Cold sensitivity and biochemical adjustments in zoysiagrass under low temperature stress.

摘要

Common Zoysiagrass (Zoysia japonica) is widely used in the transition zone for sports turf due to its excellent texture and low demand of water. However, its green period and cold hardiness restricted use to a broader geographic region. The objective of this study was to investigate the field performance and related biochemical adjustment in zoysiagrass under low temperature stress during autumn acclimatization. Discoloration started when the average of minimum air temperature for 15 consecutive days (AT15) was below 15 degrees C followed by termination of shoot growth when AT15 was below 9.7 degrees C. Zoysiagrass went dormant when AT15 further decreased. Soluble sugar concentration in green leaves increased from 12.2 to 40.7 mg/g FW from 8 September to 8 November. Soluble sugar concentration in stolons peaked to 32.27 mg/g FW at AT15 of 14.6 degrees C and then decreased and maintained at approximately 25 mg/g until 8 November with AT15 at 4.9 degrees C. There was significant accumulation of proline in both green leaves and stolons during cold acclimatization with the concentration in stolons increasing earlier than in the leaves. At the end of cold acclimatization, proline concentration in stolons was 2.5 times that in the leaves. Significant total soluble protein increase was only detected in stolons although specifically induced proteins were found in both leaves (50 and 28 kD) and stolons (36 and 22 kD). Low temperature induced elevated malondialdehyde (MDA) levels in leaves during the cold acclimatization. Increased MDA was also noticed in the stolons when AT15 was between 14.6 and 4.9 degrees C. The physiological impact and low temperature adaptation of the biochemical changes in zoysiagrass is also discussed.