Date of Graduation

12-2018

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor

Richard E. Mason

Committee Member

Pengyin Chen

Second Committee Member

Kristofer Brye

Third Committee Member

John Rupe

Keywords

Agronomy, Genetics, Plant Breeding, Soybean

Abstract

Flood tolerance in soybean (Glycine max) is not a well-characterized trait, yet flooding damage is second only to drought stress in terms of yield reduction. The objectives of this study were to determine genetic variation for flooding tolerance in two populations of soybean recombinant inbred lines (RILs) and to identify and confirm flood tolerant QTL. Population A (WHA) consisted of 111 RILs derived from the cross 5002T by 91210-350 and Population B (WHB) consisted of 79 RILs from the cross RA-452 by Osage. Experiments were conducted at the Rice Research and Extension Center (RREC) near Stuttgart, AR in 2015 and 2016. Flood damage score (FDS) was rated at three, six, and nine days after the flooding treatment was drained. In addition to FDS, plant population was measured before and after the flooding treatment to calculate the percentage of surviving plants (PS). In 2015, Chlorophyll content was measured using a SPAD meter and normalized difference vegetative index (NDVI) was calculated in 2016. Both RIL populations and parents were genotyped using the SoySNP 6k beadchip with 908 and 1,466 polymorphic markers detected in WHA and WHB, respectively. Twenty nine QTL were identified, five of which validate prior studies involving soybean flood tolerance. Logarithm of Odds (LOD) values from ranged from 3.03 to 6.56 with R squared values ranging from 0.09 - 0.29. A QTL was identified on chromosome 7 that was stable across both WHA and WHB. In population WHA, this QTL was associated with both AUFPC and FDS and explained 9-10% of phenotypic variance. In population WHB, this QTL was associated with PS and explained 15% of phenotypic variance. The results of this study will aid in future development of flood-tolerant soybean germplasm and cultivars by validating previously reported QTL and demonstrating the usefulness of instruments in evaluating flood-tolerance.

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