Effects Of Exponential Fertilization On The Growth And The Nutrient Loading Of N,P And K In Different Generations Of Chinese Fir

Chinese fir(Cunninghamia lanceolata)is a evergreen arbor of Chinese fir family.It is a strategic tree species in the construction of fast-growing and high-yield plantation in South China.It has a very important position in the development of Southern Forestry.Chinese fir has the characteristics of rapid growth,excellent material,high yield and wide application.At present,because of the growing area of planting,the demand of the seedlings is giant.In the cultivation stage of Chinese fir seedlings,it is generally used in a single time concentrated fertilization or equivalent cycle fertilization,this method of fertilization often results in the high early nutrient concentration of the container seedlings and the toxic effect on the seedlings,resulting in the loss of fertilizer.In the late stage of the growth of seedlings,the nutrient shortage is easy to cause the nutrient dilution in the container seedlings,so that the early growth of the container seedlings after the field transplantation is restricted by the nutrient.It is crucial that that growth stage of Chinese fir seedling grow in the growth stage of Chinese fir.Therefore,it is of great significance to study the cultivation of high-quality fir seedlings and improve the quality of seedling of fir seedlings by using the nutrient efficient loading technology of Chinese fir seedlings.In this study,third-generation and second-generation Chinese fir seedlings were used as experimental materials,and 7 fertilization treatments were set up for non-fertilization(control),traditional fertilization(C50,C100,C200)and exponential fertilization(E50,E100,E200).The experiment has been conducted for 20 weeks,and during the course of the process,four samples have been sampled,then the seedling height,ground diameter,biomass and N,P and K content of Chinese fir were measured respectively.The effects of different fertilization strategies and dosage levels on growth and nutrient bearing capacity of Chinese fir container seedlings were explored,in order to provide theoretical basis for third-generation Chinese fir and second-generation Chinese fir container seedling cultivation.The results of the study are as follows:(1)Fertilization can effectively increase seedling height,ground diameter and biomass of roots,stems and leaves of third-generation Chinese fir and second-generation Chinese fir seedlings.Under the same fertilization level,the seedling height and the ground diameter of the exponential fertilized container seedlings were less than the traditional fertilization.Under the same fertilization mode,the fertilization level significantly affected the growth of the third-generation Chinese fir seedlings,and the fertilization level had no significant effect on the growth of the second-generation Chinese fir seedlings.During seedling hardening,the growth rate of seedling height and ground diameter of Chinese fir seedlings treated by exponential fertilization was higher than that of traditional fertilization.The biomass,root,stem and leaf biomass of the container seedlings were not fertilized to the order of leaf>root>stem.,and after fertilization,the biomass of root,stem and leaf of container seedlings is in order of leaf>stem>root.Different fertilization methods and fertilizer dosage significantly reduced the root-top ratio of seedlings,but different fertilization methods and doses had no significant effect on the root-top ratio of container seedlings(2)Fertilization significantly increased the nutrient concentrations of N,P and K in root,stem and leaf of Chinese fir seedlings of different generations,and increased the nutrient concentration of N and P with the increase of fertilization dosage,while the fertilization method and the dosage of fertilizer had little effect on the K nutrient concentration in the various organs of Chinese fir seedlings.Under the same level of fertilization,exponential fertilization is more conducive to the increase of N and P nutrient concentrations of container seedlings of Chinese fir than the traditional fertilization methods.At the end of hardening stage,the N and P nutrient concentrations of 200 mg/seedling treatments were the highest,while There was no significant difference in nutrient concentrations of N,P and K between 100 mg/seedling and 200 mg/seedling treatments,It can be seen that the nutrient concentration of Chinese fir seedlings can be increased by exponential fertilization,and then the dosage of fertilizer can be reduced.(3)Compared with no fertilizer treatments,fertilization significantly increased nutrient accumulation in different organs of Chinese fir seedlings.In the early period of fertilization,the accumulation of N,P and K in each organ of the seedlings was significantly lower than that of the traditional fertilizer treatment,but with the increase of fertilization time,the effects of different fertilization methods on the nutrient accumulation of seedlings gradually decreased.Under the same fertilization method,the accumulation of N and P in seedlings increased with the increase of fertilization dosage,but the difference of the accumulation of K nutrient in the seedlings was not significant at the different level of fertilization at the later stage of fertilization.The nutrient accumulation of N,P and K in Chinese fir container seedlings with different fertilization treatments was leaf>stem>root in each organ,while the nutrient accumulation of N,P and K in the control organs was leaf>root>stem,and fertilization could change the proportion of nutrient.in various organs.In summary,the results showed that the growth rate and N,P and K bearing capacity of Chinese fir seedlings were significantly affected by fertilization and dosage.Exponential fertilization significantly promoted nutrient concentrations of N,P and K in different organs of seedlings,and ensured the efficient bearing of seedlings under low level of fertilization.However,the biomass of N,P and K in different organs of seedlings was lower than that of traditional fertilization,because the biomass of seedlings was lower than that of traditional fertilization.The effects of fertilization mode and dosage on seedling growth and nutrient carrying capacity were different in different generations of Chinese fir seedlings,and exponential fertilization was more beneficial to the third-generation Chinese fir container seedlings.