Study On SH6Dwarfing Interstock On N Absorption,Distribution And Storage Characteristic In Apple Saplings

The study was carried out in orchard of Shandong Agricultural University fruit research station from2012to2013. Two-year-old’Fuji’/SH6/Malus hupehensis seedlings and15N trace technique were used to research SH6interstocks impact on plant nitrogen absorption, utilization and storage, and explore the effects of different production measures for SH6dwarfed interstocks of sapling growth, endogenous hormone levels and the influence of nitrogen absorption and utilization. The main results were as follows:1. Two-year-old SH6dwarfing interstock apple trees(’Fuji’/SH6/Malus hupehensis)and vigorous rootstock apple trees (’Fuji’/Malus hupehensis)were used in the present study to explore different mechanism of N absorption, utilization storage and retreat in two kinds of apple saplings. The results were as follows:The net growth of vigorous rootstock tree was larger than that of SH6dwarfing interstock. During the same period, Ndff value of same organs vigorous rootstock was higher than that of the SH6dwarf. Meanwhile, the15N allocation rate of two kinds rootstock trees had a consistent pattern:leaf was the highest, followed by new shoots and thick roots, while the center stem was the lowest, and about40-70%of nitrogen was assigned to the new organs (new shoots and leaves). The above part of N fertilizer allocation in vigorous rootstock (63.66%)was higher than that of the SH6interstock (57.68%) in autumn shoot growth arrest stage,. After leaves fell in autum, about33.11%of the nitrogen in the vigorous rootstock leaves retreated into trees, while about36.92%retreated into the interstock trees. All organs except the fine root in the tree had15N storage, and thick roots and phloems were the main storage parts in apple trees. The increment of nitrogen in vigorous rootstock underground part was8.34%, while SH6interstock apple tree was only6.85%. Nitrogen use. efficiency of vigorous rootstock young trees (14.32%) was higher than that of SH6interstock apple trees(8.55%) at autumn shoot growth arrest stage.2. The effects on different N application rate(N50-little N application rate,N100-rational N application rate, N200-overuse N application rate) on hormone of three-year-old Borkh cv. Fuji/SH6/M hupehensis Rehd were studied. The results showed that SH6dwarfing interstock apple trees growth and nitrogen uptake were significantly related with N application levels. The total fresh weight、fine root biomass and total N content of plant of N50treatment were the lowest, N100treatment took second place, while N200treatment showing the highest.15N fertilizer utilization rate of plant was just the opposite:N50<N100<N200-N application levels had a great influence on dynamic changes and values of GA, ZR, ABA and IAA, During the vigorous growing period and slow growth period of shoots,stem tips and fine roots of IAA and GA content were as follows:N50<N100<N200, but the content of ZR and ABA declined along with the increase of nitrogen:N50> N100> N200-Compared with the vigorous growing period, in addition to the fine roots of GA content (5.13,5.68,6.17ng-g-1Fw) was increased, IAA> GA and ZR levels of each organ were significantly reduced with a significant difference during the slow growth period of shoots. In these two periods, ZR/GA and ABA/GA ratio of stem tips and fine roots were the highest under N50treatment, while the N100treatment took the second place, and those of the N200treatment were the lowest. The values of (GA+ZR+IAA)/ABA of different N application rate were different in the same organs, which N200treatment was significantly higher than other treatments.3. The effects on different interstocks buried soil depth (T1-Interstocks entirely buried, T2-Interstocks1/2buried,T3-Interstocks entirely bared) on hormone and nitrogen utilization of two-year-old SH6dwarfing interstock apple trees were studied. The results showed that interstocks buried soil depth had significant effects on plant growth. The height and diameter of plant, total fresh weight and fine root biomass of T1treatment were the highest, while T3treatment showing the lowest. The content of endogenous hormone varied with the buried depth of interstocks, and the content of GA and IAA of different buried depth from high to low was conformably T1>T2>T3at the vigorous growing stage and stop growing stage of the new shoot, while that of the ABA showed an adverse tendency. The ratio of ZR/GA in shoot tip were8.53%and6.06%more than that of T1and T3at new shoot stop growing period.The stoop tip and fine root during the period of ABA/GA, ABA/IAA ratio were T3> T2> T1.The values of (GA+ZR+IAA)/ABA of T1T2and T3in shoot tip were1.66,0.83and0.71at new shoot growing.Plant total nitrogen,15N uptake and fertilizer utilization rate of T1treatment were the highest, while the T2treatment took the second place, and those of the T3treatment were the lowest. The Ndff value also varied among treatments, with T3treatment significantly higher than others. Interstocks of different buried depth effect the tree growth, endogenous hormones and its N utilization significantly, so we should use different interstocks buried depth according to the site conditions to beneficial to early fruit to maintain strong growth on the production.