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ARS Home » Southeast Area » Tifton, Georgia » Crop Genetics and Breeding Research » Research » Research Project #445744

Research Project: Genetic Improvement and Management of Warm-Season Forage, Feedstocks, Syrup, and Turf Grasses

Location: Crop Genetics and Breeding Research

Project Number: 6048-21500-001-000-D
Project Type: In-House Appropriated

Start Date: Jan 9, 2024
End Date: Jan 8, 2029

1. Improve genetic tools and pollinator-friendly management for more sustainable turfgrass systems. 1A. Identify SNPs associated with seed yield and other morphological traits in centipedegrass. 1B. Identify pollinators and beneficial insects of turfgrasses and cultural practices that enhance their abundance. 2. Improve sorghum aphid resistance and management in sweet and forage sorghum. 2A. Evaluate combining ability of new sweet sorghum lines. 2B. Test the efficacy of applied Lecanicillium fungus for sorghum aphid control. 3. Improving forage bermudagrass cultivars for cold tolerance and yield and improving availability to growers. 3A. Breed forage bermudagrass (Cynodon spp.) for cold tolerance, high yield and BSM tolerance. 3B. Improve the establishment and availability of forage bermudagrass. 4. Establishing sustainable full-year cropping systems for Southeastern Coastal Plains using a mixture of winter covers crops.

For Sub-objective 1A, single nucleotide polymorphisms (SNPs) will be identified that are associated with seed yield and morphological traits using a genome-wide association study population of 295 diverse centipedegrass lines in a replicated experiment. Genotyping-by-sequencing will be performed on all lines to generate SNPs and all traits will be measured for at least 2 years. For Sub-objective 1B, to identify pollinators and beneficial insects of turfgrasses and cultural practices that enhance their abundance, sod will be obtained of centipedegrass, tetraploid bermudagrass, and zoysiagrass. In a split-split plot experiment, blocks will be irrigated with fertilizer, irrigated with no fertilizer, not irrigated with fertilizer, or not irrigated and no fertilizer. Mowing frequency will be weekly, every 2 weeks, and every 3 weeks. Insect type and abundance will be recorded by sweep netting, visual observations, or with cameras. Inflorescence density and height, and flowering date and period will be recorded. For Sub-objective 2A we will produce 10 sweet sorghum hybrids by crossing three sorghum aphid resistant lines (GTS1903, GTS1904, and GTS1905) and two susceptible lines each with two seed parents. These hybrids and the parental lines will be evaluated in field trials in Georgia and Texas for yield, agronomic traits, and response to sorghum aphid. For Sub-objective 2B we will culture 2 isolates of the fungal entomopathogen Lecanicillium longisporum in the laboratory. Fungal spores will be mixed into formulations and sprayed onto sorghum aphid infested plants in the greenhouse (year 1) and field (year 2). Water and blank formulation will be negative controls, and chemical insecticide will be the positive control. Aphid population and damage will be recorded weekly. For Sub-objective 3A, 20 of the most cold tolerant plant introductions from previous tests and 15 introductions identified with bermudagrass stem-maggot tolerance (BSM) will be evaluated for 3 years at 3 locations for yield, BSM tolerance and cold tolerance. The 5 highest-yielding entries from the 2 northern locations and the 5 most BSM tolerant lines will be crossed and progeny evaluated at the 3 locations. For Sub-objective 3B, 2 propagation methods (sprigs and tops) will be evaluated for establishment with current cultivars and 2 experimental forage bermudagrass lines. In year 2, a subset of 6 entries will be propagated via cut stems and tested for establishment and weed control with various herbicide treatments. The 3 best treatments will be tested against an untreated control in larger plots. From the results of these trials, a protocol will be revised to guide designated growers for establishing new fields. For Objective 4 a replicated trial will be performed with rotating summer plots as main plots. The main plots will have three different winter sub-plot crops in rotation. Half of the winter crop biomass will be harvested and weighed, and the other half will remain on the soil as compost. We will determine the effects of rotating winter crops on the summer crops. An economic analysis using WHOLEFARM will determine the best rotations for economic returns to growers.