Submitted to: Australian Journal of Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/8/2010
Publication Date: 7/1/2010
Citation: Jaradat, A.A. 2010. Genetic Resources of Energy Crops: Biological Systems to Combat Climate Change. Australian Journal of Crop Science. 4(5):309-323. Interpretive Summary: Bioenergy crops are expected to help offset greenhouse gas emissions and contribute positively to global climate change adaptation and mitigation efforts; however, quantifying that offset is complex and contentious. A combination of larger yields and more efficient processing methods are needed to maximize the environmental benefits of bioenergy crops. Positive impacts on ecosystem services will be more important when dedicated bioenergy crops are deployed at a large scale in the landscape. To maximize greenhouse gas emission reduction, one should (1) grow biomass crops that have minimal processing requirements on sites with high growth rates while minimizing external inputs such as fertilizers and pesticides, (2) use an efficient energy conversion system, and (3) increase efficiency of biomass through multiple uses. As bioenergy crops are developed further, new genetic resources need to be evaluated for their potential prior to being released; the crops that would eventually serve as sources of biofuels will likely be highly genetically-modified from existing bioenergy crop species. Therefore, there is a need to develop validation tools to assess the environmental impacts of the newly-developed bioenergy crops in various locations under a range of conditions. There is significant potential for improvement in combating climate change through genetic optimization and research on cultural practices, harvesting, storage and transport of would-be bioenergy crops. Genomic and agronomic strategies are needed to maximize biomass yield and to improve quality of bioenergy crops. Genetic modifications are needed to help simplify and streamline industrial processes to breakdown cellulose, hemicellulose, and lignin. Life cycle analysis will help validate bioenergy as a means of reducing greenhouse gas emissions through a comprehensive understanding of direct and indirect impacts and interactions of several factors, including land use and land use change, water management, water pollution, air quality, and biodiversity. Information generated by life cycle analysis will benefit geneticists, agronomists, entrepreneurs, and farmers by ensuring that future bioenergy crops have a positive and sustainable impact on global climate change adaptation and mitigation efforts.
Technical Abstract: Biological systems are expected to contribute to renewable energy production, help stabilize rising levels of green house gases (GHG), and mitigate the risk of global climate change (GCC). Bioenergy crop plants that function as solar energy collectors and thermo-chemical energy storage systems are the basis for such biological systems. There will be always a need to deploy new high-yielding bioenergy crops that can be grown in cropping systems with significantly improved phenotypic, architectural, physiological and biochemical characteristics in order to sustainably produce bioenergy and help combat GCC. Wide genetic resource bases, especially of wild and semi-domesticated perennial grasses and woody species of starch-, oil-, and lingocellulose-producing plants, are available to select, breed, genetically-modify, and develop environmentally-friendly bioenergy crops. Plant species with fast growth, tolerance to biotic and abiotic stresses, and low requirements for biological, chemical or physical pretreatments are being increasingly evaluated as potential bioenergy crops. However, using biological systems to store carbon (C) and reduce GHG emissions is a potential mitigation approach for which equity considerations are complex and contentious. Currently, bioenergy systems based on traditional sources and first generation bioenergy crops are not sustainable and their exploitation may contribute to environmental degradation. New genetic resources and technological breakthroughs are being employed to develop dedicated bioenergy crops (DECs) with better GHG profiles and with a suite of eco-physiological traits to maximize radiation interception, water and nutrient-use efficiencies, to improve lingocellulosic accessibility to enzymatic degradation, and to confer environmental sustainability. However, large-scale bioenergy crop plantations pose both opportunities and challenges, and will inevitably compete with food crops for land, water, nutrient resources and other inputs. The biodiversity consequences of increased biofuel production will most likely result in habitat loss, increased and enhanced dispersion of invasive species, and pollution resulting from chemical inputs. Recent genetic modifications and breeding efforts of bioenergy crops aim at improving biomass yield, quality, and conversion efficiency. Improvements in composition and structure of bio-chemicals in bioenergy crops will enable the production of more energy per ton of biomass and will improve its caloric value, GHG profile, and GCC mitigation potential.