| The water-falling zone is the section below the bank of the lake and the river,which expose on the wet and dry alternately.Therefore,plants grown in the fading zone must be both water-resistant and drought-tolerant.In order to screen plants for the decline zone of Danjiangkou Reservoir,three kinds of herbaceous plants that have been planted in Nanyang for many years-vetiver,calamus and cattail,were selected for planting in different degrees of flooding and drought conditions in this study.The growth and morphological changes of three kinds of plants under water flooding and drought conditions were analyzed,and the flood tolerance and drought resistance were compared.The main results are as follows:1.After removing the aerial parts of the three plants,the underground roots were subjected to a flood test for 6 months.Statistical growth patterns,physiological and biochemical indicators are as follows:1)Sprouting rate of buds are 80%,49%,and 0% for Calamus,Vetiver and Cattail,respectively;2)After 6 months root-flooding,the plant height,root length and biomass of Calamus increased significantly compaired with control,but was not inceased significant for vetiver;3)After 6 months root-flooding,photosynthetic efficiency,net photosynthetic rate,transpiration rate,stomatal conductance,chlorophyll content,root activity,and rhizosphere soil microbial biomass of vetiver and Calamus were increased more than control condition,and Calamus increased more than vetiver;4)After 6 months root-flooding,the SOD activity and CAT activity of vetiver increased significantly than control,but they increased slightly than control in Calamus.The content of MDA of Vetiver and Calamus increased slightly than control;The above results showed that the new buds germination rate of the Calamus was the highest,the ability to restore growth was the strongest,and the adaptability to the root-flooding environment was the best,the followed was Vetiver,the most difficult to adapt was Cattail.2.The water-immersed culture experiment was carried out on the three plant seedlings at different depths(shallow flooding 5 cm,semi-flooding 10 cm,deep flooding 15 cm)with normal watering as the control.The experiment was carried out for 6 months.The results show:1)Vetiver survival rate in shallow flooding,semi-flooding,deep flooding,were 83.1%,72.9% and 60.4%,respectively.Calamus survival rate in shallow flooding,semi-flooding,deep flooding were 91.8%,82.9% and 69.4%,respectively.The survival rate of the cattail is 0 in three flooding;2)After 6 months flooding,the plant height,root length and biomass of vetiver under shallow flooding increased significantly than control,but decreased than control under semi-flooding and deep flooding.The three index ofcalamus increased significantly than conteol under various water flooding depths;3)After 6 months flooding,the photosynthesis efficiency,net photosynthetic rate,transpiration rate and stomatal conductance of Vetiver and Calamus under three water flooding conditions were higher than that of the control.The chlorophyll content of Calamus increased significantly than control,but was different not significantly than control in Vetiver;The root vitality of Vetiver undershallow-flooding condition increased the most significantly than control condition,but increased no significantly under semi-submerged and deep-flooded conditions.While the calamus root vitality under semi-submerged and deep-flooded conditions increased the most significantly than control condition,but but increased no significantly underhallow-flooding.The roots microbial biomass of Vetiver and Calamus increased significantly in all flooding environments than control condition;4)After 6 months flooding,the activity of SOD of Vetiver and Calamus under three flooding conditions was not different than control condition.The CAT activity of Calamus increased significantly under three flooding condition than control condition,but was not increased significantly for Vetiver comparied with control;The MDA content of Vetiver under shallow-flooding condition decreased significant than control condition,but was not different under semi-submerged and deep-flooded conditions than control condition.The MDA content of Calamus was not decreased under three flooding conditions than control condition;This results indicated that the flooding tolerance of Calamus was the strongest,followed by Vetiver,and the weakest was Cattail.Calamus can be well adapted in the long-term and different water depths.Vetiver can adapt well to long-term and shallow flooding environments,and cattails cannot adapt to long-term flooding.3.The natural drought method was used to study the response of three plant seedlings to drought stress for 2 months.The results of the growth,physiological and biochemical are as follows:1)Counting the survival of three plants: from the first day of drought treatment,vetiver can survive for 69 days,calamus can survive for 31 days,and cattail can only survive for 18 days;2)After drought stress for 15 d,The plant height was decreased than control,but decreased degree was different between three plants.The plant height decrease comparied with control were 11.8%,32.5% and 47.1% for Vetiver,Calamus and Callail,respectively;3)After drought stress for 15 d,the maximum photosynthetic efficiency,chlorophyll content and root activity index of the three plants decreased significantly under drought stress condition than control condition,but the decreased degree of the three index for Vetiver was the lowest among there plants;4)After drought stress for 15 d,the SOD activity of the three plants decreased significantly comparied with control condition,but the decreased degree of Vetiver was the lowest among there plants.Comparied with control condition,The MDA content for Calltil and Camalus increased significantly,but increased slightly for Vetiver.Comparied with control condition,The CAT content for Calltil and Camalus decreased significantly,but increased slightly for Vetiver;Theis results indicated that the Vetiver showed the strongest tolerance to drought stress,and the adaptability of Vetiver to drought stress was significantly better than that of Calamus and Cattail.In conclusion,the growth state of Calamus was the best under different depths of water,followed by Vetiver,which was less inhibited by growth,and the Cattail was the worst among the three plants.The order of the tolerance to drought stress from strong to weak was: Vetiver> Calltil> Calamus.The above test results show that Vetiver not only has stronger sufficient flooding tolerance but also has stronger drought tolerance,which is most suitable for planting in the reservoir falling zone. |
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