Effect Of Phosphorus Rate And Hierarchy Fertilization On The Root Growth,Yield And Quality Of Platycodon Grandiflorum

Field experiments were conducted with transplanting annual P.grandiflorum as experimental materials in 2017 to study effects of phosphorus application on soil nutrient,phosphatase activity,root growth,plant dry matter accumulation and yield and quality of P.grandiflorum,and to select the optimal phosphorus rate and hierarchy fertilization.The experimental design was set up by five treatments,it was rate 0?no phosphate,CK?,40kg·hm^-2?deep?,40 kg·hm^-2?middle?,60 kg·hm^-2?deep?,60 kg·hm^-2?middle?in five different treatments.The results was shown as follow:1.Phosphorus fertilization increased contents of soil total phosphorus and available phosphorus.The content of total phosphorus with middle fertilization pattern was higher than that of deep fertilization pattern in the same of phosphorus rate,and 60 kg·hm^-2Phosphorus rate with middle fertilization pattern was highest within 90 to 120 DAT.However,the content of total phosphorus treated by 40 kg·hm^-2 Phosphorus rate with deep fertilization pattern were higher than that of the middle fertilization pattern in late growth period of P.grandiflorum.The available phosphorus content treated by 40 kg·hm^-2Phosphorus rate with deep fertilization pattern were higher than that treated by middle fertilization pattern within 90 to 120 DAT,but there was no significant difference existed.Furthermore,The available phosphorus content treated by 60 kg·hm^-2 Phosphorus rate with middle fertilization pattern were higher than that treated by deep fertilization pattern.2.Phosphorus fertilization increased soil neutral and alkaline phosphatase activity.The soil neutral phosphatase activity was the lowest at 150 DAT.The change tendency of soil neutral phosphatase activity was similar between 40 kg·hm^-22 and 60 kg·hm^-22 Phosphorus rates with deep fertilization pattern,and reached the highest value at 120 DAT.The soil neutral phosphatase activity treated by 60 kg·hm^-2 Phosphorus rate with middle fertilization pattern was higher than that treated by the phosphorus rate of 40 kg·hm^-22 with similar fertilization pattern.However,The soil neutral phosphatase activity treated by 40 kg·hm^-2Phosphorus rate with deep fertilization pattern was greater than that treated by 60 kg·hm^-2Phosphorus rate with middle fertilization pattern at 120 DAT.The alkaline phosphatase activity treated by 40 kg·hm^-2 Phosphorus rate with deep fertilization pattern was higher than that treated by the middle fertilization pattern,however the alkaline phosphatase activity treated by 40 kg·hm^-2 Phosphorus rate with middle fertilization pattern was highest.3.Phosphorus fertilization increased the pH value of soil.The pH value of the deep fertilization pattern of 40 kg·hm^-2 was higher than that of the middle fertilization pattern,and the deep fertilization pattern of 60 kg·hm^-2 was lower than that of the middle fertilization pattern at 30 DAT.The pH value of soil treated by 40 kg·hm^-22 Phosphorus rate of with middle fertilization pattern was higher than that treated by the deep fertilization pattern,but the phosphorus rate of 60 kg·hm^-2 was the opposite,and the phosphorus rate of60 kg·hm^-22 with deep fertilization pattern was highest at 150 DAT.4.Different phosphorus fertilization patterns increased the accumulation of dry matter of P.grandiflorum roots.The accumulation N and P in P.grandiflorum roots treated by 40kg·hm^-22 with deep fertilization pattern was higher than that of the phosphorus rate of 60kg·hm^-2,while the accumulation of K was lower than that treated by phosphorus rate of 60kg·hm^-2 at flowering stage.The accumulation of N?P and K in P.grandiflorum roots treated by 40 kg·hm^-2 Phosphorus rate with deep fertilization pattern was higher than that treated by phosphorus rate of 60 kg·hm^-22 during harvest stage.It is concluded that 40 kg·hm^-2Phosphorus rate with deep fertilization was beneficial to dry matter accumulation of P.grandiflorum roots.5.Phosphorus fertilization promoted root elongation,root surface area,and root volume formation,whereas it decreased lateral root numbers of P.grandiflorum.Root indicators of P.grandiflorum treated by 40 kg·hm^-2 Phosphorus rate with deep fertilization pattern were higher than other treatments at 120 DAT.Root indicators of P.grandiflorum treated by 40 kg·hm^-2 Phosphorus rate were higher than that of treated by 60 kg·hm^-2Phosphorus rate regardless phosphorus fertilization pattern.This results indicated that excessive phosphorus rate inhibited growth of P.grandiflorum.It is concluded that 40kg·hm^-2 Phosphorus rate with deep application is favour root growth of P.grandiflorum.6.Phosphorus fertilization significantly improved the quality and yield of P.grandiflorum.Phosphorus rate of 40 kg·hm^-2 with deep fertilization was significantly increased the single root weight of P.grandiflorum,thus,its yield was highest.The protein content in P.grandiflorum treated by 40 kg·hm^-22 and 60 kg·hm^-22 with deep fertilization pattern was higher than that treated by middle fertilization pattern.The total saponins content in P.grandiflorum treated by 40 kg·hm^-22 was higher than that of 60 kg·hm^-2phosphorus rate,and the phosphorus rate of 40 kg·hm^-22 with deep fertilization pattern was highest,regardless phosphorus fertilization pattern.Under the experimental condition,Phosphorus rate of 40 kg·hm^-2 with deep fertilization was the optimum treatment.