Project goals and considerations
The goal of this project was to introduce general principles of field plot design and execution through a participatory group research project. There were several logistical constraints to consider in designing an activity that would meet this goal, which are summarized in Table 1. The program would be targeted to students with no prior research experience, so all activities needed to be suitable for novices to perform. Second, the program would host ten participants per year, so we sought to design activities that would allow each student to participate while working as part of a team. The program would be nine weeks long and primarily focused on mentored research, so we needed to design a low-maintenance experiment that could be completed in that time frame and in a limited number of student meetings. Although the fellows received farm safety training, we aimed to minimize risks to student safety through design of a project that did not require heavy machinery or in-field chemical application. Finally, to maximize student investment and synergy with our own expertise, we wanted to develop a project that addressed a real research question with the potential to present and publish the data.
Ideal traits to aim for||
|1. Is it
- Can be set up manually
- Avoids use of hazardous chemicals or regulated pathogens
|Trials of many cultural, genetic, or biological control methods can be performed without heavy machinery or pesticide exposure. |
|2. Is it simple?|
- Limited experiment size
- Single treatment at setup
- Completed in 9 weeks (June-July)
- Low-maintenance crop system
- Simple rating methods
|Applying a pathogen that causes early, visible foliar symptoms will enable students to rate or measure disease before the end of July. |
|3. Is it
- Potential for translation to disease management
- Potential for publication
|Choosing a novel research question that could benefit growers can help engage students. |
Ultimately, we chose a question that stemmed from an existing project on the role of metallic oxide nanoparticles in control of plant pathogens. This was a management approach for which we had previously observed disease control using several treatment formulations in a range of pathogen-host systems including
Fusarium (Elmer and White, 2016; Elmer et al 2018). For the group field project, we designed an experiment that evaluated nanoparticles of CuO, MnO and ZnO for control of Fusarium wilt of chrysanthemum caused by
Fusarium oxysporum f. sp.
chrysanthemi. This research question would be well-suited for adaptation to a student-conducted field plot. In our experience, nanoparticle treatments can be effective after a single application on seedlings or cuttings in the greenhouse, avoiding the need for further control measures or pesticide application. Chrysanthemum wilt causes visible symptoms as well as growth reduction within a short time, and novice researchers could be quickly trained to rate and measure experimental plants. Lastly, chrysanthemum wilt is an economically important disease with limited control options (Trollinger
et al 2018), and the effects of nanoparticle treatments are unknown, so the exercise would address a novel and relevant research question. The experiment was conducted in four 90-minute activities; these are summarized briefly below and in detail in an
accompanying laboratory activity article.
Summary of Group Field Project Student Activities
We designed the project to be completed in four activities, in addition to some intermittent plot maintenance that may be assisted by students. These are briefly summarized below and in Table 2. Detailed lesson plans and learning objectives are given in the accompanying Activity Guide.
Plot Design and Planning
- Explain the problem or disease
- Formulate hypotheses and null hypotheses
- Design treatments and controls
- Identify variables and nuisance factors
- Choose assessment methods
- Generate a randomized complete block design
Activity 2: Field Plot Setup
- Prepare inoculum
- Plant and inoculate seedlings
- Follow a block design plan
Activity 3: Data Collection
- Visually rate disease on a scale
- Measure plant height
- Enter data in a table
Activity 4: Data analysis
- Generate summary statistics in Excel
- Perform T-tests and ANOVA in Excel
- Apply statistical test results to determine which null hypotheses can be rejected
- Generate bar graphs, dot plots and boxplots online
- Compare and contrast data visualization methods
Activity 5: General Audience Presentation
- At a plot display at a public field demonstration event, explain the study's hypothesis, methods, and conclusions to visitors from various backgrounds
Figure 1. The experimental design activity is held in a conference room setting.
In the first activity, conducted in the first week of the program, students gathered in an informal conference room setting to plan a basic field plot experiment (Figure 1). The experimental design activity was conducted as an interactive classroom exploratory exercise which 1) introduced the concepts necessary to design a plant disease field study, and 2) allowed the students to think creatively and contribute ideas. Program leaders introduced the plant disease problem to be addressed, then guided the students through small group discussions and individual exercises to practice hypothesis formulation, planning appropriate treatments and controls, performing randomized block design, and planning disease assessment and data collection methods. Targeted learning outcomes were that students would be able to formulate several hypotheses and null hypotheses related to a scientific question, identify the dependent and independent variables of an experiment, identify potential nuisance factors and how to control for them, and generate a randomized complete block design. With a small group, instructors were able to gauge student comprehension of these concepts by requiring students to design and explain the rationale behind alternative experiments, and ensure that the students were able to do so by the end. Specific discussion topics are listed in the accompanying Lesson Plan article. As the field study would be carried out over three or more field seasons, it was not possible for each cohort to execute different experimental designs in the field. However, we found that the student-suggested plans were generally close to the pre-planned plot design, and most of the students showed interest and investment in the research question during the activity. In addition, the activity resulted in a student-generated randomized plot design and a plan for division of labor the following week.
Figure 2. At the plot setup day, students work in teams to mix inoculum into potting media (top L), plant and label pretreated cuttings (top R), set up irrigation lines (bottom L), and set up the final field design (bottom R).
The plot setup activity was held the second week of the program at the Experiment Station farm (Figure 2). The students worked in teams to inoculate potting media with
Fusarium inoculum or heat-killed inoculum, plant and label 300 nanoparticle-treated chrysanthemum seedlings in 100 pots (3 plants/pot), and place the pots in the field according to the randomized plot design generated in the first activity. Students also worked together to install irrigation stakes. By the end of the activity, students had demonstrated the ability to divide tasks and work as a team, perform soil inoculation and planting, avoid treatment cross-contamination, and follow a plot design. This activity was completed in 90 minutes, but required several hours of materials preparation and transport by program leaders.
Although the experiment was designed to be low-maintenance, the plot still required some supervision to check for dryness or insect issues. An insecticide application was performed by farm staff each year, and irrigation adjustments were required during the hottest parts of the summer in all three years. In years 1 and 2, rotating teams of three students measured plant height and photosynthetic capacity on a weekly basis. However, weekly measurements did not yield informative results beyond what was observed in the final data collection, and were not continued in year 3. Plot supervision, management, and supervision of weekly measurements were coordinated by a program leader with the help of their designated mentee, a student from the program chosen for strong leadership qualities.
The third activity was conducted seven weeks after plot setup, in the final weeks of the program (Figure 3). Students worked in partner groups to independently rate disease symptoms on a five-point scale, and to measure plant height. Through this activity, students demonstrated the ability to follow a disease rating scale and to enter data in a table.
Figure 3. In the data collection activity, students form teams to take height measurements of visual ratings of the plants (L). In some years, students also measured stomatal conductance and photosynthetic measurements using portable tools (R).
The data analysis activity was conducted in a university computer lab a few days after students collected the data. Program leaders had entered and formatted the data in the interim. Guided by instructor demonstration and an instructional handout, students completed individual exercises performing and interpreting basic summary statistics, T-tests, and two-way ANOVA in Excel, and graphed dot plots and box-and-whisker plots in an online program. To assess comprehension, we asked students to independently repeat these analyses on data subsets of their choice, and share with the group whether any null hypotheses could be rejected based on the output. At the end of the activity, the group would discuss what conclusions could be drawn from the experiment, and what future research questions were raised.
Although disease could be rated effectively on the chrysanthemums after seven weeks, it is still much earlier than typical chrysanthemum harvest. Irrigation was continued for an additional six weeks after the program end, when we took the experiment down and measured dry weights.
A central goal of REU and REEU programs is to prepare students to explain their science to the general public. As part of the Plant Health Fellows program, we helped the students practice different types of informal science communication through one of the program's weekly enrichment workshop. This activity helped students prepare to engage with visitors to Plant Science Day, an annual public demonstration day held at the Connecticut Agricultural Experiment Station research farm. Each year of the program, students took shifts presenting a table display next to the chrysanthemum experimental plot. Students explained the goals and findings of the field experiment to Plant Science Day visitors, and answered their questions. The table was visited by 50 or more attendees each year, including backyard gardeners, children, growers, and commercial nursery professionals. Program leaders observed the students answering a wide range of questions.
Assessment of learning outcomes
As discussed in summary of activities, formative assessment of student learning was conducted through frequent questioning during these activities, aimed at improving the following:
- were students interested and engaged,
- could they explain and apply major concepts, and
- could they demonstrate independence in the targeted skills?
Although most of our participants did not have prior training in experimental design or analysis, we observed that the strong majority of the students appeared to pick up the concepts quickly and become engaged in the project, and students with prior experience helped less-experienced students. This is likely to be true for any internship with a competitive application process, which tends to select for internally motivated students with a prior interest in agricultural studies. In the year in which students did not conduct weekly data collections, we observed that students did not clearly remember the project goals at the seven-week data collection, and this could be remedied through additional review during other summer activities.
We also conducted summative assessments through anonymized final surveys. Interns were asked to evaluate whether their understanding of experimental design had improved as a result of the experiment. Specifically, students were asked to rate, on a scale of not helpful (0) to extremely helpful to their understanding (5), the chrysanthemum experiment as a whole (average rating was 4.1 out of 5) as well as rate each of the following components: experimental design activity (4.5), field plot setup (4.4), data collection (3.9), data analysis activity (4.3), and presenting to the public at Plant Science Day (average 4.0 out of 5). Together, our observations and the survey results suggest that students found the field plot activity to be helpful. The plot activity may have also affected responses to other survey questions about the program in general. Students were asked to rank their understanding of plant health research before beginning the program (average 2.4 out of 5) and after completing the program (average 3.9 out of 5). Similarly, interns gave their “awareness of agricultural careers" an average rating of 1.7 out of 5 prior to the program, and 3.5 after the program.
Conclusions and general recommendations
This report describes a general strategy we employed to expose an increased number of students to major aspects of field plot experimentation within a limited amount of time. Although this activity required a significant amount of preparation and planning in the first year, we found it was not substantially more difficult than the planning of four laboratory sessions, especially when designed to complement an existing research program. In addition to indications that the project was helpful to students, it also served as an important team-building and bonding activity for the group, and provided them something of their own to display at Plant Science Day. Although additional seasons of data are needed, the students observed some treatment significant effects on disease protection and plant growth that were consistent in two of three growing seasons, so the data generated in the study may be publishable in an applied plant health journal.
Incorporation of agricultural field research into more internship programs could enhance the student learning, career awareness, and workforce readiness of the participants. The strategy we used can be readily modified and implemented by other REEUs (Table 1). A key requirement is that a mentor or team of mentors (PIs, postdocs, or graduate students) are willing to prepare the materials and guide the students. Selecting a low-management crop system and a pathogen that develops visible symptoms in a short timeframe is strongly recommended. The project should ideally incorporate low-risk experimental treatments, such as a cultural management practice or organic amendment, and involve evaluation methods that do not require extensive and time-consuming training of the student researchers. Finally, consistent interaction and feedback between students and mentors is needed to ensure that students are engaged in the learning process, rather than simply following instructions. By providing experience in designing field plots, collecting data, analyzing the data, and presenting findings, we hope to help our students enter their careers with a sense of confidence that can stem from experiential learning.
These assessment values are based on two years of program surveys in which these questions were posed, representing 20 participants.