Effects Of Radicle Truncation And IBA Treatment On Root Quality And The Growth Of Ammopiptanthus Mongolicus Seedlings

In order to provide the theoretical basis for solving the technical problems of forestry seedling cultivation of sand holly(Ammopiptanthus mongolicus)with few capillaries and low survival rate of transplanting.The effects of different radicle cutting treatments and radicle cutting + hormone(IBA)treatments on the root quality and seedling growth of Ammopiptanthus mongolicus were conducted in this research.Ammopiptanthus mongolicus seeds of the same size and full seeds were selected in order to accelerate germination.When the radicle development length reached 1.5~2.0cm,3.0~4.0cm and4.5~6.0cm on the third,fourth and fifth day of seed germination respectively,the roots were cut off with different combinations of root tip at 0.5cm,radicle cutting one the half the root and remained root length at2 cm.Furthermore,on the basis of root cutting treatment,0.01mg·L-1,0.025mg·L-1,0.075mg·L-1 and0.125mg·L-1 of IBA were added to promote root growth,respectively.After thirty days of root culture,the root morphology,physiology,seedling growth and physiology of Ammopiptanthus mongolicus seedlings were measured in different treatments.Meanwhile,the effects of root cutting and IBA treatments on Ammopiptanthus mongolicus root in growth promoting,the effects of root cutting and IBA treatment on the growth,biomass and nutrient distribution of Ammopiptanthus mongolicus seedlings were analyzed.The main results were as follows:(1)Compared with the continuous root control,the radicle cutting treatments caused the occurrence of multiple main roots and the increase of the total amount of lateral roots and roots.Among with F2treatment(cutting root tip reached 0.5cm at radicle length reached 1.5~2.0cm)was significantly increased the number of lateral roots,root tips and branches.The effect of hormone on promoting root growth was more obvious after root cutting,in which the number of lateral roots,root tips,branches,root average diameter,root surface area,total root projection area and total root volume were increased,and the treatment of P3(0.5 cm + 0.075mg·L-1 of IBA when radicle length reached 1.5~2.0cm)and P4(0.5 cm +0.125 mg·L-1 of IBA when radicle length reached 1.5~2.0cm)were significant.(2)The radicle cutting treatment could increase seedling ground diameter,aboveground fresh weight,root fresh weight,root dry weight and root-shoot ratio,however,it was not significant.Seedling quality index showed that F2 treatment was better than other root cutting treatments,and radicle cutting treatment(F2 treatment)+ IBA treatment could further promote seedling growth and seedling quality index.On the contrast,the effect of P4 treatment was the most ideal,seedling fresh weight,root dry weight,root/shoot ratio and seedling quality index were the highest under this treatment.(3)The root activity of seedlings was increased after root cutting treatment,and the root activity of F2treatment(137.70%)was higher than that of the control treatment(P < 0.05).Meanwhile,which higher than that of other radicle development stages.After root cutting,the effect of hormone on promoting root activity was more significant,and P4 treatment was the best.The cation exchange capacity of root system was the best in T3 root cutting treatment(radicle length up to 4.5~6.0cm),followed by P3 and P4 treatment,which was significantly higher than that of the control.Correlation analysis showed that root cutting and IBA addition caused the increase of root morphological parameters,root activity and root absorption function at a certain extent.(4)After root cutting treatment,the contents of soluble protein,soluble sugar,non-structural carbohydrate(NSC)and soluble sugar lake ratio in roots were not changed significantly,which may be related to the intensity of root cutting and the process of root construction and restoration.Nevertheless,the contents of soluble sugar and NSC in roots under root cutting + IBA under P3 treatment were significantly higher than those of the control(26.04% and 29.07%,respectively),and the root soluble protein reached the peak under P4 treatment(13.27mg·L-1 of FW).(5)The results of biomass and nutrient distribution showed that root cutting and IBA treatment increased the contents of soluble protein,soluble sugar,soluble sugar and starch in roots,this was consistent with the distribution of biomass among different organs.Root cutting and IBA treatment at seedling stage resulted in the concentration of root nutrition,which was preferentially supplied to root development and root quality improvement,It can effectively improve the growth potential of seedlings.