Several hormones are involved in the biochemical and physiological responses that determine plant architecture characteristics highly correlated with biomass yield such as plant height, leaf angle, stem diameter, tillering, number of florets, etc. Brassinosteroids, gibberellins and auxins have the strongest impact without severe undesirable pleiotropic effects.
Carbon assimilation through photosynthesis is the basis of crop productivity. However, increases in crop yield achieved in the last 50 years have not been attributed to changes in photosynthetic capacity. The complex genetic architecture of C assimilation and the lack of correlation between grain yield and photosynthesis were the most important arguments to postpone significant investments in this scientific area.
Biofuels are a major contributor to the energy security of the United States, to the economic growth of Iowa and to the reduction of greenhouse gasses emission. The Energy Independence and Security Act (2007) established that 36 billion gallons of biofuels per year had to be produced by 2022. In 2018, 16 billion gallons of ethanol were produced from maize, but maize-based ethanol cannot supply the total demand and it has detrimental implications for food and feed supplies. Therefore, other sources, such as lignocellulosic feedstock, need to be developed.