Introduction
An essential part of agricultural science is the study of the microbial diversity of soil samples near the growth zone of cultivated plants. Three plant lines, Pepper, Blueberry, and Turf, grown in different locations, were used in the present study. A time-difference longitudinal analysis assessed how much the soil temperature affected the representation of bacteria and fungi on the soil samples. Thus, a vital goal of the present laboratory experiment was to determine general patterns of the relationship between soil temperature and bacterial and fungal abundance in samples for different plants.
Methodology
Sample Preparation
Three agricultural plant lines were used for analysis, including Pepper, Blueberry, and Dern. Soil samples from the active growth zone of each plant were collected in a unique agrocenosis location for which different growing conditions were used. Differences in agricultural production techniques, including soil textures, temperatures, and ecosystem biodiversity, were crucial to creating a diverse sample. Thus, analytical work was performed on three soil samples for different plants grown under individual crop conditions.
Experiment Setting
The design of the laboratory work included three consecutive tests with a difference in study time when ambient temperatures were unequal. The first was conducted on the last dates of September (28.9°C), the second test was conducted in early November (22.8°C), and the third two weeks later, in mid-November (15.6) 2021. Soil samples were isolated from different locations, with radical changes in soil texture. For Blueberry, it was clay soil; for Pepper, it was loam; and for Turf, it was sandy soil.
Procedure
Initially, it was necessary to dissolve the crop samples in sterile phosphate buffer. To do this, 10 g of each sample was placed in individual bottles containing 90 g of a buffer. After vigorous stirring, each of the bottles was left to stand. Microbial content studies were conducted using a 24-multiwell plate (Corning, 2018). 0.9 mL of phosphate buffer was placed in the first five wells, followed by the addition of 0.1 mL of previously prepared solutions with a dilution factor of 10-1. Subsequently, solutions with a dilution factor of 10-3 and 10-4 were obtained using this procedure. Thus, four experimental lines were obtained for each analyzed species: in total, twelve observations.
Twenty-four carefully labeled Petri plates were used to analyze the presence of fungal and bacterial microorganisms, twelve for each species. Bacterial microorganisms were incubated on nutrient agar, and RBG was used for fungi (HIMEDIA, 2019). 0.1 mL of each dilution obtained previously was transferred to a labeled Petri plate. A “hockey stick” sterilized on an alcohol burner was used to distribute the substance evenly. All transferred samples were placed in the dark for incubation at 30°C. Bacterial samples were removed from the incubator and transferred to counting after 24 hours and fungal samples after 96 hours.
Results
Because the soil samples were collected at different times, it was necessary to make quantitative longitudinal measurements of bacterial and fungal microorganisms. The use of four dilution lines was necessary to determine the maximum number of microorganisms. This value was counted by ECCT microscopic observation of the samples, after which specific quantities were calculated using formula (1) (Introduction to the enumeration of bacteria, 2021). Equation (1) shows an example of a calculation for the first September test to determine the number of bacteria in pepper soil. It is noteworthy that the maximum number of bacteria differed depending on the degree of dilution for fungi and bacteria. Thus, bacteria were counted at 10-3 and 10-4 dilution factors and fungi at 10-2 and 10-1. The numerical results of each such measurement were entered into the summary Table 1.
Table 1. Results of quantitative microbial presence measurements for each of the crops at different dates (all data are presented in CFU/g).
Discussion
The focus of the present experiment was to determine the effects of temperature on the presence of bacterial and fungal microorganisms in soil samples. Fungal and bacterial samples were incubated at the same temperature for different times: fungi took four times longer to grow effectively. The results from Table 1 were statistically processed to determine key trends. Figure 1 shows the dynamics of fungal microbial abundance as a function of temperature for the different agricultural samples. It is noticeable that microbial abundance was generally higher in Pepper, with the maximum fungal presence occurring in early November when the soil cooled somewhat. No increase in fungi was observed for turf in mid-November.
Figure 2 reflects similar trends: the number of microorganisms near Pepper was the highest. At the same time, the maximum representation was characteristic of the beginning of fall, and as the temperature of the environment decreased, the number of bacteria also decreased. One can also see that bacterial representation near Turf was minimal, different from the data shown in Figure 1. In addition, the number of bacteria in Blueberry was lower than in Turf only when the soil was cooled to the maximum. In addition, bacterial growth over the whole time was on average 70.6 times higher than fungal growth.
Conclusion
The study of microbial representation in soil samples of agricultural plants is of value to agricultural sciences because it covers problems related to environmental safety. The present work showed that the abundance of bacteria and fungi on the incubation isolates for Pepper, Blueberry, and Turf were different for three months. The critical differences concerned the dynamics of microbial representation as a function of time and the different numbers of microorganisms in different plants. A general conclusion can be drawn from all of the facts presented above that answer the research question. Microbial representation on crops is a function of soil temperature, but no universal rule for this relationship has been determined.
References
Corning. (2018). Surface areas and guide for recommended medium volumes for Corning® cell culture vessels [PDF document].
HIMEDIA. (2019). Rose Bengal chloramphenicol agar [PDF document]. Web.
Introduction to enumeration of bacteria. (2021). The LibreTexts.