GROWTH COMPARISONS AND GENETIC DIVERSITY OF BERMUDAGRASS (CYNODON DACTYLON) BIOTYPES IN LOUISIANA

Nineteen biotypes of bermudagrass (Cynodon dactylon L. Pers.) collected in Louisiana from 17 fields planted to sugarcane and from two fields planted to other crops were compared for growth characteristics and genetic variability. In the spring of 2011, biotypes were planted in the field at the Central Research Station, Ben Hur Research Farm, Baton Rouge, LA. Biotypes A (St. Martinville), Q (Port Allen), and R (St. Gabriel) established rapidly with ground cover averaging 94% 74 days after planting (DAP) compared with 16% ground cover for biotypes J (Samuels), N (New Iberia), and T (St. Joseph). Average internode length ranged from 26 mm for biotype T to 78 mm for biotype Q and leaf width ranged from an average of 2.8 mm for biotypes G (Napoleonville), L (Plaquemine), and M (Bunkie) to 4.2 mm for biotype S (Alexandria). Average plant height ranged from 77 mm for biotype T to 325 mm for biotype Q. Bermudagrass aboveground dry weight in the establishment year for biotypes A, Q, and R averaged 1.6 to 12 times greater than for the other biotypes. In 2012, dry weight for biotypes A, B (Jeanerette), Q, and S averaged 2.4 times greater than for the lowest yielding biotype. Although some variation among biotypes in response to cold temperature was observed in December, all biotypes were aggressive in initiating regrowth in February and March. Genotyping of the bermudagrass biotypes was performed using random amplified polymorphic DNA (RAPD) analysis and biotypes were separated into three cluster groups using an unweighted pair group mean average (UPGMA) tree generated by Jaccard’s similarity coefficient. Although biotypes within a cluster group were identified as genetically similar, this was not always reflected in growth characteristics. In cluster IA, a subgroup of cluster I, rate of establishment based on ground cover for biotypes J, N, and T averaged 5.3 times slower and plant height was 67% less compared with biotype Q. In sub-cluster IB, bermudagrass biomass production the first year for biotype R averaged 3.7 times more and plant height was 2.4 times greater compared with biotypes D, G, H, I, and P. Results support the variability in bermudagrass growth characteristics and aggressiveness observed in sugarcane in Louisiana and emphasize the importance of implementing effective fallow and in-crop bermudagrass control programs.