Two cyanobacterial culture filtrates as biocides for controlling damping-off and root-rot diseases in fennel (Foeniculum vulgare L)

The present study was conducted to evaluate in vitro and in vivo the biological control aptitude of the two cyanobacteria i. e., Anabeana variabilis and Nostoc paludosum, cultural filtrates against Fusarium solani, Macrophomina phaseolina and Pythium aphanidermatum. Culture filtrates of both blue-green algal had antifungal effect against growth of the examined fungi. Under artificial inoculation conditions in a greenhouse experiment, both algae culture filtrates were found to be effective against fennel damping-off and root-rot diseases compared with untreated control. Nostoc paludosum culture filtrate was the more effective than A. variabilis in reducing damping off and root-rot diseases as well as increased activity of hydrolytic enzymes including peroxidase, polyphenoloxidase, chitinase as well as oil content, soluble proteins and total phenols of fennel plants. Under natural field conditions during 2020/ 2021 and 2021/ 2022 seasons, both algal had biocidal effect against the fennel soil-borne diseases and significantly increased growth parameters and plant yield. It was observed that both blue-green algal filtrates increased volatile oil percentage and its frequency compared with untreated seeds.