Etiology Characters Of Eriwinia Chrysanthemi Pv.Zeae In Hubei

Bacterial foot rot of rice is caused by Erwinia chrysanthemi pv.zeae, which is more serious occurred in the rice producing areas in the southern China. The occurred region gradually expanded from the late 90s of last century to the present. Bacterial foot rot of rice was large scale occurred in July 2009 in Hubei province-including of Yangxin, Zhijiang, Day-had a very big loss of the food production in Hubei province. This paper started from the separation of bacteria, then bacteria were identified, also conducted he pathogen city of pathogens, biological characteristics, the impact on rice yield, Fungicide screening indoor a series of studies. Hope that through this study, bacterial foot rot of rice in Hubei province to have a preliminary understanding, prevention and treatment of this disease for future research as a foundation. The main results of this study are as follows.1. Significantly reduce the rate of Empty-grain percentage and increase in rate of seed setting is the main influence on the yield loss. Compared with the healthy plants, The rate of empty-grain increased about 3.5 times, seed setting is about 26% lower. Yield losses in the about 40%.2. Twenty-one strains were isolated from the incidence rice by tissue isolation and dilution separation. All of then were be identified by express Kid detection, NGM medium, specific primer amplification and ITS test. Finally, six strains identified as Erwinia chrysanthemi, we named them, respectively, Echl-01, Ech2-01, Ech2-02, Ech2-03, Ech3-01, Ech3-02. Through the identification of pathogenic to determine that acupuncture and injection the caudexes of rice can cause symptoms. On the contrary Leaves inoculated with in vitro and in vivo inoculation did not have any symptoms. We speculated that bacteria can not cause disease by infected leaves. And we speculated that bacteria may be infected from the wound, the injured leaf sheath and root(so a heavy rain in the windy made the diseases epidemic). The bacterial can also be invasive in the process of seed germination, reduce the seed germination rate, cause rot bud and putrid root.3. Some kinds of physiological and biochemical experiment such as Gram stain, capsule stain, starch hydrolysis be tested in six strains isolated from Hubei. The results were similar to other strains of domestic. We determined the optimum growth temperature of the strains isolated from Hubei is 28-32°C by temperature tests, The minimum growth temperature is 10°C, The maximum growth temperature is 41°C, The lethal temperature is 53-54°C。The results of pH test show that Erwinia chrysanthemi isolated from Hubei Province can grow between pH5.2-10.0, growing well between pH6.0-8.4, and the optimum growth pH is 6.8, the bacteria stop growing when the pH is lower than 4.4.4. We investigated the samples of rice which we collected from Yangxin, Zhijiang, Daye, Findings are as follows. There are significant differences between disease rice and healthy rice in spike per plant, seed number per spike, setting-rate,1000-grain weight. We speculated the yield loss of field by the loss of yield per plant without considering the survival number. The yield loss of all the samples collected from five different parts were about 50%, the most serious yield loss sample which was taken from Wangqiao, T You 502, the yield loss is 58.76%, and the lowest yield loss sample which was taken from Shangxu, Xinliangyou-sixth, the yield loss is also 41.69%.5. After the laboratory toxicity testing, we found that the ability to inhibit bacterial growing is significantly different between different pesticides. Wuningmeisu is the best antimicrobial activity of pesticides, the minimum effective concentration is 2.4μg/ml. Agricultural streptomycin and Chlorothalonil have a nice antimicrobial activity, the minimum effective concentration is 58.30μg/ml and 81.40μg/m.