Abstract ‘Bitter’ and ‘sweet’ cassava are normally distinguished based on the hydrocyanic acid (HCN) content of their roots. Moreover, Brazilian farmers tend to select ‘sweet’ cassava based on the taste and cooking aspects. The aim of this study was to characterize chemical traits of ‘bitter’ and ‘sweet’ cassava roots of the Amazon region and to find genetic relations among accessions based on these traits. Considerable phenotypic variation was detected among the evaluated traits moisture, ashes, total soluble solids, total titratable acidity, pH, total carotenoids, free and total cyanide, crude protein, glucose, fructose, sucrose and starch. Aside from free and total cyanide, the trait means of sugars and moisture differed in ‘bitter’ and ‘sweet’ cassava and also differentiated these in different clusters in the dendrogram using the unweighted pair-group method based on arithmetic averages (UPGMA) and in the results of principal component analysis.

RESUMO O objetivo deste trabalho foi avaliar a distribuição espacial da leprose dos citros em dois pomares na região citrícola do Nordeste Paraense/Amazônia Oriental. Realizaram-se avaliações com intervalo mensal no período de dezembro de 2011 a novembro de 2012, verificando-se plantas com sintomas característicos da leprose dos citros, anotando-se 1 para presença e 0 para ausência. Foi aplicada a geoestatística para a análise espacial da doença, modelagem dos semivariogramas e confecção dos mapas de krigagem. O modelo que melhor se ajustou à distribuição espacial da doença foi o esférico, pois apresentou maior valor do coeficiente de determinação, com variação no alcance de 18 a 29 m na área A, e de 9 a 30 m na área B. O Índice de Dependência Espacial (IDE) apresentou-se moderado para todas as avaliações da área A, ficando no intervalo de 0,25 a 0,75, e na área B com exceção dos meses de dezembro de 2011, junho e setembro de 2012, que apresentaram o IDE moderado, todos apresentaram o IDE fraco com valores abaixo de 0,25. A geoestatística mostrou-se uma ferramenta propícia para a avaliação da distribuição espacial do Citrus leprosis virus (CiLV).

ABSTRACT This study aimed to evaluate the spatial distribution of citrus leprosis in two orchards in the Eastern state of Pará/ Eastern Amazon citrus region. Two evaluations were performed at monthly intervals between December, 2011 and November, 2012 checking plants with characteristic symptoms of citrus leprosis by recording 1 for presence and 0 for absence. To analyze the disease spatial distribution in the plots, geostatistics was used for semivariogram modeling, and elaboration of kriging maps. The model that better adjusted to the disease spatial distribution was the spherical, the one with the highest coefficient of determination with variations ranging from 18 to 19 meters in area A and 9 to 30 m in area B. The Spatial Dependence Index (SDI) was moderate for all area A evaluations with interval ranging from 0.25 to 0.75, while in area B, except for the months of December 2011, June and September 2012 with a moderate SDI, all the others showed a weak SDI with values below 0.25. Geostatistical analysis has shown itself to be an ideal tool to evaluate Citrus leprosis virus (CiLV) spatial distribution.