Influence of Temperature on Heterosis for Maize Seedling Growth
- S. B. Rood ,
- R. I. Buzzell and
- M. D. MacDonald
Heterosis in crop plants may result partly from a superior ability of hybrids to tolerate environmental stress. The present study was conducted to investigate the influence of cool temperature on heterosis in maize (Zea mays L.). A four-parent diallel including reciprocals, from maize inbreds A632, B73, CH607-88, and CO109 was grown in controlled environment conditions under three temperature regimes: 20/10, 25/15, and 30/20°C (day/night). Leaf areas, heights and shoot dry weights were measured for growth analysis calculations. Potence ratios, representing the overall degrees of dominance, provided quantitative estimates of heterosis for the 12 hybrids. At all three harvests for all three temperatures, all hybrids had greater shoot dry weights and leaf areas and were taller than their parental inbreds. Consequently, potence ratios exceeded one for all parameters; considerable heterosis was observed in all hybrids at all temperatures. There were no general patterns of changes in potence ratios across the three temperatures. For example, mean potence ratios for leaf areas of the 12 hybrids over the three harvests were 16.7, 14.8, and 18.4, respectively, for the three temperature regimes. Thus, the level of heterosis in these hybrids was generally similar under favorable or unfavorable temperature conditions. This indicates that heterosis is not simply an ability of hybrids to better tolerate cool temperature stress. Rather, the hybrids from this group of elite inbreds displayed heterosis similarly under favorable or cool temperature conditions.
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