Author
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Casler, Michael |
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SOSA, SERGIO - Rutgers University |
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BOE, ARVID - South Dakota State University |
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BONOS, STACY - Rutgers University |
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Submitted to: Crop Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/23/2018 Publication Date: N/A Citation: N/A Interpretive Summary: Development of switchgrass as a perennial biomass feedstock for conversion to energy is heavily focused on the use or marginal lands to avoid competition with food and fiber production. Breeding switchgrass for use on marginal lands requires extensive field studies to define and describe how different "marginal" conditions impact the ranking of individual plants in breeding nurseries. This study demonstrated that high vs. low rates of nitrogen fertilizer had little impact on the ranking of switchgrass genotypes - for the most part, the same plants were selected regardless of the nitrogen rate. Conversely, there were strong regional and soil quality effects that drastically changed the ranking of genotypes. These factors were mostly due to differences in annual precipitation, soil water-holding capacity, and phosphorus levels in the soil. To ensure that the "correct" genotypes are selected for crossing, breeding for marginal soils that are located within low-rainfall regions or are defined by sandy soils with low water-holding capacity, or soils with extremely low phosphorus levels should be conducted on representative soils, not on prime farmland. Likewise, even though nitrogen fertilizer did not influence genotype rankings, breeding for increase nitrogen-use efficiency should be done without nitrogen fertilization. These results will have significant impacts on numerous switchgrass breeding and agronomic research programs. Technical Abstract: Development of switchgrass as a dedicated bioenergy feedstock requires intensive and extensive breeding programs that include careful and thoughful consideration of appropriate target populations of environments (TPE). The purpose of this study was to evaluate region (climate), soil quality, and nitrogen fertilization level as potential factors influencing the choice of TPE. A total of 45 switchgrass genotypes were evaluated in uniform field studies at six locations defined as prime or marginal soils in New Jersey, South Dakota, and Wisconsin, USA. Region and soil quality had strong interactions with genotype, but nitrogen fertilization had little impact on genetic variation or ranking of genotypes. Lowland genotypes were considerably more sensitive than upland genotypes to interactions with environmental factors, probably due to these locations being outside of the traditional lowland adaptation zones. Genotype rankings were highly inconsistent across regions and soil types, indicating that breeding programs that target marginal soils should be located on soils that represent the appropriate TPE. Furthermore, interactions across the three regions suggest that breeding programs for the lowland ecotype should be subdivided into different sets of TPE, which are largely a function of hardiness zone and annual precipitation. Lastly, even with negligible interactions involving nitrogen fertilization level, future definitions of TPE should be base don minimal or no nitrogen fertilizer applications to allow breeders to select plants with greater N-use efficiency, N-scavenging ability, and N-recycling efficiency. |
