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POSTERS: Host resistance screening

Hybrid rice outperforms inbred rice in resistance against sheath blight and narrow brown leaf spot
Jun Shi - Mianyang Academy of Agricultural Sciences. Xin-Gen Zhou- Texas A&M AgriLife Research Center

The introduction of hybrid rice in the United States provides producers an alternative to traditionally cultivated, conventional inbred rice. Because of its high yielding potential, hybrid rice acreage has continually increased over the past decade. The objective of this study was to compare hybrid rice with inbred rice for resistance to sheath blight (Rhizoctonia solani AG1-IA) and narrow brown leaf spot (NBLS, Cercospora janseana), two important diseases affecting rice production in Texas and other southern United States. Field evaluations were conducted on more than 40 hybrid cultivars and breeding lines and 160 inbred cultivars and breeding lines at two locations in Texas over 3 years. Sheath blight and NBLS severities were rated prior to harvest on a scale of 0 to 9 where 0 = no symptoms and 9 = most severe in symptoms and damage. Sheath blight developed on all hybrid and inbred entries evaluated. However, the average sheath blight severity over locations and years was 30% lower in the hybrid entries than in the inbred entries (4.7 vs 6.7). All hybrid entries had complete resistance to NBLS with no development of the disease whereas the inbred entries exhibited a range of NBLS severity from 0 to 8, with an average disease severity of 3.5. The results demonstrate that hybrid rice is less susceptible to sheath blight and has a higher level of resistance against the NBLS disease compared to inbred rice.