Date of Award


Document Type


Degree Name

Master of Science (MS)


Plant and Environmental Science

Committee Member

Sruthi Narayanan

Committee Member

Benjamin Fallen

Committee Member

Jose Payero


Soybean [Glycine max (L.)] is the most important oilseed and one of the most important and affordable protein sources worldwide. Enhancing the acquisition of belowground resources has been identified as an opportunity for improving soybean productivity worldwide. Root architecture is gaining interest as a selection criterion in breeding programs for enhancing soil resource acquisition and developing climate-resilient varieties. The objective of this research was to investigate whether root system characteristics are related with aboveground growth and yield of 11 selected soybean genotypes under rainfed conditions. Our goal was to identify beneficial root traits and genotypes that can be included in breeding programs. Soybean genotypes were tested under field conditions in 2019 and 2020 at two locations in South Carolina, in which one of the locations was characterized by compacted soils. Our results demonstrated mechanisms related with root production and distribution that will influence biomass production and yield formation in soybean. The elite SC breeding line SC07-1518RR, exotic pedigree line N09-12854, and slow wilting line N09-13890 were superior genotypes in terms of biomass production, seed yield, and water use efficiency. Genotypes N09-12854 and N09-13890 demonstrated reduced root development (based on total root count and length), likely to restrict belowground growth and allocate more resources for shoot growth. This characteristic, which can be referred as a parsimonious root phenotype, might be advantageous for soybean improvement under optimal and drought conditions in high-input production systems (characterized by adequate fertilizer application and soil fertility) that exist in many parts of the world. Genotype SC07-1518RR exhibited a similar strategy: while it maintained its root system at an intermediate size through reduced levels of total root count and length, it selectively distributed more roots at deeper depths. The increased root distribution of SC07-1518RR at deeper depths in compacted soil indicate its root penetrability and suitability for clayey soils with high penetration resistance. The beneficial root traits identified in this study (parsimonious root development and selective root distribution in deeper depths) and the genotypes that exhibited those traits (SC07-1518RR, N09-12854, and N09-13890) will be useful for breeding programs in developing varieties for optimal, drought, and compacted-soil conditions.



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