Semester of Graduation

Spring 2022

Degree

Master of Science (MS)

Department

Plant Pathology and Crop Physiology

Document Type

Thesis

Abstract

Bacterial panicle blight (BPB) and sheath blight (ShB) are economically important diseases of rice (Oryza sativa) in Louisiana and other rice-growing regions around the world. However, there are challenges in the current disease management practices for these diseases. Thus, the main goal of this study is to identify new materials and their application methods that effectively suppress BPB and ShB. To achieve this goal, we evaluated the effect of various materials and application methods against the rice diseases. In 2020 and 2021, various materials, such as ascorbic acid (AA), N-acetylcysteine, chitosan, the avirulent strain of Burkholderia glumae 257sh-1 and the combination of two beneficial bacteria (Pseudomonas plecoglossicida RRB 1044 (B1) and Pseudomonas parafulva RPB.NT 5 (B2)), were evaluated for their disease-suppressing effects against BPB and ShB diseases in the field and greenhouse conditions with different concentrations and timings of application. In 2020, results showed that the avirulent strain B. glumae 257sh-1and the combination of B1 and B2 suppressed the BPB symptoms for both CL111 and Bengal rice varieties in the field. In addition, Bengal rice plots treated with the avirulent strain B. glumae 257sh-1, the combination of B1 and B2, or AA (1 mM) showed a significantly higher yield compared with the untreated control. Interestingly, results of the 2021 experiments showed that seed treatment of the avirulent strain suppressed the ShB symptoms substantially in both field and greenhouse conditions. The same treatment also reduced natural infection of narrow brown leaf spot disease. In addition, seed treatment of chitosan was effective for the suppression of ShB in the greenhouse. These materials and application methods identified in this study will be an important foundation to develop innovative technologies to manage major rice diseases, such as BPB and ShB, in environment-friendly, efficient and sustainable ways.

Committee Chair

Ham, Jong Hyun

DOI

10.31390/gradschool_theses.5521

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