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51.
基于地理信息系统的耕地苜蓿斑蚜种群发生的适宜生境 总被引:4,自引:1,他引:3
基于地理信息系统(GIS)技术,将宁夏固原市原州区不同时期耕地苜蓿斑蚜种群分布插值图与生态气候图、数字高程图进行叠加,分析了苜蓿斑蚜密度与生态环境和地理分布之间的关系.结果表明:研究区苜蓿斑蚜的分布和发生程度与气候、地貌和海拔密切相关,苜蓿斑蚜在研究区的适宜生境为海拔1440~2000 m的半干旱平原区和半干旱丘陵区,最易暴发成灾的区域为海拔1600~1800 m的半干旱平原区.苜蓿斑蚜的适宜生境与不同时期的空间分布插值图相结合,可定量分析各生态区苜蓿斑蚜种群的空间动态. 相似文献
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The feasibility of using the sterile insect technique against Liriomyza trifolii (Diptera: Agromyzidae) infesting greenhouse chrysanthemum 总被引:1,自引:0,他引:1
Liriomyza trifolii is a serious pest of chrysanthemum greenhouses and other crops around the world. The larvae feed within the leaves of the host plants and create serpentine mines. The Sterile Insect Technique (SIT) has been successfully used against some Dipteran species in the field, and it is especially efficient against isolated populations like those on islands. Therefore, SIT against pest populations in confined environments such as greenhouses should have high potential for success. The objectives of this study were to determine the optimum gamma‐irradiation dosage required for the sterilisation of L. trifolii adults, and to determine the quality (emergence percentage, flight ability, longevity, copulatory success, and sperm transfer) of the irradiated males compared with that of non‐irradiated (normal) males. We found that sterility (< 0.7 mine per female) was achieved with the dose of 170 ± 5% Gy. The copulatory success and sperm transfer during copulation of the sterile males were not significantly different from those of normal males. Moreover, the longevity, emergence percentage and flight ability of irradiated males were also not significantly different from normal males. The SIT experiments suggest that the release of sterile L. trifolii can significantly reduce the reproductive capacity of a wild leafminer population. Our studies indicate that sterilisation of L. trifolii flies is feasible and that sterile males are of high quality and competitive with normal males. Based on these data, research on the use of SIT against L. trifolii populations in greenhouses is ongoing. 相似文献
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采用真菌核糖体基因转录间隔区(ITS)通用引物,PCR分别扩增了Phytophthora sojae的5个菌株(Pg1、Pg2、Pg3、CN1和S317)和1个P. medicaginis (菌株44390)的ITS1与ITS2,并对PCR产物进行了序列测定。根据Bioedit软件中的neighbour-joining methods分析法将上述序列和Genbank中已登录的P. sojae、P. medicaginis、P. megasperma和P.trifolii等4个形态学种10个登录菌株的ITS1与ITS2碱基序列进行聚类分析。结果是聚类组与形态学种有一定差别,4个种16个菌株分成7个聚类组。结果表明,分别属于同一形态学种且可聚为一组的不同个体之间的ITS碱基序列遗传相似性最高,但是也具有一定的多样性;形态学上属于不同种的个体的ITS可以聚为一组。上述结果提示L41385可能不属于P. sojae, L41380可能属于是P. trifolii,P. megasperma仍是一个复合种。同时提示ITS DNA碱基序列可以区分形态学种。 相似文献
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In this paper comparative histological studies of embryo-like structures originating from callus cultures, and zygotic embryos
originating from sexual seeds of Cuscuta trifolii are reported. The embryos of somatic cell and zygote origin showed similar morphological and anatomical features, such as
a complete lack of cotyledon development and the differentiation of a developmentally unique root primordium specialised for
water storage. Based on these findings, the regeneration of C. trifolii from callus cultures is shown to proceed along the pathway of somatic embryogenesis.
Received: 9 November 1998 / Revision received: 22 April 1999 / Accepted: 29 June 1999 相似文献
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D. H. DEMEZAS ‡ T. B. REARDON S. R. STRAIN† J. M. WATSON A. H. GIBSON 《Molecular ecology》1995,4(2):209-220
A collection of 121 isolates of Rhizobium leguminosarum biovar (bv.) trifolii was obtained from root nodules of Trifolium subterraneum L. (subclover) plants growing in an established pasture. The collection consisted of a single isolate from each of 18 plants sampled from seven microplots. The following year, a further 28 and 27 isolates were collected from the first and seventh sampling points, respectively. Analysis of restriction fragment length polymorphisms (RFLPs) of both chromosomal and Sym (symbiotic) plasmid DNA and multilocus enzyme electrophoresis (MLEE) were used to assess the diversity, genetic relationships and structure of this population. Symbiotic effectiveness tests were used to examine the symbiotic phenotype of each isolate collected in the first year. Analysis of RFLPs of the first year isolates revealed 13 chromosomal types and 25 Sym plasmid types. Similar Sym plasmid types were grouped into 14 families containing 1–6 members. No new chromosomal types and six new Sym plasmid types were detected in the second year. The symbiotic effectiveness of the first year isolates of the same Sym plasmid type was similar. Significant differences in symbiotic effectiveness were detected between different Sym plasmid types in the same plasmid family. Representative isolates of each chromosomal type Sym plasmid type identified in the first year were analysed using multilocus enzyme electrophoresis. Mean genetic diversity per locus was high (0.559). Enzyme electrophoresis revealed 17 electrophoretic types (ETs). Ouster analysis of the enzyme data revealed large genetic diversity amongst the ETs. Strong linkage disequilibrium was observed for the population as a whole, i.e. clonal population structure, but significantly less disequilibrium was observed among a cluster of ETs suggesting that recombination occurred between ETs within the cluster. Our results revealed that a population of naturally occurring isolates of Rhizobium leguminosarum bv. trifolii can be genetically diverse and support the possibility that recombination plays a role in generating new genotypes. 相似文献
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Detailed individual nodulation profiles were obtained for five strains of Rhizobium leguminosarum biovar trifolii inoculated onto roots of Trifolium repens seedlings growing on an agar medium of pH 4.5. The time of appearance and the location of every nodule were noted for a period
of 10 days after inoculation. Using these nodulation frequency profiles, pairings of strains were identified and six mixed-strain
inoculation (1:1 ratio) experiments were subsequently performed at pH 4.5. Results from the mixed-inoculum experiments showed
that the performance of a Rhizobium strain in single culture could not be reliably used to predict the outcome of a paired-inoculation study and that some seedlings
were exclusively nodulated by rhizobia that performed poorly at low pH in single-culture inoculations.
Received: 26 November 1996 / Accepted: 18 April 1997 相似文献
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Root-infecting nematodes are a major cause of white clover, Trifolium repens, not reaching its potential in New Zealand pastures. Resistance and/or tolerance are the preferred control options. Greenhouse-based, recurrent selection programs have developed resistance to Meloidogyne trifoliophila and Heterodera trifolii, and a field-based program has developed tolerance. Lines from these programs were compared with commercial cultivars as controls in a series of field trials at four sites over 4 years. Resistant lines from the CCN program performed better than susceptible lines and as well as most cultivars, reflecting the high level of resistance developed in this greenhouse-based program. In stained root from Cambridge, numbers of CCN were lower in resistant lines than in cultivars; numbers in susceptible lines were intermediate. CCN resistance was also reflected to a lesser extent in the number of cysts counted in soil under resistant lines in Palmerston North. The root-knot nematode-resistant material performed better than the susceptible and as well as most cultivars. In one trial of CRKN-resistant lines, resistant and susceptible lines had similar numbers of CRKN which were both lower than the numbers in the cultivars; in the second trial, there were fewer CRKN in resistant than in susceptible lines or cultivars. The tolerant selections, developed under field conditions, performed as well as or better than the cultivars. The selections from the breeding programmes have exhibited strong agronomic potential across locations and years, and the best material has been crossed; progeny are being assessed in current field trials. 相似文献