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160In localities where scab occurs onlysporadically. several arrangements canbe made in order to increase <strong>the</strong>possibility of <strong>the</strong> uniform occurrence of<strong>the</strong> disease. These include changes inseeding date to make flowering coincidewith <strong>the</strong> period of higher humidity. <strong>the</strong>use of sprinkler irrigation. crop rotationwith corn. leaving corn stubble withinand around plots. <strong>the</strong> use of highlysusceptible borders (triticale. durumwheat. rye and some wheat varieties).and leaving inoculated or naturallyinfected wheat or corn straw along <strong>the</strong>edges of <strong>the</strong> plots (3.4.24.43.46.47.65.74.75).Identification of resistant plantsSince <strong>the</strong> main damage caused by scabis kernel shriveling and floret abortion.<strong>the</strong> most reliable method for diseaseassessment must involve <strong>the</strong>se twoparameters. Individual threshing ofspikes (or a known number of spikes)and counting shriveled and healthygrains is necessary. The number ofplump kernels per head. grown underconditions of high scab incidence,Table 2. Modified Japanese scale for scabresistance, according to percent ofscabbed grainScale Scabbed grains Resistance level(010)o12345oLess than 89-1112-2021-50More than 50Completely resistantResistantModerately resistantModerately susceptibleSusceptibleHighly susceptiblecompared with <strong>the</strong> normal number ofplump kernels per head under healthyconditions is <strong>the</strong> best indication of <strong>the</strong>degree of resistance or susceptibility ofa cultivar. With segregating materials.since a healthy check is not possible. anestimate of <strong>the</strong> number of kernels perhead. based on spike size. is necessary(Table 2).The percentage of damaged grainsalone. overlooking flower abortion. hasbeen used in several programs (7.8.9.14.16.28.37.72). and has proven usefulin most routine screening work. Visualgrading of kernels for plumpness andshriveling is also used. Wheneverresistance scoring through kernelobservation is employed. threshingshould be done by hand or with athresher without forced ventilation.since shriveled grains tend to beeliminated in normal threshing.Observation of symptoms in heads canalso be made in preliminary selections(37). always watching out for thosecases where glume symptoms are notcorrelated with grain infections (28).The score for a plant should be <strong>the</strong>score of <strong>the</strong> most infected head(Table 3).Table 3. Modified Japanese scale for scabresistance, according to head symptomsScaleNecrotic areaof head (0/0)o 01 1-52 5·253 25-504 50-755 More than 75Resistance levelCompletely resistantResistantModerately resistantModerately susceptibleSusceptibleHighly susceptible
161Wheat Breedingfor Scab ResistanceThe main sources of resistance to scabused in <strong>the</strong> Brazilian breedingprograms are descendants of Asiancultivars. such as Nobeoka Bozu.Pekin 8. Nyu Bay. Minami Kyushu 69.Abura. Inayama. Tokai 66 and o<strong>the</strong>rs(7,9.14.15.16.17.18.19.20.21.22,32.35.36.44.45.52.53). Local cultivars.especially Toropi and Encruzilhada. arealso being used because. even though<strong>the</strong>y are moderately susceptible ingreenhouse tests. <strong>the</strong>y show someresistance under field conditions(26.27.28.31.59).Crosses followed by genealogicalselection have been used in attempts tocombine resistance to scab with o<strong>the</strong>rtraits of local interest. such as yield.quality and resistance to o<strong>the</strong>r diseases.The EMBRAPA National WheatResearch Center at Passo Fundo has aspecial program for transferringresistance to scab. via back crosses, toseveral cultivars of good agronomictype (49).Selection for scab resistance shouldstart with a preliminary selection of F2plants or. if entries are to be testedunder heavy inoculum in <strong>the</strong> field orgreenhouse. in <strong>the</strong> F3 and/or F4generations. According to Nakagawa(personal communication). selection in<strong>the</strong> F4 and F5 generations are moreeffective. In localities where scab doesnot occur every year. testing should berepeated over several generations untilreliable data can be obtained.Table 4 presents <strong>the</strong> percentage ofscabbed (shriveled) kernels ofsusceptible and resistant cultivars andTable 4. Percentage of scabbed kernels of various resistant and susceptible cultivars andcrosses after greenhouse inoculations, Pelotas, BrazilCu Itivar or crossGenerationScabbed kernels (°/0)Cultivars.!!f Selected plantsNyu BayNyu Bay x Lagoa VermeinaLagoa VermelhaIAS54IAS54 x Nobeoka BozuNobeoka BozuToropi x Nobeoka BozuToropiIAS20 x ToropiIAS20~I 5-year average9.353.770.210.832.050.315.786.8, 5.0,4.7,8.0,7.3,12.5,11.1,8.7,16.8, 7.9, 9.1, 15.4,8.8,10.86.6,7.1,7.4,10.1,8.6,4.5,9.0,8.322.6
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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
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 and 144: 141Identification ofSources of Resi
Page 145 and 146: 143References1. Adlakha, K, RD. Wil
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: 159Shinchunaga and descendants). se
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
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
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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
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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
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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
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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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