No abstract

-The objective of this work was to select an optimal set of morphological descriptors, in order to characterize the phenotipical diversity of Amerindian yam (Dioscorea trifida) landraces cultivated in the municipality of Caapiranga, in the central Amazon region of Brazil, and to develop a botanical identification key for them. A collection of 140 accessions and an experimental plot with a representative sample of 20 landraces were used to test 64 morphological descriptors for the aerial and subterranean plant parts. Fortyeight descriptors were selected, of which 13 were for tubers, 12 for stems, 14 for leaves, and 9 for inflorescences and seed. A cluster analysis based on the morphological data showed the formation of two landrace groups with greater similarity: white and purple pulp tubers. The results provide tools for in situ and ex situ conservation and for plant breeding programs, considering the importance of maintaining and recognizing the value of Ameridian yam as an important native genetic resource for food security in the region.

The Amerindian yam (Dioscorea trifida) is a food plant native to the Amazon region. Several local varieties are cultivated by traditional family farmers for consumption and local trade. However, socioeconomic processes may be causing species genetic erosion. Knowledge about species sexual reproduction is essential for its conservation and genetic improvement. The objective of this study was to observe the floral phenology, to assess the germination and dormancy of seeds, to conduct controlled pollinations and to select hybrid plants of D. trifida with agronomic potential. Seed dormancy was confirmed and was broken by after-ripening at 28 oC and 80% RH. We carried out controlled pollinations between local landraces and cultivated the resulting hybrid plants in the field. The new genotypes showed high phenotypic variability and tubers with new characteristics, which permitted the selection of genotypes with agronomic potential for further studies. The results contribute to the conservation of agrobiodiversity and genetic improvement for added value of Amazonian native food plants.