ACUÑA Carlos Alberto
congresos y reuniones científicas
IS IT POSSIBLE TO GENERATE FAST GERMINATING AND PRODUCTIVE APOMICTIC BAHIAGRASS HYBRIDS?
ALEX L. ZILLI; ELSA A. BRUGNOLI; FLORENCIA MARCÓN; ERIC J. MARTÍNEZ; CARLOS A. ACUÑA
Simposio; 5th International Symposium of Forage Breeding; 2015
Universidad de Buenos Aires
Bahiagrass (Paspalum notatum Flüggé) is a perennial grass native to South America, which is used as cultivated pasture and turf around the world. In spite of the several advantage of this species, it is not extensively cultivated due to limited biomass production and difficult establishment due to slow germination. The objectives of this work were I) generate apomixis-segregating tetraploid progenies; II) assess the level of apospory expressivity in apomictic hybrids; and III) evaluate the possibility of selecting fast germinating and productive apomictic hybrids. Eleven apomixis-segregating progenies were generated by crossing 9 apomictic and 3 sexual tetraploids genotypes, obtaining a total of 524 hybrids. Mode of reproduction was determined by a RAPD marker 100% linked to apospory in P. notatum, and the level of apospory expressivity was estimated bymature embryo sac observations. A total of 112 apomictic hybrids were planted into the field in a randomized complete block design with 4 clonal replicates. Two morphological and six agronomic traits were evaluated. Apomictic hybrids showed an apospory expressivity discontinuous variation with a range from 0 to 100%. Only 40% of the apomictic hybrids showed an apospory expressivity higher than 75%. A group of 18 apomictic hybrids was selected based on general vigor and expressivity of apospory. Germination was estimated in these 18 apomictic hybrids, 3 promising apomictic lines and 2 released apomictic cultivars (as checks) 21 days after sowing. This trait was highly variable, with values from 1% to 45.5% with an average of 16% (CV=0.99).Only 5 apomictic hybrids out of the 18 had a germination level higher than 20%.This low germination level could be due to seed dormancy, considering the short time between harvest and sowing. Therefore, the efficiency of obtaining hybrids with good performance, high apospory expressivity and acceptable germination is less than 1% of the total generated hybrids. The low germination observed in these genotypes could be due to the fact that this trait was not considered in the selection of the progenitors. An extensive search of natural and artificial fast germinating plants should be performed considering its importance.