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Vasal, S.K.

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Vasal
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S.K.
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Vasal, S.K.

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1990 - 19995
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Region: Global × Start date: 1990 × End date: 1999 ×

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Now showing 1 - 5 of 5
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    Heterotic patterns of eighty-eight white subtropical CIMMYT maize lines
    (Consiglio per la Ricerca e la sperimentazione in Agricoltura, Unità di Ricerca per la Maiscoltura, 1992) Vasal, S.K.; Srinivasan, G.; Han, G.C.; Gonzalez Ceniceros, F.
    Hybrid-oriented source germplasm with established heterotic pattern is essential for initiating hybrid development. The objective of this study to identify and from heterotic groups of maize (Zea mays L.) with subtropical adaptation. Eighty-eight inbred maize lines derived from six CIMMYT subtropical maize populations and pools were crossed to four tester lines, one each from Pool 32 and Populations 34, 42 and 44. The 352 line x tester hybrid combinations were divided into four sets, each set comprising of crossed of 22 lines with the four testers, and evaluated during two seasons at Tlaltizapan, Mexico during 1989 and 1990. Mean grain yields for the four sets ranged from 9.0 t/ha (set 1) to 8.2 t/ha (set 4). General combining ability (GCA) and specific combining ability (SCA) for grain yield were calculated by line x testers analysis. Of the 88 lines tested, 14 from Population 44, 11 from Population 42, nine from Pool 32 and one from Population 34 had positive GCA effects for grain yield. Among testers, Tester 2 (Pop. 44) showed positive GCA effects for yield, and Tester 1 (Pool 32) had negative GCA effects for yield. Significant differences were observed for SCA effects for yield in the different line x tester crosses. Several combinations were identified having yields of 10 t/ha or more and possessing high SCA effects. Interpopulation crosses generally outyielded and had greater SCA effects as compared with intrapopulation crosses. Superior intrapopulation combinations, however, were observed among crosses involving lines from Populations 44. Two heterotic groups STHG "B" are being formed from these materials using the testcross data. Several of the lines included in this study were announced as CIMMYT maize lines (CML) during 1991 and are made available to our cooperators worldwide. Twelve of the 20 top-yielding single crosses (fice from each set) were between CML lines. The material and information generated from this study may be useful for future hybrid development work at CIMMYT and in other public and private breeding programs, particularly in the developing world.
    Publication
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    Inbred line evaluation nurseries and their role in maize breeding at CIMMYT
    (Consiglio per la Ricerca e la sperimentazione in Agricoltura, Unità di Ricerca per la Maiscoltura, 1999) Vasal, S.K.; Srinivasan, G.; Cordova, H.S.; Pandey, S.; Jeffers, D.P.; Bergvinson, D.J.; Beck, D.L.
    CIMMYT initiated its hybrid maize (Zea mays) research programme in 1985 in response to the growing needs of the national programmes for hybrid-oriented source germplasm. Since 1991 CIMMYT has released a total of 424 inbreds that are widely distributed and used by public and private sector researchers around the world. Inbred line evaluation nurseries are an important component of a hybrid research programme. At CIMMYT, inbreds are routinely evaluated for various biotic and abiotic stresses, their yield potential and other agronomic attributes. Several promising lines have been identified for specific stresses, although they were not selected during the development process which can be attributed to the genetic diversity of CIMMYT's source germplasm. Resistant/tolerant lines have been identified for abiotic stresses (drought, low-N use efficiency and acid soils). In addition, resistant lines have been identified for biotic stresses, including fusarium ear/stalk rot (Fusarium spp.), banded leaf and sheath blight (Rhizoctonia spp.), tar spot (Phyllachora maydis), grey leaf spot (Cercospora zeae-maydis), rust (Puccinia polysora), maize streak virus (MSV), fall armyworm (Spodoptera frugiperda), sugarcane borer (Diatraea saccharalis) and Striga. Lines with above average general combining ability and yield stability were identified. These lines are available for public use
    Publication
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    Heterosis and combining ability of CIMMYT's tropical late white maize germplasm
    (Consiglio per la Ricerca e la sperimentazione in Agricoltura, Unità di Ricerca per la Maiscoltura, 1992) Vasal, S.K.; Srinivasan, G.; Beck, D.L.; Crossa, J.; Pandey, S.; De Leon, C.
    Seven tropically adepted, late maturity maize gene pools and populations (Populations 21, 22, 25, 29, 32 and 43, and Pool 24) developed and improved at CIMMYT were crossed in a 7 x 7 diallel mating system. The parent and 21 crosses were evaluated for graind yiedl, days to silk and plant height at five locations in México, and one each in Colombia and Thailand. The objectives of the study were to determine the heterosis and combining ability among these materials and to identify appropriate germplasm suitable for hybrid development work. The combined analysis of variance for all three traits measured showed no significant genotype x environment (G xE) interaction. Genotypes themselves showed significant differences for all three traits, as did their partitions into partents and crosses. General combining ability (GCA) was significant for all traits whereas specific combining ability (SCA) was not significant for any of the traits. Mean grain yeild for the trial was 6.98 t/ha. the highest yielding combination was Population 21 x Population 43 (7.83 t/ha) followed by crosses of Population 22 with Population 32 (dent x flint) yielded 7.36 t/ha while exhibiting the maximun high-parent heterosis (12.7%) for yield. Population 43 (La Posta) was the tallest and latest parent and produced high yields in crosses whit other populations. All crosses to Population 43 per se. Population 21 (0.24 t/ha), Population 22 (0.13 t/ha) and Population 43 (0.23 t/ha) possessed significant positive GCA for yield. Populations 21 and 43 also showed significant positive GCA for days to silk while only Population 43 showed positive GCA for plant height. Aignificant (P <0.05) positive SCA effects for yield were observed in two crosses involving Population 32 whit Population 22 and 29 (flint x dent). Based on our study the best choices for initianting hybrid work are Populations 21, 22, 29 and 43. Many of the Tuxpeño based populations are ideal candidates forinterpopulation improvement using Population 32 (ETO Blanco) as heterotic partner.
    Publication
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    Heterotic patterns of ninety-two white tropical CIMMYT maize lines
    (Consiglio per la Ricerca e la sperimentazione in Agricoltura, Unità di Ricerca per la Maiscoltura, 1992) Vasal, S.K.; Srinivasan, G.; Pandey, S.; Cordova, H.S.; Han, G.C.; Gonzalez Ceniceros, F.
    Development of inbread-based populations which are heterotic to each other was considered one of the primary goals when CIMMYT started of this study were to determine the combining ability and heterotica patters of tropical maize(Zea mays L.) inbred lines developed at CIMMYT and to identify and form beterotic grous for the topics. 92 tropical late white inbred lines at S3-S6 levels of inbreeding derived from nine CIMMYT populations and pools were crossed to four tester lines(two dent and two flint).
    Publication
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    Heterosis and combining ability of CIMMYT's tropical early and intermediate maturity maize (Zea mays L.) germplasm
    (Consiglio per la Ricerca e la sperimentazione in Agricoltura, Unità di Ricerca per la Maiscoltura, 1990) Beck, D.L.; Vasal, S.K.; Crossa, J.
    A 10 parent diallel was formed to determine combining ability and heterotic patterns among CIMMYT'S tropically adapted, early and intermediate maturity maize (Zea mays L.) gene pools and populations. The parents and their crosses were avaluated for yeild (t/ha), plant and ear height (cm), and days to silk at five locations in México, and one each in Colombia, Ecuador, India and Thailand. The test for average heterosis, parents vs. crosses, was significant for graind yield, and plant and ear height in the combined analysis of variance. General combining ability (GCA) was significant for all traits. Specific combining anility (SCA) was significant anly for ear height. Although yield heterosis over the better parent was low in most crosses, moderate levels were observed in the Population 49 x Population 26 cross (9.6%). Population 26 also combined over the better parent. Pool 22 had the highest GCA effect for yield (0.37 t/ha), and was a parent in three of the five top yielding crosses. High yielding combinations included Pool 22 with Pool 20 (6.33 t/ha), Population 23 (6.24 t/ha), and Population 26 (6.23 t/ha). However, maximun heterosis over the better parent was only 3.2% in these crosses. The only cross wiht a significant positive SCA effect for yield was Population 23 x Pool 20 yielding 6.13 t/ha with 6.7% heterosis. Heterosis for plant and ear height, and days to silk were generally low. Based on our study, the best choices for initiating hybrid work among white grain materials are Population 23 and Pool 20, and among yellow grain materials Populations 26, Pool 21, and Pool 22.
    Publication