| Abstrakt: |
The effects of recurrent selection in maize (Zea maysL.) for cold tolerance on genotypic ✕ environmental (G ✕ E) interactions for cold tolerance and other agronomic traits were studied using stability analyses. Selection altered G ✕ E interactions of traits subjected to direct selection (seedling dry weight and percentage emergence), but did not cause indirect selection effects in G ✕ E for seedling vigor score, grain yield, root lodging resistance, or grain moisture. Selected cycles had significantly higher and lower regression coefficients determined by the 1966 Eberhart‐Russell stability analyses for seedling dry weight and percentage emergence, respectively, than did the original populations. Use of the 1978 stability analysis by Moll and coworkers indicated that selected cycles had greater responsiveness in seedling dry weight to environmental variation and lower responsiveness in percentage emergence. Direct gain from selection was greatest in warmer environments for seedling dry weight and was greatest in cooler environments for percentage emergence. A stability analysis utilizing accumulated heat units as a physical assessment of environments was not an accurate measurement of environmental factors affecting these cold tolerance traits. Using the Eberhart‐Russell stability‐analyses, we found that regression coefficients of the selected cycles and original populations were not significantly different for seedling vigor score, grain yield, or root lodging resistance. Selected cycles had significantly lower regression coefficients than did the original populations for grain moisture. However, this change in G ✕ E by selection could not be simply interpreted in terms of responsiveness or correlations of entries in different environments. The data suggest that G ✕ E interactions may be altered for traits under direct recurrent selection, but not necessarily for correlated traits. |
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