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242<strong>the</strong> movement of small amounts ofcalcium down <strong>the</strong> profile shouldincrease effective rooting depth. Thework of Ritchey et al. (10) presentsvarious ways of solving this problem.As can be seen from Figure 4. <strong>the</strong> rateand amount of movement of calciumdown <strong>the</strong> profile is an electricallyneutral phenomenon. Every Ca+ + ionmust be accompanied by twomonovalent anions. such as CI-. on onedivalent anion. such as SO--4. Theaccompanying anion. <strong>the</strong>refore. plays avery important role.Calcium carbonate (CaC03) isneutralized by hydrogen ions at <strong>the</strong> soilsurface; <strong>the</strong>refore. <strong>the</strong>re is no anion toaccompany <strong>the</strong> calcium down <strong>the</strong>profile. This results in very littlecalcium movement from this level.CaCl2 is very soluble in water and.since it is monovalent. it reacts verylittle with <strong>the</strong> soil colloids. This sourceof calcium shows <strong>the</strong> fastest movementdown <strong>the</strong> profile and. possibly. even outof <strong>the</strong> rooting zone. CaS04 or gypsumis less soluble and <strong>the</strong> SO--4 ion reactsmore strongly with <strong>the</strong> soil. leading to amore desirable distribution of calciumthroughout <strong>the</strong> profile.The practical way of achieving gooddistribution of calcium in <strong>the</strong> soil is toapply one of <strong>the</strong> following:• CaS04 (gypsum)• Single superphosphate (SSP), whichcontains calcium sulfate. Thereaction for producing SSP is:CalOF2 (P04)6 + 7 H2S04 + 3 H2(fluorapatite) (sulfuric acid)3 Ca(H2P04)2°H2) + 7 CaS04 + 2 HF(monocalcium (calcium (hydrophosphate)sulfate) fluorlcacid)The effect of varying rates of SSP oncalcium and magnesium movementdown <strong>the</strong> profile are shown inFigure 5.E~..c: .....s::.!!'Ql).....&10 •:;0.1 0.2Calcium (Meq/l00g)0.4Figure 4. The effect of various anions on <strong>the</strong> distributions of calcium in adark red latosol after leaching. with <strong>the</strong> equivalent of 1200 mm of rainfall.BrazilSource: Ritchey et al. (10)
243• Ammonium sulfate [(NH4)2S04] as anitrogenous fertilizerLow phosphorus levelsPhosphorus is highly and universallydeficient in <strong>the</strong> Cerrados area.Therefore. correction of this deficiencyis imperative for <strong>the</strong> production of cropsin <strong>the</strong>se soils. Crop responses tophosphorus fertilization. as shown inFigure 6. include quite high yields. but<strong>the</strong> amount of phosphorus necessary isalso high, with economic levels being in<strong>the</strong> range of 250 to 500 kg P205/ha.Much work has been carried out ondifferent management strategies for <strong>the</strong>use of phosphorus, such as broadcastversus banded applications and a largesingle application versus smallerrepeated applications. This work issummarized in Table 2.,-These results show that. in <strong>the</strong> longterm, yields are determined by <strong>the</strong> totalamount of P205 applied; differentmethods of application give similarresults. However, it was observed thatbroadcast applications outyieldedbanded applications for <strong>the</strong> first crop;<strong>the</strong> opposite was found after <strong>the</strong> thirdcrop. An initial broadcast applicationseems to give better root developmentand. <strong>the</strong>refore, better water extraction.Low levels of o<strong>the</strong>r nutrientsInsufficient zinc and potassium veryoften limit yields on <strong>the</strong>se soils and<strong>the</strong>ir deficiencies need to be corrected.Nitrogen and sulphur usually becomedeficient after several years of cropping.1Ca + Mg (Meq/lOOg)2 3 430-S45.£.c: ..... 600-Q.)(:)7590105120Figure 5. Effect of varying rates of phosphorus (kg/ha) as SSP on <strong>the</strong>distribution of calcium + magnesium in <strong>the</strong> soil profile of a dark redlatosol. BrazilSource: Ritchey et al. (10)
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The International Maize and Wheat I
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3AcknowledgementsThe Tropical Wheat
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5Wheat Production in Bangladesh: It
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7Chemical Control ofHelmtn.thosport
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1 9PrefaceThe international worksho
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uToluca, a high-elevation station a
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13In Bangladesh. many farmers' fiel
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global cooperation that permits apo
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17Recognizing the
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19With UNDP assistance. CIMMYTexpan
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4 21Introduction to the</st
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23grain-filling stages are required
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Table 1. Countries growing whut in
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27Month of sowing and month afterfl
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29. Table 3. Correlation coefficien
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31Earliness-Earliness is needed if
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33requires more than technical solu
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3~from other crops
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37Table 2. Advanced lines selected
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39If Bol1via does not radically cha
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41Table 5. Water efficiency utiliza
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4320-year period. Also indicated ar
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Table 2. (Con't)Cross and pedigreeN
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47respectively. for central AlaJuel
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49Table 1. Climatological data, Fra
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51Wheat Research in the</st
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53Table 3. Average yield of best wh
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Selection of Wheats forSubtropical
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Nigeria is high temperature. South
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59Wheat Production in Bangladesh:It
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61Research PrioritiesVarietal devel
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63Wheat Improvement Programsfor <st
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65In India, a series of wheat varie
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67in temperature are capable of cau
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69primarily due to a lack of financ
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71Triticale ImprovementRegular bree
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73The climate in this region is war
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75Recently, the pe
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77Variety improvement must also bec
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79those areas that are suitable for
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Wheat Growing in the</stron
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83Thailand Winter Cereals ProgramP.
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Many farmers are now exploring <str
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87crop is present, and known. at pl
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6 ~89Contributed PapersI. BreedingB
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91area at flowering. Vegetative vig
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93of the plants se
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Screening for tropical adaptationTh
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97Table 3. Best advanced lines of b
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99Table 4. Highest yielding advance
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101very late, high temperatures at
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103hence, select for drought tolera
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106References1. Anonymous. 1972. Wh
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107Breeding Wheats for Heatand Drou
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109unit area. However, looking at s
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111Identifying Wheats Adapted to Mo
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113standard date for sowing. In spi
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115transferred into high-yielding a
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117Table 1. Chemical properties of
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119• Resistance to shattering•
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121References1. Araujo. J.E.G. 1949
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123hours of sunlight monthly. Altho
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125Screening Wheats for QualityA. A
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127Wide Crosses and New Genesfor Wh
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129The introduction of alien geneti
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131averaged about 2.5 tonslha. Howe
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133must also demonstrate a yieldadv
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135II. Diseases and Disease Control
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137beaker with 200 ml sterilized di
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139Table 1. (Cont'd)Resistance reac
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141Identification ofSources of Resi
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143References1. Adlakha, K, RD. Wil
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Breeding Wheats with Resistanceto H
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147conditions. whereby infectionper
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149CIMMYT Methods for Screening Whe
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151Selection under Field Conditions
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153February. Environmental conditio
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156Each trla1 had two replications
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157References1. De Milliano. W.A.J.
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159Shinchunaga and descendants). se
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161Wheat Breedingfor Scab Resistanc
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163References1. Andersen. A.L. 1948
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16526. Luzzardi. G.C.. C.R. Pierobo
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18748. Nisikado. Y. 1958. Studies o
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Head Scab Screening Methods Used at
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171Wheat spikes are spray-inoculate
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173Reference.1. Bekele. G.T. 1984.
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1'71SThe species and varieties with
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177suspension. This method has prov
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179How the pathoge
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18112. Takegami, S. 1961. Proceedin
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183Documented Foot RotDlseaBes in W
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185References1. Anderson. N.A. 1982
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187against leaf rust by the
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-188Distribution and Importance ofR
Page 193 and 194: 191Surprisingly. little or no stem
Page 195 and 196: 193temperatures. but this differenc
Page 197 and 198: 19~14. Lapis. D.B. and M.C. Kamatoy
Page 199 and 200: 197According to a new criterionesta
Page 201 and 202: 199Loss in yield is directly propor
Page 203 and 204: Chemical Control ofHelminthosportum
Page 205 and 206: 203H. sattvum on foliage and heads
Page 207 and 208: 205Table 1. Mean number of lesions
Page 209 and 210: 20'7Table 4. Effect on lelf spot in
Page 211 and 212: 209III. AgronomyPhysiological Limit
Page 213 and 214: Table 1. Actual and pouible wheat1l
Page 215 and 216: 213Table 2. Wheat yield determinati
Page 217 and 218: 216unpublished). A role of thumb de
Page 219 and 220: 217seasonally and cloudiness persis
Page 221 and 222: 219developmental periods. to around
Page 223 and 224: 221Growth at high temperaturesEarly
Page 225 and 226: CertainlY crop growth rates in exce
Page 227 and 228: 225rice, another C
Page 229 and 230: 227105% that of C306 for th
Page 231 and 232: 22913. Fischer. RA.. I. Aguilar. R
Page 233 and 234: Soil Management as an Alternativefo
Page 235 and 236: 233water content in the</st
Page 237 and 238: 23~Tolerance to soil aciditySoil ac
Page 239 and 240: 237applied without increasing <stro
Page 241 and 242: The Cerrados: Future WheatProductio
Page 243: 241there is utiliz
Page 247 and 248: 245Physical Soil ProblemsThe soils
Page 249 and 250: 247program. these
Page 251 and 252: 249References1. Commisao Norte Bras
Page 253 and 254: 251was rather poor
Page 255 and 256: 253Tolerant vartettes-The yield ofv
Page 257 and 258: 255Alternative locations-An evaluat
Page 259 and 260: 257Wheat Production Constraintsand
Page 261 and 262: 259numerical grading which showed <
Page 263 and 264: 261directed towards minimum loss of
Page 265 and 266: '.2636. Cheng, C.P. 1977. Wheatprod
Page 267 and 268: Wheat in Rice...BasedCropping Syste
Page 269 and 270: 267Rice varietiesAs mentioned above
Page 271 and 272: 269A problem of declining yields ha
Page 273 and 274: 271_.z.:::-~:J.."•._,:.\--_.r+++v
Page 275 and 276: 273Agronomic Practices and Problems
Page 277 and 278: 275water percolation in rice. For w
Page 279 and 280: 277Rice-Wheat Cropping Systemsin So
Page 281 and 282: 279Table 1. Yield and economic retu
Page 283 and 284: 281was higher with the</str
Page 285 and 286: 283to compete with othe</st
Page 287 and 288: for tropical environments. Highesta
Page 289 and 290: 287can be used. The computer is a u
Page 291 and 292: 289The computer has become a valuab
Page 293 and 294: 291IV. SeedWheat Seed Production,St
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293On average, no more that 100 mm
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295Storage in 20-liter biscuit or k
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Production, Storageand Marketing of
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299true to type. are selected and t
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301discussed and ascertained; <stro
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303V. EconomicsWheat in the
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305than in Asia and Africa (about 1
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307wheat consumption). However, <st
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309These changing consumption patte
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311Finally. it should be clarified
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313in areas where wheat yields arer
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31510. FAO. 1982. The bread economy
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317Lowlands withinadequate dry-seas
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319Table 1. Private and social prof
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The Local-Use Approach to t
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323fired oven has been used at oneu
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325ControlliDg fungal diseasesThe i
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The Relative Priority andEconomics
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329Comparative MarketPrices of Stap
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331References1. Agricultural Extens
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Table 1. Area, average yield and to
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Table 3. Annual domestic wheat prod
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337Table 5. Financial costs of whea
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Comments'D.L. WiDkelmaDll, DIrector
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7341------_1Closing Remarks, <stron
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343Table 1. Probleml for th
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345While efforts to develop wheatge
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347Appendix IIWheat Pests and Disea
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349Appendix IIIParticipants. <stron
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351NigeriaMr. Ahmed M. FalakiResear
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353CIMMYT Staff. MexicoMr. Robert D
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