Environmental Engineering Reference
In-Depth Information
16
Maize
Shoba Sivasankar, Sarah Collinson,
Rajeev Gupta, and Kanwarpal S. Dhugga
Pioneer Hi-Bred International, Inc.
contents
16.1 Introduction ........................................................................................................................ 405
16.2 Maize Breeding and Production .........................................................................................406
16.2.1 Global Production of Maize and Other Cereals ...................................................406
16.2.2 Origin and Evolution ............................................................................................407
16.2.3 Maize Breeding over the Past Century .................................................................408
16.2.4 Biomass Production and Harvest Index ............................................................... 411
16.2.5 Stover Removal and Soil Organic Matter ............................................................. 412
16.3 Biomass Structure and Composition .................................................................................. 412
16.4 Cell Wall Biosynthesis ........................................................................................................ 412
16.4.1 Cellulose Synthesis ............................................................................................... 413
16.4.2 Hemicellulose Synthesis ....................................................................................... 414
16.4.3 Lignin Synthesis ................................................................................................... 416
16.5 Cell Wall Cross-linking and Mechanical Strength ............................................................. 417
16.6 Bioenergetic Considerations for Biomass Interconversion ................................................ 418
16.6.1 Mutants Relevant to Bioenergy ............................................................................ 420
16.6.2 Bioenergy and Agronomic Traits ......................................................................... 421
16.7 Systems Approach in Improving Maize Bioproductivity ................................................... 421
16.8 Biotechnological Opportunities, Outcomes, and Future Prospects .................................... 422
16.9 Conclusions ......................................................................................................................... 426
References ...................................................................................................................................... 426
16.1 IntroductIon
Fossil fuels have finite reserves. For example, oil has been projected to have already reached its peak
capacity for production and may run out over the next several decades even at the current pace of
use, i.e., not accounting for increased demand from China and India as their respective economies
expand (Dhugga 2007). These concerns have intensified the debate on the potential of renewable
fuels as supplements to fossil fuels. Biofuels, a collective term used to describe fuels derived from
biological sources, offer a partial solution to the energy demand along with solar, wind, geothermal,
and hydroelectric power.
Commercial production of ethanol from the maize grain is a growing industry with upward of
50 GL of ethanol already produced in the United States annually. However, a competing demand
for the grain from the food and feed industries makes it less likely a source for renewable energy for
the long term. This concern is somewhat mitigated if stover, the proportion of which in the plant is
approximately equal to grain, can be utilized to produce energy.
405
