Phytopathological condition of soil and development of soybean diseases depending on cultivation technology in the conditions of the Northern Steppe of Ukraine

Abstract

Purpose. To investigate the influence of soybean cultivationtechnology on the phytopathological condition of soiland the development of crop diseases in the conditions of the Northern Steppe of Ukraine. Methods. Field and laboratorystudies were carried out in accordance with modernrequirements and standards of research in agronomyand agriculture. Results. Growing soybeans using no-tilltechnology, leaving plant residues on the soil surface, contributedto the change in environmental conditions for theformation and development of microorganisms in the soilthroughout the years of research.According to the results of the phytopathological analysisof soil samples, on average over the years of research,the total number of fungi was from 79.5 to 94.4 thousandCFU/g of soil. The increase in the number of all groupsof microorganisms in the soil contributed to significantnatural biological control of the number and manifestationof soybean disease pathogens. Most soybean plants,regardless of the experiment variant, were affected bythe fungi Alternaria alternata, Peronospora manshuricaand Fusarium oxysporum. On average over the years ofresearch and by cultivation technology variants, plants ofthe Fortetsya variety were slightly more affected by thepathogens of Alternaria and Peronosporosis – the intensityof disease development in the flowering phase – thebeginning of bean formation was higher compared to theBetina variety by 15.6 and 5.4 percentage points, respectively.At the same time, the Fortetsya variety was somewhatmore resistant to the pathogen of fusarium wilt ofplants – the intensity of disease development was lowercompared to the Betina variety by 5.3 percentage points.The same trend was observed during the period of seedripening. Regarding the soybean growing technologyoption, it should be noted that the better conditions forplant growth and development that have developed overall years of research using no-till technology have contributedto the manifestation of greater plant resistance to diseasepathogens.Conclusions. On average over the years of research,the total number of fungi in soil samples of experimentalplots was from 79.5 to 94.4 thousand CFU/g of soil, with theadvantage of the no-till technology option. On average overthe years of research, the proportion of pathogenic fungi insoil samples under this cultivation technology was 7.8 thousandCFU/g of soil, which is 66.4% less than the indicatorsof the classical soybean cultivation technology option. Thestudies determined that the increase in the number of allgroups of microorganisms in the soil contributed to a significantnatural biological control of the number and manifestationof soybean disease pathogens. On average over theyears of research and by variety factor, the intensity of plantdamage by Alternaria alternata, Peronospora manshuricaand Fusarium oxysporum fungi was lower, depending onthe phase of plant growth and development, by 1.7-20.6;8.0-12.1 and 29.9-36.6 percentage points, respectively,compared to classical technology.