Effect Of Biochar On Seed Germination And Growth Of Vallisneria Natans

Biochar has many environmental benefits due to its special structural properties and material characteristics,it has generated great interest in water remediation for scientists in recent years.But the influence of biochar on aquatic lives which are contact closely was not defined before now.In this work,several disposal measures of biochar were used to plant Vallisneria natans and its seeds with different volume of additions,in order to affrm the effect of biochar on seed germination and growth of Vallisneria Natans,water environment.qualities and microorganism of substrate.The main results of this thesis are as follows:1.In closed system biochar can improve the germination rate of Vallisneria seeds,and small size biochar is more effective,which can improve the germination rate from 50%to 80%.Large size biochar can also improve the germination rate under high concentration nitrate.In high concentration nitrate condition,biochar can reduce itrate nitrogen release orthophosphate,in that case small size biochar is better for Vallisneria seedling.2.Plant adult-plant stage Vallisneria by the biochar modifying with ferric chloride,origin biochar,silica sand and natural bottom mud,the results show that modified biochar has toxic effect on Vallisneria,which can kill the plants.Furthermore,the length of Vallisneria which planted with two kinds of biochar were shorter than control groups,the reduce ranged from 23.3%to 40.6%.The biomass,chlorophyll content and root activity were also decrese,it reminded that over-dose biochar can inhibit Vallisneria.16S rDNA community profiling shows that the microflora of two kinds of biochars are different from silica sand and natural bottom mud,most of microorganism are Burkholderia,and the community structures of biochars are simplification,which may have adverse effect on Vallisneria.3.Simulated the wild environment by using river water and natural mud,and added different proportion biochar to mud to plant the Vallisneria.The results show that the total N,total P and ammonia nitrogen of water could be reduced under the combined action of biochar and Vallisneria,and the total organic carbon of mud was increase along with the proportion of biochar increasing.While the proportion of biochar was more than 10%,the length of Vallisneria could be shorter obviously,the length was decrease to 59.7-72.9%.It also caused the increasing of carbon content Vallisneria and decreasing of chlorophyll content,in that case the proportion of biochar adding to mud should not more than 5%.16S rDNA community profiling shows that the microflora community structure and abundance of mud with different proportion biochar and the origin mud were similarity,the main contents were Gp6,Sphingomonas and Thiobacillus.Sum up,biochar can improve the germination rate of Vallisneria seeds,Fe-modified biochar and the mud which added more than 5%biochar have a negative impact on Vallisneria natans.It provided powerful data support to the aplication of biochar in restoration water and aquatic vegetation.