| With more and more serious water pollution and water eutrophication problem,is already become one of the difficult problems of environmental pollution control at home and abroad,received extensive attention of limnetic and environment experts around the world.The cultivation of aquatic plants,especially large aquatic plants,can be used as an efficient and low-consumption ecological method to improve water quality.In recent years,it has become one of the hotspots in the field of ecological environment.In this paper,we studied the effects of natural light / water depth on the germination,seedling growth and physiological characteristics of Potamogeton crispus,to explore the germination,growth process and physiological response mechanism under the different natural light / water depth condition.And provide certain theoretical basis to the restoration,establishment and stability of the ecosystem.The main results are as follows:(1)Effects of light intensity on germination,seedling growth and physiology of P.crispus:The germination rate reached 100% within the range of 20% ~ 100% natural light,under the extremity weak light conditions,the germination rate was low.The plant height and leaf number of P.crispus.had a trend of rise first then drop with the increase of light intensity.And the plant height,leaf number and biomass of P.crispus which within 20% ~ 60% of natural light grew well;As time goes on,the contents of Chl a,Chl b,Car and Chl a + b which in the leaves of P.crispus.had the trend of rise first then drop,and reached the maximum on 60% group at the early,but at the mid and late,the 20% group got over the 60% group,reached maximum.the root activity was larger in 20% ~ 60%,and the trend of plant height,leaf number and biomass is consistent.The Antioxidant enzyme activity of SOD,POD and CAT had a trend of increase first then decrease during the whole experiment,but the activities of SOD,POD and CAT in leaves were decreased,and the content of MDA rising constantly,in the range of 20% ~ 40% of natural light the content of MDA was lower,and the minimum was 1.85 umol · g-1.In the stage of germination of P.crispus,in the early stage of growth(60 days or so),60% of the natural light can ensure that its growth is good;And the late growth period,should be covered,20% of the natural light is appropriate,the highest should not exceed 40%.(2)Effects of water depth on germination,seedling growth and physiology of P.crispus:Under the different water depth condition,the germination of P.crispus was rapid in the first 60 days,after 60 days was slower,and the depth of 50cm~150cm was the best.At the beginning of the experiment,the height of 110cm~130cm P.crispus growth well,and the later stage of the experiment,the water depth of 70 ~ 90 cm was more suitable for the growth of P.crispus and the biomass trend of each group was consistent;The contents of Chl a,Chl b,Car and Chl a + b in the leaves of P.crispus had a trend of increase first then decrease,and the chlorophyll content in the range of 70-130 cm water depth was higher,and the root of 70 ~ 18 cm water depth of P.crispus grew well;The activity of SOD,POD and CAT in the leaves of P.crispus had a trend of increase first then decrease during the whole expeiment,and had a slower decrease of activity of SOD,POD and CAT within the depth of 70 ~ 110 cm in the later stage of the experiment,and the MDA content of each group had a rising trend with the extend of time.The content of MDA in the leaves of P.crispus.reached minimum in the 90 cm group.In the stage of germination of P.crispus,the water depth should be maintained in the range of 50cm-130 cm,in order to facilitate its germination.At the beginning of its growth,the water depth of 110cm-130 cm is beneficial to its growth,but the growth of P.crispus seedlings in the range of 70 ~ 90 cm,indicating that it grows in the middle and later growth in the shallow water environment. |
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