Study on the water level ecological amplitude of the wetland plant Triarrhena lularioriparia

Water level plays an important role in the growth and development of wetland plants. To study the ecological responses of the growth and physiology of Triarrhena lularioriparia under different water levels, seedlings were used as the study materials and in 13 water level gradient treatment groups, -67, -54, -42, -34, -29, -16, -3.5, 10, 20, 30, 40, 50, 60 cm. The results showed that (1) the plant height, leaf number and root activity of T. lularioriparia first increased and then decreased with the increment of the water level gradient, and the highest values appeared at a water level of approximately 0 cm; (2) the concentrations of chlorophyll a (Chl a), chlorophyll b (Chl b), chlorophyll (a + b) (Chl a + b) and biomass first increased and then decreased with the increment of the water level gradient. The malondialdehyde (MDA) and antioxidant enzyme concentrations of T. lularioriparia first increased and then decreased, and both reached their maximums at a water level of approximately 20 cm. The soluble protein decreased and then increased with the change in the water level gradient and reached its lowest value at 31 cm; soluble protein increased slightly at 30-40 cm but showed a stable trend after the waterlogging depth exceeded 40 cm. (3) The water level ecological amplitude of T. lularioriparia was [-38.62, 41.07 cm], and the optimum water level ecological amplitude was [-11.04, 20.15 cm]. This study demonstrates that T. lularioriparia could adapt to drought and flooding stress to a certain extent, but it could be stressed if the water level exceeded the suitable range.