Dusenge Projects

Project offering: Honours

Project title: Testing heat tolerance of leaf carbon exchange among Corteva ERA hybrids of Maize

Background: Ongoing global warming is associated with increased intensity and frequency of heatwaves, which pose a significant threat to many staple food crops and the agriculture sector globally. Heat stress reduces uptake of atmospheric CO₂ by photosynthesis (A) while also increasing carbon loss by dark respiration (R_dark). As a result, heat-stressed plants often exhibit reduced net carbon gain, biomass accumulation and grain development. To develop novel heat-tolerant maize germplasm, the heat sensitivity of A and R_dark – as well as the ability of these processes to adjust (acclimate) to sustained heat – needs to be screened in current Corteva ERA hybrids of maize.

Project Aims:
Aim 1: To assess the variation in key temperature thresholds related to photosynthesis - specifically T_crit, T_optA, and T_maxA (T_maxA being the highest temperature at which net CO₂ assimilation is zero) - as well as the variation in acclimation capacity of these physiological traits to warming among 15 Corteva ERA hybrids developed between 1926 - 2019.

Aim 2: To investigate heat tolerance and thermal adjustment in respiration in maize ERA hybrids, by measuring rates of R_dark across a range of moderate to high temperatures and identifying the temperature at which R_dark rates are maximal (T_maxR).

Techniques: During this project, the student will learn advanced techniques commonly used in the field of plant eco-physiology. These techniques use advanced gas exchange systems to study photosynthesis and leaf respiration. The student will also learn different chlorophyll fluorescence techniques commonly used to study heat tolerance of the Photosystem II (PSII).