Defoliation Management of Bahiagrass Germplasm Affects Dry Matter Yield and Herbage Nutritive Value

Abstract

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.