The amount of biomass available is limited because plants, on average, capture only about 0.1% of the solar energy reaching the Earth (Pimentel and Pimentel 1996). Temperature, water availability, soil nutrients, and the feeding pressure of herbi­vores all limit biomass production in any given region. Under optimal growing con­ditions, natural and agricultural vegetation produce about 12 million kcal/ha/year (approx. 3 t/ha dry biomass). The productive ecosystems in the world total an es­timated 50 billion ha, excluding the icecaps. Marine ecosystems occupy approx. 36.5 billion ha, while the terrestrial ecosystems occupy approx. 13.5 billion ha.

Sustainable production of biomass will limit supply. The total biomass produced is approx. 77 billion t or approx. 12.6 t/person/year (Pimentel 2001). Globally, suit­able abandoned cropland and pastureland amounts to approx. 1.5 million square miles. Realistically, energy crops raised on this land could be expected to yield about 27 exajoules (EJ) of energy each year (1EJ = 1018 J). This is a huge amount of energy, equivalent to 172 million barrels of oil. In 2003 the EU biomass pro­duction was about 69 Mtoe, covering about 4% of EU energy needs; the production potential is estimated to increase to 186 to 189Mtoe in 2010, to 215 to 239Mtoe in 2020, and up to 243 to 316 Mtoe in 2030 (EEA 2005). One analysis carried out by the UN Conference on Environment and Development (UNCED) estimates that biomass could potentially supply about half of the present world primary energy consumption by the year 2050 (Ramage and Scurlock 1996).

Global biomass production on the Earth’s land surface is equal to 4,560 EJ (the gross primary production), of which half is lost by autotrophic respiration and de­composition, leaving 2,280 EJ (net primary production or NPP) (Smeets et al. 2007). The availability of the NPP for use in food and energy production is restricted by many factors, e. g., logistics, economics, or legal restraints. Without intervention this NPP is in balance with natural decomposition. There are three types of biomass energy sources: dedicated bioenergy crops, agricultural and forestry residues and waste, and forest growth. The bioenergy potential in a region is limited by vari­ous factors, such as the demand for food, industrial round wood, traditional wood fuel, and the need to maintain existing forests for the protection of biodiversity. The global potential of bioenergy production from agricultural and forestry residues and wastes was calculated to be 76 to 96EJ/year by the year 2050. The potential of bioenergy production from surplus forest growth was calculated to be 74 EJ/yr by 2050 (Smeets et al. 2007).

Biomass resources can be divided into six categories: energy crops on surplus cropland, energy crops on degraded land, agricultural residues, forest residues, an­imal manure, and organic wastes. The range of the global potential of primary biomass (in about 50 years) is very broadly quantified at 33 to 1,135EJ/year (Hoog — wijk et al. 2003).

Plant height, main stem diameter, stems, leaves, leaf length, leaflet width and length, and leaflets are important traits that are used to estimate herbage yield (Ates and Tekeli 2005). Trait characterization is part of sustainable crop systems. The im­provement of crops for tolerance to various forms of abiotic stress and for utilization in semiarid regions can be achieved by using trait analyses in multiple environments. This involves analyzing crop phenotypes for stress physiology and agronomic traits (e. g., high yield, grain quality) in different locations under different growth environ­ments.

There is a need to accelerate breeding applications to improve quality traits in crops that contribute to food security, health, and agricultural sustainability. The complex genetics and quality traits of many crops are difficult to manipulate by conventional breeding. There is a lack of useful variability for key quality traits and stress tolerance in cultivars and adapted germplasm.