The Effect of Biopreparations and Biostimulants on the Chemical Composition and Microorganisms Associated with Verticillium Wilt of Horseradish Roots (Armoracia rusticana Gaertn.)

Abstract

The basic foundation of plant production consists in plant protection treatments, which largely shape the quality of plant raw material intended for the food industry. Due to its long growing season, horseradish requires more treatments than average. Intensive protection based on synthetic pesticides favours the accumulation of their residues in plants and generates serious environmental problems. We have examined the effect of chemical protection and its reduced variant as well as three variants of biological protection, differentiated in terms of preparations used for seedlings treatment (Pythium oligandrum, Bacillus subtilis, and Ecklonia maxima), on the content of dry matter, protein, fat, carbohydrates, and the disease severity index (DSI) of Verticillium wilt of horseradish roots. The quantitative and qualitative changes in the microorganism communities associated with this disease were determined. Thirty-four species of fungi and Globisporangium irregulare have been shown to contribute to the pathogenesis of Verticillium wilt. The following were found with the highest frequency: Verticillium dahliae (14.37%), G. irregulare (6.87%), Ilyonectria destructans (6.73%), Fusarium acuminatum (6.53%), Rhisoctonia solani (6.75%), Epicoccum nigrum (5.56%), and Alternaria brassicae (5.36%).We found that water deficit promotes the increase of DSI and reduces the number and richness of fungal species isolated from diseased roots. The variant of biological protection with treatment of seedlings of E. maxima extract and with reduced chemical protectionin dry seasons give the best protective effects. Under conditions of optimal water supply, biological protection (P. oligandrum) is more effective than chemical protection. Biological protection increases biodiversity in the population of microorganisms that contribute to blackening of the conductive bundles of horseradish roots. There is a significant negative correlation between the number of isolated microorganisms and the DSI value. Increasing the number of the CFUs is accompanied by a reduction in the symptoms of Verticillium wilt of horseradish roots. Biological protection in years with sufficient water supply results in a significant increase in the content of dry matter, protein, and carbohydrates in horseradish roots. Under the influence of protective treatments, the ash content in the roots and its alkalinity decrease.

Health Parameters of Potato Tubers under the Influence of Soil Applied Bio-Preparations and Bio-Stimulants

“…Cytokinins have an impact on the enhancement and growth of the plant root system [106,107]. Therefore, the results obtained are not surprising; they only confirm the yield-enhancing role of PGPEm [108][109][110]. The conducted research study has shown that PGPEm protects potato tubers against silver scurf better than MSADs (Figure 4).…”

“…The representative of the kingdom of Chromista (class Oomycetes), Pythium oligandrum, is one of the best-known organisms used in plant protection for the longest [43,44,95,96]. According to Brozowa [97], P. oligandrum contributes to an increase in the soil population of antagonists, which reduces the density of many important pathogens, including R. solani.…”

“…Knowledge of the causes of diseases is crucial for the successful management of potato production. In practice, the fight against pathogens living in soil and carried with seed potatoes is not easy [20,21,30,32,[40][41][42][43][44]. It should be highlighted that the use of chemical protective agents may be ineffective if environmental conditions promote the dispersion of pathogens or if fungicide-resistant genotypes appear [45][46][47].…”

“…It should be highlighted that the use of chemical protective agents may be ineffective if environmental conditions promote the dispersion of pathogens or if fungicide-resistant genotypes appear [45][46][47]. The use of synthetic pesticides has numerous times been shown to lead to a loss of soil biodiversity and an accumulation of pathogenic bacteria, fungus-like organisms, and fungi in soil [42][43][44]48]. The introduction of organic matter to soil is one of the more effective methods of restoring soil biodiversity and balance between populations of beneficial and pathogenic microorganisms [42,49,50].…”