Phenotype Traits of Bermudagrass Ecotypes From Pastures Stocked at Different Intensities During a 40-Year Period.

Phenotype traits of bermudagrass ecotypes from pastures stocked at different intensities during a 40-year period.

F. M. Rouquette, Jr. ¹, W. F. Anderson², K. Harris-Shultz², and G. R. Smith¹

¹Texas AgriLife Research, Overton, TX

²USDA/ARS Crop Genetics and Breeding Research, Tifton, GA

Stocking intensities can affect persistence of bermudagrass pastures. The objectives of this study were to compare phenotype traits of bermudagrass [Cynodon dactylon (L) Pers] (BG) ecotypes (ECOT) selected from both ‘Coastal' (COS) and common (COM) BG pastures stocked at different, controlled intensities (STK) for a 40-year period. On average, COS were stocked at about 2.5, 4.5, and 7.5 cow-calf pair ha^-1 (680kg), and COM stocked at 2, 3.5, and 5 pair ha^-1. From 1985 to 2010, fertility regimens of N + ryegrass (Lolium multiflorum L) vs no N + clover (Trifolium sp) were superimposed on each STK x BG pasture. During October when visual phenotypic differences were evident, whole plant-root cores which exhibited ECOT diversity were collected from pastures. Plant cores were transferred to a greenhouse in Tifton, GA and growth traits were measured. The ECOT were fingerprinted using AFLP markers, analyzed via a coefficient of genetic similarity matrix, and clustered in genetically-related groups. Original COS plants had a leaf coarseness (LFCR) score of 3.1, plant height (PHT) of 41.7 cm, leaf length (LFL) of 17.9 cm, and leaf width (LFW) of 3.1 mm. Originally-seeded COM had LFCR of 1.7, PHT of 17.5 cm, LFL of 8 cm, and LFW of 2.3 mm. The LFCR of BG ECOT that invaded COS pastures was 1.75 and those in COM pastures was 1.5. The LFL of invading BG ECOT was similar in both COS and COM at about 13 cm, and LFW of ECOT was similar in both COS and COM at about 2.5 mm. An inflorescence (INFL) amount score (0-5) was 0.6 for standard COS and 3.4 for COM. The INFL scores of two clusters of ECOT in COS were 0.8 and 3.3. The INFL score of ECOT in COM had three groupings at 0.9, 1.5, and 2.6.