Monitoring leaf physiology in response to drought stress in intact plants

Physio-chemical processes in plants are very sensitive to water-status. Slight reductions in leaf water content, for instance, can inhibit CO2 uptake and growth. Farmers lack easy-to-use and reliable sensors for plant water-status. It is known that the reflectance of light at specific wavelengths can provide information about the micro-structure and water content of the leaf in non-invasively. For example, reflectance at a wavelength of 940 nm is highly sensitive to both water-content and structural changes in the leaf-mesophyll tissue, while at 1550 nm it is predominantly sensitive to water-content.  For developing compact and easy-to-use sensors in the field, we seek time-resolved data to establish a link between changes in leaf micro-structure and in leaf optical reflectance. The project thus involves detailed botanical measurements to support the optical reflectance measurements led by Satadal Dutta. This work is linked to the “Plantenna” project (https://www.4tu.nl/plantenna/en/), a 4TU collaboration funded by NWO, where you can work in a multidisciplinary team involving researchers on plant ecophysiology (WUR-HPP) and dynamics of micro/nano systems (TU Delft).

This is a follow-up to a previous M.Sc. thesis project at HPP, which showed that changes in leaf light reflectance correlated well with changes in transpiration rate and leaf weight in detached tomato leaves. For greater reliability, we would like the M.Sc. student to repeat a set of these measurements. Also, we would like to know whether the same sensor measures changes in intact, water-stressed plants, preferably of several species. This will be mostly experimental (lab work). Activities include (a) use of a custom-built LED system to measure reflectance at 940 nm, (b) gas exchange to monitor transpiration rate, stomatal conductance and photosynthesis, and (c) weight-loss monitoring. Optional activities subject to the student’s interest include measuring light reflectance in the field and/or conducting part of the experiments in a climate chamber or greenhouse. While the student is expected to work towards a valuable MSc thesis, the results will have a strong contribution to publications in reputed conferences/journals.


    References

    H.W. Gausman et al., Appl. Optics, vol. 9, no. 3, pp. 545-552 (1970).

    S. Torre et al., J. Amer. Soc. Hort. Sci. 128(4), pp. 598-602 (2003).


    Interested in doing a BSc or MSc thesis at HPP? Please contact the HPP student coordinator Katharina Hanika.