A Chilling Response Test for Early Growth Phase Maize
- D. Mark Hodges ,
- Robert I. Hamilton and
- Christiane Charest
Results from a new laboratory screening technique for the determination of chilling responses in maize (Zea mays L.) at the early growth phase were compared with those obtained from the field. This laboratory technique consisted of growing plants hydroponically in Styrofoam rafts floated on Hoagland's solution at a constant low temperature. Seedlings of eight inbred maize lines were pinned into the rafts and placed in controfied environment chambers at 11°C and 98% relative humidity for 28 d until the four-leaf stage. A control test used a constant 25°C for 7 d, at which point all lines were at the four-leaf growth stage. Total, shoot, and root dry mass, and the shoot and root water content were the responses measured. Comparisons between the chilling and the chilling/control ratios showed that they were good indicators of chilling tolerance. Field trials of the same eight inbreds were sown in Ottawa (45°24′ N, 75°43′ W) in the early spring of 1992 and 1993 and the shoot dry mass recorded at the four-leaf stage. The chili/control ratios of the shoot dry mass of seven of the eight lines from the laboratory were correlated with the averaged field shoot dry mass (r = 0.780, P = 0.032). Thus, this laboratory screening procedure was successful in that the lines indicated by shoot dry mass to be the most chilling resistant or the most sensitive in the laboratory responded similarly in the field.
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