Effects Of Bag Controlled-Release Fertilizer On Growth And Nitrogen Absorption And Utilization Of Apple Tree

The study was carried out in orchard of Shandong Agricultural University fruit research station in 2015.One-year-old Malus hupenensis Rhed.and ¹⁵ N trace technique were used to explore plant growth and the characteristics of absorption,distribution and utilization of N under different nitrate nitrogen levels.At the same time,the study was carried out in orchard of Laishan District of Shandong city in Yantai Province in 2016.Six-year-old ‘Yanfu3’/SH6/Malus hupehensis Rehd.and ¹⁵ N trace technique were used to explore the effects of bag-controlled release fertilizer（BCRF）on the soil mineral nitrogen and ¹⁵N-urea absorption,utilization and loss of Fuji apple.The main results were as follow:1.The effects of plant growth and the characteristics of absorption,distribution and utilization of N under different nitrate nitrogen levels（0.00,4.00,8.00,12.00,16.00,20.00 and 24.00 mmol/L N_O3-,N₁,N₂,N₃,N₄,N₅,N₆ and N₇,respectively）in sand culture were explored in the study.The main results were as follow:with the improvement of nitrogen levels,chlorophyll（SPAD）,leaf area,biomass,root length,root surface area,number of root tips,root activity and total nitrogen in plant of Malus hupehensis seedlings were first increasing and then decreasing,nitrogen levels rose to their highest level at 12.00 mmol/L N_O3-;N_dff% values,¹⁵ N uptake and nitrogen use efficiency with the improvement of nitrogen levels were decreasing.In low N levels（N₁^N₂）,¹⁵ N was mainly distributed in the leaf,N₁,N₂,respectively were 51.39%,45.9%,followed by the root and stem.Under high N levels（N₄^N₆）,transfer of ¹⁵ N to root,N₄,N₅ and N₆,respectively were 43.80%,45.40%,51.46%.Consider in ensuring the high nitrogen use efficiency at the same time,Hoagland nutrient nitrate nitrogen concentrations in the 12.00 mmol/L level,significantly improve the growth of Malus hupehensis and plant root,the nitrogen distribution in each organ was relatively uniform and growth best.2.Explore the effects of furrow applicator fertilizer（FSA）,half applicator and half bag-controlled release fertilizer（FS+BC）,bag-controlled release fertilizer（BCRF）on the soil mineral nitrogen and ¹⁵N-urea absorption,utilization and loss of Fuji apple.The main results were as follow: BCRF treatment provided the soil mineral nitrogen content steadily and incessancily throughout the growing season,FSA treatment provided the soil mineral nitrogen content increased rapidly in the short term,and then a sharp reduction.The root activity of bag controlled-release fertilizer treatment was significantly higher than other treatments,and reached 45.12mg/g/h.The protect enzyme activity of bag controlled-release fertilizer treatment were significantly higher than other treatments and Malondialdehyde content of root were significantly lower than other treatments in the midlle dand late growth period;however,there was no significant difference between FS+BC treatment and FSA treatment in the late growth period.The plant leaf area,soil and plant analyzer develotrnent（SPAD value）and total N of apple leaves of BCRF treatment were obviously highest at fruit maturity stage.The distribution ratio of ¹⁵ N was significantly under different fertilizer application treatments,and that of the reproductive organs of BCRF treatment was higher than other treatments,but that of the vegetative organs of FSA treatment was higher than other treatments,and the storage organs was no obviously.BCRF treatment（121.64 g）of nitrogen in the plant was higher than FSA treatment（79.01 g）at the fruit maturity stage,slightly higher than FS+BC treatment（95.92 g）.N_dff in different organs was significantly affected by the different fertilizer treatments,and the N_dff of fruits was the highest,N_dff in different organs was highest with BCRF treatment,and then FS+BC treatment,the last was FSA treatment.BCRF treatment increased N use efficiency significantly,being 1.82 and 1.32 times of the FSA treatment and FS+BC treatment,and ¹⁵ N loss rate was 36.23%,which was obviously lower than FSA treatment（57.44%）and FS+BC treatment（51.16%）.¹⁵ N residue in soil of BCRF treatment mainly concentrated in the upper soil region（0-40cm）,deep soil leaching and losses decreased.The results suggested that,BCRF treatment was beneficial to ensure a steaty supply of soil nitrogen,improved of nitrogen use efficiency and reduced nitrogen loss.