肉桂精油对辣椒疫霉菌的生物活性

为了研究肉桂精油对辣椒疫霉菌Phytophthora capsici的生物活性，离体条件下测定了肉桂精油对辣椒疫霉菌各个生长发育阶段的影响；观察了处理后供试菌菌丝形态结构的变化；测定了对菌丝体细胞膜通透性的影响；盆栽试验测定了药剂对辣椒疫病的防治效果。结果表明，肉桂精油对辣椒疫霉菌菌丝生长的有效中浓度（EC₅₀）为111.89 mg/L；对病菌孢子囊产生的EC₅₀为61.09 mg/L；对孢子囊萌发的EC₅₀为95.14 mg/L；对游动孢子萌发的EC₅₀为54.88 mg/L。肉桂精油可显著降低辣椒疫霉菌菌丝的鲜重和干重，并使菌丝分支增多、变短；亦能提高该菌的细胞膜通透性。盆栽试验表明，肉桂精油对辣椒疫病具有很好的保护和治疗作用。可见，肉桂精油对辣椒疫霉菌具有明显的抑制作用，在防治辣椒疫病上具有较大的应用潜力。

Anti-oomycete Activity of Cinnamon Essential Oil against Phytophthora capsici

The aim of this study was to evaluate the effectiveness of cinnamon essential oil on controlling pepper blight caused by Phytophthora capsici. The toxicities of the essential oil against P. capsici at their four different life stages were examined in vitro conditions and the control efficacies were also investigated in vivo conditions. Moreover, morphology and structure of mycelial treated with the essential oil were observed and the effect of the essential oil on the permeability of the cell membrane was determined. The results showed that the EC₅₀ value of cinnamon essential oil against the mycelial growth was 111.89 mg/L. The oil could effectively inhibit sporangium formation, sporangium germination and zoospore germination with EC₅₀ values of 61.09 mg/L, 95.14 mg/L and 54.88 mg/L, respectively. The zoospore of the tested pathogen strain was sensitive to the cinnamon essential oil. The mycelial fresh weight and dry weight were significantly decreased by the essential oil. Morphological and structural observation showed that cinnamon essential oil caused the excessive branching and shortening of hyphae. The conductivity of mycelia cell suspension increased in the presence of the essential oil, indicating that the oil affected the cell membrane permeability. The conductivities of mycelia treated by essential oil at four concentrations increased with time, significantly higher than that of control. The above results showed that cinnamon essential oil had good protective and therapeutic effects on pepper blight, and the protective effect was stronger than the therapeutic effect. Therefore, cinnamon essential oil is worthy of further study and has a strong application potential.