Determinants of Leaf Water Use Efficiency in the C4 Crop Sorghum Bicolor
Global environmental change combined with shortage of arable lands are impacting agricultural systems, adding to further food security concerns caused by rising world population. Hence, the need to propagate crop varieties that can withstand stress without sacrificing yield. Water use efficiency (WUE) is one trait that predicts a crop’s success and viability. It describes the efficiency of water use per carbon gain. Breeding for genetic determinants of WUE is a complex trait that involves the contribution of many processes. At leaf level, WUE is usually measured as the ratio of carbon assimilation, A to transpiration, E. Stomatal conductance to water vapour, gs, can also be a proxy for E. To achieve high WUE, this ratio needs to be maximized. However, excessive decrease in gs ends up limiting A due to reduced CO2 diffusion. In C4 crops, the carbon concentrating mechanism enables achievement of high A at lower gs compared to C3 crops. This presents a further challenge to find traits to maximize WUE in C4 crops. My PhD project aims to identify traits, especially leaf anatomical traits, which lead to higher WUE in Sorghum. I will utilise a variety of sorghum genotypes to find links between anatomical and functional traits that result in higher WUE, and how those traits respond to environmental factors.
A/Professor Oula Ghannoum and Dr Javier Cano Martin