Study of agronomic factors important to the establishment of various perennial grass bioenergy feedstock species

miscanthus;switchgrass;prairie cordgrass;biofuels feedstock;herbicides;weed control;salt tolerance

Anderson, Eric

关键词: miscanthus;    switchgrass;    prairie cordgrass;    biofuels feedstock;    herbicides;    weed control;    salt tolerance;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/49689/Eric_Anderson.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Perennial grasses are expected to comprise a substantial portion of the lignocellulosic biomass to meet renewable energy mandates in the U.S. in the next decade.Miscanthus x giganteus, a high-yielding warm-season, perennial, rhizomatous grass that has been grown for cellulosic biomass production, shows great promise as a biomass feedstock in the U.S.Miscanthus × giganteus cv. ‘Illinois’ is a widely studied sterile cultivar that must be planted from plantlets or rhizomes; this asexual propagation is relatively expensive, thereby limiting more widespread acceptance.A tetraploid seeded variety of M. × giganteus (seeded miscanthus) has been developed that could reduce establishment costs while producing high biomass yields.Weed control during the year of establishment is essential as seeded miscanthus does not compete well with weeds in the first year.Chapter 1 of this dissertation presents a set of experiments designed to identify preemergence (PRE) and postemergence (POST) herbicide options that are safe to use on seeded miscanthus and provide robust weed control.Several PRE and POST herbicides were identified that did not negatively affect miscanthus growth under greenhouse and field conditions.However, no combination of herbicides was found that did not impede miscanthus establishment while providing adequate weed control under the field conditions experienced in this experiment, suggesting the need for further herbicide studies with this newly-developed seeded grass.Chapter 2 presents a field experiment that attempted to identify an optimum establishment protocol for seeded miscanthus by comparing different seeding rates and planting methods under irrigated and rainfed conditions.Drought conditions in both establishment years coincided with stand establishment failure under rainfed conditions, suggesting that seeded miscanthus may not establish well in water-stressed environments.Although significant differences among planting methods and seeding rates were found with most crop growth parameters, biomass yield goals were achieved with all planting methods at 20 and 40 seeds m-2. Switchgrass (Panicum virgatum L.) is another warm-season perennial grass that has been identified by the U.S. Department of Agriculture as a model biomass crop for several reasons, including its relatively high yields, its adaptability to a wide range of environments, the fact that it is native to the U.S., and its ability to grow well on marginal land.Prairie cordgrass (Spartina pectinata Link) is another native tall prairie grass with characteristics similar to switchgrass, and it has been studied recently for its ability to produce high biomass yields under saline soil conditions.Similar to M. × giganteus, these two native grasses are slow to establish from seed, and so establishment is often compromised by weed interference.Chapter 3 presents greenhouse experiments that were conducted to determine the tolerance of switchgrass and prairie cordgrass to several PRE and POST herbicides applied at different timings and under different light intensities.Preemergence herbicides were identified that did not inhibit seedling emergence for each species.Phytotoxic effects of POST herbicides decreased when applied at successively later growth stages, and several herbicides were found that were safe with respect to biomass production in each respective species.However, no herbicide was identified that could be used in establishing both grasses together without negatively impacting crop growth.Chapter 4 presents greenhouse experiments designed to determine the effects of irrigating with water having different levels of salinity and sodicity on seed germination and plant growth in several populations of switchgrass and prairie cordgrass.Higher levels of salinity negatively impacted seed germination with switchgrass more so than with prairie cordgrass overall, although significant differences existed among populations within species as well.In a two-season greenhouse pot experiment, aboveground dry biomass production with two prairie cordgrass populations was higher than in a lowland switchgrass cultivar when treated with pure water, but when irrigated with moderately saline water, the lowland switchgrass yielded the highest.An upland switchgrass cultivar was also found to have very low salt tolerance and was not considered a good candidate for biomass production on salt-affected land.