Fenotipado de la germinación y del peso de semillas de una población de líneas puras recombinantes de Paspalum flavescens y Paspalum plurinerve

The native field in our region represents the majority of the area in our country. Incorporating warm-season C4 perennial grass into the pastures sowed in our country with winter pastures would add ecological stability to the systems, among other ecosystem services. Paspalum dilatatum is a native species with great forage potential and could cover the forage deficiency from summer to autumn. However, this species shows difficulties for its improvement because of being apomictic. The seeds have dormancy that results in a slow and little synchronized emergence, limiting their productive adoption. Paspalum dilatatum is part of the Dilatata group, an allopolyploid species complex. This complex includes five sexual tetraploids species that do not show breeding limitations, like the apomictic species. These sexual tetraploids present high variability for characteristics with agronomic interest, including seed dormancy. For this task, we harvested seeds from 176 recombinant inbred lines (RIL) obtained from crossing P. flavescens and P. plurinerve. For the RIL population and the parental lines, the weight of 50 seeds and the germination phenotype in two consecutive temperature conditions was measured: First, a more restrictive temperature condition (14 days in alternating 15/25°C, Gp), and later, the optimum temperature condition (7 days in alternating 20/30°C, Gf). A germination index (IGA) was built as an additive product of Gp and Gf. The broad-sense heritability of each variable and the correlations among them were estimated. For all the variables, there were significant differences between the parental lines, which supports previous results that P. plurinerve has lower seed dormancy than P. flavescens. Also, some recombinant inbred lines showed evidence of transgressive segregation. The heritability was high for all variables, among which Gp and IGA showed the higher ones (0.88 and 0.87, respectively), highlighting them as phenotypes with little environmental influence. Significant correlations among all the germination variables were found, but there was no correlation between them and the weight of 50 seeds. The correlation between the variables Gp with Gf was lower than other correlations (r = 0,65), indicating that they may be considered different phenotypes.