Date of Graduation

12-2014

Document Type

Thesis

Degree Name

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

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor/Mentor

Pengyin Chen

Committee Member

Edward Gbur

Second Committee Member

Kenneth Korth

Third Committee Member

Kristofor Brye

Keywords

Abiotic Stress, Flood Tolerance, Soybean, Water-logging

Abstract

Water-logging can be detrimental to soybean growth and development; effects range from chlorosis and stunting to yield loss and plant death. Soybean response to, and the effects of, water-logging are dependent on the growth-stage of the plant at the initiation of water-logging. The objectives of this study were to screen a diverse soybean germplasm collection for water-logging tolerance (WLT) at both the V5 and R1 growth stage and to develop a method to screen soybean for WLT in greenhouse. One hundred thirty five genotypes consisting of historical genotypes, PIs, drought and WLT tolerant breeding lines were screened for WLT in Stuttgart, Arkansas during the 2009 and 2010 growing seasons. Plots were laid out in a split-plot experimental design, soybean were planted into a Dewitt silt loam. Water-logging stress was applied through the pulling of soil levees around each whole-plot factor. WLT for genotypes was assessed using a 0 to 9 visual rating based on severity of plot damage with 0 being no damage and 9 being 90% of the plot severely damaged to plot death. Differences in WLT ratings were significant in both 2009 and 2010, despite different weather conditions in 2009 and 2010 the genotype Young was identified as tolerant across growth stage and year. However, growth stage specific tolerance was observed for other genotypes in the study. Two greenhouse WLT methodologies were evaluated: Flooding with the addition of CO2 to flood water and flooding without the addition of CO2. Each methodology consisted of six genotypes thee identified as tolerant and three as susceptible, however, not all genotypes were used in both methods. Screening soybean for WLT under flooded conditions with CO2 added to the flood water produced visual symptoms that best represented the effect of water-logging in the field environment with visual ratings strongly correlating (r=0.926) with ratings from the 2010 field screening. Identification of WLT genotypes, the observation of growth stage specific tolerance and the development of a greenhouse screening methodology will aid plant breeders in developing WLT cultivars.

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