Crop yield response to water - Cra

Lead AuthorRoxana Savin(University of Lleida, Lleida,Spain)Contributing AuthorGustavo A. Slafer(University of Lleida, ICREA,Lleida, Spain)Rossella Albrizio(formerly CIHEAM-IAMB, Bari,Italy; currently CNR-ISAFOM,Ercolano, Italy),AcknowledgmentTheodore C. Hsiao(University of California, Davis,USA)Scientists contributingwith experimentalDATA and tests for thecalibration of AquaCropMarie Therese Abi Saab(formerly CIHEAM-IAMB, Bari,Italy; currently LARI, Fanar,Lebanon),Rossella Albrizio(formerly CIHEAM-IAMB, Bari,Italy; currently CNR-ISAFOM,Ercolano, Italy),Mladen Todorovic(CIHEAM-IAMB, Bari, Italy)BarleyGeneral descriptionBarley (Hordeum vulgare L.) ranks fourth among cereals in termsof total world production. In 2009, around 54 million ha of barleywere harvested, producing 152 million tonne of grain at an averageyield of 2.8 tonne/ha (FAO, 2011). Over the last 50 years, the average yieldper hectare has increased noticeably. However, because of changes inthe area cropped, total production rose only to the 1980s, followed by adecline in the 1990s, and possibly stabilizing since then (Figure 1). Barley isthe main feedstock for beer and also an important feedstock for whisky.The fluctuation in area harvested may partly be the result of changingmarket demand.Barley was one of the first domesticated cereals, originating in the FertileCrescent area of the Near East about 10 000 years ago. It is adapted toand produced over a wide range of environmental conditions. It is a coolseasoncrop cultivated in the spring and summer at higher latitudes andin the tropics at high elevations, and in the winter and spring at lowerto semitropical latitudes. The main production countries are the RussianFederation, Ukraine, France, Germany, Spain and Australia (Figure 2).Two botanical types can be distinguished, two- and six-row barleys,depending on the number of fertile and developed spikelets at eachnode of the rachis. Spikelets alternate on nodes along the rachis. Inwild relatives, the two lateral spikelets are infertile and only the centralspikelet is fertile, giving the appearance of having two-rows of spikelets,one at each side. Cultivars that retain this wild characteristic are tworowbarleys. In six-row barleys, mutations resulted in the lateral spikeletsbeing fertile, with three (one central and two lateral) spikelets at eachnode of the rachis.The two main uses of barley grains are as animal feed and as malting forbeer and whisky. In general, six-row barley tends to have higher proteinconcentration than two-rowed barley and, therefore, it is better suitedfor animal feed. Two-row malting barley has been traditionally grown inEurope, Australia, South America, and some other regions of the world,while six-row malting barley is more common in North America. Currently,two- and six-row malting barley can be found in all growing areas of theworld.Barley is similar to wheat and consequently several aspects of the crops`management are analogous. Although direct comparisons between the134crop yield response to water