Tamanho de coleção original, métodos de agrupamento e amostragem para obtenção de coleção nuclear de germoplasma

Abstract

Resumo -O objetivo deste trabalho foi verificar o efeito do tamanho da coleção original de germoplasma sobre eficácia de diferentes métodos de agrupamento e de amostragem, utilizados na obtenção de coleções nucleares, e comparar esses métodos no estabelecimento de coleções nucleares. Foram simulados sete tamanhos de coleções originais e utilizadas sete estratégias de amostragem para estabelecimento de coleções nucleares, com uso de caracteres morfo-agronômicos. Oito estratégias de obtenção de coleção nuclear foram empregadas, seis com técnicas de agrupamento (Tocher e Tocher sequencial) e duas sem agrupamento (aleatória e Tocher invertido). Nas estratégias de agrupamento, foram empregadas as amostragens constante, logarítmica e proporcional. Determinaram-se a variância explicada, o valor do coeficiente de determinação, o coeficiente de coincidência e o coeficiente de coincidência do desvio-padrão entre a coleção nuclear e a coleção original. As estratégias de amostragem constante e logarítmica geram coleções nucleares representativas da coleção original. O agrupamento de Tocher sequencial é mais eficaz na representação da coleção original pela coleção nuclear do que o agrupamento de Tocher. Entre as estratégias avaliadas, a amostragem pelo método de Tocher com critério de aglomeração inverso foi a mais eficiente na geração de coleções nucleares representativas das coleções originais.Termos para indexação: agrupamento de acessos, estratégias de amostragem, método de Tocher inverso, recursos genéticos. Size of original collection, grouping and sampling methods for the obtention of germplasm core collectionAbstract -The objective of this study was to verify the effect of original germplasm collection size on the effectiveness of different clustering methods and sampling, used to obtain core collections, and to compare these methods in the establishment of core collections. Simulations were made for seven sizes of original collections, and seven sampling strategies were used for the establishment of core collections using morpho-agronomic traits. Eight strategies for obtaining core collections were used, six of them by grouping techniques (Tocher and sequential Tocher), and two without grouping (random and Tocher with inverted criteria grouping). For grouping strategies, constant, logarithmic and proportional sampling were used. The explained variance, the value of the determination coefficient, the coincidence coefficient, and the coincidence standard deviation coefficient between the core and the original collections were determined. The constant and logarithmic sampling strategies generate core collections which are representative of the original collections. The sequential Tocher grouping is more efficient in representing the original collection by the core collection than the Tocher's. Among the evaluated strategies the sampling by Tocher's inversed grouping criterion is the most efficient to generate representative core collections of the original collections.

Core collection of common bean formed from traditional Brazilian germplasm

“…In comparisons among the accessions sampled and the traditional collection, considering the similarity coefficient (CR%), phenotypic diversity coefficient (PD), and the homogeneity measured by the Shannon index (H ' ), the accessions sampled exhibited maximum similarity (100%) with the traditional collection. Values higher than 100% were found in various studies of composition of core collections using information of phenotypes in peanut and sweet potato crops (UPADHYAYA et al, 2002;HOLBROOK;DONG, 2005;VASCONCELOS et al, 2010). According to Hu et al (2000), for the sample to be considered representative of the collection, the minimum limit for the similarity coefficient is 80.0%.…”

“…Thus, there is greater facility in effectively using the genetic resources (NAYAK et al, 2014;MARCHINI, 2019), and that encourages researchers to more frequently draw on the stored germplasm. Consequently, various authors have presented strategies and sampling methods in selection of accessions to obtain a core collection (CHANDRA et al, 2002;LI et al, 2004;ZEWDIE et al, 2004;ABADIE et al, 2005;VASCONCELOS et al, 2007;VASCONCELOS et al, 2010). These principles and methodologies concerning the ideal size and the appropriate choice of individuals are still controversial.…”

Establishing a core collection from the integration of morphoagronomical, phytopathological and molecular data

“…However, the large size of these collections has often been an obstacle to their use, conservation and management (VASCONCELOS et al, 2010). With the objective of enhancing utilisation and accessibility, and minimising maintenance difficulties, Frankel (1984) proposed the concept of the core collection, as being a subsample derived from a set of germplasm chosen to represent, with minimum redundancy, the maximum genetic variability of the initial collection or base of a particular species.…”