Evaluation of resistance of lotus germplasm resources to <italic>Fusarium commune</italic> and screening of fungicides

<bold>Objective</bold> This study aims to explore the biological characteristics of <italic>Fusarium commune</italic>，clarify the resistance of different lotus germplasm resources to <italic>Fusarium commune</italic>，and screen the effective control agents under laboratory conditions，thus promote the development of lotus industry. <bold>Method</bold> The effects of different culture media，pH，and nitrogen and carbon sources on their growth were determined using the mycelial growth rate method.Indoor resistance analysis of 229 lotus germplasm resources was conducted by using indoor wounded inoculation，and the resistance of lotus germplasm was evaluated by the mean spot diameter method and cluster analysis.The virulence of six commonly used fungicides，including 450 g/L prochloraz，40% difenoconazole and 50% carbendazim，against <italic>Fusarium commune</italic>，was determined by growth rate method. <bold>Result</bold> Biological characterization shows that the pathogen grows most rapidly on oatmeal agar（OA），the most suitable nitrogen source is peptone，the most suitable carbon source is maltose，and the pH suitable for mycelial growth is 9.The average lesion diameter and cluster analysis divide the lotus germplasm into five categories，namely high resistance，resistance，medium resistance，susceptibility and high susceptibility.According to the classification standard of the average lesion diameter method，there were 56 high-resistance varieties，71 disease-resistant varieties，65 medium-resistant varieties，33 susceptible varieties and 4 high-susceptibility varieties，which are basically consistent with the results of cluster analysis.The selected germplasms cover the varieties of seed lotus，flower lotus，root lotus and wild lotus.Flower lotus and root lotus show no significant difference in resistance to lotus rhizome rot，while no significant difference is observed between the germplasm of wild lotus and seed lotus.Among them，the high-resistance germplasm of root lotus includes Yachengou and Xiaomiaoqianoulian；the wild lotus germplasms with high resistance include Puzheheibailian，Donggualian，Wenxihonglian，Siluokumu，Nangengyelian，Wuxilian，Jiangsuhongzexianyelian，etc..The high-resistance germplasm of seed lotus includes Ganlian Liushierhao，Changshun Yihao，Cunsanlian Yihao，Jinque，Baihuajianlian，Taikonglian Wushibahao，Cunsanlian Liushiwuhao，etc..The flower lotus germplasm with high-resistance includes Fenqinglian，Yitiansihai，Jinfenghuang，Qiuyang，Fenqianye，Peilizhixing，Jiaoxiangyi，Yidianhong，Baixuegongzhu，etc..The results of laboratory test show that 450 g/L prochloraz，40% difenoconazole，50% carbendazim and 325 g/L benzoazoxystrobin have a good inhibitory effect，with EC₅₀ values of 0.009，0.386，2.936 and 3.714 μg/mL，respectively. <bold>Conclusion</bold> In this study，the growth characteristics of <italic>Fusarium commune</italic> are revealed，and 56 germplasm resources with high resistance are screened，and 450 g/L prochloraz and 40% difenoconazole can be used as candidate agents for the prevention and control of lotus rot，which provides reference for the breeding of disease-resistant varieties and the prevention and control of the disease.