Submitted to: Agricultural Experiment Station Publication
Publication Type: Experiment Station
Publication Acceptance Date: 6/1/2011
Publication Date: 6/15/2011
Citation: Zhou, X., McClung, A.M. 2011. Comparison of disease severity and yield potential of rice varieties in two organic cropping systems. Texas Rice Special Section, Highlighting Research in 2011. p. XXIV-XXV.
Technical Abstract: The market demand for organically produced rice has driven the steady increase in acreage of organic rice in the U. S., with Texas and California having the most acreage. Yield potential and disease management are among the principal challenges associated with organic rice production. Organic rice can be produced in different production systems, and disease severity and yield potential may vary from one system to another. The objective of this research was to evaluate 27 rice varieties and breeding lines to determine their response to diseases under two different organic cropping systems in 2010. For the first cropping system, Durana white clover was planted in fall 2009, plowed down in spring 2010, followed by tillage, and water-seeding. For the second system, Durana white clover was planted as in the 1st cropping system but mowed prior to planting rice. Dry rice seed was directly seeded using a no-till drill into the mowed clover. Diseases were monitored throughout the cropping season. Diseases severity was assessed using a scale of 0 to 9, where 0 represents no symptoms and 9 represents most severe. Grain yield was determined near maturity. Narrow brown leaf spot caused by Cercospora janseana was severe on Jazzman, Presidio, Sierra, Cocodrie, RU0703144, and RU0703190 in both cropping systems. In the no-tilled production system with a significant amount of previous cover crop residue, straighthead caused by unknown physiological disorders occurred in all varieties, with Cocodrie, RU0703144, and RU0703190 having the most severe symptoms. Brown spot caused by Cochliobolus miyabeanus was also commonly present in both production systems, whereas sheath blight caused by Rhizoctonia solani, bacterial panicle blight caused by Burkholderia glumae, and leaf smut caused by Entyloma oryzae were minor in severity for the majority of the varieties. The varieties Tesanai 2, GP2, Rondo, PI312777, and PI338046 had the lowest levels of all of these diseases and produced grain yields that ranked among the highest in both cropping systems. Tesanai 2, a variety from China, outyielded all other varieties and lines. These results can help to identify rice varieties suitable for organic production relative to disease susceptibility and yield potential.