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Agroforestry Systems - 相似文献
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Artificial hybridization between Robinia pseudoacacia L. and R. pseudoacacia var. monophylla Carr. 总被引：1，自引：0，他引：1
Results regarding artificial cross- and self-pollination betweenRobinia pseudoacacia L. and R. pseudoacacia var. monophyllaCarr. are reported. Parental clones involved in a diallel matingscheme were selected according to leaf type phenotype and included(1) single-leaf type, (2) 25-leaf type, (3) three-leaf typeand (4) common Robinia. Artificial pollination proved to bea difficult and delicate procedure. A total of 33 pollinationswere made that resulted in the formation of 84 pods, of which24 developed fully and produced 65 seeds. Fifteen seeds weregerminated, resulting in the production of two putative fertilehybrids. The success of hybridization was assessed by geneticmarkers, while parental clones and hybrid progeny were assignedmultilocus genotypes. The mode of inheritance of the leaf typetrait was studied in open-pollinated families where the monophyllatype was the maternal parent. The study indicated that leaftype in the monophylla variety may be associated with majorgene effects. 相似文献
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The species complex Arion hortensis s.?l. is among the most important pestiferous slugs in Europe. The species A. distinctus Mabille and A. hortensis de Férussac have traditionally been grouped together under the denomination A. hortensis. Therefore, neither the feeding behaviour nor the susceptibility of the individual species to control measures are known. In the laboratory, mean daily consumption of lettuce was similar for both species. In a series of laboratory bioassays, A. distinctus and A. hortensis s.?s. were exposed to the rhabditid nematode Phasmarhabditis hermaphrodita and to the chemical molluscicides metaldehyde and iron phosphate, and their feeding and health were measured. Both species showed a similar and low susceptibility to the biocontrol agent P. hermaphrodita. In field-collected slugs, the incidence of nematodes was much lower in A. hortensis s.?l. than in Deroceras reticulatum or Arion lusitanicus. Metaldehyde and iron phosphate affected both slug species similarly. Therefore, our results do not indicate any major difference between the two slug species of agronomical relevance. 相似文献
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P. J. C. Harris N. M. Pasiecznik S. J. Smith J. M. Billington L. Ramírez 《Forest Ecology and Management》2003,180(1-3):153-164
Two species of Prosopis, Prosopis juliflora and Prosopis pallida, native to Central America and northern South America, have been widely introduced and are now found throughout the world’s hot arid and semi-arid zones. However, these species are frequently misidentified, especially where introduced, hampering genetic improvement and effective management. Samples from trees previously identified as either P. juliflora or P. pallida were divided into two groups by multivariate analysis using selected foliar characters. One group contained known tetraploids and the other contained known diploids. It was concluded that the tetraploid and diploid groups correspond to P. juliflora and P. pallida, respectively. Triploid individuals were also identified, the first report of these in the genus Prosopis. A dichotomous key was developed to differentiate the species, using number of interfoliar glands per rachis, number of leaflet pairs per pinna and leaflet length. P. juliflora and P. pallida grown from seed collected within their respective native ranges were correctly identified using the key. Where introduced, samples from Burkina Faso, Jordan and India were confirmed as P. juliflora, but those from Brazil, Cape Verde and Senegal were identified as P. pallida, rather than P. juliflora, the species assumed to be naturalized in these countries. The correct identification of these two species will facilitate the genetic improvement and management of P. juliflora and P. pallida. There is a strong case for basing future selection and genetic improvement programs on P. pallida rather than P. juliflora. Further collection and evaluation of P. pallida is therefore required, together with conservation programs in the native range. 相似文献
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毛竹胸径分布和竹林生产力的估测 总被引：1，自引：0，他引：1
该文通过毛竹样地的胸径及枝下高调查，并运用电子计算机分析研究，结果表明：毛竹胸径、枝下高及鲜重的分布是遵从正态分布，这为毛竹林生产力的抽样及估测提供了理论依据。 相似文献