Barley (Hordeum vulgare L. emend. Bowden) is grown on 14.5 million hectares in developing countries, often on the fringes of deserts and steppes or at high elevations with modest or no inputs. Average barley yields are about 1.0 t/ha in Africa. The average for developing countries is about 1.7 t/ha, versus 3.0 t/ha in developed countries. Drought limits yield in dry areas.
Barley grain is used as feed for animals, for malting and as food for direct human consumption. About 75% of world barley is used for animal feed and 20% for malting, with the remaining 5% for direct food use. Barley straw is used as animal feed in many developing countries, and for animal bedding and as cover material for hut roofs. After combine harvesting, barley stubble is grazed during the hot dry summers across large areas of West Asia and North Africa. Barley is also used for green grazing or is cut before maturity and either directly fed to animals or used for silage.
Malt is the second largest use of barley, and malting barley is grown as a cash crop in a number of developing countries. Utilization for malting by the brewing industry has picked up recently with an increase of consumption of beer and other malt products in many countries.
In the highlands of Tibet, Nepal, Ethiopia, Eritrea and North Africa, barley is consumed by humans. These regions are characterized by harsh living conditions and are home to some of the poorest farmers in the world who subsist on low-productivity systems. Barley is an important food source for 60% of the population in the highlands of Ethiopia.
Barley grain is rich in zinc (up to 50 ppm), iron (up to 60 ppm) and soluble fibers, and has a higher content of Vitamins A and E than other major cereals. Barley bran flour accelerates gastrointestinal transit time, thereby reducing the incidence of colon cancer.
Hulless or "naked" barley is a form of barley that is easily de-hulled. Naked barley is an ancient food crop, but a new industry has developed around hulless barley in order to increase the digestible energy of the grain, especially for swine and poultry. Hulless barley has been investigated for several potential new applications such as whole grain, and for value-added products such as bran and flour for different food applications.
Constraints and opportunities
Major constraints to barley production include drought, frost, salinity, low soil fertility, low soil pH and poor soil drainage stresses; foliar and root diseases such as net and spot blotch, scald, powdery mildew, fusarium head blight, rusts and dryland root rots; insects such as Russian wheat aphids and barley stem gall midge; nematodes such as cereal cyst nematode; and viruses such as barley yellow dwarf virus. In some barley-growing areas of developing countries, the risk of crop failure is very high and few farmers use fertilizers, herbicides or pesticides.
Priority opportunities in barley improvement include: the development of improved varieties for feed, food and malt uses; improving drought and heat tolerance to adapt to climate change; utilizing rich genetic-resources; genomic tools to improve tolerance/resistance to abiotic and biotic stresses and the nutritional value of grain and straw; and value-addition opportunities in alternative food products.