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208Table 6. Protective effect of fungicides against three soil-borne pathogens, Los Banos"Philippines, 1984FungicidePercent germination oftreated seedsS. rolfsii R. solani F. moniliformeHomai 43.3 44.9 45.1Vitavax-thiram 44.4 43.9 44.5Vitavax-eaptan 41.4 43.3 44.1Arasan 76 42.8 40.9 43.6Control 36.9 38.7 38.9Table 6. Eradicative effect of fungicides on ..ed-bornepathogens on ..eds of wheat variety UPLW2, Los Banos,Philippines, 1984FungicideHomaiVitavax-eaptanVitavax-thiramArasan 75ControlPathogen-free ..ed~(%)46.829.214.29.00.0~/ Pathogens commonly encountered on untreated seedsare species of Fusarium, Curvalaria, Helminthosporium,Alternaria, Penicillium and Rhizophus
209III. AgronomyPhysiological Limitations to Producing Wheatin Semitropical and Tropical Environments andPossible Selection CriteriaR.A. Fischer, Division of Plant Industry, Commonwealth Scientificand Industrial Research Organization, Canberra, AustraliaAbstract''Tropica.l'' wheat environments are characterized by short winter photoPeriods(11 and 12.5 hours) with high temperatures, <strong>the</strong> mean temperaturefor <strong>the</strong>coolest month varyingfrom warm (l5°C) to hot (20°C) to very hot (25°C).Diurnal temperature range, solar radiation, vapor-pressure deficit and watersupply (irrigated or rainfed) vary considerably between regions:frosts and hotwinds constitute meteorological hazards in some locations. In suchenvironments, wheat may establish poorly because of high soil temperatures.More seriously, development is accelerated (approximately in proportion totemperature), while growth rate is stable or may decline, so that leaf size,tillering, spike size and yield potential suffer, even under irrigation. Excessiverespiration and possible direct effects of high temperature on sinkformationmayfur<strong>the</strong>r reduce potential, while kernelfilling is curtailed by hasteneddevelopment and/or carbohydrate shortage. There is little physiologicalexperience with wheat at high temPeratures, but some o<strong>the</strong>r plant genera showremarkable <strong>the</strong>rmal adaptation. It is possible to leng<strong>the</strong>n <strong>the</strong> seeding-tofloweringinterval in wheat with daylength and cold-sensitivity genes, <strong>the</strong>rebyincreasing biomass production. Selecting in such materialfor harvest index(currently very low) would seem a rational physiological approachforimprovement of yield potential. In order to avoid high temperatures at criticalstages, and to maximize water-use efficiency, it is desirable to have seeding dateand cultivar maturity class such thatflowering is around <strong>the</strong> coolest point of <strong>the</strong>year and, if <strong>the</strong> crop is rainfed, subsoil moisture reserves arefully explotted.Crop research comprises <strong>the</strong>complementary activities of adaptingenvironments to plants, and adaptingplants to environments. At first glance,<strong>the</strong>re is not much that agronomists cando about <strong>the</strong> <strong>the</strong>rmal regimes of <strong>the</strong>tropics, but genotypic adaptation tosuch conditions may offer possibilitiesto plant breeding. Genotypic adaptationto superoptimal temperatures is also ofinterest to physiologists; ecophysiologistsalready recognize manyadaptations to hot regimes in o<strong>the</strong>rplants (37). The tropics being a newenvironment for wheat. it might permiteasier prediction of advances than <strong>the</strong>well-trodden field of geneticimprovement in more temperate areas.In this paper. important features ofwheat climates in <strong>the</strong> tropics and ofyield determination in wheat will besummarized, before passing to specificphysiological problems of tropicalwheat and possible genotypicadaptations. Possible selection criteriaand interactions with agronomy wUlalso be discussed. Disease and weedfreeconditions and adequate fertilitywill be assumed. The indulgence isasked of researchers in <strong>the</strong> tropics for<strong>the</strong> author's haVing ventured fromtemperate agriculture into a field inwhich he has had little researchexperience.
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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
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
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: 20'7Table 4. Effect on lelf spot in
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 and 244: 241there is utiliz
Page 245 and 246: 243• Ammonium sulfate [(NH4)2S04]
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
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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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