A Physiological Strategy to Raise Wheat Yields to Meet Global Demand in 2050.

Increasing crop production to feed a world population of 10 billion by 2050 is a considerable challenge, especially in light of climate change.  Wheat provides ~20% of total calories consumed by humans worldwide yet the fundamental bottleneck to raising its productivity, namely radiation use efficiency (RUE), has barely changed.   Theory suggests that yield potential could be increased by up to 50% through genetic improvement of RUE. However, to achieve agronomic impacts, structural and reproductive aspects of the crop must be improved in parallel. A wheat yield consortium (WYC) has been convened to develop a complementary portfolio of research activities that will accelerate impacts. Attempts to increase RUE will focus on improving performance and regulation of Rubisco, introduction of C4-like traits such as CO2 concentrating mechanisms, and improvement of light interception and whole canopy photosynthesis. Reproductive aspects of growth must be tailored to a range of agro-ecosystems to ensure that stable expression of a high harvest index is achieved. Adequate partitioning of assimilates among plant organs will also be crucial to ensure that plants with heavier grain weight have strong enough stems and roots to avoid lodging. To achieve simultaneous expression of these traits in elite germplasm within the shortest time-frame possible will require considerable breeding effort, including trait-based strategic crossing, interspecifc hybridization where adequate diversity does not exist within conventional genepools, and genomic selection to complement the crossing of complex but complementary traits by identifying favourable allele combinations among early generations.