Monday, November 13, 2006 - 1:45 PM

Daylength and bahiagrass genotype affect herbage accumulation and rhizome and root mass.

Sindy Interrante1, Lynn Sollenberger1, Ann Blount1, Thomas Sinclair1, Jose Dubeux2, Joao M. Vendramini1, and Kesi Liu1. (1) University of Florida, Gainesville, FL 32607, (2) Universidade Federal Rural de Perna, "Av. Dom Manoel De Medeiros, S/n, Do", "Av. Dom Manoel De Medeiros, S/n, Do", Recife, 52171-900, BRAZIL

Bahiagrass is the primary pasture grass in Florida and is productive from April to November in northern Florida. The reduction in bahiagrass growth during winter months may be attributed in part to shorter daylength. Research has aimed to increase bahiagrass productivity during short-daylength months through genetic selection and development of cultivars that are insenstive to daylength. Increasing above-ground growth in the cool season may negatively affect the partitioning of organic matter to storage structures, possible resulting in reduced tolerance to defoliation and stand loss. A two-year field study was conducted to evaluate a cold tolerant, less daylength-sensitive bahiagrass type (PICA C4) against existing bahiagrass cultivars (Pensacola and Tifton 9). Treatments were the factorial combinations of two daylength treatments, two fertilizer treatments, and three genotypes in four replications of a split-plot arrangement of a completely randomized design. Dry matter (DM) yields were determined by regular harvests to an 8-cm stubble height. Destructive samples were collected three times per season, and plants were divided into shoot, rhizome, and root fractions. There were no differences in Yr1 total-season DM yields between extended and normal daylength treatments or genotypes (P>0.05). In Yr2, PICA C4 and Tifton 9 total-season DM yields were greater than Pensacola (P<0.05). In April, Pensacola and Tifton 9 root and rhizome masses were greater than PICA C4 (P<0.1) in Yr1 but were not different in Yr 2 (P>0.1). Above-:below-ground DM ratios was greater for normal than extended daylength (P<0.1) in April Yr1, while PICA C4 and Tifton 9 above-:below-ground ratios were greater than Pensacola (P<0.1) in April Yr2. Spring root and rhizome mass of PICA C4 are less than Pensacola and Tifton 9, which may negatively affect its persistence in the field.