Chin J Plan Ecolo ›› 2007, Vol. 31 ›› Issue (3): 521-527.doi: 10.17521/cjpe.2007.0065
• Research Articles •
LI Jun; ZHOU Shou-Biao*; WANG Chun-Jing; LI Jin-Hua
Aims Dichondra repens is a warm-season lawn substitute that remains green for long periods and reproduces strongly. Dichondra repens forms short, dense cover and is important in conservation of water and soil. It retains its green color during winter to -8 ℃ with only slight leaf browning and is resistant to diseases and heavy metals contamination. Little is known about the drought tolerance of wild and cultivated D. repens. Our objectives were to determine the drought-tolerant characteristics of wild and cultivated D. repens and explore the physiological foundations for drought tolerance in both.
Methods We watered wild and cultivated D. repens every 3, 7 and 15 days from March 1 to May 1, 2004 and made growth and development measurements after water treatment. As soil drought conditions developed, we measured changes in superoxide dismutase activity (SOD), peroxidase activity (POD), nitrate reductase activity, soluble sugar content, free proline content, soluble protein, nitrate and nitrite (NO2-/NO3-) content and DNA fragments of leaves.
Important findings Under drought stress, the content of free proline, soluble sugar and NO2-/NO3- in wild and cultivated D. repens leaves was enhanced. Activities of SOD and POD were regulated, protecting leaf cells of wild and cultivated D. repens from oxidative damage caused by drought stress. There were marked differences in drought resistance between the wild and cultivated D. repens. Antioxidant enzyme activities and osmotic adjustment substance content in wild D. repens leaves were higher than in cultivated D. repens leaves, while damage to DNA of wild D. repens was less serious than in cultivated D. repens. NO2-/NO3- content and nitrate reductase activity in wild D. repens leaves were significantly higher than in cultivated D. repens. Maximum NO2-/NO3- content and nitrate reductase activity in wild D. repens leaves were 10 and 2.2 times larger, respectively, than that in cultivated D. repens leaves. Wild D. repens had more antioxidant response to drought stress than cultivated D. repens. Under drought stress, change of NO2-/NO3- content may be associated with endogenous NO concentrations, which probably cause the drought tolerance of wild D. repens to be greater than that of cultivated D. repens.
LI Jun, ZHOU Shou-Biao, WANG Chun-Jing, LI Jin-Hua. COMPARATIVE STUDY OF DROUGHT TOLERANCE AND TOLERANCE MECHANISMS IN WILD AND CULTIVATED DICHONDRA REPENS[J].Chin J Plan Ecolo, 2007, 31(3): 521-527.
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