Screening Diverse Soybean Germplasm for Flood Tolerance.

Screening Diverse Soybean Germplasm for Flood Tolerance

Flooding, or water-logging, in the mid-south is a major abiotic stress on soybean. Flooding reduces vegetative growth, grain yield and can cause plant death when severe. Currently, there is limited research on evaluating soybean flood tolerance at varying growth stages. The objective of this study was to evaluate flood tolerance at the V5 and R1 growth stages in a diverse soybean germplasm collection for breeding purposes.  A total of 135 historical and recently released conventional soybean varieties were screened in Stuttgart, AR during the summer of 2009 and 2010 in a RCBD with five replications.  Genotypes were divided into four maturity groups and planted in a 3 m single-row plot with a seeding rate of 100 seeds per plot.  Maturity groups were screened for flood tolerance independently at the R1 and V5 growth stages.  Flood stress was imposed by surrounding each maturity block with raised soil levees. The flood water was maintained at 10 cm above the soil surface for two weeks. A visual rating on a 0 to 9 scale, based on chlorosis, stunting, and plant death, was taken two weeks after the removal of the flood for each plot and repeated weekly for two weeks.  Genotypic differences in the visual ratings for flood tolerance were observed across maturity groups and growth stages, although relative rank changed among genotypes due to the stage at which the plots were flooded.  Desirable flood tolerant genotypes were selected for use in the Arkansas breeding program and evaluated for yield in 2010.  Identification of flood tolerant lines will help soybean breeders incorporate flood tolerance in future high-yielding soybean varieties.