Metodologia dos modelos mistos para seleção combinada em progênies segregantes de mamoeiro

Abstract

RESUMOApesar de o Brasil se destacar como um dos principais produtores mundiais de mamão, ainda existe um reduzido número de linhagens/híbridos disponíveis para comercialização. O presente trabalho objetivou selecionar linhagens entre e dentro de progênies em uma população segregante de mamoeiro para avanço das autofecundações. Originalmente a população foi desenvolvida via retrocruzamento objetivando a incorporação (característica Golden) para tolerância à mancha fisiológica nos genitores do híbrido UENF/CALIMAN01, motivo pelo qual foi utilizado um índice de seleção denominado IG2 amparado nos valores genotípicos individuais obtidos via modelos mistos, pelo procedimento REML/BLUP. O resultado da análise permitiu selecionar oito progênies que segregaram para a característica "tipo Golden": 11, 13, 14, 15, 16 19, 18 e 12; dentro das progênies as plantas apresentaram valores superiores de ganho e média predita em relação às testemunhas (JS12, SS72/12 e Golden) para as seguintes características: altura de inserção do primeiro fruto, firmeza da polpa e do fruto e produção. Foram selecionadas 20 plantas com a característica "tipo Golden" visando ao avanço de geração de autofecundação e retrocruzamento. Palavras-chave:Carica papaya L., índice de seleção, REML/BLUP Mixed model for combining selection in segregate progeny of papaya ABSTRACT Although Brazil stands out as a leading global producer of papaya still exists a small number of lines/hybrids available for its cultivation. To obtain new cultivars it is necessary to direct efforts towards the identification and selection of superior genotypes and broadening the genetic basis of the species. This study aimed to select lines between and within families in a segregating population of papaya for advancement of self pollination and backcross. Originally the backcross population aimed the introgression of the physiological disturb (Golden type) into the UENF/CALIMAN01 genitors. For this a selection index named IG2 was used supported in individual genotypic values obtained through mixed models by REML/BLUP. Analysis of results permitted selection of eight progenies and segregated for the trait "Golden Type": 11, 13, 14, 15, 16, 19, 18 and 12. The selected genotypes within each progeny showed higher values of gain and predicted average than the controls (JS12, SS72/12 and Golden) for the following characteristics: height of insertion of the first fruit, firmness of fruit and production. Twenty plants e selected with the characteristic "Golden Type" for the advancement of generation of selfing and backcross.

Productivity and quality of Formosa and Solo papaya over two harvest seasons

“…The mean value of SS contents was 13.66 °Brix, TA was 0.098% citric acid, and the SS/TA ratio was 145.99 (Table 2). These values agree with those obtained by Pinto et al (2013a) and Reis et al (2015), except for fruit weight, which was lower in the present study, but compatible with that of traditional Solo cultivars (Oliveira & Vitória, 2011;Costa et al, 2013). For the genotypes of the Formosa group, the mean number of fruits was 16.12, each weighing 1,298.82 g, and plant production per plant was of 20.37 kg.…”

“…The Golden cultivar was grouped with the genotypes with lower PP and FW in the two harvest seasons. This reinforces the results obtained by Pinto et al (2013aPinto et al ( , 2013b, who observed the degeneration of the Golden cultivar due to the indiscriminate production of seeds, which causes the loss of its original characteristics.…”

“…These values were higher than those reported by Oliveira et al (2010) and Reis et al (2015). However, when considering characteristics of great phenotypic variation, the CV values were acceptable for papaya (Pinto et al, 2013a(Pinto et al, , 2013b and allowed identifying differences between treatments.…”

“…The H 2 values obtained for PP (50.49%) and TA (37.95%) in the Solo group, and for FD (16.81%) and the SS/TA ratio (35.45%) in the Formosa group were considered low. Silva et al (2008) observed heritability values between 28 and 86% for PP, whereas Pinto et al (2013a) reported values of 2% for FD and 0% for SS contents. Both heritability and H 2 , although not identical parameters, express how much of the variation observed is inheritable.…”

“…Both heritability and H 2 , although not identical parameters, express how much of the variation observed is inheritable. Low heritability estimates can be attributed to the narrow genetic base of the population, which reduces the available genetic variability (Pinto et al, 2013a), as well as the effects of climate and of the nutritional conditions of the crop on fruit development (Moretti et al, 2010).…”