Seed yield and quality of interspecific hybrids of Paspalum plicatulum x P. guenoarum at different harvest times

Paspalum guenoarum is a warm-season perennial grass, with a caespitose growth habit. The species is native to southern Brazilian grasslands and has been used in interspecific hybridizations because of its high palatability, resistance to trampling and grazing, and cold tolerance. Previous studies reported improvements in forage production and the nutritive value of hybrid material. However, there are limited data about seed production and seed quality of these hybrids. The aim of this study was to quantify the optimal time to harvest seed of three Paspalum plicatulum x P. guenoarum hybrids (08Q01, 104026, and 105052). Seed yield and seed quality were determined. Hybrids were harvested at 10, 20, and 30 days after flowering and evaluated for the components of seed yield, vigor, and viability. The optimum time to harvest was 20 days after the beginning of flowering. A >50% yield reduction, due to seed shattering, occurred when harvesting was delayed beyond 20 days. Harvesting <20 days after flowering resulted in a high percentage of empty spikelets and seeds with low vigor and viability. About 75% of the seed shattering took place 10-20 days after flowering, and for the 104026 and 105052 hybrids, >50% of seed was during this period. Hybrid 105052 had superior seed yield (2380 +/- 280 kg ha(-1)) and similar seed quality. These two characteristics, among others, are the most important ones when recommending a new commercial cultivar for release.