Comparison of Effects Between Foliar and Soil N Applications on Soil N and Growth of Young Gala/M9 Apple Trees

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1 Comprison of Effects Between Folir nd Soil N Applictions on Soil N nd Growth of Young Gl/M9 Apple Trees Shufu Dong, Denise Neilsen, Gerry H. Neilsen Pcific Agri-Food Reserch Center Agriculture nd Agri-Food Cnd 42 Highwy 97 Summerlnd, BC VH 1Z Cnd Liling Cheng Deprtment of Horticulture, Cornell University, Ithc NY 14583, USA Leslie H. Fuchigmi Deprtment of Horticulture Oregon Stte University Corvllis, OR 97331, USA Keywords: folir, soil ppliction, N, Mlus domestic Astrct The incresing concern out environmentl contmintion y nitrte leching from griculturl lnd hs stimulted serch for more efficient wys to pply N fertilizers. An experiment ws crried out to compre the effectiveness of folir nd soil N pplictions on pple tree growth nd soil nitrogen sttus in order to evlute N use efficiency. One-yer-old, uniform Gl/M9 pple trees were selected nd trnsplnted into 4-litre pots with typicl lomy snd soil. The plnts grew in the greenhouse nd were rndomly divided into five groups of 17 trees. The experiment included control (no N) nd 4 N tretments where the sme mount of N s ure ws pplied once every two weeks strted when shoot growth exceeded 5cm. N ws pplied y 1) folir only, 2) soil only, 3) soil erly nd lte, folir midsummer (comintion I), or 4) folir erly nd lte, soil midsummer (comintion II). New shoot numer ws recorded, nd shoot length, plnt nd soil N nutrients were mesured throughout the growing seson. Plnts were moved from the greenhouse in lte Octoer to over-winter outside. Five trees were smpled for totl N nlysis t the dormnt stge. The reminder ws put in the screen house for re-growth evlution in the following seson. Shoot numer ws unffected y tretments in the first seson, ut soil N ppliction lone nd comintion I significntly incresed shoot length. All N tretments significntly incresed lef N sttus nd lef color (s indicted y SPAD-chlorophyll redings) compred to the unfertilized control, ut there were no significnt differences mong different N tretments. Folir ppliction incresed reserve N content t the dormnt stge nd promoted re-growth, ut ll N tretments resulted in similr root/shoot rtios, which were lower thn tht of the control tretment. Both soil NO 3 - nd NH 4 + were significntly incresed y soil N ppliction compred with either control or folir ppliction, n indiction tht soil N ppliction creted higher potentil for leching loss. INTRODUCTION Nitrogen (N) is n essentil element for griculturl production, nd N fertilizers re the most widely used fertilizers in the world (Mengel nd Kirky 1978). Although the ppliction of N fertilizers hs drmticlly improved plnt production, it hs lso resulted in world-wide prolem of environmentl contmintion. Incresing pulic concern out excessive nitrte leching from griculturl lnds hs encourged serch for more efficient wy to pply N fertilizers (Dinnes et l, 22). Soil ppliction is the trditionl method of supplying N to sustin plnt production in griculture, ut it is often ssocited with high soil N leching nd low efficiency of use. Folir N ppliction to fruit trees cn hve higher use efficiency (Weinum, 1988), ut it my dversely ffect plnt vigor nd reduce the economic yield if relied upon solely. Comintions of soil nd folir N ppliction might chieve optimum N use nd plnt production, ut there hve een no consistent results reported in literture (Johnson et l, 21). The ojective of this study is to compre effects of folir, Proc. XXVI IHC Sustinility of Horticulturl Systems Eds. L. Bertschinger nd J.D. Anderson Act Hort. 638, ISHS 24 Puliction supported y Cn. Int. Dev. Agency (CIDA) 267

2 soil or their comined N ppliction on the growth of young pple trees. MATERIALS AND METHODS One-yer-old uniform Gl/M9 pple trees were selected nd trnsplnted into 4- litre pots with lomy snd soils. The plnts were grown in the greenhouse under stndrd growth conditions nd rndomly divided into five groups with 17 trees in ech group. The experiment included control (no N ppliction, CK) nd 4 N tretments where the sme mount of N s ure ws pplied once every two weeks from mid My (when shoots were 5cm-long) to erly mid Septemer nd out 4g N in totl ws pplied to ech tree. N ws pplied y 1) folir only (Folir), 2) soil only (Soil), 3) soil erly nd lte, folir midsummer (comintion I, Com.I), or 4) folir erly nd lte, soil midsummer (comintion II, Com.II). New shoot numer ws counted, nd shoot length, plnt nd soil N nutrients were mesured periodiclly during the growing seson. Lef greenness redings, mesured y SPAD meter (Minolt Corportion), were lso mde. Plnts were moved from the greenhouse in lte Octoer nd llowed to over-winter outside. Five trees were smpled for totl N nlysis in the dormnt seson. The rest of trees were plced in screen house for n evlution of regrowth with no N ppliction in the following seson. Plnts were portioned into leves, stems nd roots, dried nd weighed. Totl N in leves, stems nd roots ws determined with LECO FP-528 N nlyzer (LECO + CORPORATION, 3 Lkeview Avenue, St. Joseph, MI , USA). Soil NH 4 - ws nlyzed y the Nessler method, nd NO 3 y the nitrophenoldisulfonic-yellow method (Jckson, 1958). All dt were sujected n ANOVA nlysis with NCSS 97 Sttisticl System softwre (NCSS Sttisticl Anlysis Softwre, Kysville, UT, USA). RESULTS Plnt Growth Neither soil nor folir N pplictions nor their comintions ffected the numer of new shoots produced in the first yer (dt not showed). Both soil N ppliction lone nd soil-folir comined N pplictions significntly incresed the first-yer shoot length, while folir N ppliction lone did not ffect new shoot length (Fig. 1). At the end of the growing seson, ll N tretments hd similr root/shoot rtio (.45), while the control tretment hd significnt higher root/shoot rtio (.55) (Fig. 2). Plnt N Sttus During the growing seson, ll N tretments significntly incresed lef SPAD redings (Fig. 3) nd lef N content (Fig. 4) compred with the control tretment, nd there ws no significnt difference etween different N tretments. All N tretments significntly incresed shoot nd root N concentrtions t dormncy, ut the highest N content ws chieved fter folir N ppliction (dt not showed). Soil N Soil NO3 - nd NH 4 + were oth incresed y Soil, Com.I nd Com.II tretments (Fig. 5 nd Fig. 6), nd there ws positive reltionship etween ville soil N nd the mount of N pplied to the soil. Folir ppliction lso incresed the ville soil N compred with the control, ut the increment ws much less thn tht of soil ppliction (Fig. 5 nd Fig. 6). Regrowth Performnce Folir nd soil N pplictions nd their comintions ll promoted n equivlent mount of new shoot growth in the following seson (Fig. 7). There ws positive reltionship etween plnt N content t dormncy nd new shoot growth (Fig. 8). Folir N ppliction promoted flower ud initition, nd out 75% of trees treted with folir N ppliction egn flowering nd less thn 5% for ll other tretments (dt not showed). DISCUSSION 268

3 Nitrogen is essentil for plnt development, nd N fertilizers usully promote plnt growth (Mengel nd Kirky 1978, Mrschner 1995). This experiment showed tht oth soil nd folir N pplictions nd their comintions were le to supply enough nitrogen to young pple trees for growth nd development. Soil ppliction resulted in higher soil ville N sttus (oth NO 3 - nd NH 4 + ), which incresed the potentil risk of N leching loss. In term of nitrogen usge, folir ppliction should e more efficient thn soil ppliction s reported previously (Hill-Cottinghm nd Lloyd-Jones 1975, Weinum 1988, Khemir 1995). Soil N ppliction promoted plnt vigour nd produced more long shoots. As result, trees receiving soil N pplictions hd delyed flower initition. Flower ud initition requires high vilility of nutrients nd lnce etween nutrients such s cron nd nitrogen (Fust 199). The formtion of long shoots likely consumed more cron thn nitrogen, decresing C/N rtio, which my explin why soil N ppliction retrded the flower ud formtion. Roots re the min orgn y which plnts sor nutrients nd wter from soil (Fllhi 1994). When soil nutrient vilility ecomes limited, plnts usully invest more resources into root production to increse soring surfce re nd counter the decline in supply of soil nutrients (Mrschner 1995). As result, root growth cn e promoted t low nutrient supply, resulting in n increse in root/shoot rtio s in the control tretment in this experiment. However, different methods of N ppliction did not ffect root/shoot rtio in the experiment, which my indicte the plnt hd unique mechnism to sense internl N sttus. The plnt did not expend too much resource for root construction s long s enough N ws supplied, no mtter how N ws supplied whether through soil or vi folir ppliction. Literture Cited Dinnes, D.L., Krlen, D.L., Jynes, D.B., Kspr, T.C., Htfield, J.L., Colvin, T.S. nd Cmrdell, C.A. 22. Nitrogen mngement strtegies to reduce nitrte leching in tile-drined Midwestern soils. Agronomy Journl. 94: Fllhi, E Root physiology, development nd minerl uptke. In: A. Brooke Peterson nd Roert G. Stevens (eds.) Tree Fruit Nutrition. Good Fruit Grower, Ykim Wshington, USA. Pp19-3. Fust, M Physiology of Temperte Zone Fruit Trees. John Wiley & Sons. Pp Hill-Cottinghm, D.G. nd Lloyd-Jones, C.P Nitrogen-15 in pple nutrition investigtions. J. Sci. Food nd Agri. 26: Jckson, M.L Soil Chemicl Anlysis. Prentice-Hll, INC., Englewood Cliffs, N. J., USA. Pp Johnson, R.S., Rosecrnce, R., Weinum, S., Andris, H. nd Wng, J. 21. Cn we pproch complete dependence on folir pplied ure nitrogen in erly-mturing pech? J. Amer. Soc. Hort. Sci. 126: Khemir, H Nitrogen prtitioning nd remoiliztion in field-grown pple trees. Ph. D. Disserttion, Oregon Stte University, Corvllis, OR, USA. Mrschner, H Minerl Nutrition of Higher Plnts (the second edition). Acdemic Press. Pp Mengel, K. nd Kirky, E.A Principles of Plnt Nutrition. Interntionl Potsh Institute, Worlufen-Bern, Switzerlnd. Weinum, S.A Folir nutrition of fruit crops. In: Neumnn, P. E. (ed.) Plnt Growth nd Lef Applied Chemicls. CRC Press, Boc Rton, Florid, USA. Pp

4 Figuress cm/plnt Ck Folir Soil Com.I Com.II Fig. 1. Totl shoot length t the end of the first growing seson..6.5 Root/Shoot rtio CK Folir Soil Com.I Com.II Fig. 2. The root/shoot rtio s ffected y N tretments t the end of the first growing seson. 27

5 5 45 SPAD 4 Ck 35 Folir Soil 3 Com. I Com. II 25 5/1/1 5/3/1 6/19/1 7/9/1 7/29/1 8/18/1 9/7/1 Fig. 3. Chnges of SPAD redings during the growing seson Lef N % Control Folir soil Com.I Com.II Fig. 4. Lef nitrogen content in the mid of the first growing seson. ug/g d d c Ck Folir Soil Com.I Com.II Fig. 5. NO 3 - content in the pot soil. 271

6 ug/g e d c Ck Folir Soil Com.I Com.II Fig. 6. NH 4 + content in the pot soil. New shoots (g/plnt) CK Folir Soil Com.I Com.II Fig. 7. Regrowth performnce in the following seson. Biomss (g/plnt) y = 33.45x R 2 = N % Fig. 8. Reltionship etween N content t dormncy nd shoot regrowth (iomss) in the following seson. 272