Ecologia e genetica da mandioca na agricultura itinerante do litoral sul paulista : uma analise espacial e temporal




This study focuses the inter-relationships between the men, the farm environment, and the domesticated crop species, under the perspective of the evolutionary dynamics of cultivated plants. The main objective of this study was to evaluate the features related to the conservation, loss, and amplification of the varietal diversity of manioc (Manihot esculenta Crantz), cultivated by local populations in itinerant agricultural systems. Through an interdisciplinary approach, the conservation, loss, and amplification of varietal diversity were framed in three different scales: the geographic unit, representing an regional scale in the space; the cultural unit, representing the scale in the human community level; and the evolutionary unit, representing the household level and the cultivated plots. Ethnobotanical, ecological, and genetic information about the manioc cultivated diversity by caiçara populations were integrated. The analysis encompasses spatial and temporal scales, and is subdivided in chapters. 1n the first chapter, the sample of studied agriculturists is characterized and described, as well as the use of the soils of the itinerant plots. Soil samples from the region of the estuarine-lagoon complex of Cananéia-1guape-Ilha Comprida, in the Atlantic Forest, are also compared to soil samples from caboclo plots, managed in the region of the middle and lower Negro River, in the Amazon. This chapter focuses in the local context of the plot management, describing the environments under an edaphic milieu, The second chapter focuses on the regional context of changes in the Vegetal land cover, in the areas of traditional agricultural use, in the southern coast of São Paulo state. The approach is centered in the analysis of spatial and temporal changes, with the examination of satellite images between 1975 and 1999. In the third chapter, the regional context of the management of species and varieties is analyzed. The broad framework of conservation, loss and genetic erosion is discussed. Cassava is analyzed as a part of the whole management of species and varieties cultivated by caiçaras. In the fourth chapter the morphological characteristics of cassava were analyzed, as well as the major criteria of varietal identification used by caiçaras. The flow of varieties between agriculturists, based on the spatial position of These varieties, is also analyzed. In the fifth chapter, the analysis of the cassava varietal diversity is deepened, under the aspect of genetic diversity. Using a population genetics approach, the spatial distribution and structure of cassava are evaluated. Genetic conservation and amplification of infra-specific diversity were also analyzed in the fifth chapter. In the sixth chapter, some characteristics of the relationship between itinerant management and life history traits of the species were analyzed, and some evolutionary processes of amplification of the diversity were discussed. Intentional and non-intentional interchanges of varieties in a regional level create a buffer effect to the local losses. The strategy of policultural farming, and the allogamous behavior of the species, allow the infra and intra-specific outcrossing in the plot level. Due to the strict relationship between itinerant agricultural cycles and the amplification of diversity, the reduction of the agricultural activity tend to decrease the frequency of the incorporation of genetic diversity, produced by these outcrossing and by random mutations. Many factors are responsible to the decrease il1 the agricultural activities and loss of cultivated diversity. The forest regeneratioI1 in the cultivated areas is a strong indicator of the abandonment of agricultural activities. With the ageing of agriculturists and the reduced family labor, the losses of both the varietal diversity and the traditional knowledge associated to the farming and to the use of this diversity, tend to be irreversible. However, the gel1etic diversity stock conserved by caiçaras is considerable, which makes the region a priority area to the conservation of genetic resources on farm, under agricultural activities being itinerant or not


mandioca ecologia humana etnobotanica genetica

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