Lack of oxygen is the major cause of limited plant growth in waterlogged soils. When soils become waterlogged less gas diffuses to and from the roots through the soil pores; there are changes in concentrations of mineral elements in soil solutions; and toxic products of roots and soil microorganisms begin to accumulate. These changes adversely affect germination, growth and development of plants.
Setter, Tim and Belford, Bob
"Waterlogging : how it reduces plant growth and how plants can overcome its effects,"
Journal of the Department of Agriculture, Western Australia, Series 4: Vol. 31
, Article 5.
Available at: http://researchlibrary.agric.wa.gov.au/journal_agriculture4/vol31/iss2/5