Physiological study of drought-tolerant Nassella tenuissima under water

We measured some of the physiological markers of the annual grass species Nassella tenuissima during a period of water stress imposed by potted water control to provide a theoretical basis for conservation management and rational use of this grass in the garden. Results showed that growth rate, in terms of plant height, and leaf relative water content of plants treated with 20%, 40% and 60% (D20, D40, and D60 treatments) of soil maximum water-holding capacity decreased significantly with duration of the drought stress. After rewatering, the difference in leaf relative water content between D20, D40 and D60 treatments, relative to the controls (80% of soil maximum water-holding capacity) was 7.11%, 2.68% and 0.80%, respectively. Plants under treatment 20 did not return to the control level, and the difference between the two was highly significant (P<0.01). Relative electric conductivity and malondialdehyde (MDA) content increased gradually with increasing duration of water stress. After rewatering, relative electric conductivity of each treatment increased by 12.1%, 5.92%, and 2.42% over the mean control value, respectively. MDA contents were 152.18%, 151.92%, and 133.97% relative to the control, respectively, and the difference was highly significant (P<0.01). Under water stress, superoxide dimutase (SOD) and peroxidase (POD) activities increased first and then decreased. After rewatering, SOD activity of D20, D40, and D60 treatments returned to 82.65%, 90.68% and 97.13% of the control level, respectively. Again, plants under treatment D20 were significantly different(P<0.05)with respect to the control, while the rest of the treatments returned to control level. POD activity in D20, D40, and D60 plants was 7.54%, 5.55% and 11.73%, respectively, compared with control. D20 and A40 treatments were significantly different(P<0.05)from controls. Based on these observations, we conclude that N. tenuissima is characterized by a remarkable drought resistance; it can adapt to 40% of soil maximum water-holding capacity, and, furthermore, it was an excellent garden ground-cover plant in arid areas.