Methods in Plant Ecophysiology

This course aims at strengthening and deepening the knowledge and skills of students on measuring methods and protocols in the plant sciences. It is specifically intended for students who aim to do a M.Sc. thesis in plant-environment research, with a focus on climate-controlled environments. This course is obligatory for students that plan to do their M.Sc. thesis in the pre-harvest track of the chair group Horticulture and Product Physiology (HPP; course is not required for post-harvest theses). Other students that are attracted to experimenting with plant-environment interactions and plant phenotyping are welcome as well. The course contains lectures, hands-on practicals, tutorials, and group assignments. There is ample teacher-student interaction during practicals, class-room assignments and discussions, and active preparation and participation of students is required.

During lectures and tutorials, special attention will be given to the factors light (duration, periodicity, intensity and spectrum; characteristics of natural and of artificial light (e.g. by LEDs)) and the effects of extreme climates that might occur in protected growth environments (e.g. high/low temperature, shade, high light, high CO2 concentration, high air humidity, 24h light). Measuring and characterizing light and other climate and plant variables will be discussed in detail, as well as photosynthesis, chlorophyll fluorescence, transpiration, water relations and other physiological processes that are relevant for plant production. Focus will be put on acquiring information about plant and crop behavior by measuring and analysing physical and physiological processes that are decisive for plant growth and performance in environments with a high degree of controllability (e.g. greenhouses, plant factories, growth environments for research).

The lab practical consists of a “carousel” of 5 experiments. Students in small groups practice with key measuring methods: by gathering, processing, analyzing and managing data per experiment. Experiments encompass several advanced measuring techniques, including photosynthetic gas exchange on leaves, chlorophyll imaging on leaves, spectral radiation measurements, biochemical analysis of chlorophyll content and morphological characterization of plants. Experiments will be conducted on a set of tomato plants that have been grown under several conditions. Each group will perform all experiments, during weeks 1-3 of the course. A large dataset of variables will be acquired through collaboration between all groups, and can be analyzed in greater detail after all groups have finished the practical.

Data generated by students during the practicals will be used for small scientific projects, resulting in one scientific poster per group that will be presented at the end of the course.

After successful completion of this course students are expected to be able to:

• Execute, analyze and critically evaluate dose response curves of net photosynthesis rate to light intensity and CO2 concentration. Explain the meaning of derived parameters of both types of curve
• Execute, analyze and critically evaluate measurements of chlorophyll fluorescence and derived parameters
• Measure, analyze and critically evaluate light intensity and spectrum in a plant production environment. Calculate and explain the meaning of key parameters derived from light measurements
• Measure common parameters of plant morphology and pigmentation, including biomass, specific leaf area, chlorophyll concentrations and stomatal density
• Name and describe the functions of key equipment and its essential components used in the course
• Document and store data correctly, such that it can be re-used by others. Evaluate and analyze data produced by others
• Formulate research questions and hypotheses that can be answered using data collected in the course. Construct, present and discuss results in a scientific poster

Assumed Knowledge:
MPS students:

• students that completed the BPW-program at Wageningen University: HPP22803 Concepts in Environmental Plant Physiology; HPP20306 Physiology and Development of Plants in Horticulture and Crops Plants Environment and HPP23806 Crops, Physiology and Environment;

• students that completed a BSc or MSc program before enrolling in MPS:Basic physiological knowledge on photosynthesis, plant-environment interactions (effects of light intensity and colour, temperature and humidity on plant growth and acclimation), and plant/crop water relations;

Other students:

• contact the course coordinator before enrolling to check whether your pre-knowledge is sufficient for attending this course;

In addition to the biological, physical and chemical concepts introduced in the above-mentioned plant physiology courses, students should have basic knowledge of (physical) chemistry, physics and mathematics. In particular, students will be expected to be familiar with the following concepts:
(1) Quantitative thinking and reasoning;
(2) Basic algebra, including working with more complex equations including logs and exponentials, and the use of symbols to represent factors and variables;
(3) The uses and significance of scientific units (moles, meters, kilograms, Pascals etc), and familiarity with the basic physics of light (spectra, photons and energy, wavelength, absorption), the gas law (PV = nRT), absolute temperature, the conservation of energy, Ohm's law and Fick's law and the relationship between conductance and resistance, the concept of change in physical systems, flow or flux. Students should have a basic understanding of electrons in atoms (an elementary understanding of quantization and energy levels);
(4) Concerning chemistry/physical chemistry, students should be familiar with chemical formulae and terminology, the basics of oxidation and reduction, chemical kinetics and rate constants, and simple physical-chemical concepts such as pH, heat capacity, vapour pressure and humidity, concentration etc.

It is also assumed that students taking this course will have basic statistical knowledge, the most important of which are: t-test (independent samples or pairwise), F-test (Analysis of Variance), linear regression, experimental design (blocking). In Wageningen, these topics are covered in Statistics 1+2 and Advanced Statistics courses.

Assumed Writing and Reporting Skills: Students are expected to be able to write well in English in terms of grammar, syntax structured reasoning and argument. They should be able to write using normal scientific vocabulary and phrasing, and scientific units, species names, the names of chemicals etc should all be written according to the normal rules for scientific writing. To illustrate their work and effectively present their data they should be able to make graphs and tables (including captions) of a standard comparable to that encountered in normal scientific writing (e.g. a scientific paper). Students should also be able to include literature references in their text in a normal and consistent way.