Heterosis in Testcrosses of 27 Exotic Peanut Cultivars¹

Abstract

A study was conducted to determine the extent of and genetic basis for heterosis in crosses between 27 exotic peanut (Arachis hypogaea L.) cultivars and an adapted virginia breeding line. Because their subspecific taxonomy was not always clear, principal components were used to cluster the exotic parents into five morphologically distinct groups roughly corresponding to the botanical divisions of the species. Heterosis (measured as the deviation of F~ performance from the midparent) was observed for pod yield, pod size parameters, seed yield and other traits. Heterosis up to 19% above the higher parent occurred for pod size and length. A significant portion (27 to 68%) of the variability in heterotic effects was attributable to difference among the parental groups with generally higher levels expressed in intersubspecificcrosses. Heterotic deviations were broken into two components reflecting the relative contributions of dominance and epistasis to nonadditive genetic variation. For pod and seed yield and pod length, dominance was the more important source while epistasis was more important for pod and seed number and meat content. The two sources made approximately equal contributions to heterosis for pod and seed size. The degree of genetic divergence between exotic parents and the adapted line was estimated by a Euclidean distance based on the vegetative and reproductive characters used in the principal component analysis. For characters exhibiting more dominance, the relationship of heterosis to divergence between parents was linear and increasing. The relationship was curvilinear for traits largely influenced by epistasis. An optimum level of divergence was detected for pod number only.

Utilization of Plant Genetic Resources in Peanut Breeding Program of Bulgaria

“…al (1989) show heterosis in the plant height, weight of the fruit and the yield in its hybrid materials. Isleib and Wynne (1983) obtain similar results, as the established heterosis effect on fruit yield reaches 19,2%. According to many authors this is due to the genetic distance of the parental pairs (Gowen and Frey, 1987).…”

A first insight into population structure and linkage disequilibrium in the US peanut minicore collection

“…As a result, high selection pressure would have been applied on favorable alleles over the generations resulting in LD between non-syntenic loci pairs. Epistatic selection is also reported in peanut, between genes controlling some vital traits in segregating populations (Isleib et al 1978;Layrisse et al 1980;Isleib and Wynne 1983). Hence, selection might be one of the factors inducing LD between unlinked loci pairs in the peanut genome.…”

Diversidade morfológica de frutos e sementes de baru (Dipteryx alata Vog.)

“…é uma leguminosa arbórea (Papilionoideae), que ocorre geralmente nas Estudos de procedências e progênies de baru (também conhecido como cumbaru) têm mostrado diferenças no crescimento (Siqueira et al, 1986;Aguiar et al, 1992;Sano et al, 1994), e indicam necessidade de seleção. As características morfológicas das sementes podem ser utilizadas para identificação de cultivares (Isleib & Wynne, 1983).…”