What effect does heating the soil have on the rhizosphere and the fungal pathogens?
From the experiment, it is apparent that heating of the soil has extreme effects on the soil properties, as well as the soil microorganisms that make up the rhizosphere. According to Mendes et al. (2011), disease suppressive soils are uniquely constituted to protect the plants from the soil-borne pathogens, a trait mostly attributed to the activities of other microorganisms within the soil. The rhizosphere, therefore, contains a significant composition that enhances balance certain soil temperatures.
The tampering with the temperature or heating of the soil beyond the extreme measures for microorganisms leads to their destruction. Consequently, the deficient rhizosphere is left with little components that can give the soil its soil-suppressive qualities. Hence, the fungal pathogens in these conditions can flourish without resistance to affect the roots of the plants. Generally, the increased heat decreases the rhizosphere’s suppressive abilities and increases the survival chances of the fungal pathogens in the soil. The results can be confirmed from the experiment whereby the heated soil at the highest temperature produced the highest percentage of seedlings with fungal disease.
What conclusion can be drawn about the relationship between the rhizosphere, fungal pathogens, and disease resistant soil? Support your conclusion by referring to the data and graph. Discuss all of the treatment results.
From the experiment, some conclusions can be drawn from the relationship between rhizosphere, fungal pathogens, and the disease-resistant soil. From the pot with the disease suppressive soil, there was recorded the minimum percentage of the seedlings with fungal infections. The trend can highly be attributed to the optimum nature of the microorganism activities within this soil that protects the seedlings from the pathogen attacks. On the contrary, when the disease-suppressive soil was heated to 80 degrees Celsius, the disease resistant qualities diminishes, hence producing the highest percentage of the seedlings with the fungal disease at 70%. When the disease suppressive soil was heated at 50 degrees Celsius, the percentage of the seedlings with the fungal disease reduced by over a half to 31%. From this trend, it can quickly be concluded that that increased heat destroys the resistant properties of the disease suppressive soil.
On the other hand, soil from the margin of the field appears to have little pathogen infection resistance, and for that reason, seedlings planted in these soils produce the second highest percentage of fungal disease, at 62%. Nonetheless, when the soil from the margin of the field was supplemented by a 10% disease suppressive soil, the percentage of the seedlings with fungal disease reduced by almost a half to 39%. The introduction of the disease suppressive soil highly increased the resistant abilities of the soils from the margin of the field, highlighting that some soil properties could be upgraded when mixed with increasing their productivity.
You are interested in continuing the work of Dr. Mendes. What is one additional question that you might logically ask about this issue? Justify the problem that you propose by reasonably describing why this is an important question to ask.
From the experiment, numerous factors could be explored in this area of soil properties and microorganisms. The additional question, therefore, is: how can poor disease resistant soils be improved to enhance pathogen resistance for the seedling? From the experiment by Mendes et al. (2011), it is evident that some soil properties could be improved to become even better in resisting fungal diseases for the plants. For instance, in the soil treatment procedures, when only 10% of the disease resistant soil was mixed with the soil from the margin of the field, the percentage of the seedlings affected by the fungal disease drastically reduced almost by half. For this reason, there is clear evidence that soil properties could be improved through some biological mechanisms to enhance desirable outcomes. According to Almario et al. (2014), the area of soil resistance to the fungal diseases is increasing emerging field within the agro-ecosystems with considerable implications, as these soils play a crucial role protecting plants prone to pathogen-borne infections. Hence, from all angles, this question is relevant for researchers as it could provide valuable answers.
Design and describe how to run an experiment to test the question you proposed
For the enhanced validity of the proposed question, this section provides a clear blueprint through which the testing process could enhance the efficacy of the proposed question above. The procedure involves the outline of the basic experimental fundamentals, including the required equipment, the framework of the experiment process, pinpointing of the independent and dependent variables, control variables and the description of how the variables would be manipulated.
Equipment and Supplies Needed
The experiment would require three jars of soil from the margin of the field, two jars of the disease resistant soil, ten seedlings of sugar beet crops for each jar, fungal pathogen (Rhizoctonia solani), and a greenhouse.
The Basic Protocol to Follow
The experiment process would involve getting arranging jars in systematic order, jar A and B containing soil from the margin of the field, and jar C and D holding disease suppressive soil. The contents of Jar A and Jar C would be mixed in equal ratio 1:1 (treatment pot A), and the materials of jar B would be added a 70% content from jar D (treatment pot B). The third jar (jar E) of the pure soil from the margin of the field would represent the treatment pot C. Seedlings would be placed in each treatment pot, under 18 degrees Celsius, and same 12-hour day and night cycle for 25 days in the greenhouse. Each treatment pot would be inoculated with the Rhizoctonia solani fungal pathogen to determine the effects on the type of the soil mixtures. The goal is to determine the number of pathogen-infected seedlings in each treatment port, as per the soil mixture.
Independent and Dependent Variables
The independent variable for this experiment would be the amount of disease-resistant soil because of its uniform applicability across the test, and with which the results of the analysis will depend on to arrive on the conclusive findings.
The dependent variable is the soil from the margin of the field, because, to determine its increased efficiency and protectiveness for the seedlings against the pathogens, will be determined by the amount of mixture from the diseases resistant soils.
The Control Variable
The control variable, in this case, is the pathogen Rhizoctonia solani which would be inoculated on the treatments in equal measure and standards, to remain constant across the whole experiment.
How and Why to Manipulate the variables
From the experiment, the goal is to determine how to improve the less resistant soil to pathogens, and this means that the soil from the margin of field is less resilient and dependent on the other ways to improve. Therefore, the introduction of the disease suppressive soils is (an independent variable) can be used to mitigate the shortcomings. For the studies, increasing the amount of the suppressive soils (independent variable) would consequently lead in the improved qualities of the soil from the margin of field (dependent variable). The pathogen Rhizoctonia solani (control variable) would be applied equally across the ports, and the results on the seedlings would be determined by the amount of mixture between the independent and dependent variables.
References
Almario, J., Muller, D., Défago, G., & Moënne-Loccoz, Y. (2014). Rhizosphere ecology and phytoprotection in soils naturally suppressive to Thielaviopsis black root rot of tobacco. Environmental Microbiology, 1949-60.
Mendes, R., Kruijt, M., de Bruijn, I., Dekkers, E., van der Voort, M., JH, S., . . . JM., R. (2011). Deciphering the rhizosphere microbiome for disease-suppressive bacteria. Nature Reviews Microbiology, 1097-100.