ROOT-ZONE TEMPERATURE EFFECTS ON FLOODING TOLERANCE OF LEGUMES

In a growth chamber alfalfa and sainfoin improved in flooding tolerance as root-zone temperatures were lowered, and birdsfoot trefoil survived equally well under flooding at root-zone temperatures of 25, 19, and 13 C. After 28 days of flooding no plants of alfalfa or sainfoin were alive at 25 C root-zone temperatures, but 25% of the alfalfa plants and 11% of the sainfoin plants were alive at 19 C, and at 13 C 95% of alfalfa plants and 54% of the sainfoin plants were alive. Crowns were more resistant to damage and decay than roots, and damaged plants of alfalfa and sainfoin often regrew from the crown when all roots had decayed. The study indicated that less flooding damage will occur in the spring when soil is cool than when it is warm in summer.