the Symposium on Wheats for More Tropical Environments - cimmyt

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94<strong>the</strong> distribution and adoption ofsuitable germplasm. a number ofactivities are underway or in <strong>the</strong>planning stages.Sbuttle breecllngThe main activity is shuttle breedingbetween two contrasting climates inMexico. one for a winter crop at CiudadObregon (27°20'N latitude. 40 metersaltitude) and <strong>the</strong> o<strong>the</strong>r for a summercrop at Toluca (l9°N latitude. 2640meters). Both are characterized byendemic rust attacks. and enablebreeders to select for day-lengthinsensitive. Widely adapted types withhigh levels of rust resistance. Selectionscan also be made at Toluca forresistance to septoria and fusariumdiseases. This two-cycle approach alsocuts in half <strong>the</strong> time needed to developa new variety.In addition to <strong>the</strong>se testing sites.CIMMYT regularly employs <strong>the</strong>screening environments of EI Batan(l9°N. 2240 meters) for low rainfallconditions. Tlaltizapan (l8°N. 940meters) for heat tolerance. and PozaRica (21 ON. 60 meters) forhelminthosporium diseases. Similarly.tropical Tampico (22°N. 40 meters) isalso used in cooperation with <strong>the</strong>Instituto Nacional de InvestigacionesAgricolas (lNIA). as a supportinglocation for screening work undertropical conditions. The relationship of<strong>the</strong>se experimental locations is -illustrated in Figure 1.CIMMYT employs additional tropicallocations in o<strong>the</strong>r countries to ga<strong>the</strong>rgenetic information for use in <strong>the</strong>crossing program and for generalscreening activities. Maximumutilization of advanced materialscoming from <strong>the</strong> bread wheat programis also considered a major part of <strong>the</strong>overall strategy of <strong>the</strong> Tropical WheatImprovement Program.In <strong>the</strong> future. shuttle breeding between<strong>the</strong> locations of Poza Rica. forhelminthosporium disease and leaf rustscreening during <strong>the</strong> winter. andTlaltizapan. for heat tolerance andplant-type screening during <strong>the</strong>summer. will be used as an alternativebreeding strategy.Figure 1. Location and elevations of experiment stations in Mexico atwblcb CIMMYT conducts researcb for tropical wbeat
Screening for tropical adaptationThe world wheat germplasm collectionis also being screened for materials withdesirable characteristics which will becontinuously introgressed into <strong>the</strong>breeding program for <strong>the</strong> tropics.In carrying out all of <strong>the</strong> abovementionedobjectives, CIMMYT utilizesa multidisciplinary, coordinatedapproach, involVing <strong>the</strong> participation ofscientists trained in various disciplines.Program ResultsEarly maturityCIMMYT's breeding objective for <strong>the</strong>last few years has been to select anddevelop wheats with earlier maturity. Intrying to obtain such lines. <strong>the</strong> earliestmaturingsegregates are selected fromF2 segregating populations. Forcomparison, <strong>the</strong> variety Sonalika fromIndia is used as <strong>the</strong> early check variety.When a low percentage of plants in asegregating population reachphysiological maturity, <strong>the</strong>y areselected and harvested. Then, as F3s.<strong>the</strong>y are handled in a separate nursery,toge<strong>the</strong>r with o<strong>the</strong>r segregating andadvanced early materials. This systemof handling <strong>the</strong> materials is more forpractical reasons. since damage frombirds and o<strong>the</strong>r pests is particularlysevere on early plants left in <strong>the</strong> field.Using this selection method. advancedlines that are as early as Sonalika havebeen obtained. Two hundred sixty earlylines were tested for yield in CiudadObregon in <strong>the</strong> 1983-84 cycle. Table 2presents 14 lines that were as early asSonalika or earlier. but which havebetter yield potential. These materialsare now in <strong>the</strong> First International EarlyScreening Nursery. toge<strong>the</strong>r with o<strong>the</strong>rearly germplasm in <strong>the</strong> program.HelmiDthosporium resistanceEfforts to improve resistance toHelmtnthosportum spp. began in <strong>the</strong>early 19808. Helminthosporiumscreening work is done at Poza Rica. in<strong>the</strong> tropical area of Mexico. and also at<strong>the</strong> Tlaltizapan station. It is hoped thatgermplasm with both helminthosporiumresistance and heat tolerancewill result from selections at <strong>the</strong>selocations. Helminthosporium resistanceis evaluated on <strong>the</strong> basis of <strong>the</strong>follOWing characteristics:• Slow development of <strong>the</strong> disease;• Acceptable agronomiccharacteristics;• "Good finish," <strong>the</strong> ability to haveclean, fertile and bright heads atmaturity. and• Good seed quality.Table 3 presents <strong>the</strong> best varieties andadvanced lines which were foundresistant to helminthosporium in PozaRica in 1983-84. These lines are now in<strong>the</strong> new Crossing Block and ThirdHelminthosporium Screening Nursery.All of <strong>the</strong>se lines showed betterresistance than BH1146. a resistantcheck variety from Brazil.Heat toleranceIn <strong>the</strong> breeding program. testing hasbeen initiated to identify varieties andadvanced lines haVing tolerance to hightemperature. Heat tolerance isevaluated in Ciudad Obregon byplanting advanced lines in midJanuary. so that early growth stagesoccur during a period of rapidly risingtemperatures. The final performance of<strong>the</strong> lines is evaluated in late April. ThefollOWing characteristics are used asselection criteria for heat tolerance:• Longer leaf duration. <strong>the</strong> "staygreen"characteristic• High tillering capacity• Acceptable spike fertility• Relatively high grain weight• High hectoliter test weight• Relatively high yieldMore than 200 advanced lines wereidentified as haVing some heattolerance in 1983. These same lineswere reevaluated in Ciudad Obregon in
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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
Page 45 and 46: 4320-year period. Also indicated ar
Page 47 and 48: Table 2. (Con't)Cross and pedigreeN
Page 49 and 50: 47respectively. for central AlaJuel
Page 51 and 52: 49Table 1. Climatological data, Fra
Page 53 and 54: 51Wheat Research in the</st
Page 55 and 56: 53Table 3. Average yield of best wh
Page 57 and 58: Selection of Wheats forSubtropical
Page 59 and 60: Nigeria is high temperature. South
Page 61 and 62: 59Wheat Production in Bangladesh:It
Page 63 and 64: 61Research PrioritiesVarietal devel
Page 65 and 66: 63Wheat Improvement Programsfor <st
Page 67 and 68: 65In India, a series of wheat varie
Page 69 and 70: 67in temperature are capable of cau
Page 71 and 72: 69primarily due to a lack of financ
Page 73 and 74: 71Triticale ImprovementRegular bree
Page 75 and 76: 73The climate in this region is war
Page 77 and 78: 75Recently, the pe
Page 79 and 80: 77Variety improvement must also bec
Page 81 and 82: 79those areas that are suitable for
Page 83 and 84: Wheat Growing in the</stron
Page 85 and 86: 83Thailand Winter Cereals ProgramP.
Page 87 and 88: Many farmers are now exploring <str
Page 89 and 90: 87crop is present, and known. at pl
Page 91 and 92: 6 ~89Contributed PapersI. BreedingB
Page 93 and 94: 91area at flowering. Vegetative vig
Page 95: 93of the plants se
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 and 144: 141Identification ofSources of Resi
Page 145 and 146: 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
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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
Page 271 and 272:
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
Page 279 and 280:
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
Page 311 and 312:
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
Page 349 and 350:
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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