| Wetland is often in a dry-wet alternate state,and the submergence depth and submergence time of plants vary periodically.Drought affects plant growth,photosynthesis and reactive oxygen species,and the submergence depth indirectly affects the growth and spatial distribution of emergent plants through the influence of environmental factors such as light and temperature under water.Typha orientalis is an aquatic plant of Typha family.It is a perennial water-bursting plant of the world species with strong ecological adaptability and wide distribution area.In this paper,the interaction between Typha orientalis and soil water condition and submergence depth was determined by control experiments in Typha orientalis.The results are as follows:1.The effects of different soil moisture conditions on the growth and physiology of Typha orientalis were studied through laboratory simulation experiments.The results showed that the growth of plant height,basal diameter and leaf characteristics were inhibited with the decrease of soil water content,and the plant withered and died under 9%soil water content for 36 days 114 d after 114 d under 14%soil moisture.22%38%of the soil moisture plants all grow well,and the growth trend is consistent.The biomass accumulation of Typha orientalis was the highest at 8.82 g/plant and8.78 g/plant with 36%38%soil moisture.The content of Chlorophyll a and b in Typha orientalis reached the maximum under 22%36%soil moisture,and the content of Carotene reached the maximum under 33%38%soil moisture.SOD activity was higher under water condition,and with the decrease of soil water content,the POD content in Typha orientalis increased.The CAT activity of plants was increased under high and low soil water content.Lower soil water content led to the decrease of soluble protein content and root activity,and the increase of MDA content in plants.2.The effects of different submergence depths on the growth and physiology of Typha orientalis were studied by setting different submergence depths.The results showed that after 60 days,most of the submerged plants were dead and the height of the plants was 89 cm,after 84 days,the submerged plants of 50 cm tended to die and the height of the plants was 157.02 cm.The leaf characteristics of Typha orientalis seedlings decreased with the increase of submergence depth.The biomass increment of root,stem and leaf of 040 cm waterlogged plants was the most,leaf was the next,stem was the least.The contents of Chlorophyll a,b and Car decreased with the increase of submergence depth.The effect of water depth on the activity of antioxidant enzymes in Typha orientalis was significant?p<0.05?.After 60 days,the activity of SOD increased by 149%700%,and the activity of POD and CAT increased first and then decreased with the increase of water depth.The contents of soluble protein and Malondialdehyde increased with the submergence depth,while the root activity decreased with the submergence depth,from 0.95 mg·g-1·h-1 to 0.23mg·g-1·h-1.Water depth of 5060 cm inhibited the growth and physiology of Typha orientalis,and 040 cm submergence was beneficial to the growth of Typha orientalis population and the recovery of aquatic ecosystem.3.According to the fitted equation,the ecological range of Typha orientalis was analyzed by mathematical method.The optimum water level for Typha orientalis growth was about 14.43 cm,and the limit water level for Typha orientalis was-52 cm and 74.93 cm,water levels above 74.93 cm and below-52 cm can not meet the normal growth and development of Typha orientalis. |
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