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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 98 (1999), S. 840-844 
    ISSN: 1432-2242
    Keywords: Key words Ipomoea batatas ; Duplicate accessions ; Genebank ; Genetic resources ; Phenotypic diversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Sweetpotato [Ipomoea batatas (L.) Lam.] ranks among the seven most important food crops of the world. The International Potato Center (CIP) holds one of the largest sweetpotato (2n=6x=90) genebanks with more than 5000 cultivated accessions from America, Africa, Asia and the Pacific. This collection is clonally maintained because it comprises farmer-selected cultivars that have been asexually propagated for many years. Because of this, numerous duplicate accessions of the same cultivar are to be expected. Considering that almost 30% of the sweetpotato accessions assembled in this collection were from Perú, the first step to select a sweetpotato core collection was to identify duplicates in this group. Duplicate identification, using detailed comparisons of morphological characters and electrophoretic banding patterns of total proteins and esterases, reduced the number of Peruvian accessions in the collection from 1939 to 673. The number of duplicates of the same cultivar ranged from 1 to 99 accessions. A Peruvian sweetpotato core collection was selected to enhance the utilization of this germplasm. A total of 21 morphological descriptors were scored in all the different Peruvian cultivars. The unweighted pair-group method using an arithmetic average (UPGMA) determined the pairwise distance for members of distinct clusters based on these morphological descriptors. A core subset was selected considering the square root of the number of accessions for each Peruvian department and respective cluster, as defined by UPGMA. The original core collection consists of 85 accessions (12.6%) from all Peruvian departments, except that of Madre de Dios, where sweetpotato was never collected, and from all agro-ecological zones except Paramo, which has only 0.5% of the accessions of the entire collection. The sampling for this core collection was appropriate as determined by comparisons of means and frequency distributions for all morphological descriptors. Furthermore, this sampling was validated by the partial assessment of this sweetpotato germplasm for resistance to diseases and pests, tolerance to salt, storage root dry matter content, and vegetative period.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5036
    Keywords: arbuscular mycorrhizae ; Anthyllis ; heavy metals ; Lygeum ; Pb ; Zn
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of arbuscular mycorrhizae (AM) on plant growth and Zn and Pb uptake by Lygeum spartum and Anthyllis cytisoides was studied in soils with different levels of these heavy metals. A. cytisoides is highly dependent on AM for optimal growth, while L. spartum is a facultative mycotroph. Mycorrhizal and nonmycorrhizal plants were grown in soil supplemented with 0, 10, 100 and 1000 mg of Zn kg-1 soil or 0, 100 and 1000 mg of Pb kg-1 soil. Two different mycorrhizal fungi were separately studied: Glomus macrocarpum isolated from a non contaminated site and a strain of Glomus mosseae isolated from a soil contaminated with these metals. The infectivity of the fungi was not affected by the presence of Zn or Pb in the soil. In unamended soil, both fungi were equally effective in promoting plant growth, but when Zn or Pb were added to soils, G. mosseae was more efficient than G. macrocarpum in stimulating plant growth of A. cytisoides. A. cytisoides was unable to grow unless mycorrhizal. Metal addition to the soil induced a reduction in the biomass of L. spartum and of mycorrhizal A. cytisoides, and a decrease in shoot P concentration of mycorrhizal plants. The concentration of metals in the plants varied according to the amount added to the soil and to the inoculation treatment: at low doses, mycorrhizal plants showed equal or higher concentration of Zn or Pb than nonmycorrhizal ones; at higher doses, however, metal concentrations in the plants inoculated with G. mosseae were lower than those found in the corresponding controls, while the plants inoculated with G. macrocarpum showed similar (L. spartum) or even higher (A. cytisoides) levels than the controls.
    Type of Medium: Electronic Resource
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