Heterosis among Insect-Resistant Maize Populations
- N. W. Widstrom ,
- K. Bondari and
- W. W. McMillian
Information on heterosis is critical to assimilation of desirable traits into usable maize, Zea mays L., germplasm. Our objective was to identify maize populations with heterosis for desirable traits. Twelve southern-adapted maize populations with resistance to damage by ear and leaf-feeding insects and all 66 possible population crosses were evaluated in a randomized complete-block design in three environments. Population effects, heterosis, and specific combining ability (SCA) effects were estimated for seven plant traits. Population effects were significant (P ≤ 0.01) for all traits except yield, heterosis effects were significant for all traits, and SCA effects were significant for all traits except insect damage. Population and average heterosis effects were less important amongenetic effects than SCA, which accounted for more than one-half the heterosis sums of squares for all traits. Population performance as a predictor of relative crossbred performance was least effective for grain yield and quality. Average heterosis, relative to midparent values, varied from 2.2% for lodging to 22.$% for yield. Crosses existed with SCA effects for resistance to one or more insects for all traits. Genotype × environment interactions were significant for all traits except insect damage. Heterosis interactions with environment accounted for more variation than population × environment interactions. Among beterosis interactions with environments, those due to average heterosis and SCA effects were of greatest significance. The information will be useful in the development of germplasm with resistance to insects and improved agronomic performance.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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