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Sprague and Tatum (1942) demonstrated that GCA effects were larger and more important for unselected lines and that SCA effects were more important in crosses between lines that have had previous testing. Jenkins (1935) and Sprague (1946) demonstrated that the combining ability of lines was established relatively early in the inbreeding process and remained relatively stable thereafter. The collective information provided by these studies have established that the potential value of new lines can be determined in the early generations (51 to S3) of inbreeding with the use of the testcross procedures. The production and evaluation of testcrosses is a very important and standard component of all modern hybrid corn breeding programs. Although testcrosses are a standard and key component, there are variations among maize breeders when testcrosses of new lines are produced and tested. The generation used to produce and conduct testcross evaluations varies among plant breeders, but all conduct testcross evaluation of lines at some stage of inbreeding (Table 10). It. seems, however, that maize breeders are gradually evaluating lines at earlier stages of inbreeding, even earlier than the data reported by Bauman (1981). The proponents of early testing (Jenkins, 1935; Sprague, 1946) did not claim that a perfect correlation would occur between early and later generation testcrosses. Proponents for early testing indicated that the only value of early generation testing was to only continue breeding effort in those lines that had above average combining ability---they claimed no more or no less for advantages of early generation testing. Additional support for the value of early generation testing includes the progress realized from recurrent selection programs (Hallauer, 1992) and the ineffectiveness of visual selection for agronomically important traits (Table 9). It seems testcross evaluation will continue to be conducted at earlier generations of inbreeding to determine the relative combining ability of new lines with testing conducted with fewer replications--more evidence of the value of early testing. Recurrent selection and com breeding Each of these two aspects have been discussed separately, but it is only if both aspects are considered equally important that the potential of both will have their greatest benefits (Hallauer and Miranda, 1988). Eberhart et a1. (1967) outlined how the products of recurrent selection can be used effectively to provide products for both the small and large growers in Kenya. The same applications can be made in any situation whether the programs are focused on improved cultivars or emphasis given to developing inbred lines for use in single-cross hybrids. Neither of the methods, which are quite different operationally and have different objectives, have clear advantages over one another (Duvick, 1977). Some excellent lines have been developed by classical pedigree breeding methods (C103, Oh43 , and Mo17) and some excellent lines have been Table 10. Initial samples sizes, selection intensity during inbreeding, and generation of inbreeding that lines are evaluated for combining ability (Adapted from Bauman, 1981). Generation of inbreeding Number of progenies Initial sample Previous generation Generation for testcross evaluation so S1 S2 S3 54 55 Other 500 500 180 80 40 100% 36 16 8 100% 36 44 50 0% 18 33 27 9 13 developed by recurrent selection methods followed by pedigree selection (B14, B37, B73 and B84). All of these lines also have been effectively used in developing recycled lines by pedigree selection methods (Smith, 1988). Hence, the materials developed by either of the two distinct 174
eeding methods have contributed to the genetic progress realized since the inbred-hybrid concept was proposed by Shull (1909). Both methods contribute to the develop of lines: line developed from recurrent selection programs are used in pedigree selection programs of elite-line crosses, and pedigree selection methods are used in developing lines from different cycles of recurrent selection. Recurrent selection programs that are not an integral part of applied breeding programs probably, in most instances, will not have a direct impact on the applied breeding program. This can happen because the traits emphasized in recurrent selection .programs may not be the ones that are necessary in the applied breeding programs. If the same individuals are directly involved with both germplasm enhancement and development of lines and hybrids, a concerted and coordinated effort for genetic advance of the important traits necessary for a given area will be ensured. Gonducting recurrent selection programs without any coordination with the applied breeding programs will not be a fruitful endeavor. References Bauman, L.F. 1977. Improvement of established maize inbreds. Maydica 22:213-222. Bauman, L.F. 1981. Review of methods used by breeders to develop superior hybrids. Proc. Annu. COrn SOrghum Ind. Res. Gonf. 36:199-208. compton, W.A., and R.E. comstock. 1976. More on modified ear-to-row selection. Crop SCi. 16: 122. comstock, R.E. 1964. selection procedures in corn improvement. Proc. Annu. COrn SOrgh,-", Ind. Res. COnf. 19:87-94. comstock, R.E., H.F. Robinson, and P.H. Harvey. 1949. A breeding procedure designed to make maximum use of both general and specific combining ability. Agron. J. 41:360-367. COvarrubias-Prieto, J., A.R. Hallauer, and K.R. Lamkey. 1989. Intermating F 2 populations of maize. Genetika 21:111-126. Devey, M.E., and W.A. Russell. 1983. Evaluation of recurrent selection for sta'ik quality in a maize cultivar and effects on other agronomic traits. Iowa State J. Res. 58:207-219. OUvick, D.N. 1977. Genetic rates of gain in hybrid maize yields during the past 40 years. Maydica 22:187-196. Eberhart, S.A. 1970. Factors affecting efficiencies of breeding methods. African SOils 15:669 680. Eberhart, S.A., M.N. Harrison, and F. Ogada. 1967. A comprehensive breeding system. Zuchter 37: 169-174. Eyherabide, G.H., and A.R. Hallauer. 1991. Reciprocal full-sib selection in maize. I. Dire~t and indirect responses. Crop Sci. 31:952-959. Gardner, C.O. 1961. An evaluation of effects of mass selection and seed irradiation with thermal neutrons on yield of corn. Crop SCi. 1:241-245. Hallauer, A.R. 1985. compendium of recurrent selection methods and their application. Critical Reviews Plant Sci. 3:1-24. Hallauer, A.R. 1990. Methods used in developing maize lines. Maydica 35:1-16. Hallauer, A.R. 1990. Germplasm sources and breeding strategies for line development in 1990's. Proc. Annu. COrn SOrghum Res. Gonf. 45:64-79. Hallauer, A.R. 1992. Recurrent selection in maize. Plant Breeding Rev. 9:115-179. Hallauer, A.R., and S. A. Eberhart. 1970. Reciprocal full-sib selection. Crop SCi. 10:315-316. Hallauer, A.R., and J.B. Mirada Fa. 1988. Quantitative Genetics in Maize Breeding. Iowa State Univ. Press. Ames, IA. Hallauer, A.R., W. A. Russell, and K.R. Lamkey. 1988. COrn breeding. p. 463-564. In G.F. Sprague and J.W. Dudley (ed). COrn and COrn Improvement. American Society of Agronomy, Madison, WI. Hopkins, C.G. 1899. Improvement in the chemical composition of the corn kernels. Illinois Agric. Exp. Stn. Bull. 55:205-240. Horner, E.S. 1985. Effects of selection for S2 progeny versus testcross performance in corn. Proc. Annu. COrn SOrghum Ind. Res. Gonf. 40:142-150. 175
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Proceedings of the Fifth Asian Regi
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Page Foreword List of participants
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For several years, the Asian countr
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LAOS MALAYSIA MYANMAR NEPAL PAKISTA
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Chamnan Chutkaew Dept. of Agronomy
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I t· PRIVATE PRIVATE SECTOR: SECTO
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Pioneer Overseas Corp. ProAgro Seed
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MP COP NGOs TK = Muriate of Potash.
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Table 3. Land suitability for maize
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Depending on how this wheat is rele
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Individual field sizes in the GKF a
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Table 12. Demonstration block resul
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alance of composite, synthetics and
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Elias, S.M., F.S. Sikder and J.Ahme
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~IZE ItAIMJ4ENT PRXJW4ME IN IHlf'AN
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3. Low level of soil fertility. Exp
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3. Farmers could not afford to purc
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Table 1. Hybrid maize production in
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100,000 mu (1 ha = 15 mu). Fran 198
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+ The planting area of inbred line
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ty levels. Selection interia should
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Dao13, Oa19, SSE232 etc.). b. combi
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~ZE I~ IN IN>IA - AN OVERVIEW WITH
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inbred 1ines possessing good genera
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Table 3. Details of medium and earl
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increasing the yield levels of the
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Production of ~zygous diploid inbre
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EntQllOlogical research. In the fie
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A 1) OUr coordinated efforts for ma
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Table 1. Maize area harvested, proW
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Table 4. Grain yield of Semar 1 and
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ut they have been selecting ears fr
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MAIZE ~ N«J ~ION IN LAOS. Kanyavon
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to rice in order to reach self-suff
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0\ 0\ ."'0- ~I.u'. u: 0 50 100 STAT
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. According to the findings of the
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IR:EDIIIG IHJ N:RHJotIC RESEAfDI C
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tion with estate or mini-estate typ
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Table 4. MYR grain maize yields ove
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techniques. References Anonymous. 1
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Table 1. Total area under maize and
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Year Township Area planted Total pr
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cover, short plant stature, and sat
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Table 3. Res.Stat. Multilocational
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3. Plant protection: a. Diseases Th
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Questions to the author: FROM: S. K
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were unacceptable in some parts due
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Table 2. CCRI maize hybrid yield tr
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HYBRID MAIZE BREEDlt.G AN> ALH»DII
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of highly productive technologies,
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Maize varietal improvement continue
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Peronosc lerospora phi 1ippinensis
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elow to help clarify the farm level
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Premium Grade (emulsifiable concent
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support. The versatile planter/fert
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Table 1. Climatic conditions in the
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T1l1t:i----------------------------
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the maha season. Yala season is cha
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. Spacing Blackgram Maize 40 em x 5
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Sri Lanka. Ariyanayagam, R. P. 1967
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It took almost 10 years to develop
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g; CUS0 4 (5H 2 0): 0.39 g; NaF: 0.
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3. Making single cnosses: Plant the
Page 130 and 131: experiments showed that the fertili
Page 132 and 133: Long term evaluation of mass releas
Page 134 and 135: Chang, S.C., and Y.Z. Wu. 1976. Pra
Page 136 and 137: DEVELCHENT OF HYBRID ~ IN THAILAN>
Page 138 and 139: Table 2. Quantity and value of Thai
Page 140 and 141: was approved by KU and OOA in 1991
Page 142 and 143: Table 8. Mean yields of fresh dehus
Page 144 and 145: 4. Prevention and control of aflato
Page 146 and 147: Table 17. Mean grain yield and agro
Page 148 and 149: Sittipanuwong, S., C. Chutkaew, A.
Page 150 and 151: Early rainy season plantings have a
Page 152 and 153: P. R.CHINA TMilAKD CAMPUCHiA
Page 154 and 155: In 1992, the hybrid maize acreage i
Page 156 and 157: organizing visits as well as field
Page 158 and 159: Table 1 Area, production and yield
Page 160 and 161: plants per hill) 4. Intercropping e
Page 162 and 163: VIEl1'W4 YELLOW MAIZE EXRRT: MARKET
Page 164 and 165: 6,------------------~3,5 Producllon
Page 166 and 167: MAIZE BREEDUG Arnel R. Hallauer-L!
Page 168 and 169: method was provi ded by Eberhart (1
Page 170 and 171: can vary by the complexity of inher
Page 172 and 173: Table 3. Response to selection for
Page 174 and 175: Table 5. Comparative responses for
Page 176 and 177: increased response for grain yield.
Page 178 and 179: Sure Crop (0h43 and C103). several
Page 182 and 183: Horner, E.S., E. Magloi re, and J .
Page 184 and 185: evaluation are conducted in only on
Page 186 and 187: Table 1. Maize: Production Unit 100
Page 188 and 189: Table 3. Maize: Area harvested Unit
Page 190 and 191: v) Incentives to private sector are
Page 192 and 193: possible through adoption of suitab
Page 194 and 195: will be described highlighting thos
Page 196 and 197: will fluctuate. As a general rule,
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Page 200 and 201: Table 4. Possible heterotic partner
Page 202 and 203: use as OPVs and broad based synthet
Page 204 and 205: c. Integrat;on of populat;on ;mprov
Page 206 and 207: Table 8. Announced CIMMYT lines 199
Page 208 and 209: HYBRID MAIZE ~ 1l£ SMALL-SCALE FNI
Page 210 and 211: Table 2. Growth rate of maize area
Page 212 and 213: At the same time that CIMMYT was sh
Page 214 and 215: when grown under farmers' condition
Page 216 and 217: seed often varies substantially bec
Page 218 and 219: kilograms of maize grain that must
Page 220 and 221: Table 8. COst of producing, process
Page 222 and 223: case in which the hybrid replaces a
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Page 226 and 227: egions which do not allow a suffici
Page 228 and 229: participation; where foreign compan
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Wellhausen, E.J. Walden (ed.) 1978.
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To recover value, seed companies ca
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In recent years, many new companies
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nology and its reliance on patents,
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Table 6. Intellectual property righ
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for crop improvement programs. It i
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capabi 1ities Despite these constra
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TftNlAlll CAMPUCI-1iA Fig. 1. Seven
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* Yield potential of 8.0 t/ha. II.
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CAOOILL MAIZE RESEAFDI ACTIVITIES I
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RESEARCH AN> POTENTIAL OF HYBRID (X
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ClBA SEEDS IN SJJ11£AST ASIA. Jose
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ACTIVIlY OF MAHYOO IN INJIA Rajendr
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PACIFIC SEEDS - PlANT ~ FOO ASIA Pe
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Questions to the author: FROM: R. S
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Just start In 1980 the demonstratio
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VOLUME 1000 IQnt/ 10.--------------
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(Notes by Dr. V.L. Chidley, Raporte
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1. Rhizoctonia leaf and sheath blig
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