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J. E. Parlevliet 《Euphytica》2007,153(3):353-362
Improved cultivars loose their identity and healthiness unless maintained properly. Contaminating and degrading forces, such
as outcrossing, volunteer plants, mixing, natural selection, mutation and seed-borne diseases, are at the root of this. Maintenance
selection can prevent this deterioration. How it is carried out depends on the reproduction system of the crop. Crops are
therefore classified into four categories; typical cross-pollinating crops, self-pollinating crops with a substantial amount
of outcrossing, typical self-pollinating crops with little outcrossing, and the vegetatively reproduced crops.
Generally some of the “breeder seed” is used to plant a small plot with spaced plants. A fair number of healthy plants of
the cultivar type is selected and the seed is harvested per plant. The progenies of the selected plants are grown in small
plots. Non-uniform or deviating plots and plots with a seed-borne disease are removed. The seed of the progenies that are
healthy, uniform and similar (and so of the cultivar type) are harvested per progeny to be tested next season on larger plots.
The same selection is applied and only the seed of the progenies that are healthy, uniform and similar are harvested together
to produce the “breeder seed”. The details of this maintenance selection vary with the reproduction system, the multiplication
rate of the crop and the possibilities available to the breeder. Seven crops, potato, common bean, barley, wheat, faba bean,
quinoa and maize are discussed here as they represent the different reproduction systems and multiplication rates, while being
important Andean food crops. 相似文献
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春兰根状茎增殖与分化培养 总被引:8,自引:0,他引:8
以10种培养基进行了春兰根状茎增殖培养研究,结果表明,不同培养基对增殖率有明显影响,以White NAA 5 mg/L培养再转入1/2 MS NAA 5 mg/L培养基,可获得较高的平均生长速度,但获得的根状茎总量以2号培养基最多。春兰根状茎的最适增殖条件为:1/2 MS为基本培养基,不加或添加少量NAA,60 d为1个增殖周期;5种培养基分化培养结果表明,根状茎分化受BA浓度影响较大,当BA浓度达3 mg/L时,经45 d培养平均每g根状茎可分化出20个芽,每芽重约0.15 g。活性炭的存在会抑制分化。 相似文献
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