Breeding procedures developed for apomictic species are based on the idea of fixing superior hybrids by apomixis. However, scarce information is available about the occurrence of heterosis in apomictic hybrids. The objective was to generate a group of apomixis‐segregating tetraploid bahiagrass (Paspalum notatum Flüggé) families, evaluate the occurrence of heterosis for a series of agronomic and morphological traits, determine the level of apospory expressivity among hybrids, and estimate the genetic distance among parents and its relationship to heterosis and apospory expressivity. In total, 11 tetraploid families were generated by crossing sexual and apomitic genotypes. The segregation for mode of reproduction was analyzed using a random amplified polymorphic DNA (RAPD) marker linked to apospory in bahiagrass, and the level of apospory expressivity was determined using embryo sac observations. The genetic distances between parents were determined using inter‐simple sequence repeat (ISSR) markers. The ratio between sexual and aposporic hybrids varied from 1:1 to 7:1 among families. Discontinuous variation for apospory expressivity was observed in the hybrids, with either low or high levels being exhibited. Midparent, high‐parent, and standard heterosis was observed for all evaluated characteristics. The level of heterosis was dependent on the combination of parents involved and also on the specific trait. There was a low correlation between genetic distances among parents and initial growth and the level of apospory expressivity. The occurrence of heterosis and the segregation and expressivity for apospory were highly dependent on the combination of sexual and apomictic parents.

The objective of this review is to analyze and describe the impact that mode of reproduction in Paspalum has on germplasm conservation, genetic improvement, and commercialization of cultivars. Germplasm collection and conservation can now be rethought considering the newly available information related to how diversity is allocated in nature and how it can be transferred between the sexual and apomictic germplasm using novel breeding approaches. An inventory of species and accessions conserved around the world is analyzed in relation to the main germplasm banks. Because of the importance of apomixis in Paspalum species different breeding approaches have been used and tested. Knowledge related to the inheritance of apomixis, variable expressivity of the trait and techniques for early identification of apomicts has helped to improve the efficiency of the breeding methods. Novel breeding techniques are also being developed and are described regarding its advantages and limitations. Finally, the impact of reproductive mode on the adoption of the released cultivars is discussed.

The improvement of bahiagrass, Paspalum notatum Flüggé, has been inhibited by reduced levels of genetic diversity in sexual tetraploid germplasm. A few experimental sexual tetraploid genotypes (ESTGs) have been generated by chromosome doubling, but these plants typically exhibit low vigor. The objectives of this work were to generate and characterize the ploidy level, mode of reproduction, and fertility of a novel 308 individual sexual synthetic tetraploid population (SSTP) developed by intercrossing 29 sexual F1 hybrids originated by hybridizing several naturally occurring apomictic tetraploids from diverse origin with a few ESTGs. Ploidy levels were determined using flow cytometry, and reproductive modes were evaluated by a molecular assay with apospory‐linked markers and embryo sac observations. The tetraploid level and the sexual mode of reproduction remained stable after two cycles of recombination during the generation of the SSTP. Fertility was evaluated based on seed set under self‐ and open pollination during 3 yr. The SSTP exhibited in average 30.2 and 15.2% seed set under open and self‐pollination, respectively, showing a predominantly cross‐pollination behavior with variable levels of self‐fertility. There were no differences in terms of fertility between the SSTP and the ESTG. The novel tetraploid population behaves as sexual and cross‐pollinated, and it is expected to allow a more efficient genetic improvement under the proposed breeding approaches.

Bahiagrass (Paspalum notatum Flüggé) is one of the main components of the South American grasslands, and it is cultivated for forage and turf around the world. At present, hybridization is the most common breeding technique for the species, and its goal is to obtain superior apomictic hybrids. The objective of the present study was to determine the relationship between heterosis, reproductive behavior, and genetic distances between parents in tetraploid bahiagrass. Genetic distance between 24 sexual tetraploid genotypes and 24 apomictic tetraploid genotypes of P. notatum was evaluated using simple sequence repeat (SSR) and inter simple sequence repeat (ISSR) markers. Crosses were made between parents with low, intermediate, or high genetic distances. Six families were generated. A marker linked to apospory in bahiagrass was used to determine segregation for mode of reproduction, and embryo sacs were characterized to estimate the level of apospory expressivity. The ratio between sexual and aposporous hybrids ranged from 1:1 to 9:1 among families. Discontinuous variation for apospory expressivity was observed among hybrids, with either low or high levels being exhibited. A significant relationship between genetic distance and proportion of aposporous hybrids was observed. Heterosis was observed for all the evaluated traits and its level was dependent on the parental combination. Genetic distances between parents were related to heterosis, mainly for forage yield, which is the most important trait in forage species. Hence, molecular markers may be useful to predict the occurrence of heterosis for this trait.