| In order to investigate the effects of litter extract on seed germination,seedling growth and physiology of Phoebe bournei,and to clarify the relationship between litter and poor growth and high mortality of regenerated seedlings and young trees under Phoebe bournei forest,different concentrations of litter branch,leaf extract,and mixed litter extract were used to treat Phoebe bournei seeds,annual seedlings and seeding seedlings.Some indicators of seed germination,seedling growth and seedling of physiological and photosynthetic were tested.The results show that:(1)The extract of litter branches and litter leaves of Phoebe bournei inhibited seed germination on all concentration.Besides,the inhibition intensity was enhanced with the increase of the concentration of the two extracts.However,the inhibition intensity of litter branches extract was greater than that of litter leaves extract.The inhibition intensity was branch extract>leaf extract in germination index,the inhibition intensity was leaf extract>branch extract in root and stem length,and comprehensive allelopathy was branch extract>leaf extract.The inhibition intensity of seed germination rate in the soil was less than that in the laboratory.However,the Early seedling survival rate is greatly reduced.The high concentration of litter extract can seriously inhibit the early growth of seedlings.(2)The extract of litter branches inhibited the growth of one-year-old Phoebe bournei seedlings,while the extract of litter leaves showed the effect of "low promoting and high inhibiting".The high concentration of the extract could seriously inhibit plant height,ground diameter,leaf length,leaf width,leaf area,total root length,root surface area,root volume and number of root tips of Phoebe bournei seedlings,and cause a large number of leaves with spots,atrophy and yellow.The low concentration of extract(50g/L)could promote seedling diameter,leaf number per plant,taproot length,root diameter,first order lateral root number,longest lateral root,stem root biomass and total biomass.When the concentration was higher than 50 g/L,seedling height,ground diameter,crown width,leaf length,leaf width,leaf area,taproot length,root diameter,first order lateral root number,longest lateral root and biomass were inhibited significantly.(3)The effects of litter extract on the physiology of Phoebe bournei seedlings were complicated.The relative electrical conductivity and MDA content of one-year Phoebe bournei seedlings and sow seedlings significantly increased with the increase of extract concentration and the time of pouring the extract.In the early stage,The high concentration of extract can significantly increase the activities of SOD and CAT in seedling leaves,but as time prolongs,the activities of SOD and CAT in seedling leaves were gradually decreased,and the antioxidant enzyme system was gradually destroyed.Low concentration treatment had little effect on the antioxidant enzyme system in the early stage,and the antioxidant enzyme activity was increased to a certain extent in the later stage.There was no obvious regularity in the influence of extracts on the soluble sugar content of Phoebe bournei seedling leaves.The soluble sugar content of sow seedling leaves increased with the increase of extract concentration and the time of pouring the extract,and the extract inhibited the proline content of seedling leaves on the whole.The high concentration(≥100g/L)of extract significantly inhibited the antioxidant oxidase activity in the roots of Phoebe bournei seedlings.The soluble sugar content in roots first increased and then decreased with the increase of the concentration of litter extract,and the content of prol ine decreased with the increase of the concentration of litter extract.(4)The chlorophyll content of one-year seedlings firstly increased and then decreased with the increase of the concentration of litter-branch extract,and the high concentration(≥100g/L)of extract significantly inhibited chlorophyll content of seedlings.In the litter-branch extract treatment,the chlorophyll content showed that low concentration promoted,high concentration inhibited in the early stage,and low concentration inhibited,high concentration promoted in the late stage.Mixed litter extract showed low promoting and high inhibiting of chlorophyll content of sow seedlings.Fo,Fm and Y(NPQ)of Phoebe bournei seedlings showed an increasing trend on the whole,while Fv/Fm,Y(Ⅱ)and qP showed a decreasing trend with the increase of the concentration of the two extracts.The net photosynthetic rate,transpiration rate and stomatal conductance of Phoebe bournei seedlings decreased with the increase of the concentration of the two extracts.At the same concentration,the inhibition intensity of litter branches extract was greater than that of litter leaves extract,and the intercellular CO2 concentration increased with the increase of the concentration of the extract.The net photosynthetic rate,transpiration rate and stomatal conductance of seedlings treated with high concentration extracts(100g/L and 150g/L)were lower than those of the contrast in the whole day,and the effective photosynthetic time of seedlings was shortened.The intercellular CO2 concentration was higher than that of the contrast in the whole day. |
