Purification And Tolerance Of Salix Matsudana Seedling To Aniline Stress

Aniline is a kind of synthetic compound widely used in industry and pesticide production.It was a potential environmental pollutant,which seriously affects human health and the surrounding environment.Therefore,it is urgent to purify aniline in the environment.In this study,the biomass,photosynthesis,chlorophyll fluorescence,spectral reflectance of leaves,stems and roots of Salix matsudana seedlings,and the content of aniline in water and plant organs were determined by hydroponic experiment.The aim was to reveal the purification effect of Salix matsudana on aniline in water,to explore the tolerance range of Salix matsudana seedlings to aniline wastewater,and to provide technical support for further application of phytoremediation technology to purify aniline wastewater.The main results are as follows:（1）With the increase of aniline stress concentration,the photosynthesis of Salix matsudana seedlings was inhibited.Net photosynthetic rate（P_n）,transpiration rate（T_r）,stomatal conductance（G_s）and stomatal limit（L_s）of Salix matsudana seedlings decreased with the increase of aniline concentration,while intercellular carbon dioxide concentration（C_i）increased.The inhibition of aniline on photosynthesis of Salix matsudana belonged to non-stomatal limit.With the increase of aniline stress concentration,the maximum photosynthetic rate(P_nmax)and light saturation point（LSP）showed a significant downward trend,while the light compensation point（LCP）and dark respiration rate（R_d）showed a significant increase trend,indicating that under aniline stress,the light energy utilization ability of plants to strong light and weak light decreased.（2）In this experiment study the chlorophyll fluorescence parameters and leaf index of absorb light energy,the initial fluorescence（F_o）,non photochemical quenching coefficient（NPQ）,regulated energy dissipation（Y（NPQ））,antenna heat dissipation（D）and the photochemical reaction of dissipation（Ex）of Salix matsudana seedings gradually increase with the invrease of aniline concentration in water.The other indexes showed a trend of gradual decline with the increase of aniline concentration in the water.These results indicated that the PSII reaction center was destroyed or inactivated,and photoinhibition and photodestruction occurred.The photochemical efficiency of PSII was reduced due to the damage of PSII light capture complex.These results indicated that PSII reaction center in Salix matsudana seedling leaves was destroyed or inactivated,photoinhibition and photodamage occurred,and the light capture complex of PSII was damaged,which reduced the photochemical efficiency of PSII.（3）In this study,the chlorophyll normalized index（chl NDI）and photochemical reflectance index（PRI）of Salix matsudana seedlings decreased significantly under high concentration of aniline stress（P<0.05）,and the carotenoid reflectance index（CRI）and red edge position increased significantly(λ_RE).The results showed that the chlorophyll content of Salix matsudana seedlings decreased with the increase of aniline concentration,which reduced the photosynthetic capacity of the plant,and the investment in photoprotective pigments and photochemical efficiency.At the same time,the excess light energy dissipated by lutein cycle was increased,which indicated that aniline stress inhibited and damaged the photosynthesis and growth of Salix matsudana seedlings,and affected the normal growth of Salix matsudana seedlings.（4）Under different concentrations of aniline stress,the root,stem,leaf biomass and total biomass of Salix matsudana seedlings decreased gradually with the increase of aniline concentration in water.When the initial concentration of aniline in water was 200 mg·L^-1,the accumulation of aniline in leaves and roots of Salix matsudana seedlings reached the maximum.When the concentration of aniline was 100 mg·L^-1,the maximum removal rate of aniline was 88.6%.Salix matsudana seedlings is suitable for phytoremediation of aniline wastewater with concentration less than 200mg·L^-1.（5）The biomass and total biomass of each organ of Salix matsudana seedlings were negatively correlated with the total accumulation of aniline（P<0.05）.In this study,the photosynthetic parameters except intercellular carbon dioxide concentration（C_i）were significantly positively correlated with the biomass and total biomass of each organ of Salix matsudana seedlings（P<0.05）.The accumulation of aniline in Salix matsudana seedlings was significantly correlated with maximum fluorescence（F_m）,maximum photochemical quantum yield of PSⅡ（F_v/F_m）,unregulated energy dissipation（Y（NO））and photochemical reaction dissipation（P）.