Heterotic Relationships among Nine Temperate and Subtropical Maize Populations

Mickelson, H.R.; Córdova, Hugo; Pixley, K.V.; Bjarnason, M.S.

doi:10.2135/cropsci2001.4141012x

Cited by 38 publications

(28 citation statements)

References 14 publications

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“…These heterotic groups were presented in detail by Gevers and Whythe (1987) and Mickelson et al (2001). Drought tolerant lines were selected under managed drought environments at CIMMYT, in Zimbabwe.…”

Section: Germplasmmentioning

confidence: 99%

Gene action controlling grain yield and secondary traits in southern African maize hybrids under drought and non-drought environments

Derera

Tongoona

Vivek³

et al. 2007

Euphytica

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Breeding maize hybrids for drought tolerance would significantly reduce yield loss due to drought in southern Africa. Mode of gene action controlling yield and secondary traits was investigated by mating 27 inbred lines, in sets according to a North Carolina design II scheme. The resultant 72 experimental and eight commercial hybrids were evaluated in 8 · 10 a-lattice design with two replications, in four drought and two non-drought environments. Under drought conditions, only general combining ability (GCA) variance was significant for yield, indicating predominance of additive effects. In non-drought environments, both GCA and specific combining ability variances were significant for yield, indicating importance of additive and non-additive effects, respectively. Contributions of male (GCA m ) and female GCA (GCA f ) effects to hybrids varied depending on the trait and conditions. Superior GCA f to GCA m effects for yield under drought conditions, and for ASI, prolificacy and ear aspect under both drought and non-drought conditions, suggested that maternal effects might have modified these traits. Larger GCA m than GCA f for ASI and silking dates under normal conditions indicated that paternal genotypes played a greater role in determining these traits. Similar GCA m and GCA f for yield under normal conditions, silking and anthesis dates under drought indicated that both parents made similar contribution to hybrids. Possibly, complications due to modification of traits by cytoplasmic effects and cross-over G · E for yield might partly explain why only a few drought tolerant hybrids have been developed. Practical implications of these findings in breeding drought tolerance in maize are discussed.

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Section: Germplasmmentioning

confidence: 99%

Gene action controlling grain yield and secondary traits in southern African maize hybrids under drought and non-drought environments

Derera

Tongoona

Vivek³

et al. 2007

Euphytica

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“…Thus, group A is thought to exhibit heterosis similar to N3, Tuxpeño, Kitale and Reid. Group B is thought to be exhibit heterosis similar to SC, ETO Blanco, Ecuador and Lancaster (Mickelson et al 2001). Materials deWned as being in group AB have high heterosis with both groups A and B germplasm.…”

Section: Genotype (Entry) By Environment Interactionmentioning

confidence: 99%

Combining ability amongst CIMMYT’s early maturing maize (Zea mays L.) germplasm under stress and non-stress conditions and identification of testers

Pswarayi

Vivek²

2007

Euphytica

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CIMMYT (International Maize and Wheat Research Institute) Zimbabwe's early maturing maize program, which aims to supply seed to approximately 4 million hectares of maize area in eastern and southern Africa, lacks adequate information on heterotic relationships among early maturing germplasm and has no early maturing testers for hybrid development. Open-pollinated varieties (OPVs) and hybrids are the products targeted for this region. Among the hybrids, three-way and doublecross hybrids are desired. Thus the use of single crosses as testers would be an appropriate choice for such a breeding program as one could potentially identify three-way combinations during the early generation test. A twelve-parent diallel was formed and crosses evaluated to identify heterotic groups and single-cross testers. Crosses were evaluated under four diVerent environments in Zimbabwe, two optimal, one low nitrogen stress and one drought stress. P5 (an early maturing line from heterotic group A) and CML 395 (a late maturing inbred line from heterotic group B) were used as reference parents to establish heterotic groupings of germplasm used in the diallel. The single cross (P7/P8) was identiWed as a potential group A tester because of: (a) co-classiWcation of inbred lines into heterotic group A, (b) good yields-9.8 t/ha (optimal), 3.4 t/ha (low nitrogen) and 2.1 t/ha (drought); and (c) good GCA eVects for grain yield (0.49 t/ha) of line P7 while line P8 contributed to reduced height and anthesis-silking interval.

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“…Besides the high mid-parent heterosis observed in most crosses, high parent heterosis (h ii , not shown but easily calculated from table 2) must be also taken into account, and only those crosses with high means should be considered. Thus, the best crosses for SY (AxB, and AxD) showed h ij and h ii (in parenthesis) values of 10.3% (7.7%) and 17.4% (16.1%) respectively, while for EY, (Miranda Filho and Vencovky 1984, Crossa et al 1990, PerezVelazquez 1995, San Vicente et al 1998, Bertoia 2001, Mickelson et al 2001, Reif et al 2003, Soengas et al 2006.…”

Section: Source Of Variationmentioning

confidence: 95%