Heterosis in tetraploid Paspalum notatum: evaluation of its occurrence, its prediction and breeding techniques

MARCÓN, FLORENCIA; MARTÍNEZ, ERIC J.; BRUGNOLI ELSA A.; ZILLI ALEX L.; ACUÑA CARLOS A.

Workshop; Proceedings of the 7th Series of Seminars on Advances in Apomixis Research; 2020

Paspalum notatum Flüggé is one of the main components of the South American grasslands. At present, hybridization is the most popular breeding technique in the species, and its goal is to obtain superior apomictic hybrids. Occurrence of heterosis in tetraploid P. notatum hybrid progenies in relationship with the genetic distance among parents was determined. Secondly, recurrent selection based on combining ability (RSCA) and recurrent phenotypic selection (RPS) were evaluated in a sexual synthetic tetraploid population (SSTP). Genetic distances among parents with different origins were determined using molecular markers. Group of crosses among parents with low, intermediate and high genetic distances were identified. The progeny obtained was evaluated for a series of agronomic and morphological traits. There was a significant relationship between genetic distances among parents and heterosis mainly for forage yield. For this reason, molecular markers could be used as a tool to predict the occurrence of heterosis for this trait. On the other hand, two new sexual populations were created by RSCA and RPS. Sexual genotypes obtained by both methods were crossed with superior apomictic genotypes. Both methods allowed us to obtain hybrid progenies that were evaluated for summer, fall and spring growth. RPS progenies exhibited greater summer growth and heterosis than RSCA progenies, although for fall and spring growth were similar. RPS was equal or more efficient than RSCA since it allowed obtaining equal or more genetic progress and heterosis. The breeding techniques used in this work allow exploiting the heterosis in tetraploid P. notatum.