Artificial selection related with important agronomic characteristics of Stevia rebaudiana may cause genetic divergence and formation of genetically structured populations with genetic uniformity or diversity within cultivars. Current study employed inter simple sequence repeats of DNA (ISSR markers) to assess genetic diversity within and among a single cultivated population maintained through sexual propagation (SR1) and four cultivated populations generated by artificial selection and maintained by vegetative propagation (SR2–SR5). Highest polymorphism rate was reported in SR1 (89.24%), whilst the lowest rate of polymorphism occurred in SR2 (60.13%). ISSR markers revealed that selection of plants with traits of vegetative-propagated interest may lead towards the generation of genetically more uniform DNA-level populations, while plants maintained by sexual propagation have high genetic variability. High estimated genetic divergence level indicated that the five areas of stevia form genetically structured populations. SR2 and SR4 are constituted by plants more homogeneous at DNA level for the selected characteristics than plants of SR3 and SR5 populations. Predominant and homogeneous genotypes selected at SR2 and SR4 areas could be valuable for tracing strategies to obtain stevia plants with the desirable agronomic characteristics through crosses between contrasting individuals in future breeding programs.

The physical and physiological characteristics of fruits and seeds were analyzed so that parameters may be determined to differentiate cactus plants of the Cereus genus from south and northeastern Brazil. Length, width, bark thickness, pulp diameter, weight of fruits, and sugar content (°Brix) of the fruit pulp, number of seeds (NS), weight of 100 seeds (P 100) and germination taxa (%G) of the seeds from plants of the two regions were evaluated. Fruit length, bark thickness and Brix degree were higher in Cereus plants from Maringá (south) than in plants from Picos (northeast), whilst the P 100 of plants cultivated in Picos was higher than the P 100 of plants grown in Maringá. NS and %G, at 30°C, were not significantly different in the seeds of the plants cultivated in Maringá and Picos. Positive Pearson correlation was reported between NS and the fruits´ weight, length, width, and diameter. Fruit width had a positive correlation with the weight, length, diameter, bark thickness and sugar content. The length, diameter and thickness of the bark were also positively correlated with the fruits´ sugar content. Above evidences suggest that larger fruits present higher Brix degree. The present study was important to shown that the Cereus plants from Maringá may be a source of bigger and sweeter fruits, essential characteristics for breeding programs..