Thisbookisconcernedwiththewaysinwhichcropsmightbedevelopedfor soilsthatare,atthepresent,agriculturallyunproductivebecauseofexcesses and/ordeficienciesofcertainminerals. Wehaveconcentratedonsoils,rather thanonenvironmentalconditionsthatlimitproductivity,sincetherehavebeen anumberofrecenttextsdealingwithtopicssuchasdroughtandtemperature. Theaimisthatthoseworkingtoderivecropsforgrowthonthese"problem" soilsshouldbeawareofthemanydiverseavenuesthatareavailable. These comefromthedisciplinesofplantbreeding,geneticsandphysiology,andthe interfacesthataredevelopingbetweenthem. Thebackground,therequirementstofeedtheprojectedincreaseinhuman population,issetoutintheintroductorychapter. Thenextfivechaptersthen dealwiththeapproachestocropimprovement:themeritsofaconventional breedingprogramme,theimportanceofphysiologicalcharactersinmaking selections,theuseofinvitrotechniques,ofcytogenetics,andthevalueof developingnativeplantsintocropsintheirownright. Althoughsalinityisoften usedasanexample,reflectingtheresearchinterestsofmanyoftheauthors,the methodsandapproachesdescribedhavemuchwiderapplicability. Twochap tersarethenconcernedmorespecificallywithbreedingfortolerancetoother metaltoxicitiesandwithdeficienciesandtoxicitiesofmicronutrients. Finally,in theconcludingchapter,wesummariseandfindcommongroundbetweenthe differentapproachesandpointsofview. Brighton,April1994 ANTHONYR. YEO TIMOTHY J. FLOWERS Contents Chapter1 Introduction:WorldPopulationandAgriculturalProductivity T. 1. Flowers 1. 1 HowManyPeopleAreThere? . 1 1. 2 AgriculturalRequirements. . 2 1. 2. 1 FoodRequirements. . . . . . . . . . . 2 1. 2. 2 FoodSupply. . . . . . . . . . . . . . . 4 1. 3 Population-CarryingCapacity. . . . . . . . . . . . . . . 5 1. 4 HowMuchLandIsThere? . 6 1. 5 IncreasingFoodProduction . 7 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Chapter2 ConventionalPlantBreedingforTolerancetoProblemSoils C. N. ChaubeyandD. Senadhira 2. 1 ScreeningTechniques . 11 2. 2 VariabilityinToleranceforSoilStresses . 14 Rice . 15 2. 2. 1 2. 3 GeneticsofToleranceforSoilStresses. . . . . . . . . . . . 16 19 2. 3. 1 GeneLocationandLinkages. . . . . . . . . . . . . . . . . . CorrelatedChanges. . . . . . . . . . . . . . . . . . . . . . . 20 2. 3. 2 2. 4 Crop-Improvement . 21 2. 4. 1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . 21 2. 4. 2 PureLineandMassSelection. . . . . . . . . . . 21 2. 4. 3 HybridisationandSelection. 23 2. 4. 3. 1 PedigreeMethod. . . . . . . 23 2. 4. 3. 2 BulkMethod. . . . . . . . . 23 BackcrossBreeding. . . . . . 2. 4. 3. 3 26 2. 4. 3. 4 RecurrentSelection. . . . . . . . . . . . . . . . . . . . . . . . 26 2. 4. 3. 5 RapidGenerationAdvanceProcedures. . . . . . . . . . . . 27 2. 4. 4 MutationBreeding. . . 28 2. 4. 5 PolyploidBreeding. 28 2. 4. 6 HeterosisBreeding. 29 2. 5 Summary. . . . 29 References. . . . . . 29 VIII Contents Chapter3 PhysiologicalCriteriainScreeningandBreeding A. R. Yeo 3. 1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 3. 2 ReasonsfortheUseofPhysiologicalSelection . 38 3. 2. 1 TheComplexityofTolerance. . . . . . . . . . 38 3. 2. 2 ImportingTolerancefromWildRelatives . 39 3. 2. 3 MeasuringStressTolerance . 40 3. 2. 4 InteractionBetweenEnvironmentalStresses. . . . . . . . . 42 3. 2. 5 LimitationstotheUseofYieldasaSelectionCriterion. . . 42 3. 3 Salinity . 43 3. 3. 1 BasicProblems. . . . . . . . . . . . . . . . . . . . 43 SaltExclusion. . . . . . . . . . . . . . . . . . . . . . 44 3. 3. 2 3. 3. 3 ConditionsRequiringOsmoticAdjustment. . 45 3. 3. 4 CharacteristicsNeededinSalt-TolerantPlants . 46 3. 3. 4. 1 ControlofSaltUptake. . . . . . . . . . . . . . . . . . .

Inhalt
1 Introduction: World Population and Agricultural Productivity.- 1.1 How Many People Are There?.- 1.2 Agricultural Requirements.- 1.3 Population-Carrying Capacity.- 1.4 How Much Land Is There?.- 1.5 Increasing Food Production.- References.- 2 Conventional Plant Breeding for Tolerance to Problem Soils.- 2.1 Screening Techniques.- 2.2 Variability in Tolerance for Soil Stresses.- 2.3 Genetics of Tolerance for Soil Stresses.- 2.4 Crop-Improvement.- 2.5 Summary.- References.- 3 Physiological Criteria in Screening and Breeding.- 3.1 Introduction.- 3.2 Reasons for the Use of Physiological Selection.- 3.3 Salinity.- 3.4 Drought.- 3.5 Physiological Selection Procedures.- References.- 4 Cytogenetic Manipulations in the Triticeae.- 4.1 Introduction.- 4.2 Background to Wheat and Salinity.- 4.3 Cytogenetics of Wheat.- 4.4 Transfer into Wheat of Alien Genes for Tolerance to Salt.- 4.5 The Development of Hybrids as New Crop Species.- 4.6 The Interface Between Cytogenetics and Physiology.- 4.7 GeneticControl of Salt Tolerance in Barley.- 4.8 Genes for Abiotic Stress Tolerance in the Triticeae.- 4.9 Examples of Alien Introduction.- 4.10 Genetic Markers in Plant Breeding.- 4.11 Summary.- References.- 5 Tissue Culture in the Improvement of Salt Tolerance in Plants.- 5.1 Introduction.- 5.2 Application of Tissue Culture to Obtain Salt-Tolerant Plants.- 5.3 Tissue Culture in the Identification and Characterisation of Cellular Determinants of Salt Tolerance.- 5.4 Conclusion.- References.- 6 The Agricultural Use of Native Plants on Problem Soils.- 6.1 Evolution of Domestic Species.- 6.2 Limits of Improving Existing Crops.- 6.3 Availability of Alternatives.- 6.4 Methods of Domestication.- 6.5 Time Scale for Agricultural Development.- 6.6 Conclusions.- References.- 7 Metal Toxicity.- 7.1 Introduction: Sources of Toxicity.- 7.2 The Measurement of Tolerance.- 7.3 Variability in Wild Species.- 7.4 Variability in Cultivated Species.- 7.5 The Genetic Basis of Metal Tolerance.- 7.6 The Physiological Basis of Tolerance to Metals.- 7.7 Synthesis.- References.- 8 Micronutrient Toxicities and Deficiencies in Rice.- 8.1 Introduction.- 8.2 Iron.- 8.3 Manganese.- 8.4 Zinc.- 8.5 Copper.- 8.6 Boron.- 8.7 Molybdenum.- References.- 9 Summary: Breeding Plants for Problem Soils Current Knowledge and Prospects.- 9.1 Why Grow Crops on Problem Soils?.- 9.2 Approaches to the Utilisation of Problem Soils.- 9.3 Selection of Parents and Within Breeding Populations.- 9.4 Tolerance and Potential Yield.- 9.5 Genetics of Tolerance to Problem Soils.- 9.6 Transfer from Other Species.- 9.7 Domestication of New Crops from the Native Flora.- 9.8 Outlook.