An examination was made of the ability of the previously defined growth parameters to distinguish between Marquis and several other cultivars of wheat under controlled non-hardening (25 °C) and hardening (2–4 °C) temperature conditions. The spring wheats Marquis and Pitic were compared with the winter wheats Cappelle, Talbot, Rideau, and Kharkov. The maximum growth coefficient, kmL, for cv. Pitic significantly exceeded all others, those for Cappelle and Rideau were intermediate, and that for Talbot was lowest, but the range for winter wheats was not different from that for spring wheats at either temperature. Considerably reduced growth occurred under the lower temperature but neither the inverse relationship that is generally recognized to exist between plant growth and hardiness nor the recent evidence for growth in hardening tissues themselves were supported by any quantitative match between the growth parameters and freeze tolerance. It was concluded that the intrinsic growth coefficient, rather than the gross growth coefficient with its storage component, must be determined for correlation with hardening.
