Pseudomonads associated with soil lumbricides as promising agents in root rot biocontrol for spring grain crops

doi:10.15389/agrobiology.2019.1.91eng

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DOI Доступ к ресурсу на сайте издателя			10.15389/agrobiology.2019.1.91eng

#ризобактерии

#противогрибковая активность

#фитопатогены

#псевдомонады

Title: Pseudomonads associated with soil lumbricides as promising agents in root rot biocontrol for spring grain crops
Creator: Akimova, Elena E.
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Tereshchenko, Natalya N.
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Kravets, A. V.
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Zyubanova, Tatyana I.
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Apenysheva, M. V.
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Minaeva, Oksana M.
Date: 2019
DOI: 10.15389/agrobiology.2019.1.91eng
Description: Currently, crop yields can be increased by high farming standards which include environmentally friendly use of chemical fertilizers and pesticides, as well as their replacement by bioformulations having similar activity. That is why both search for new promising species, strains and isolates of bacterial antagonists for their potential use as biocontrol agents, and study of antifungal activity mechanisms, particularly the relationship between the activity in model tests and in agrocenoses, are relevant. The aim of this study was to estimate bacterial isolates from redworm coprolites as potential bioactive agents to control phytopathogenic fungi causing root rot of crops. The experiments were conducted in 2013-2015. In the preliminary laboratory screening for fungistatic and growth-promoting activity we selected two strains, Pseudomonas sp. GS4 and Pseudomonas sp. PhS1, and assessed their ability to decrease the growth rate of fungal colonies in Petri dish test on nutrient agar medium and to reduce seed infestation of soft wheat (Triticum aestivum L., Irgin cultivar) in sterile paper roll test. Seeds soaked in distilled water served as control. As a standard, we used seed treatment with a chemical fungicide Dividend® Star («Syngenta AG», Switzerland) (30 g/l difenoconazole, 6.3 g/l cyproconazole) at recommended rates. In field tests, we recorded root rots in soft wheat Irgin cultivar plants and in barley (Hordeum vulgare L.) Acha cultivar plants during tillering and beginning of blooming. The laboratory tests showed a statistically significant (р < 0.05) 1.5-2.5-fold decrease in the growth rate of phytopathogenic fungi Fusarium oxysporum, Bipolaris sorokiniana and Alternaria spp. as compared to control. In all experiments with bacterization, there was a 53-76 % decrease (р < 0.05) in total seed infestation by pathogens as compared to non-bacterized plants. The effect of the bacteria in planta was assessed in small model systems. The obtained data show a statistically significant (р < 0.05) reduction in the root rot disease incidence in bacterization with Pseudomonassp. GS4 (by 33-37 %) and Pseudomonas sp. PhS1 (by 57-60 %). Root rot disease severity decreases 2.1-2.4-fold and 3.3-3.5-fold, respectively. In 2015, we revealed a tendency towards a 19-70 % increase in the total number of rhizosphere microorganisms at the beginning of plant blooming depending on the crop and type of bacterization. The number of hosphate-mobilizing bacteria in the rhizosphere under bacterization was, on average, 5.5-7.2-fold higher in wheat and 2.1-3.2-fold higher in barley than that without bacterization. Our results of root rot field study in the 2013-2015 showed the efficacy of both monocultures and complex bacterization which provided a decrease in wheat and barley root rot disease severity by 6.5-57.6 % and 18.6-50.0 %, respectively, depending on the bacterial culture and the weather conditions. The maximum biological efficacy of the isolates is noted at the beginning of blooming.