Abstract
Plant-based screening experiments were conducted with the aim of identifying biocontrol bacteria and fungi for seed treatment of maize. Candidate microorganisms were evaluated for their protective effects against soilborne infections by species of Fusarium, Globisporangium (syn. Pythium) and Rhizoctonia. The microorganisms tested were bacteria and fungi from maize roots or other sources, including some active microbial components of commercial biocontrol products. Due to the method of isolation chosen, the majority of bacteria from maize roots were spore formers, most of them species of the genera Bacillus,Brevibacillus and Paenibacillus. In pot tests with the potting substrate inoculated with F. culmorum, the level of control provided by seed treatment with the most efficacious bacterial and fungal isolates was comparable or close to the chemical reference seed treatment thiram. The most effective bacteria were species of Pseudomonas, Burkholderia and Streptomyces. Among a subset of approx. 100 bacteria studied, the in vivo and in vitro activities against F.culmorum were only weakly correlated, although some strains deviated from this pattern. The most effective fungi were two strains of Clonostachys rosea and isolates of Trichoderma. The latter and a strain of Gliocladium virens provided also protection against R.solani. Activity against Globisporangium ultimum was recorded for one isolate of Trichoderma and the two strains of C. rosea. A reduction in the impact of seedborne F. culmorum was also observed after seed treatment with two strains of F. oxysporum f. sp. strigae. The results are discussed in relation to previous reports on rhizosphere bacteria of maize and their use in biocontrol of plant pathogens or for plant growth promotion.
Highlights
In maize, seedling emergence and establishment of vigorous stands can be impeded by a variety of seed- and soilborne fungal pathogens that attack seeds and seedlings
230 bacterial strains were used to inoculate maize kernels that were sown in pots with the potting substrate inoculated with F. culmorum
In view of an expected later combined use with electron seed treatment, we used maize seed pre-treated with electrons in the screening experiments
Summary
In maize, seedling emergence and establishment of vigorous stands can be impeded by a variety of seed- and soilborne fungal pathogens that attack seeds and seedlings. Fungi of the genus Fusarium are among the most important seedand soilborne pathogens of maize, causing seed rot, root rot and seedling blight. The fungi F. verticillioides, F. proliferatum, F. subglutinans, F. oxysporum, F. temperatum and F. graminearum are especially involved in maize seedling diseases (Munkvold and O’Mara 2002; Pintos Varela et al 2013). In addition to Fusarium spp., Rhizoctonia solani and different species of Globisporangium Pythium) are important soilborne pathogens of maize (Buddemeyer et al 2004; Thomsen et al 2018; Schmidt et al 2020). Maize seed is typically treated with chemical fungicides in order to reduce the impact of these pathogens (Sharma et al 2015)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
