Variabilidade entre materiais genéticos de eucalyptus spp quanto à distribuição de raízes finas em latossolos profundos

• Autor(a) principal: Pinheiro, Rafael Costa [UNESP]
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/123249; http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/13-04-2015/000819688.pdf
• topic: Eucalipto - Melhoramento genético; Analise foliar; Desidratação (Hídrica); Latossolos; Dehydration

Root behavior in deep soil layers is a subject poorly known for tree species. This topic can be important for breeding programs because a fast displacement of the root front is likely to explain different survival rates among clones in deep Ferralsols during exceptional drought periods. Although an inter-clonal variability in root development might account for different strategies to take up large amounts of water stored in deep soil layers after clearcutting, fine root distributions below a depth of 1 m have been poorly investigated for eucalypt clones. The objectives of our study were: a) to assess the inter-clonal variability among different Eucalyptus genetic materials in fine root densities down to the root front in 2 and 4-years-old clonal tests and in soils with different textures; b) to assess if the ratio between leaf area index (LAI) and root area index (RAI) was similar for different Eucalyptus genetic materials; and c) to assess if the relationship between mean stand height and maximum fine roots depth, as already found for a single E. grandis progeny, is similar for all genetic materials. Soils were sampled using a cylindrical auger at several distances from trees, down to a depth of 17 m for each genetic material. Fine roots (≤ 2 mm in diameter) and leaves were scanned and analysed by WinRhizo and ImageJ softwares, respectively. Fine root densities dropped from 0.2-0.4 g kg-1 in the upper soil layer to values < 0.1 g kg-1 below a depth of 25 cm, irrespective of the genetic material. Seedlings and clones exhibited a similar pattern of fine root development in very deep soil layers. However, mean fine root densities were higher for the seedlings and one clone (clone 14) than for the 2 other clones. Soil water content profiles showed that all the clones and seedlings had the capacity to withdraw water down to ...