Abstract
Abstract Selection of superior genotypes based on the simultaneous responses to different characteristics is a fundamental strategy in plant breeding. This study aimed to compare the efficiency of four selection index constructed using phenotypic and genotypic values in a segregating population of the cultivar Rubi Incaper 511. Eight morpho-agronomic variates and the severity of black-spot and phoma-spot were evaluated under field conditions. The classical selection index were calculated based on non-standardized phenotypic means (NSM), standardized means (SM), and genotypic values predicted by REML/BLUP (GVP), using predetermined economic weights. Additionally, the rank sum (RS) was obtained on the basis of the classification of individuals in these three selection index. For ten characteristics, the selected individuals showed a higher mean than did the original population. The best selection differential values were obtained by SM, however, the highest degree of coincidence among the selected individuals was obtained between GVP and RS (80%). The index used were efficient at selecting individuals with higher soluble solids and lower diseases severity evaluated. Therefore, for the papaya breeding programs, different selection index need to be evaluated to maximize genetic gain.
Highlights
The Brazil is one of the leading papaya-producing (Carica papaya L.) countries globally
The low soluble solids content of its fruits prevents its use on a commercial scale, which reinforces the need to continue the papaya breeding program developed by Incaper, which seeks to improve fruit quality of ‘Rubi Incaper 511’.The objective of this study was to compare different selection index based on the phenotypic and genotypic values predicted by REML/
1Selection Index based on non-standard means (NSM), standardized means (SM), genotypic values predicted by REML/BLUP (GVP), and rank sum (RS). 2PH: plant height; SC: stem circumference; insertion height of the first fruit (IHFF): height of insertion of the first fruit; length of the fruit (LF): fruit length; width of the fruit (WF): fruit width; PT: pulp thickness; mass of the fruit (MF): mass of fruit; SS: soluble solids (°Brix); BSL: severity of black-spot on leaves; BSF: severity of blackspot on fruit; and phoma-spot on leaf (PSL): severity of phoma-spot in leaf spot
Summary
The Brazil is one of the leading papaya-producing (Carica papaya L.) countries globally. One way to increase the effectiveness of selection would be to use individual genotypic values, which are additive and have greater accuracy (RAMOS et al, 2014; QUINTAL et al, 2017). These individual genotypic values can be estimated using mixed linear models of the restricted maximum likelihood/ best linear unbiased prediction type (REML/BLUP) (FERREIRA et al, 2016b; RESENDE, 2016)
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