Great Basin Naturalist


Common mallow (Malva neglecta Wallr.) and tomato (Lycopersicon esculentum L. var. Ace 55) were compared as to certain characteristics: CO2 fixation properties, ribulose diphosphate carboxyl activities, (RuDPCase) photosynthesis, respiration, and compensation points. Significant differences in these factors were observed in all cases except dark respiration. Mallow enzyme (RuDPCase) activities were higher per unit of enzyme than those of tomato. The Mallow RuDPCase exhibited slightly higher activity at 5 to 25 C. Mallow leaves retained their capacity for photosynthesis and respiration after long periods of exposure to subfreezing temperature. The cold adapted mallow had a higher CO2 compensation point, suggesting a lower efficiency for CO2 fixation. The results suggest that cold acclimation in common mallow affects photosynthesis but has little effect on respiration.