Doctor of Philosophy (PhD)
Plant, Environmental Management and Soil Sciences
Bermudagrass (Cynodon dactylon L. Pers.) collected from 17 Louisiana sugarcane (Saccharum spp. hybrids) fields and two sites outside sugarcane-growing area was evaluated for genetic diversity, growth characteristics and response to glyphosate. Random Amplified Polymorphic DNA (RAPD) genetic analysis and Jacard’s similarity coefficient, a dedrogram, based on unweighted pair group mean average (UPGMA) identified two cluster groups based on presence of common alleles. Bermudagrass considered most aggressive in establishment rate based on ground cover, plant height, and biomass production included the biotypes A (St. Martinville) and Q (Port Allen) in cluster A and R (St. Gabriel) in cluster B. Biotypes J (Samuels), N (New Iberia), and T (St. Joseph) considered least aggressive were included in cluster A. Rate of establishment for biotypes J, N, and T averaged 5.3 times slower and plant height was 61% less compared with A, Q, and R. Biomass production the first year averaged 7.8 times greater for biotypes A, Q, and R compared with J, N, and T. In greenhouse and field studies, bermudagrass biotypes A, C (Baldwin), and Q in cluster A were least sensitive to glyphosate and biotypes D (Centerville) and P (Patterson) in cluster B were most sensitive to glyphosate. In a competition study, pre-sprouted single node stem cuttings of ‘HoCP 96-540’ sugarcane were planted in 26.5 L pots with one, two, or four bermudagrass plants, sugarcane shoot weight 56 days after planting (DAP) was reduced on average 58%; two and four bermudagrass plants reduced sugarcane root weight on average 39%. In another study, two bermudagrass plants did not negatively affect shoot population 56 DAP for the cultivars HoCP 96-540, ‘L 97-128’, ‘L 99-226’, ‘HoCP 00-950’, ‘L 01-283’, and ‘L 03-371’. For L 97-128 and L 99-226, shoot weight averaged 1.7 to 3.0 times greater than the average of the other cultivars and root weight averaged 1.8 to 2.1 times greater than the average of the other cultivars. When the sugarcane cultivars were watered over a 42-day period with leachate collected from actively growing bermudagrass, sugarcane tiller height, tiller number, shoot weight, and root weight were not negatively affected.
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Fontenot, Dexter Paul, "Assessment of bermudagrass (Cynodon dactylon) biotypes and bermudagrass interference with sugarcane (Saccharum spp. hybrids" (2014). LSU Doctoral Dissertations. 2500.