Leaf Gas Exchange and Plant Growth of Winter Rye, Triticale, and Wheat under Contrasting Temperature Regimes
- M. Winzeler,
- D. E. McCullough and
- L. A. Hunt
Field stands of winter rye (Secale cereale L.) often accumulate dry matter faster than wheat (Triticum aestivum L.). This study was conducted to determine whether this superiority is expressed at different temperatures and whether it is also apparent in triticale (✕ Triticosecale Wittm.), and to investigate the physiological reasons for the superiority. Rates of dry matter accumulation, dry matter partitioning, and net photosynthesis and respiration of fully expanded leaf blades were measured under controlled environment conditions of 10/7 °C and 20/15 °C day/night temperature. Total day matter accumulation rates of rye and triticale were consistently greater than for wheat irrespective of growth temperature. Intergeneric differences in light-saturated net photosynthetic rates were evident, with rates for rye being lower than those for wheat and triticale, but they were not significantly correlated to plant dry weight. In contrast, respiration rates of fully expanded leaf blades were 63 and 36% lower for triticale and rye than for wheat under the 10/7 °C temperature regime. At 20/15 °C, leaf respiration rates did not differ between rye and triticale, although both were 50% lower than wheat. Intergeneric differences increased and were more apparent for respiration of expanded leaves of plants grown at 10/7 °C as compared to 20/15 °C. The leaf respiration rates were negatively correlated (r = −0.86) to plant dry weights. Further investigation of the significance to crop productivity of the low respiration rate trait of rye appears warranted.
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