2013 Annual Report
1a.Objectives (from AD-416):
1. Improve the productivity, quality, and persistence of warm-season grasses grown for forages, bioenergy, and turf by enhancing germplasm to increase stress tolerance under a variety of environmental conditions and improving tools that will efficiently assess forage quality.
2. Develop improved production strategies that include warm-season grasses, legumes, and winter cover crops to meet life-cycle objectives for feedstock production and quality, carbon sequestration, and greenhouse gas emission reductions for the Southeast regional conditions.
1b.Approach (from AD-416):
Objective 1: Three bermudagrass populations with desirable traits for forage, good seed production, and synchronous pollination will be used in a system of recombinant recurrent selection to develop a uniform, highly productive seeded bermudagrass for forage and/or turf. Multiple cycles of selection and crossing will be done to create populations that will be tested in multiple replicates at different locations. In napiergrass, a similar approach will be developed to develop vegetatively propagated high yielding, disease resistant genotypes for multiple location testing and eventual release. Also for napiergrass, sequence data generated from genomic DNA from the cultivar Merkeron will be used to mine single sequence repeat (SSRs) markers and match them with genotypic traits of interest as marker assisted selection. Similarly, SSR markers will be developed for salt tolerance in segregating populations of seashore paspalum. Near infrared spectroscopy (NIRS) will be developed as a tool to screen for forage and biomass quality from available genotypes with diverse cell wall characteristics. Non-grain sorghum germplasm from multiple sources will be evaluated in replicated trials in the field and greenhouse for susceptibility to anthracnose, root-knot nematodes, and fall armyworm. Selected lines will be used as parents to test hybrids for biotic stress and yield characteristics for eventual public release. Linkage maps will be developed for markers of biotic traits.
Objective 2: Replicated tests will be performed to determine appropriate nitrogen-fixing winter legume cover crops (clovers and alfalfa) for use in forage bermudagrass (Tifton 85, Russell) to reduce fertilizer applications and improve forage quality. Similar tests will be conducted for efficient production of biomass from energy cane, napiergrass and biomass sorghum (rotated with traditional row crops). Winter cover crops (lupine, clover, others) will be tested against inorganic and unfertilized controls to determine efficient ways of reducing inorganic fertilizer use. These replicated tests will be conducted at multiple sites. Production systems will be tested to determine water and nutrient requirements for maximum biomass yields of napiergrass using a replicated split block design with three irrigation rates and six fertilizer treatments. In collaboration with other research units, greenhouse gas emission comparisons will be determined for the cropping systems of biomass crops as well as for forage bermudagrass cultivars compared to traditional row crops.
This is a new project approved and begun in January of this year. As such most of the objectives are just now being started. Bermudagrass trials are being established to commence trials on overseeding with legumes and also for testing forages versus annual crops for greenhouse gas studies. The parental populations for the development of seeded type bermudagrass forages have been selected, are in the greenhouse and will be planted during the summer of 2013. Sorghum lines are continuing to be evaluated and used in crosses for a number of traits that will be useful in the biofuel arena. Sweet sorghum lines have been identified that are resistant to root-knot nematodes (Richard Davis-USDA). Initial sweet sorghum hybrids have been developed and a subset of these is being evaluated this summer in a replicated planting date trial. Napiergrass plots have been established for crossing in Florida, but the environment has not been the best for conducting crossing and is 6 hours drive away. Alternatively, we are completing a large growth chamber which we hope will allow us to induce flowering with the short-day plants and save tremendous amounts of time and labor. We should soon determine the success of this effort. Production trials for both the annual and perennial biomass grass crops have been established and data will soon be obtained. For the seashore paspalum objective, a microsatellite enriched library was created by Renee Arias (USDA-Dawson) and run on a 454-GS FLX instrument (USDA-Stoneville) to generate 18,967 contigs (=100 bp) and 158,595 singletons. From these sequences, 3,511 simple sequence repeats (SSR) were identified from contigs and 31,949 SSRs were identified from singletons. 84 of these sequences were selected and were used to genotype 17 lines with different responses to salt. Two markers have been identified that are present in only the most resistant cultivars. 88 additional accessions are being evaluated by Paul Raymer (University of GA) for tolerance to salt. These 2 markers will be evaluated on these lines once the multiyear phenotyping of the 88 lines is completed. For the napiergrass objective, DNA from cultivar Merkeron was isolated and Phillip Wadl (University of TN) will create a library enriched for microsatellites and sequence this library on an Ion Torrent instrument.