Bacterial leaf blight (Xanthomonas oryzae pv. oryzae) is an important rice disease. This study tested disease-reducing effects of methanol Kalanchoe pinnata leaf extracts prepared by the liquid-liquid extraction method and investigated the mechanism involved in the observed disease reduction. Three extract concentrations (1, 1.5, and 2%) were tested under net house conditions using three application methods [seed soaking combined with foliar spraying at (1) 14 days before inoculation (DBI), (2) 7 DBI and (3) both 14 and 7 DBI]. The disease was assessed through lesion lengths at 7, 14 and 21 days after inoculation. Seed soaking combined with foliar spraying at 14 DBI using 1.5% extract showed significant disease reduction similar to that of the chemical control using Starner 20WP. Induced resistance involved in the disease reduction through increased activities in rice tissues of the four defense-related enzymes, i.e., peroxidase (POX), catalase (CAT), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL). Activities of POX, CAT and PPO generally increased while those of PAL decreased after pathogen inoculation. By extract application, activities of POX, PPO and PAL increased earlier compared to those of CAT. Activities of these enzymes reached higher levels with the presence of both extract application and pathogen inoculation.
Tạp chí khoa học Trường Đại học Cần Thơ
Khu II, Đại học Cần Thơ, Đường 3/2, Phường Ninh Kiều, Thành phố Cần Thơ, Việt Nam
Điện thoại: (0292) 3 872 157; Email: tapchidhct@ctu.edu.vn
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