ABSTRACT
Salinity of the arable lands is a global problem that has restricted productivity on 955 million hectares(Mha)oflands(Szabolcs,1987)ofwhich580Mha(>60%)aresodicsoils(Qadiretal.,2006). Ofthe230Mhaofirrigatedland,about45Mha(19.5%)aresaltaffected(FAO,2000).Thescenario isthusworsethanitwas6000yearsagowhentheword“salinization”rstappearedintheliterature (Jacobsen,1982).Todate,salinityofarablelandshasresultedin26%landlossinPakistan,50% in Iraq, 30%–40% in Egypt, 30%–35% in Arab Republic, 27% in India, 20%–35% in the United States,20%inColombia,16%inJordon,10%–15%inAlgeria,15%inChina,13%inSriLankaand Israel,and12%inPeru(Rains,1991).Theupcomingchallengeofglobalclimatechange(Guyet al., 2006)isfurtheraddingtothedeterioratingsituation.Itisanticipatedthatabout30%moreland losswouldoccurduetosalinizationofarablelandswithinthenext25yearsand50%bytheyear 2050 (Wang et al., 2003a). This would happen at a time when world population would be approximately8billion,ofwhich6.8billionwouldbelivingindevelopingcountries(Anonymous,1998), especiallyinSouthAsiahavingwheatandwheat-basedproductsastheirmajorstaplecereals.The breathtakingeconomicgrowthindevelopingcountriesofEastandSoutheastAsiahasincreased
46.1 Introduction ........................................................................................................................ 1153 46.2Magnitude and Development of Salinity and Desertication in Arid Regions .................. 1155 46.3Types of Salinity and Saline Soils in Arid Regions ........................................................... 1156 46.4Development and Status of Existing Salt Tolerance in Wheat Genotypes ......................... 1157
46.4.1Transferring Salt Tolerance from Perennial Wheat Grass Species ........................ 1157 46.4.2 Transfer of Salt Tolerance from Annual Goat Grass Species ................................. 1158 46.4.3Transfer of Salt Tolerance through Genetic Engineering Approaches ................... 1159
46.5Strategies and Rationale of Using New Approaches .......................................................... 1160 46.6Possible Impact of Cultivating Salt-Tolerant Genotypes on Saline Soils ............................1162 46.7Conclusion .......................................................................................................................... 1164 References .................................................................................................................................... 1164
their purchase power, hence there is a rising trend of consuming more calories. It is anticipated that incertaincountriesofEastAsia,intakeofcalorieswillincreasebymorethan14%bytheendof 2010 (Table 46.1).
