Effects Of Different Phosphorus Additions On The Growth And Development Of Vitex Negundo Seedlings

In this paper,Vitex negundo,a typical shrub species in the southern foothills of Taihang Mountains,was selected as the experimental material.The blank control treatment(CK,0gPm-2·a-1)and low-phosphorus treatment(LP,10gPm-2·a-1)Phosphorus application at four different gradients of medium phosphorus treatment(MP,20gPm2·a-1)and high phosphorus treatment(HP,30gPm-2·a-1).Growth indicators(plant height,basal diameter,number of leaves),leaf photosynthetic indicators(net photosynthetic rate,intercellular CO2 concentration,stomatal conductance,transpiration rate),leaf enzyme activities(POD activity,SOD activity,CAT activity,MDA content),Root system indicators(root length,root diameter,root surface area,root volume)and other responses to different phosphorus application levels.The main research findings are as follows:(1)The plant height,basal diameter,and leaf number of Vitex negundo seedlings under different phosphorus treatments did not change significantly in the early stage(030 days)of the experiment,and the growth trends in the middle and late stages of the experiment showed MP>HP>LP>CK Under different phosphorus treatments,the plant height and basal diameter of Vitex negundo had a very significant positive correlation(p<0.01),and a significant positive correlation with the number of leaves(p<0.05).The basal diameter of Vitex negundo was significantly positively correlated with the number of leaves(p<0.05).Adding phosphorus can promote the growth and development of Vitex negundo,and MP treatment has the most significant effect on promoting the growth and development of Vitex negundo seedlings.(2)The lowest values of net photosynthetic rate,intercellular CO2 concentration,transpiration rate,and stomatal conductance of Vitex negundo seedlings under different phosphorus treatments all appeared in CK treatment,and the net photosynthetic rate,intercellular CO2 concentration,and stomatal conductance were the highest.The value appeared in the MP treatment,and the highest value of the transpiration rate appeared in the HP treatment.The net photosynthetic rate,intercellular CO2-concentration,stomatal conductance and transpiration rate of Vitex negundo leaves under MP treatment were significantly higher than those of CK treatment(p<0.05).There was no significant difference in net photosynthetic rate of leaves treated by HP and LP in the middle and late stages of Vitex negundo culture(30-90d).In the early growth stage(015d),there was no significant difference in the intercellular CO2 concentration of the leaves of Vitex negundo under the four treatments,and the leaves of the three phosphorus treatments after 30d were significantly higher than those of the CK treatment(p<0.05).Stomatal conductance gradually increased with the growth and development of Vitex negundo.Under different phosphorus treatments,the net photosynthetic rate of Vitex negundo leaves was significantly positively correlated with intercellular CO2 concentration(p<0.05),and was significantly positively correlated with stomatal conductance and transpiration rate(p<0.01).Intercellular CO2 There was a very significant positive correlation between concentration and transpiration rate(p<0.01).Phosphorus application can significantly increase the photosynthetic level of Vitex negundo leaves,increase the accumulation of vitex organic matter,and promote the growth and development of vitex.Among them,MP treatment has the most significant effect on the growth and development of vitex.(3)The enzyme activities of leaves of Vitex negundo seedlings under different phosphorus treatments were all higher than those of the control.MP had the highest POD activity and CAT activity,and LP had the highest SOD activity.Among them,in terms of POD activity,MP treatment was significantly higher than CK treatment(p<0.05),and in SDO activity,LP treatment was significantly higher than CK treatment(p<0.05),MP treatment in CAT activity was significantly higher than the other three treatments(p<0.05).The content of MDA was the highest in CK treatment.the lowest in MP treatment,and there was no significant difference between LP and HP.There was no significant difference between the four treatments,and the specific performance was CK>LP>HP>MP.The POD activity and SOD activity of Vitex negundo leaves under different phosphorus treatments had a significant positive correlation(p<0.05),and a very significant positive correlation with CAT activity(p<0.01).There was a significant positive correlation between SOD activity and CAT activity(p<0.05).The activities of POD,SOD and CAT all had significant negative correlation with MDA content(p<0.05).Phosphorus application can increase the antioxidant capacity of Vitex negundo leaves and reduce the MDA content of vitex leaves.Among them,the effect of MP treatment is the most obvious,which indicates that MP treatment has the strongest effect on improving the anti-stress and disease resistance of vitex,and can slow the cell membrane The degree of damage is conducive to the growth and development of the plant.(4)There were no significant differences in the root length,root diameter,root volume,and root surface area of Vitex negundo under different phosphorus treatments.HP treatment had the longest root length,and MP treatment had the largest root diameter,root surface area,and root volume.MP treatment had the most obvious effect on promoting root growth of Vitex negundo,and LP treatment and HP treatment had no obvious inhibitory effect on root growth.Under different phosphorus treatments,the root length of Vitex negundo was significantly correlated with root diameter and root volume(p<0.05),and the root diameter of vitex negundo was significantly correlated with root volume(p<0.01).(5)There is a certain correlation between the indexes of Vitex negundo L.under different phosphorus treatments.The growth status of Vitex negundo seedlings is caused by the interaction of various indexes.