Submergence stress occurs in rainfed areas where water control is limited.
Submergence is also a viable strategy for weed control, especially in water-seeded rice.
The best source of submergence tolerance in rice is the Indian cultivar FR13A, a selection from a local land race. This gene was mapped between two RFLP markers RZ698 and C1232, spanning a genetic distance of nearly 10 cM. We generated an F 2 population of 3000 plants to develop a fine-scale map around Sub1 . The flanking RFLP markers were applied to the F 2 population and seed of plants with recombination between these markers were selected for submergence screening of the F 3 progeny. The RFLP marker R1164 mapped within 1 cM of Sub1 . Several AFLP markers mapped within 0.1 cM of the gene.