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The growing demand for quality of papaya by the domestic and international markets requires the development of genotypes that are capable of incorporating traits, such as high yield and fruit quality. This study estimated the genetic parameters and the specific combining ability of F 4 papaya lines crossed to the SS-72/12 tester to identify genotypes with higher genetic value for hybrid production. We evaluated 169 treatments consisting of 62 topcross hybrid combinations, 97 F 5 lines, and 10 controls in a 13 × 13 lattice design with five replicates and two plants per plot. The following traits were evaluated: plant height (PH), stem diameter (SD), first-fruit insertion height (FFIH), number of marketable fruits (NMF), number of deformed fruits (NDF), number of fruitless nodes (NFN), average fruit weight (FW), and yield (YLD). Differences p < 0.05 were found in most traits evaluated. The specific combining ability estimates indicate that hybrids formed by the cross between SS-72/12 tester and the following lines are promising, considering the multiple traits: UCLA08

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Although potato leafhopper, Empoasca fabae (Harris) (Hemiptera: Cicadellidae), is highly polyphagous, classic host studies do not recognize grapevines (Vitis spp.), as suitable hosts. Recently, injury has been reported and reproduction documented within grape vineyards, suggesting a host expansion for the leafhopper. To document this apparent expansion in host use, we determined whether grape plants were suitable hosts for potato leafhopper reproduction, measured the consequence of feeding injury on gas exchange rates of grape leaves, and compared the susceptibility to feeding injury among cultivars. We found that potato leafhopper adults survived equally well on grape (Vitis vinifera L.), alfalfa (Medicago sativa L.), and fava bean (Vicia faba L.). The total number of offspring was greater on fava bean but did not differ between alfalfa and grape. Injury to grapevines was assessed by measuring gas exchange responses of leaves in field cages and in greenhouse tests. We found marginally significant declines in photosynthesis and transpiration rates in the field (9.6 and 13.2%, respectively), and much stronger effects in greenhouse tests (ranging between 22 and 52%). Our results verify that Vitis is a suitable host, and that potato leafhopper is capable of injuring its gas exchange physiology. We discuss possible explanations for the host expansion, and its potential to damage commercial grapevines.

This study aimed to analyze the genetic variability and to estimate diversity parameters of 23 elite papaya lines based on microsatellite molecular markers. The plant material was composed of elite lines, 18 from the 'Formosa' and five from the 'Solo' group. The expected heterozygosity (HE), observed heterozygosity (HO), and the coefficient of inbreeding (ƒ) for each genotype were estimated. The weighted index obtained the dissimilarity matrix, and the estimated genetic distance was presented graphically through the cluster analysis by the Ward method, as well as by the principal coordinates analysis (PCoA). The genotypes were also analyzed for genetic structure, using the Bayesian clustering method. Genetic variability was observed among the analyzed genotypes, mainly among the lines from the Formosa group. As for HO, four elite lines from the 'Solo' group had values equal to zero. However, the elite lines from the 'Formosa' group showed higher segregation in the loci with values ranging from 0.05 to 0.14. About ƒ, from the five lines in the 'Solo' group, four exhibited maximum fixation indexes for the analyzed loci, with the variation observed from 0.90 to 1.0, while the lines from the 'Formosa' group had a variation from 0.61 to 1.00. These results indicate the need for greater care in the process of obtaining inbreeding seeds to avoid pollen contamination, as well as the need to advance generations of self-fertilization with the lines from the 'Formosa' group to increase the level of inbreeding and ensure greater stability to hybrids that are developed from them.

Selection indexes represent the real efforts of a breeding program to obtain genetic gains for various significant traits simultaneously. As such, this study selected superior F 5 lines by combined selection for fruit quality using an index based on predicted genotypic values via residual or restricted maximum likelihood/best linear unbiased prediction (REML/BLUP) methodology weighted by agronomic weights. To do so, 97 F 5 papaya lines obtained by the single seed descent method, resulting from the biparental cross between the genotypes JS-12 and Sekati, were evaluated for the main traits related to fruit quality. Results of the analysis of deviance and the genetic parameters indicated that there was genetic variability, indicating possible success in the selection process. Based on the selection index, 29 lines were selected as superior for fruit quality with 'Formosa' pattern. The strategy of the selection index combining BLUPs of multiple traits of interest associated with agronomic weights allows maximizing genetic progress while discarding less-promising genotypes.