Identification or Creation of a Putative Triploid Seashore Paspalum.

Seashore paspalum (Paspalum vaginatum) is a salt tolerant, predominately diploid (2n = 2x = 20) species that is well adapted to coastal regions in tropical and subtropical environments.  Because a majority of the available cultivars are propagated vegetatively and most genotypes are cross-fertile, a sterile cultivar which does not produce segregating seedlings would benefit sod growers and turfgrass managers who demand uniformity for certification and performance.  Therefore, three independent laboratory and glasshouse experiments were conducted during 2009, 2010, and 2011 to induce polyploidy in seashore paspalum with the goal of developing a sterile form.  During 2009, four colchicine seed pretreatments were evaluated including soaking seeds in 0.05% and 0.1% colchicine solutions for one week prior to planting with or without a one week pretreatment soak in water before adding colchicine.  In both 2010 and 2011 seeds were soaked in an aqueous solution of 0.1% colchicine and 2.0% dimethyl sulfoxide (DSMO) pretreatment solution for 24h before planting.  Percent germination of seed was similar in all three experiments, varying from 14.2% (2011), 15.3% (2009), to 18.1 % (2010).  Seedling ploidy levels were determined using flow cytometry.  One putative triploid genotype (11-TSP-1) was identified from the 2010 test and remains stable.  Although there is a possibility that this event was triggered by the colchicine/DSMO treatment, a more likely explanation is that it resulted from the union of a normal and unreduced gamete.  Pollen shed was observed from 11-TSP-1 in 2011, but individual pollen grains stained with iodine-potassium iodide were irregularly shaped and typically had lower starch content than several diploid cultivars.  11-TSP-1 has been used as the female parent in crosses with ‘SeaIsle 1’, ‘SeaIsle 2000’, and ‘SeaStar’, but no viable seed has been produced to date.  Field testing has begun in Tifton to determine the turf potential of this genotype.