11

麦茎谷蛾在山西南部麦区普遍发生，丘陵旱塬地区为害较重。大发生时，孕穗～灌浆期小麦被害穗率达３０％以上。药剂防治试验表明，３月上旬卵态幼虫孵化时用４０％甲基异柳磷、２０％菊马乳油等进行一次性防治，均有较好的效果。  相似文献   

中籼稻穗部性状遗传力研究     

赵德新  林森 《信阳农业高等专科学校学报》1991,(2)

本文研究了中籼稻穗部性状的广义遗传力和变异系数。其分别为:一次枝梗71.46％,36.08％,千粒重67.79％,9.67％;着粒密度60.77％,23.9％;二次枝梗59.41％,23.22％;穗粒数56.67％,23.38％;结实率54.3,13.39％;穗粒重48.02％,25.64％;穗长38.15％,11.26％。其中穗长的遗传力在不同组合间有较大的差异,最低为10.76％,高的达60.02％,相差6倍;变异系数一次枝梗在不同组合中也有较大的差异,最低为13.66％,高达50.31％,相差4倍。因此在杂交亲本和杂种后代选择时应注意穗长和一次枝梗这两个性状。  相似文献   

乌骨鸡的研究进展及产品开发   总被引：6，自引：1，他引：5  

房兴堂  薛忠  王庆林  赵雪锋 《经济动物学报》2001,5(2):52-58

论述了我国乌骨鸡的研究现状及其产品开发情况 ,旨在促进乌骨鸡养殖业的发展  相似文献   

Morphology of Day-7 Bovine Demi-Embryos and their Post-transfer Viability*     

A. Albihn  H. Gustafsson  H. Rodriguez-Martinez 《Reproduction in domestic animals》1991,26(2):85-87

Day 7 bovine embryos were microsurgically bisected and replaced into surrogate zonae pellucidae. They were fixed immediately after bisection and at various intervals of in vitro incubation at 35 °C in modified Dulbecco's medium. At the light microscopical level, the bisected embryos restored the prebisection morphology within 30 min. after splitting. The electron microscopy confirmed these findings, suggesting that day 7 bovine demi-embryos for transfer purposes, should be cultured for 30 min before morphologically evaluated. Eleven pairs of bisected day 7 bovine embryos were transferred to 11 synchronized heifers. The recipient heifers were slaughtered at day 15, and the recovered embryos evaluated. Nine of the demi-embryos developed to morphologically, normal spherical to elongated, embryos.  相似文献   

桑青尺蠖的生物学特性研究     

余虹  周勤  陈伟国 《蚕业科学》2001,27(1):1-5

研究了桑树常见害虫桑青尺蠖的形态特征、继代繁殖等生物学特性 ,以及幼虫食叶量、寄生性天敌及温度对青尺蠖发育历期的影响。该虫在室温下全年可继代繁殖 5代 ,以蛹越冬。随着饲养温度的升高 ,其发育历期缩短。在 2 0 95、2 4 16和 2 9 70℃的温度下 ,全代历期分别为 5 8 1、43 9和 35 2d。幼虫多为 6龄 ,少数 5龄。平均每头幼虫全龄食叶量为 2 948 11mg ,其中第 5龄和第 6龄食叶量占全龄食叶量的 95 48%。  相似文献   

花卉常规杂交育种的研究进展   总被引：5，自引：0，他引：5  

张惠君  罗凤霞 《沈阳农业大学学报》2001,32(4):317-320

本对花卉育种的历史和花卉常规常规杂交育研究进展及各种杂交技术方法进行综述。花卉常规杂交育种的应用领域人：（1）培育花色、花型和香味等观赏性状更加新颖的品种；（2）改变花期；（3）提高花卉适应性和抵抗病虫害能力。并对花卉常规杂交育种未来的研究方向作了展望。  相似文献