Microencapsulation of a Pseudomonas Strain (VUPF506) in Alginate–Whey Protein–Carbon Nanotubes and Next-Generation Sequencing Identification of This Strain

Alginate is a common agent used for microencapsulation; however, the formed capsule is easily damaged. Therefore, alginate requires blending with other biopolymers to reduce capsule vulnerability. Whey protein is one polymer that can be incorporated with alginate to improve microcapsule structure. In this study, three different encapsulation methods (extrusion, emulsification, and spray drying) were tested for their ability to stabilize microencapsulated Pseudomonas strain VUPF506. Extrusion and emulsification methods enhanced encapsulation efficiency by up to 80% and gave the best release patterns over two months. A greenhouse experiment using potato plants treated with alginate–whey protein microcapsules showed a decrease in Rhizoctonia disease intensity of up to 70%. This is because whey protein is rich in amino acids and can serve as a resistance induction agent for the plant. In this study, the use of CNT in the ALG–WP system increased the rooting and proliferation and reduced physiological complication. The results of this study showed that the technique used in encapsulation could have a significant effect on the efficiency and persistence of probiotic bacteria. Whole genome sequence analysis of strain VUPF506 identified it as Pseudomonas chlororaphis and revealed some genes that control pathogens.

The Influence of Biochar and Substrates Application on the Parameters and Yield of Mini-Tubers of the Charoit Potato Variety

The objects of research were potato meristem plants of the Charoite variety, mass and the number of mini-tubers grown on the “Agrobalt S” peat fertilizer and in a mixture of “ORVI” and biochar substrate in a closed greenhouse. A statistically significant effect of the use of this substrate and biochar on the increase in the number of standard mini-tubers relative to the control variant using only peat soil was established. The yield of standard tubers (9 – 60 mm) was 78 % when using “Agrobalt S” peat soil; 10 % of the substrate "ORVI" and 5 % of biochar, 78 %; 20 % of the substrate “ORVI” and 5 % of biochar, 77 %. A decrease in the standard material of mini-tubers of the Charoite variety against the background of an increase in quantitative indicators does not occur when using the substrate and biochar. Evaluation of latent viral infection of meristem plants and mini-tubers grown from them was performed by ELISA (Sandwich variant) in July and February and did not reveal latent infection in any of the variants. The determination of growing parameters was carried out a month after harvesting and showed that mini-tubers in all variants had no signs of the late blight disease, rhizoctonia disease, common scab, etc.

Entomopathogenic fungi decrease Rhizoctonia disease in potato in field conditions

Rhizoctonia potato disease is widespread in the world and causes substantial yield and quality losses in potato. This study aimed to evaluate the efficacy of entomopathogenic fungi Metarhizium robertsii and Beauveria bassiana in the inhibition of potato Rhizoctonia complex disease. The efficacy of the entomopathogenic fungi M. robertsii and B. bassiana in the defense of potato against Rhizoctonia disease (stem cancer, black scrulf and other forms of manifestation on tubers) was estimated under field conditions in Western Siberia. Preplanting treatment of the tubers with B. bassiana decreased Rhizoctonia disease in the stems and stolons. At the same time, treatment with M. robertsii did not cause a decrease in Rhizoctonia disease in these organs. However, both fungi decreased the sclerotium index on the tubers of new crops. We demonstrated two mechanisms of inhibition of Rhizoctonia solani by M. robertsii and B. bassiana, including (1) direct effect, expressed as inhibition of R. solani sclerotium formation in cocultivation assays, and (2) indirect effect, which is associated with increased peroxidase activity in potato roots under the influence of colonization by entomopathogenic fungi. We suggest that the treatment of seed tubers with B. basiana can effectively manage Rhizoctonia disease during the plant vegetative season and that both fungi significantly improve the quality of the new tuber crop.

Effects of Crop Rotation and Biocontrol Amendments on Rhizoctonia Disease of Potato and Soil Microbial Communities

Rotation crops and biocontrol amendments were investigated for suppression of Rhizoctonia solani on potato (Solanum tuberosum) and their interactive effects on soil microbial communities. Greenhouse trials were conducted to evaluate selected rotation crops, including barley, common and “Lemtal” ryegrass, clover, potato, and combinations of barley with ryegrass or clover, for their effects on populations of R. solani and Rhizoctonia disease. Potato and clover preceding potato resulted in higher disease severity than most other rotations, whereas ryegrass reduced stem canker severity. In addition, all ryegrass treatments resulted in substantially higher populations of R. zeae. Field trials evaluating selected biocontrol treatments in combination with different rotations were conducted at two locations in Maine. Potatoes were treated with the biocontrol organisms Laetisaria arvalis, Trichoderma virens, or Bacillus subtilis and planted following rotation crops of barley and ryegrass, barley and clover, or potato. The barley/ryegrass rotation significantly reduced incidence and severity of stem canker and increased tuber yield at one location. Efficacy of the biocontrol treatments varied by rotation and location, with L. arvalis and T. virens reducing black scurf in some rotations and increasing some aspects of tuber yield at one location. Soil microbial community characteristics differed among rotation crops and biocontrol treatments. Significant crop by biocontrol interactions were observed demonstrating the complex interactions among rotation crops, biocontrol treatments, and soil microbial communities, as well as indicating that biocontrol can be enhanced within beneficial rotations.

The effectiveness of a new biological product Spud on the basis of Bacillus subtilis in the cultivation of potatoes

It is shown the efficiency of the application of preparative forms (dry and liquid) of Kartofin during the growing season 2016-2018 years against major diseases of potatoes and the impact on the growth and development of culture. Biopreparation possesses high fungistatic effect, protecting potato plants against rhizoctonia disease, potato blight and late blight under field conditions and tubers of the new crop from dry rot. In years of low and moderate disease development, the effectiveness of the studied Potato biopreparation on the Sante variety was at the level of the reference chemical variant, equally reducing the distribution and degree of disease development. In the years of epiphytotic disease development fungistatic effect of the biopreparation was inferior in efficiency to chemical fungicides, but had a significant protective effect compared to the control, reducing the distribution of rhizoctonia disease by 22.5%, potato blightby 20.7%, late blight by 12.8% on average. The results of tuberous analyses after harvesting showed a decrease in the percentage of tuber damage by dry rot in variants with Kartofin (1.7 and 1.4%). The yield of the standard potatoes after application of Kartofin was slightly higher than in the control – by 5.1–7.7%.