بررسی تاثیر نانوکپسول اسانس آویشن شیرازی بر شدت بیماری بذرزاد لکه‌قهوه‌ای و رشد گیاهچه های نورسته برنج

Rice brown spot disease, caused by Bipolaris oryzae is one of the most important seed-borne and air-borne diseases of rice worldwide. This disease can affect the quantity and quality of rice seeds. Seed disinfection is the best way to control the seed-borne inoculum of this disease. So far, no registered specific fungicide is available in Iran to control the seed-borne inoculum of fungus. However, seed disinfection with registered fungicides for Fusarium foot rot disease can reduce the severity of this disease in rice nurseries. To avoid the misuse of non-specific chemical fungicides, it is necessary to introduce effective and safe compounds for rice seed disinfection. In our previous study, we found the effectiveness of Zataria multiflora essential oil (ZEO) and the nano-capsule form of ZEO with β-Cyclodextrin (ZEON) against rice foot rot disease. Here, we evaluated the possible negative effects of these compounds on the germination and growth of rice seedlings, as well as their positive effect on the reduction of seed-borne inoculum of rice brown spot disease. To set up this, we first surface-sterilized the seeds of the Khazar cultivar with 1% bleach and then separately treated every 100 seeds with 184 ppm of ZEO, 368 ppm of ZEON, 368 ppm of background β-Cyclodextrin (BC) and sterile water for 20 minutes. Treated seeds were placed in 15-cm-diameter plates containing two layers of moist sterile Whatman paper. After 14 days, seed germination, Infection of seedlings with fungus B.oryzae , the length of root and shoot, and the fresh and dry weight of the seedlings were evaluated. Results showed that relative to water treatment, ZEON, ZEO, and BC decreased the percentage of infection in seeds and seedlings by 46, 30, and 30%, respectively. The germination percentage in ZEON-, ZEO-, and BC-treated seeds was almost equal to the control (94±2%). Data revealed the highest (8 cm) radicle length and seedling fresh weight in ZEON- and water-treated seeds and the highest (8/45cm) stem length in the ZEO-treated ones. No significant difference was observed among the dry weight of the different treatments. According to the data, nanoencapsulation of ZEO not only increases its antifungal activity but also positively enhances seed germination and seedling growth. Combining the results of this and our previous study shows that ZEON is a promising compound for seed treatment against both brown spot and foot rot disease of rice.