High-biomass C4 grasses-Filling the yield gap.

A significant increase in agricultural productivity will be required by 2050 to meet the needs of an expanding and rapidly developing world population, without allocating more land and water resources to agriculture, and despite slowing rates of grain yield improvement. This review examines the proposition that high-biomass C4 grasses could help fill the yield gap. High-biomass C4 grasses exhibit high yield due to C4 photosynthesis, long growth duration, and efficient capture and utilization of light, water, and nutrients. These C4 grasses exhibit high levels of drought tolerance during their long vegetative growth phase ideal for crops grown in water-limited regions of agricultural production. The stems of some high-biomass C4 grasses can accumulate high levels of non-structural carbohydrates that could be engineered to enhance biomass yield and utility as feedstocks for animals and biofuels production. The regulatory pathway that delays flowering of high-biomass C4 grasses in long days has been elucidated enabling production and deployment of hybrids. Crop and landscape-scale modeling predict that utilization of high-biomass C4 grass crops on land and in regions where water resources limit grain crop yield could increase agricultural productivity.