Effects Of Different Planting Methods On The Growth Of Vallisneria Natans In The Dynamic And Static Water Environment

Planting methods serve as an important technical means of restoration and reconstruction of Vallisneria natans,which also have a certain impact on the growth of V.natans.Furthermore,most of the influencing factors of V.natans were carried out in a static water environment,which can not accurately simulate the dynamic water environment of the lake,ignoring the influence of the dynamic water environment on the influencing factors and the growth of V.natans.This research set static water environment and constant dynamic disturbance of the water to study the growth of V.natans under the condition of cutting,gauze wrapped and covered soil in bag,and compare the growth of V.natans in the dynamic and static water environment.Then the research try to find the best planting methods to the growth of V.natans and to provide a new idea of dynamic and static water environment for the study of the factors affecting the growth of V.natans.The following conclusions are obtained by experimental study and result analysis:(1)In terms of the morphological characteristics,different planting methods have significant effects on the number of ramets,plant height,leaf width and root length of V.natans.The result showed that the average plant height and average leaf width of V.natans were obviously higher than those of cutting and gauze wrapped under the pattern of covered soil in bag,but the number of ramets and average root length of V.natans were less than that of cutting and gauze wrapped.The dynamic and static water environment only had a significant effect on the number of ramets of V.natans,and had no significant effect on other morphological indexes.The static water environment had more ramets than the dynamic water environment at the same planting method.(2)Different planting methods have significant effects on the biomass and chlorophyll content of V.natans.The result showed that the average dry weight of aboveground part,average dry weight of underground part,the average dry weight of biomass and the chlorophyll content of V.natans were obviously greater than those of cutting and gauze wrapped under the pattern of covered soil in bag,but the ratio of underground to aboveground part of V.natans was less than that of cutting and gauze wrapped.The dynamic and static water environment had no significant effect on the biomass and chlorophyll content of V.natans.The biomass and chlorophyll content of V.natans in the static water environment is slightly better than that in the dynamic water environment(3)V.natans have a better removal effect on TN and TP in water.The removal rate of TN and TP in water decreased with the increase of biomass,and the removal rate of TN and TP in cutting was higher than that of gauze wrapped and covered soil in bag.Constant dynamic disturbance of the water will cause the sediment in the water to resuspend.In the early stage of V.natans,the concentration of TN and TP in the water was higher than the initial concentration,and the removal rate was negative.The removal rate of TN and TP in the water under the static water environment was higher than that in the dynamic water environment.(4)Different planting methods had no significant effect on the DO and pH,so was the static and dynamic water environment.(5)During the experiment,due to the high temperature of the water,the growth of the V.natans in the static water environment showed varying degrees of coverage of the algae,but there was no algae in the dynamic water environment,indicating that the dynamic water environment can reduce the emergence or formation of the algae.(6)In the early stages of the cultivation of V.natans,different planting methods form a different micro-environment,which will have a certain impact on the growth of V.natans.When the V.natans grow stable,the planting methods were no longer the main factor affecting the growth of V.natans,and the intraspecific competition caused by the increase of the density of V.natans became the main factor affecting the growth of V.natans.The single V.natans grows better under covered soil in bag than other two planting methods.In the relatively stable flow of lakes,the choice of cutting and gauze wrapped method is more conducive to the breeding of V.natans;in the relatively fast flow of water,poor barren lake,select the bag cover method is more conducive to the growth of V.natans.