Effect Of Different Developmental Stages On Characteristics Of Absorption, Utilization Of Nitrogen And Endogenous Hormones For Apple

1. The characteristics of absorption, utilization and distribution of fifteen-year-old’Gala’ apple(Malus domestica/Malus hupehensis) under the treatment of different developmental stages with the same condition of nitrogen application rate using15N-urea tracer method. The results showed that there was obvious difference between different stages, the efficiency of15N absorption and utilization of the plant from4/21-5/19and6/16-7/21is2.28g and2.18g, and the15N-urea utilization rate was9.15%and8.71%, which occupied about35.20%and33.75%of annual absorption amount respectively. It was dramatic higher than other stages, which from3/17-4/21(0.37g),5/19-6/16(0.97g) and6/16-7/21(0.68g). There was significant difference of different organic Ndff at the same stages. The comparison of Ndff value from4/21-5/19was roots> fruits (flowers)> leaves> annual fine shoots and from7/21-8/19was fruits> annual shoots> leaves>fine roots.2. This experiment was designed to used4yea-old apple tree(Fuji/SH1/Malus robusta Rehd)as the model, which was treated with15N at different period.The aim of the present study was to test the alteration of the endo-hormone at the same content of15N. Results showed that after about one month15N treatment, there was significant difference of endo-hormone at the different period compared with the controls. In addition, treated with15N at different period, IAA, GA, ZRs of shoot tip and fine roots increased significantly however ABA reduced significantly. At the two periods (20th April to20th May,20th July to20th August), the comparison of15N treatment groups and controls showed that there was significant difference of endo-hormone of shoot tip and fine roots whereas there was no significant difference of the other three periods. The ratio of (IAA+GAs+ZRs)/ABA of shoot tip and fine roots increased significantly compared with the controls at the two periods, which indicated that the treatment stimulated the growth of fine roots. Furthermore, the activity of fine roots of15N treatment groups increased significantly (by21.78%treated on20th April and by19.26%treated on20th July) compared with the controls however, there was no significant difference of the left three groups. This present study indicated that15N treatment at two periods (20th April to20th May and20th July to20th August) promotes the release of the endo-hormone and the growth of tree remarkably significantly.