Project
Response of rice photosynthesis to light transitions under water stress
Under field conditions, light is constantly changing, forcing the leaves of crops to adjust on very quick timescales. This project aims to decipher the controls on the photosynthetic and stomatal response to changing light in rice varieties under water deficit.
Project description
Under field conditions, the light environment available to crops can vary significantly. Fast photosynthetic responses to high light can be driven by quick photosystem responses and electron transport rate, availability of strong sink pull, or by fast stomatal responses allowing rapid CO2 diffusion. These limitations can be affected by plant architecture and leaf anatomy, as that determines the light environment the leaves grow under, as well as the levels of nitrogen and chlorophyll investment, which feedback on the strengths of those limitations.
We have rice varieties that have shown differences in some of these limitations as well architectural and compositional differences. We will grow them under water stress and measure with different oxygen and carbon dioxide levels in order to disentangle the different limitations. We will attempt to measure photosynthetic responses along different canopy depths, and we will compare the findings to whole-plant water use and biomass production to see if there is an affect on higher scale processes.
Objectives and methods
Key questions are:
- Are photosynthesis and stomatal conductance different in their speed of response to increase and decrease of light levels?
- Is this speed of response different under different oxygen (O2) and carbon dioxide (CO2) levels?
- Are these differences underpinned by anatomical factors (stomatal anatomy) or biochemical (photosystem quantum efficiency, carboxylation rate, sink limitation).
- Does plant water status affect what limits photosynthesis during response to changing light?
Key Measurements:
- Light transients with the Li-6800, under high and low CO2 and O2.
- Absorptance and transmittance of leaves will be measured using integrating sphere.
- Leaf morphology and anatomy.
- Plant harvest and yield determination.
Expectations
Student should be willing and capable, after appropriate training, to conduct sampling and data collection by themselves inside the climate room, and able to conduct the measurements using the techniques above.
Required skills
Understanding of some leaf physiology, alongside willingness to work in labs and growth rooms collecting data. Some experience in data analysis will be desirable, but student will get more training throughout.
Types of research/work
Experimental sampling
inside the climate room and then analysis of samples in the wetlab.
Period
June 2024 to November 2024
Location
Unifarm climate controlled chamber