Agrobiodiversidade do cará (Dioscorea trifida L.) e sua conservação in-situ em Caapiranga, Amazonas

Abstract

The Amerindian yam (Dioscorea trifida L.) is a food plant native to the Amazon region. Local varieties are cultivated in agroecosystems.However, processes occur that may be causing genetic erosion of the species, running the risk of loss of varieties before knowing their potentials. The research of the thesis had as objectives to register and analyze in-situ conservation practices of the agrobiodiversity, to identify morphological descriptors that discriminate varieties, to develop identification keys for the varieties, to select varieties with favorable agronomic characteristics, to test the viability of hybrid seeds obtained from controlled pollinations and to evaluate the morphological diversity of the hybrid plants. Semi-structured interviews were conducted with the producers generating knowledge about the management of the in-situ agrobiodiversity. The diversity of varieties in the main production center of the Central Amazon region was raised using the snowball method. An experimental plantation with four randomized blocks and four plants per plot for 20 varieties was installed and evaluated the morphological diversityand agronomic characteristics. Sexual reproduction and seed germination were studied and carried out controlled pollinations between varieties and the hybrid plants generated were evaluated. Producer’s knowledge of diversity, propagation methods, exchange of propagating material and the local classification system of varieties were revealed. Morphological descriptors were identified that allowed the creation of an identification key for the aerial and subterranean parts of the local varieties studied. There were significant differences between the varieties in relation to the production of tubers and acceptance by the consumers, which allowed the identification of varieties with higher agronomic potential. Seed dormancy was confirmed and dormancy was broken bystorage (post-dispersion maturity). New genotypes were created by crossings that showed high phenotypic variability and tubers with new characteristics. The results provide tools for the conservation of agrobiodiversity and for genetic improvement, aiming at the rescue and valorization of the native food plants of the Amazon.