Manual phenotyping for papaya Carica papaya (L) breeding purposes limits the evaluation of a great number of plants and hampers selection of superior genotypes. This study aimed to validate two methodologies for the phenotyping of morpho-agronomic plant traits using image analysis and fruit traits through image processing. In plants of the 'THB' variety and 'UENF/ Caliman-01' hybrid two images (A and B) were analyzed to estimate commercial and irregularly shaped fruits. Image A was also used in the estimation of plant height, stem diameter and the first fruit insertion height. In 'THB' fruits, largest and smallest diameters, length, and volume were estimated by using a caliper and image processing (IP). Volume was obtained by water column displacement (WCD) and by the expression of ellipsoid approximation (EA). Correlations above 0.85 between manual and image measurements were obtained for all traits. The averages of the morpho-agronomic traits, estimated by using images, were similar when compared to the averages measured manually. In addition, the errors of the proposed methodologies were low compared to manual phenotyping. Bland-Altman's approach indicated agreement between the volume estimated by WCD and EA using caliper and IP. The strong association obtained between volume and fruit weight suggests the use of regression to estimate this trait. Thus, the expectation is that image-based phenotyping can be used to expand the experiments, thereby maintaining accuracy and providing greater genetic gains in the selection of superior genotypes.

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Developing superior lines based on a simultaneous response from many traits of agronomic importance is a fundamental strategy to expand papaya cultivar supply, mainly the much-needed cultivars belonging to group Formosa. Our goal was to associate the pedigree method with REML/Blup procedure to select plants of progenies F 2:3 with superior agronomic performance. The variance components and genetic parameters were estimated using REML approach, and the genetic values were predicted using Blup methodology. The combined selection was performed using the IG2 selection index based on weights associated with agronomic values to indicate the best progenies and lines. The heritability estimates of progeny mean were high in most traits and evidenced significant genetic variability between progenies. The narrow-sense individual heritability was moderate in traits such as commercial fruits and soluble solid contents, which indicates a PLANT BREEDING -Article favorable condition for selections within progenies. The index was consistent in the selection of six superior progenies according to the assessed traits. This index also enabled promising genetic gains in traits of great interest such as yield and pulp thickness.Although the progenies are derived from self generations, they proved to be superior in traits of significant importance such as yield, commercial fruits, and pulp thickness when compared to the Tainung-01 hybrid, which is a worldwide-planted cultivar used as a reference to Formosa representatives. Six lines were selected within the superior progenies to continue the Formosa group-lines development program. The association of the pedigree method with REML/Blup procedure can be useful to assist breeders in an autogamous breeding program.

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Manual phenotyping (MP) methodology for papaya breeding demands intensive labor and is time-consuming. This study aimed to validate a low-cost image-based phenotyping (IBP) methodology of fruit traits to speed up the process in breeding program. Two groups of 50 fruits of the 'THB' at the zero-maturity stage were used. The fruits were sliced longitudinally and half part of the fruit was scanned in Flat-bed Scanner to obtain the digital image. In the first group, the length and diameter of fruits were measured by image processing (IP) using a two-bit binary image and the ovarian cavity length, ovarian cavity diameter, thickness pulp were measured by image analysis (IA) in RGB format using the straight tool of ImageJ software. The traits were measured by digital caliper. The fruit mass (FM) was measured by analytical scale and de fruit volume (FV) was estimated using the water desplacement method (WDM). The second group was used to estimate the FV and FM through IP and MP. The trait averages were estimated using IBP, similar to those averages measured manually. The coefficients of variation estimated by IBP were low compared to the measurement by MP, indicating that this methodology is more accurate. The Bland-Altman approach showed agreement between the FV obtained by the WDM and IP. Since the IBP is about four times quicker and less-dependent on labor, it is expected to be incorporated to papaya breeding as a way to increase the number of accessed (being evaluated) genotypes and, consequently, increasing the genetic gains.