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142characters made in segregatingpopulations. Heavy inoculum pressureis a prerequisite to testing and. during<strong>the</strong> process of subsequent selections.<strong>the</strong>re is <strong>the</strong> danger that resistance willbe lost. Never<strong>the</strong>less. if a particularsource possesses a very high degree ofresistance. it will be able to endurethrough <strong>the</strong> pedigree method. In Brazil.a high degree of resistance has not yetbeen found in T. aestivum. It ispossible that. in most cases. resistanceis polygenic and is governed by minorgenes.Quite frequently. a bulk or modifiedbulk system is used when desirablecharacters are obscured by unfavorableenvironmental conditions or o<strong>the</strong>rstresses. The backcross method alsomight be used with success to transferresistance to B. sorokintana. Thismethod works best when resistance isgoverned by one or only a few majorgenes. The CIMMYT germplasmdevelopment program has used thismethod to incorporate diseaseresistance into acceptable plant types(M.M. Kohli. personal communication).In case resistance to B. sorokintana isgoverned by a large number of minorgenes with low expression and lowheritability. <strong>the</strong> best approach would beto use <strong>the</strong> recurrent selection method.The aVailability of some effectivegametocides makes <strong>the</strong> method feasibleand would help to establish a largenumber of genetic pools which couldsubsequently be combined. Thesegenetic pools or recurrent selectionpopulations could serve as a bridge fortransferring resistance without losingimportant characters such as yield andadaptation.There is an urgent need to identifyresistant sources in alien speCies.Transfer of resistance from such speciesto T. aesttvum is a ra<strong>the</strong>r complicatedand difficult task. Difficulties in makinginterspecific crosses is due mainly todifferences in levels of ploidy (8).However. problems such as lack ofchromosome pairing and crOSSing-over.failure of crosses after fertilization.difficulties in rearing hybrid plants and<strong>the</strong> lack of Vigor and fertility of hybridplants can be overcome by <strong>the</strong> use ofvarious techniques and chemicals suchas colchicine and gibberellin.Information on"<strong>the</strong>se points is given byKnott and Dvorak (8).In general. <strong>the</strong> most important objectiveof breeding programs is to enhanceyield stability through effectiveresistance to a complex of diseases.However. uniform screening proceduresand techniques have not yet been fullyimplemented. InVariably. diseasescreeninghot spots are lacking. andartificial inoculation techniques varyamong national programs. Althoughplant pathologists have beguninoculating selected materials toidentify progenitors. segregatingpopulations and advanced lines are stillbeing selected under variable andnatural disease pressure. Only uniformartificial inoculation can guarantee <strong>the</strong>successful screening of germplasm forresistance to B. sorokiniana. A networkof hot-spot locations for this diseaseneeds to be established within eachcountry in order to permit uniformscreening and. consequently. providereliable information on resistance.
143References1. Adlakha, K, RD. Wilcoxson andS.P. Raychaudhuri. 1984.Resistance of wheat to leaf spotcaused by Bipolaris sorokiniana.Plant Disease 68(4):320-321.2. Auster, M.Y., E. Levi and Z. Eyal.1983. Assessment of interactionsbetween cultivated and wild wheatsand Septoria tritict. Phytopathology73:1077-1083.3. Christensen, J.J. 1925. Physiologicspecialization and mutation inHelminthosportum sativum.Phytopathology 15:785-795.4. Clark, RV., and J.G. Dickson.1958. The influence of temperatureon disease development in barleyinfected by Helminthosportumsativum. Phytopathology 48:305310.5. Dubin. H.J. 1984. Regional and incountryactivities: Andean region.In Report on Wheat Improvement1981. CIMMYT, Mexico.6. Dubin, H.J., and S. Rajararn. 1982.CIMMYT's international approachto breeding disease-resistant wheat.Plant Disease 66(10):967-971.7. Joshi, L.M., KK. Srivastava,D.V. Singh. L.B. Goel and S.Nagar~an. 1978. AnnotatedCompendium of Wheat Diseases inIndia. Indian Council onAgricultural Research, New Delhi,India.8. Knott, D.R. and J. Dv01ak. 1976.Alien germplasm as a source ofresistance to disease. AnnualReview of Phytopathology 14:211235.9. Luz, W.C., G.C. Luzzardi andJ.C. Santiago. 1976. Pesquisa defontes de resistencia a helminthosporiose(Helminthosporiumsativum P.KB.) do trigo. Paperpresented at <strong>the</strong> Eighth AnnualWheat Research Meeting,EMBRAPA. Ponta Grossa, Parana,Brazil.10. Mehta, Y.R 1978. Doencas do trigoe seu controle. Ed. AgronomicaCeres, Sao Paulo e SummaPhytopathologica. Sao Paulo, Brazil.11. Mehta, Y.R. 1981. Identification ofraces of Helminthsoporiumsativum of wheat in Brazil.Pesquisa Agropecuaria Brasiliera(Brasilia) 16(3):331-336.12. Mehta, Y.R 1981. Conidialproduction, sporulation period andextension of lesion ofHelminthosporiumsativum on flag leaves ofwheat. Pesquisa AgropecuariaBrasiliera (Brasilia) 16(1):77-99.13. Rajararn, S., P. Brajcich andL. Butler. 1984. Bread wheatimprovement. In Report on WheatImprovement 1981. CIMMYT,Mexico.14. Saari. E.E. 1979. Wheat in <strong>the</strong>developing countries from <strong>the</strong>Atlantic to <strong>the</strong> Pacific. InProceedings of <strong>the</strong> Symposia of <strong>the</strong>Ninth International Congress onPlant Protection, vol. II,T. Kommendahl, ed. Washington,D. C., USA.15. Srivastava, a.p., J.K. Luthra andP.N. Narula. 1971. Inheritance ofseedling resistance to leaf blight ofwheat. Indian Journal of GeneticPlant Breeding 31:209-211.
Page 2 and 3:
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
Page 93 and 94: 91area at flowering. Vegetative vig
Page 95 and 96: 93of the plants se
Page 97 and 98: Screening for tropical adaptationTh
Page 99 and 100: 97Table 3. Best advanced lines of b
Page 101 and 102: 99Table 4. Highest yielding advance
Page 103 and 104: 101very late, high temperatures at
Page 105 and 106: 103hence, select for drought tolera
Page 107 and 108: 106References1. Anonymous. 1972. Wh
Page 109 and 110: 107Breeding Wheats for Heatand Drou
Page 111 and 112: 109unit area. However, looking at s
Page 113 and 114: 111Identifying Wheats Adapted to Mo
Page 115 and 116: 113standard date for sowing. In spi
Page 117 and 118: 115transferred into high-yielding a
Page 119 and 120: 117Table 1. Chemical properties of
Page 121 and 122: 119• Resistance to shattering•
Page 123 and 124: 121References1. Araujo. J.E.G. 1949
Page 125 and 126: 123hours of sunlight monthly. Altho
Page 127 and 128: 125Screening Wheats for QualityA. A
Page 129 and 130: 127Wide Crosses and New Genesfor Wh
Page 131 and 132: 129The introduction of alien geneti
Page 133 and 134: 131averaged about 2.5 tonslha. Howe
Page 135 and 136: 133must also demonstrate a yieldadv
Page 137 and 138: 135II. Diseases and Disease Control
Page 139 and 140: 137beaker with 200 ml sterilized di
Page 141 and 142: 139Table 1. (Cont'd)Resistance reac
Page 143: 141Identification ofSources of Resi
Page 147 and 148: Breeding Wheats with Resistanceto H
Page 149 and 150: 147conditions. whereby infectionper
Page 151 and 152: 149CIMMYT Methods for Screening Whe
Page 153 and 154: 151Selection under Field Conditions
Page 155 and 156: 153February. Environmental conditio
Page 157 and 158: 156Each trla1 had two replications
Page 159 and 160: 157References1. De Milliano. W.A.J.
Page 161 and 162: 159Shinchunaga and descendants). se
Page 163 and 164: 161Wheat Breedingfor Scab Resistanc
Page 165 and 166: 163References1. Andersen. A.L. 1948
Page 167 and 168: 16526. Luzzardi. G.C.. C.R. Pierobo
Page 169 and 170: 18748. Nisikado. Y. 1958. Studies o
Page 171 and 172: Head Scab Screening Methods Used at
Page 173 and 174: 171Wheat spikes are spray-inoculate
Page 175 and 176: 173Reference.1. Bekele. G.T. 1984.
Page 177 and 178: 1'71SThe species and varieties with
Page 179 and 180: 177suspension. This method has prov
Page 181 and 182: 179How the pathoge
Page 183 and 184: 18112. Takegami, S. 1961. Proceedin
Page 185 and 186: 183Documented Foot RotDlseaBes in W
Page 187 and 188: 185References1. Anderson. N.A. 1982
Page 189 and 190: 187against leaf rust by the
Page 191 and 192: -188Distribution and Importance ofR
Page 193 and 194: 191Surprisingly. little or no stem
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193temperatures. but this differenc
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19~14. Lapis. D.B. and M.C. Kamatoy
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197According to a new criterionesta
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199Loss in yield is directly propor
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Chemical Control ofHelminthosportum
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203H. sattvum on foliage and heads
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205Table 1. Mean number of lesions
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20'7Table 4. Effect on lelf spot in
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209III. AgronomyPhysiological Limit
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Table 1. Actual and pouible wheat1l
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213Table 2. Wheat yield determinati
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216unpublished). A role of thumb de
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217seasonally and cloudiness persis
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219developmental periods. to around
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221Growth at high temperaturesEarly
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CertainlY crop growth rates in exce
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225rice, another C
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227105% that of C306 for th
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22913. Fischer. RA.. I. Aguilar. R
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Soil Management as an Alternativefo
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233water content in the</st
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23~Tolerance to soil aciditySoil ac
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237applied without increasing <stro
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The Cerrados: Future WheatProductio
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241there is utiliz
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243• Ammonium sulfate [(NH4)2S04]
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245Physical Soil ProblemsThe soils
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247program. these
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249References1. Commisao Norte Bras
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251was rather poor
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253Tolerant vartettes-The yield ofv
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255Alternative locations-An evaluat
Page 259 and 260:
257Wheat Production Constraintsand
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259numerical grading which showed <
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261directed towards minimum loss of
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'.2636. Cheng, C.P. 1977. Wheatprod
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Wheat in Rice...BasedCropping Syste
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267Rice varietiesAs mentioned above
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269A problem of declining yields ha
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271_.z.:::-~:J.."•._,:.\--_.r+++v
Page 275 and 276:
273Agronomic Practices and Problems
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275water percolation in rice. For w
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277Rice-Wheat Cropping Systemsin So
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279Table 1. Yield and economic retu
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281was higher with the</str
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283to compete with othe</st
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for tropical environments. Highesta
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287can be used. The computer is a u
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289The computer has become a valuab
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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
Page 345 and 346:
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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