| 論文英文摘要 |
Rice is the most important food crop in Taiwan, with the largest planting area and output among all crops. In the process of rice production, rice sheath blight (ShB) caused by Rhizoctonia solani AG-1 IA is one of the major diseases, which can seriously affect rice yield and quality once it breaks out. Currently, the prevention and control of ShB rely mainly on chemical pesticides, but long-term and large-scale use of chemical pesticides has the risk of polluting the environment and harming human and animal health, as well as potentially leading to pathogen resistance. In contrast, natural plant protection products have advantages such as low toxicity to humans and animals, low residue, and unique effects on diseases and pests, which can effectively control pests and diseases and are less likely to develop resistance. Therefore, this study aims to develop a simple method for preparing aqueous garlic extract and evaluate its applications in three aspects: 1. inhibitory effect on ShB pathogen; 2. storage conditions; 3. prevention and control of ShB in rice. According to the experimental results, the aqueous garlic extract prepared from 10 g of garlic and 50 mL of sterile water (undiluted solution) can inhibit the growth of R. solani, the causal agent of rice sheath blight, by 79.78%. When the undiluted solution was diluted two-fold or the amount of garlic and sterile water was increased proportionally (using 200 g of garlic and 1000 mL of sterile water), the inhibition rates were 58.09% and 46.54%, respectively. In terms of storage, the undiluted aqueous garlic extract showed the best preservation effect, with a 50.99% inhibition rate after 28 days of storage at -20°C. Although the inhibition effect decreased when the garlic extract was stored at 25°C and 4°C, it still showed inhibition rates of over 45.93%. The results of the germ tube inhibition test showed that the undiluted aqueous garlic extract can inhibit germ tube growth by 92.95%, which is similar to the effect of a commercially available garlic extract solution at a concentration of 150 μg/ml (150 ppm). In addition, the efficacy of the garlic extracts in controlling rice sheath blight was proportional to the amount of garlic used (1, 3, 5, 7, and 10 g). The inhibition rates were 31.35%, 57.06%, 79.18%, 80.85%, and 84.76%, respectively. In comparison, the control group treated with 150 ppm garlic extract solution showed a disease control rate of 94.88%. Based on the comprehensive evaluation results, the evaluated aqueous garlic extract has the potential to be used as a non-pesticidal alternative and reduce food loss for controlling rice sheath blight. |