Defoliation management of bahiagrass germplasm affects dry matter yield and herbage nutritive value
Bahiagrass (Paspalum notatum Flügge) cultivars are daylength sensitive and have minimal cool-season production. A new bahiagrass breeding line is less daylength sensitive and more cold tolerant, but its dry matter (DM) yield and nutritive value responses to defoliation treatments are unknown. A 3-yr field experiment studied effects of two stubble heights (4 and 8 cm) and two harvest frequencies (7 and 21 d) on diploids ‘Pensacola’, ‘Tifton 9’, and the less photoperiod-sensitive, cold-adapted (PCA) Cycle 4 bahiagrass; and the tetraploids ‘Argentine’ and Tifton 7. Stubble height had minimal effect on responses measured. When harvested every 7 d, Cycle 4 had the lowest and Argentine the greatest yield (8.4 vs. 11.8 Mg DM ha–1). When harvested every 21 d, Cycle 4 yield was similar to the other diploids (10.6 Mg DM ha–1) and less than the tetraploids (12.6 Mg DM ha–1). Cycle 4 yield distribution was similar to other diploids and generally greater in spring but less in summer than the tetraploids. Across defoliation treatments, Cycle 4 in vitro digestible organic matter (IVDOM) averaged 546 to 562 g kg–1 and was greater than all entries in 2006 and all but Tifton 9 in 2005. These data indicate that Cycle 4 was less productive than other bahiagrasses when harvested every 7 d during the warm season, as productive as other diploids at 21-d harvest intervals, and slightly more digestible than other currently used bahiagrasses. Inferior yield under frequent harvest may imply less defoliation tolerance, thus persistence of PCA Cycle 4 should be studied further.