the Symposium on Wheats for More Tropical Environments - cimmyt

More documents

Recommendations

Info

214Briefly. plant development (<strong>the</strong> firstcomponent in Table 2) proceedsthrough four phases or periods.delineated by <strong>the</strong> successive discretestages of noral initiation, penultimateleaf emergence on <strong>the</strong> main shoot(approximate gUide to <strong>the</strong> onset of spikegrowth). an<strong>the</strong>sis and loss of green in<strong>the</strong> spike. Control of <strong>the</strong> duration ofeach period by <strong>the</strong> listed environmentalfactors and by genotype is reasonablywell understood. These stages are bestconsidered as representing switches in<strong>the</strong> allocation of assimilate or drymatter between different organs. First.<strong>the</strong> crop grows leaves and roots and. in<strong>the</strong> second period, stems as well. In <strong>the</strong>third period, commencing some 20 to30 days before an<strong>the</strong>sis, spikes andstems become <strong>the</strong> major sinks forassimilate; in <strong>the</strong> final period. grainsare <strong>the</strong> dominant sink.The second component in Table 2refers to <strong>the</strong> build-up of <strong>the</strong> leaf area inperiods one and two. Leaf area at <strong>the</strong>end of period two plays a major role indetermining spike growth (component3), a role best summarized in <strong>the</strong>percentage of solar radiationintercepted by leaves dUring <strong>the</strong> spikegrowth period which, along withphotosyn<strong>the</strong>tic rate and periodduration, determine total crop growthin <strong>the</strong> period. Approximately 25 to 50%(depending on cultivar) of this total dryweight at an<strong>the</strong>sis is considered pivotalin this analysis, because a giveninvestment in spike tissue (rachis,awns, floral parts, etc.) is necessary tobuild a competent floret (approximately10 mg. depending on <strong>the</strong> cultivar)., Therefore. spike dry weight determinespotential grain number; some environmentaland possibly genotypic factorsaround an<strong>the</strong>sis (component 4) can, intum, affect actual grain number byreducing grain set (grain per floret) toless than <strong>the</strong> <strong>the</strong>oretical maximum ofone.Understanding individual grain-weightdetermination follows more broadlyaccepted lines [component 5);conditions soon after an<strong>the</strong>sis maydetermine potential grain weight, butoften limitations on <strong>the</strong> duration and/orrate of grain filling affect <strong>the</strong> realizationof this potential, with final grain weightfalling below potential, especially if<strong>the</strong>re are many grains to be filled.In situations without water limitation,for a given an<strong>the</strong>sis date, a simple yieldindex can be derived which integrates<strong>the</strong> major environmental effects listedin Table 2. This relies on <strong>the</strong> fact thatgrain number is reasonably wellpredicted by <strong>the</strong> photo<strong>the</strong>rmal quotientover <strong>the</strong> 20 to 30 days precedingan<strong>the</strong>sis (17,27). Photo<strong>the</strong>rmal quotient(Q) is defined as mean solar radiationdivided by mean temperature less4.5°C (units of MJ/m2/d/degree). Itspecifically integrates <strong>the</strong> positive andlinear effect of radiation on crop growthrate and of mean temperature (less basetemperature) on developmental rate(reciprocal of duration). Hence, asdefined, it is an index of total cropgrowth in <strong>the</strong> approximate spikegrowthperiod. It can be improved bycorrecting for incomplete radiationinterception (<strong>the</strong>reby reducing Q) insituations where leaf-area index isinsufficient in this period for full lightinterception (e.g., ~3).The relationship of grain number tocorrected Q (and to total dry weight atan<strong>the</strong>sis) for a set of representativecultivars and a range of sowing datesand sites in central Mexico (20°Nlatitude) is shown in Figure 2; PozaRica and Tlaltizapan have hot andhumid and hot and dry tropicalregimes, respectively. A similarrelationship was derived from a widerange of sowing dates and years at <strong>the</strong>CIANO station in Ciudad Obregon innorthwest MexiCO (R.A. Fischer,
216unpublished). A role of thumb derivedfrom this work suggests <strong>the</strong> followingsimple relationship for good growingconditions and semidwarf cultivars:Grain number/m2 = 11.000 xcorrected Q (Equation 1)At <strong>the</strong> same time. in many studies (i.e..39). individual grain weight appears tobear a consistent negative linearrelationship to grain-fi1l1ng temperature.This relationship could not be derivedin central Mexico because of diseaseattack during grain filling at severalC'iIi~~2016100AAA•Be6 @>00.6 1.0 1.6Corrected Photo<strong>the</strong>rmal Quotient(Mj/m2/degree)2.0OPoza Rica.. TlaltlzaPaneEl Batan• Toluca•AAA600 '7150 1000 12CK)TWA (gIm2)I'tpre 2. The r.latioa....p of.......,..2 to a) corrected photo<strong>the</strong>rmalquotient ID <strong>the</strong> 30 4&,.. before &a<strong>the</strong>". (Me teu) &ad b) total drJ' welptat ath..... Kuala are <strong>the</strong> a••ace of 10 to 19 '.Dotype. Mwa at foar"tea ill ceDtralll.zlco (aboat 20-1f lat). Pou Rica (80 ID). TIa1tlApaa (940ID). &1 BataD (2249 ID) ad Toluca (2840 ID).8oarce: IIldJDore et ale (27)
Page 2 and 3:
The International Maize and Wheat I
Page 5 and 6:
3AcknowledgementsThe Tropical Wheat
Page 7 and 8:
5Wheat Production in Bangladesh: It
Page 9 and 10:
7Chemical Control ofHelmtn.thosport
Page 11 and 12:
1 9PrefaceThe international worksho
Page 13 and 14:
uToluca, a high-elevation station a
Page 15 and 16:
13In Bangladesh. many farmers' fiel
Page 17 and 18:
global cooperation that permits apo
Page 19 and 20:
17Recognizing the
Page 21 and 22:
19With UNDP assistance. CIMMYTexpan
Page 23 and 24:
4 21Introduction to the</st
Page 25 and 26:
23grain-filling stages are required
Page 27 and 28:
Table 1. Countries growing whut in
Page 29 and 30:
27Month of sowing and month afterfl
Page 31 and 32:
29. Table 3. Correlation coefficien
Page 33 and 34:
31Earliness-Earliness is needed if
Page 35 and 36:
33requires more than technical solu
Page 37 and 38:
3~from other crops
Page 39 and 40:
37Table 2. Advanced lines selected
Page 41 and 42:
39If Bol1via does not radically cha
Page 43 and 44:
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 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 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 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 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: 213Table 2. Wheat yield determinati
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
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
Page 295 and 296:
293On average, no more that 100 mm
Page 297 and 298:
295Storage in 20-liter biscuit or k
Page 299 and 300:
Production, Storageand Marketing of
Page 301 and 302:
299true to type. are selected and t
Page 303 and 304:
301discussed and ascertained; <stro
Page 305 and 306:
303V. EconomicsWheat in the
Page 307 and 308:
305than in Asia and Africa (about 1
Page 309 and 310:
307wheat consumption). However, <st
Page 311 and 312:
309These changing consumption patte
Page 313 and 314:
311Finally. it should be clarified
Page 315 and 316:
313in areas where wheat yields arer
Page 317 and 318:
31510. FAO. 1982. The bread economy
Page 319 and 320:
317Lowlands withinadequate dry-seas
Page 321 and 322:
319Table 1. Private and social prof
Page 323 and 324:
The Local-Use Approach to t
Page 325 and 326:
323fired oven has been used at oneu
Page 327 and 328:
325ControlliDg fungal diseasesThe i
Page 329 and 330:
The Relative Priority andEconomics
Page 331 and 332:
329Comparative MarketPrices of Stap
Page 333 and 334:
331References1. Agricultural Extens
Page 335 and 336:
Table 1. Area, average yield and to
Page 337 and 338:
Table 3. Annual domestic wheat prod
Page 339 and 340:
337Table 5. Financial costs of whea
Page 341 and 342:
Comments'D.L. WiDkelmaDll, DIrector
Page 343 and 344:
7341------_1Closing Remarks, <stron
Page 345 and 346:
343Table 1. Probleml for th
Page 347 and 348:
345While efforts to develop wheatge
Page 349 and 350:
347Appendix IIWheat Pests and Disea
Page 351 and 352:
349Appendix IIIParticipants. <stron
Page 353 and 354:
351NigeriaMr. Ahmed M. FalakiResear
Page 355 and 356:
353CIMMYT Staff. MexicoMr. Robert D
show all

the Symposium on Wheats for More Tropical Environments - cimmyt

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?