The Mediation Mechanism for Flood-Induced Rice Blast Field Resistance

Rice blast, an erratic niche disease incited by Magnaporthe grisea Cav., frequently limits rough rice yields and grower cultivar options in Arkansas rice production areas. Scientists poorly understand why some blast-susceptible varieties such as ‘Newbonnet’, ‘LaGrue’, ‘Mars’, and ‘Cypress’ become increasingly more blast resistant if grown in continuously flooded soil. A greenhouse depth-of-flood test duplicated this field resistance response and identifies dissolved oxygen as a primary variable in induced rice blast resistance. A solution culture experiment confirmed oxygen aeration has dominant influence on rice blast resistance, separate from influences of nitrogen form and rate. The relative value of flood-induced blast resistance has been demonstrated by the fact that, without fully understanding the scientific principles involved, Arkansas rice specialists and growers have utilized flood-induced blast field resistance as their primary control measure. During the blast-conducive years 2000 to 2003, growers have produced record rough rice yields growing hig-yielding but blastsusceptible cultivars ‘Wells’, LaGrue, and ‘Francis.’