The use of dwarf lines to obtain mini-tomato hybrids has provided agronomic and economic benefits. In Brazil, round tomatoes predominate over other varieties. The benefits of using a dwarf parent in round tomato hybrids has yet to be explored, making it important to develop dwarf round tomato lines. Backcrossing is the most suitable method to develop these lines. Evaluation and selection of the dwarf populations can improve the development of such lines. Thus, the aim of this study was to select BC1F2 populations of dwarf round tomatoes with agronomic potential and high-quality fruit. The study was conducted at the Vegetable Experimental Station of the Federal University of Uberlândia (UFU). A randomized block design was used, with 15 treatments and three replicates. The genetic material analyzed consisted of 12 BC1F2 dwarf tomato populations, plus both parents (recurrent and donor) and a commercial hybrid. The characteristics assessed were: average fruit weight (g), total soluble solids (ºBrix), number of locules (locules per fruit-1), fruit shape, pulp thickness (cm), longitudinal (cm) and transverse fruit diameter (cm), internode length (cm) and plant height (cm). The data were submitted to mean testing, multivariate analyses and a selection index. In general, average fruit weight in the dwarf populations increased significantly after the first backcross, with some fruits exhibiting a similar shape to round tomatoes. Selection of the populations UFU-DTOM7, UFU-DTOM10, UFU-DTOM5, UFU-DTOM9, and UFU-DTOM3 resulted in an estimated 6% increase in the number of locules, transverse diameter, TD/LD ratio and average fruit weight. The BC1F2 dwarf populations UFU-DTOM7 and UFU-DTOM10 were the most promising for develop inbred lines with round fruits. Despite the considerable progress achieved in this study, we suggest a second backcross, in order to obtain lines and, posteriorly, hybrids with round fruits and compact plants.

The aim of this study was to estimate genetic divergence and select BC 1 F 3 populations of dwarf tomato plant within the Santa Cruz segment by computational intelligence techniques. The experiment was conducted in a greenhouse in the Vegetable Crop Experimental Station of the Universidade Federal de Uberlândia (UFU), Monte Carmelo, MG, Brazil. A randomized block experimental design was used with 17 treatments and four replications. The genetic material evaluated comprised thirteen dwarf tomato plant populations obtained by a backcross and two self-fertilizations, plus both parents (recurrent and donor), and two commercial check varieties. The traits evaluated were mean fruit weight (MFW), soluble solids content (SSC), fruit diameter (FD), fruit length (FL), fruit shape (FS), pulp thickness (PT), number of locules (NL), distance between internodes, and acylsugar, β-carotene, and lycopene content. The data were analyzed by means testing, and genetic divergence was measured using Mahalanobis generalized distance by the unweighted pair group method with arithmetic mean (UPGMA) and through computational intelligence using Kohonen self-organizing maps (SOM). Genetic dissimilarity in relation to the donor parent could be confirmed through both methodologies. However, the SOM was able to detect differences and organize the similarities among the populations in a more consistent manner, resulting in a larger number of groups. In addition, the computational intelligence techniques allow the weight of each variable in formation of the groups to be ascertained. Among the BC 1 F 3 populations, UFU-SC#3 and UFU-SC#5 stood out for agronomic traits, and UFU-SC#10 and UFU-SC#11 stood out for quality parameters.

This study aimed to select promising F2RC1 populations of saladette-type dwarf tomato plants for the development of breeding lines based on agronomic characteristics, fruit quality, and whitefly resistance. The experimental design was randomized blocks containing 13 treatments (10 F2RC1 populations of dwarf tomato plants, both parents, and a commercial hybrid) with four replicates. The evaluations were performed included weight, length, diameter, shape, pulp thickness, number of locules, soluble solids, β-carotene, and lycopene concentration of the fruit; plant internode length; acylsugars concentration; and number of whitefly eggs, nymphs, and adults on the leaflets. The data were analyzed using ANOVA, selection indices, and multivariate analysis. The first backcross increased the agronomic characteristics of the populations in relation to the donor parent, especially for fruit weight (169.1%), fruit length (26.1%), and fruit diameter (16.6%). The UFU SDi 7, UFU SDi 9, and UFU-SDi 17 populations were selected using two selection indices and were therefore considered promising.

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The success of breeding programs depends on genetic variability. Individuals selected based on a few traits may be a limitation. One alternative is the use of nonparametric indices. However, there is no information on the use of selection indices in melon germplasms. The present study aimed to estimate genetic dissimilarity in a melon germplasm and select potential parent plants for future breeding programs. The genetic material consisted of 37 melon accessions. The traits assessed were fruit diameter and length, diameter and length of the fruit cavity and total soluble solids. Genetic dissimilarity was assessed by multivariate analyses (UPGMA and Tocher). Selection gain estimates were analyzed by comparing the classic Smith-Hazel and sum of ranks indices. Genetic diversity was observed between accessions. The variable that contributed most to genetic dissimilarity was fruit cavity length. Simultaneous selection for the traits assessed based on the sum of ranks index is better suited to melon germplasm assessment. The best accessions for the five variables simultaneously were UFU07, UFU23, UFU09, UFU21, UFU28 and UFU30.