SNA Research Conference Vol Field Production. Raul Cabrera Section Editor and Moderator. Field Production Section

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1 Field Production Rul Crer Section Editor nd Modertor 50

2 Growth nd physiology of field-grown Acer pseudopltnus L. trees s influenced y irrigtion nd fertiliztion Alessio Fini 1, Frncesco Ferrini 1, Piero Frngi 2 nd Griele Amoroso 2 1 Dipto. di Ortoflorofrutticoltur Università di Firenze Vile delle Idee, 30, Sesto Fiorentino (FI), Itly 2 Fondzione Minoprio Centro MiRT Vile Rimondi, 54, Vertemte con Minoprio (CO), Itly frngi@fondzioneminoprio.it Index Words: Chlorophyll fluorescence, lef gs exchnge, field production, sycmore mple Significnce to Industry: Irrigtion nd fertiliztion re commonly used prctices in nurseries to otin trees of dequte size nd qulity for sle in short time. This study focused on the effects of slow-relese fertilizers nd drip irrigtion on the physiology nd growth of widely used field-grown shde tree species. Results confirmed tht fertiliztion is useful men to improve growth, ut my cuse stress to the trees if provided without dequte irrigtion. On the other hnd, irrigtion hd only limited effect on growth ut gretly incresed lef gs exchnge nd cron ssimiltion. To mximize stnd productivity, irrigtion should e coupled with fertiliztion. Nture of Work: Nutrient nd wter mngements re key fctors for determining the qulity nd the growth rte of plnts in the nursery. The importnce of these prctices hs een reported y mny studies: irrigtion is widely recognized s fundmentl men to improve growth oth in the nursery nd fter plnting in the lndscpe (6), nd previous reserch highlighted tht irrigtion increses growth, lef gs exchnge nd rdition use efficiency (1, 15). Other uthors look to irrigtion in the nursery with scepticism, nd found tht induction of moderte stress during the nursery period my increse drought tolernce fter plnting in the lndscpe (2). Anywys, if drought in the nursery penlizes cron ssimiltion, the consequent reduction of growth nd reserves stored within the plnt my led to reduced plnt qulity nd mrketility (16). Fertiliztion increses growth, lef re index (LAI), cron ssimiltion, folir nitrogen nd llows nutrient loding during the nursery period (9, 3, 11). Nutrient nd crohydrte loding in the nursery my e good strtegy to improve post-trnsplnt performnces, since fertiliztion t trnsplnt is not lwys effective to id estlishment in the lndscpe (4). On the other hnd, nurseries re under incresing pressure to reduce chemicl input nd nutrient runoff. This mens tht rtionl nd sustinle use of wter nd fertilizers hs to e chieved. To rech this trget, nutrients hve to e supplied only if they cn effectively contriute to increse plnt growth nd gs exchnge. For exmple, some uthors (7) found tht P fertiliztion incresed drought tolernce of Eucliptus grndis in lck soils, wheres in sndy soils oth N nd P fertiliztion 51

3 decresed gs exchnge under drought conditions. Moreover, it hs een reported tht fertiliztion my reduce tolernce to drought stress y stimulting shoot growth to greter degree thn root growth, thus incresing tree wter demnd nd simultneously reducing tree ility to cquire wter during drought (8). In generl, fertiliztion my result ineffective if trees re sujected to other limiting stresses (i.e. drought) (12). The im of this work ws to investigte the effect of irrigtion nd fertiliztion on growth nd lef gs exchnge of sycmore mple trees grown in the field. In spring 2005, 60 uniform cm (4-5 in.) circumference Acer pseudopltnus trees were plnted in the field. The experiment ws locted in the orchrd of Fondzione Minoprio, in Vertemte con Minoprio (Como, Itly; N, 9 04 E). The experimentl design ws 2x2 fctoril, consisting of two irrigtion nd two fertiliztion tretments repeted three times. Fifteen trees were irrigted (I), 15 were fertilized (F), 15 were oth irrigted nd fertilized (F+I). The remining 15 trees were selected s controls nd were neither wtered nor fertilized. Fertiliztion of F nd F+I trees ws done t plnting y incorporting in the plnting hole 0.5 kg (1.1 l) of 8-9 month controlled-relese fertilizer, Ficote ( ). In spring 2006 F nd F+I plnts were re-fertilized with 0.5 kg (1.1 l) per plnt of Nitrophosk Gold, used s topdressing plced ner the stem. Irrigtion ws provided y drip irrigtion only to I nd F+I trees, which were irrigted once per week from erly-july until the end of August in 2005, nd from mid-my until the end of July in In-row weed control ws performed with n hericide, while turf ws left etween the rows nd periodiclly mowed. Mesured prmeters were shoot elongtion, stem dimeter t rest height nd plnt height (mesured in winter 2005 nd 2006). Lef gs exchnge ws mesured 10 times in 2005 nd 4 times in 2006 with portle infrred gs nlyser (CIRAS-2, PP Systems, Hertfordshire, UK). Mesured vriles were instnt net photosynthetic rte (A; µmol m -2 s -1 ) nd trnspirtion rte (E; mmol m -2 s -1 ). Wter use efficiency (WUE; µmol CO 2 / mmol H 2 0) ws clculted s A to E rtio. Mesurements were tken etween 8.00 nd h. Fifteen fully expnded leves (3 leves per 5 plnts) per irrigtion nd fertiliztion tretment were used for gs exchnge. For ech mesurement, leves from the outer prt of the crown t different heights were smpled. Chlorophyll fluorescence ws mesured twice with portle nlyzer (Hndy Pe, PP Systems, Hertfordshire, UK) during summer Chlorophyll fluorescence is good indictor of drought stress in plnts (10). All dt were sujected to two-wy ANOVA nd Duncn s multiple rnge test ws used to seprte mens of the min effects (fertiliztion nd irrigtion). Differences were considered significnt for P 0,05. Sttisticl nlysis ws mde with SPSS sttisticl pckge for Windows (SPSS Inc., Chicgo, IL). Results nd Discussion: In 2005 shoot elongtion ws incresed in oth irrigted nd fertilized trees (Tle 1). The effect of fertiliztion ws more evident (lower P-vlue) nd went on lso in 2006, while irrigtion lone filed to increse shoot elongtion in the second yer of the experiment. Stem dimeter ws 52

4 incresed y irrigtion oth in 2005 nd 2006, while fertiliztion incresed secondry growth only in Plnt height ws unffected y the tretments. There ws cler interction etween irrigtion nd fertiliztion: plnts tht were oth irrigted nd fertilized developed thicker stems nd longer shoots thn control plnts or plnts tht were only irrigted or fertilized (Tle 1). This ws lso confirmed y greter weight of the pruned mteril of the F+I tretment, if compred to the other thesis. In plnts tht were oth irrigted nd fertilized, the fresh weight of the pruned mteril ws respectively 47%, 41% nd 35% higher thn in plnts which were either irrigted or fertilized nd thn in control plnts. This prmeter is highly representtive ecuse it is good indictor of vegettive growth. Irrigtion significntly incresed lef gs exchnge: wellwtered plnts hd greter cron ssimiltion nd trnspired more wter thn non-wtered trees oth in 2005 nd 2006 (Tle 2). The doption of wterconservtive strtegy limiting trnspirtion y incresed stomtl resistnce is common in drought-stressed plnts. The lower stomtl conductnce reduces net photosynthesis, s well s trnspirtion, nd this my led to lower crohydrtes to support future growth. Irrigtion decresed wter-use efficiency nd the decline of WUE is typicl of plnts with fvourle wter sttus (14). Fertiliztion, whether or not coupled with irrigtion, significntly reduced cron ssimiltion in the first yer fter trnsplnt (2005). In 2005, fertilized, nonirrigted plnts showed lower cron ssimiltion nd trnspirtion if compred to irrigted plnts nd control plnts (Tle 2). This mde us hypothesize tht, s reported y some uthors (8), nutrient supply cn decrese plnt tolernce to drought. In 2006, cron ssimiltion ws no more ffected y fertiliztion, which only decresed trnspirtion either in presence or sence of irrigtion. Chlorophyll fluorescence ws influenced y irrigtion nd fertiliztion tretments on 28 th June, while no significnt differences were found on 14 th July (Tle3). Percivl et l. (10) proposed tht, in the sence of stress, the rtio etween vrile fluorescence nd mximum fluorescence (Fv/Fm) should remin ove 0,75. On 28 th June, the irrigted plnts were not stressed, while some stress occurred in non-irrigted mples. Fertiliztion lso decresed fluorescence on 28 th June, nd fertilized plnts were more stressed thn those which did not receive nutrient supply. A significnt interction etween fctors showed tht fertiliztion, if provided without irrigtion, leds to greter stress in the period fter plnting (Tle 3). On the other hnd, if coupled with irrigtion, fertiliztion my help producing fst-growing, unstressed trees. In conclusion, our results show tht fertiliztion incresed shoot growth of sycmore mple. However, if fertiliztion is pplied in the sence of irrigtion, it my led to stomtl closure, reduced cron ssimiltion nd gs exchnge nd my increse tree predisposition to wter stress. Thus, in fertilized, nonirrigted tree stnds, nutrient vilility my increse shoot growth t the expense of root growth nd storge of reserves, t this my led to trnsplnt filing, especilly in the first yer (13, 5, 8). Irrigtion hd slight effect on shoot growth, ut incresed stem dimeter, gs exchnge nd chlorophyll ctivity. As reported y other uthors (1, 3, 15), our results confirm tht, in order to mximize 53

5 tree stnd productivity, irrigtion should e coupled with fertiliztion. Acknowledgements: We would like to thnk Regione Lomrdi Project Tecniche eco-comptiili di gestione del vivismo e del verde ornmentle (Pino per l ricerc e lo sviluppo 2004). Literture Cited: 1. Allen C.B., R.E. Will, R.C. McGrvey, D.R. Coyle nd M.D. Colemn Rdition-use efficiency nd gs exchnge responses to wter nd nutrient vilility in irrigted nd fertilized stnds of sweetgum nd sycmore. Tree Physiol. 25: Bñon S., J. Ocho, J.A. Frnco, J.J. Alrcón nd M.J. Sánchez-Blnco Hrdening of olender seedlings y deficit irrigtion nd low ir humidity. Environ. Exp. Bot. 56: Choi W.J., S.X. Chng, H.L. Allen, D.L. Kelting nd H.M. Ro Irrigtion nd fertiliztion effects on folir nd soil cron nd nitrogen isotope rtios in lololly pine stnd. For. Ecol. Mng. 213: Dy S.D. nd J.R. Hrris Fertiliztion of red mple (Acer rurum) nd littlelef linden (Tili cordt) trees t recommended rtes does not id tree estlishment. Aroriculture & Urn Forestry 33(2): Frnco J.A., J.J. Mrtìnez-Sànchez, J.A. Fernàndez nd S. Bñon Selection nd nursery production of ornmentl plnts for lndscping nd xero-grdening in semi-rid environments. J. Hort. Sci & Biotec. 81(1): Gilmn E.F., J, Grosky, A. Studol nd M.D. Mrshll Irrigtion nd continer type impct red mple (Acer rurum L.) 5 yers fter lndscpe plnting. J. Aroric. 29(4): Grcino C., J.J. Guimét nd J.F. Goy Impct of nitrogen nd phosphorus fertiliztion on drought responses in Eucliptus grndis seedlings. For. Ecol. Mng., 212: Lloyd J.E., D.A. Herms, M.A. Rose nd J. Vn Wgoner Fertiliztion rte nd irrigtion scheduling in the nursery influence growth, insect performnce, nd stress tolernce of Sutyzm crpple in the lndscpe. HortScience 41: Mc Alister J.A. nd V.R. Timmer Nutrient enrichment of white spruce seedlings during nursery culture nd initil plnttion estlishment. Tree Physiol. 18: Percivl G.C., I.P. Kery nd S. Al-Hsi An ssessment of drought tolernce of Frxinus genotypes for urn lndscpe plnting. Urn Forestry & Urn Greening 5:

6 11. Smpson D.A., R.H. Wring, C.A. Mier, C.M. Gough, M.J. Ducey nd K.H. Johnsen Fertiliztion effects on forest cron storge nd exchnge, nd net primry production: A new hyrid process model for stnd mngement. For. Ecol. Mng. 221: Snds R. nd D.R. Mullign Wter nd nutrient dynmics nd tree growth. For. Ecol. Mng. 30: Wlters M.B. nd P.B. Reich Response of Ulmus mericn seedlings to vrying nitrogen nd wter sttus. 1 Photosynthesis nd growth. Tree Physiol. 5: Wrren C.R., J.F. McGrth nd M.A. Adms Wter vilility nd cron isotope discrimintion in conifers. Oecologi 127: Wterworth R., R.J. Rison, C. Brck, M. Benson, K. Prtp nd P. Keryn P Effects of irrigtion nd N fertiliztion on growth nd structure of Pinus rdit stnds etween 10 nd 29 yers of ge. For. Ecol. Mng. 239: Zwck J.A., W.R. Grves nd A.M. Townsend Lef wter reltions nd plnt development of three freemn mple cultivrs sujected to drought. J. Amer. Soc. Hort. Sci. 123:

7 Tle 1. Shoot elongtion, stem dimeter t rest height, plnt height nd weight of pruned iomss fter pruning trees to uniform size in sycmore mples grown with different irrigtion nd fertiliztion tretments. Shoot elongtion (cm) Stem dimeter (mm) Plnt height (cm) Weight of pruned mteril (g) Tretment Irrigtion Irrigted 13.7 z Non-irrigted P-vlue Fertiliztion Fertilized Non-fertilized P-vlue Irrigtion x Fertiliztion Fertilized, nonirrigted Irrigted, nonfertilized c Fertilized nd irrigted Control c P-vlue z Mens within the sme column with different letters re significntly different, Duncn s multiple rnge test (P 0.05). 56

8 Tle 2. Cron ssimiltion, trnspirtion nd wter use efficiency in sycmore mple grown with different irrigtion nd fertiliztion tretments. Cron ssimiltion (µmol m -2 s -1 ) Trnspirtion (mmol m -2 s -1 ) Wter Use Efficiency Tretment Irrigtion Irrigted 6.47 z Non-irrigted P-vlue Fertiliztion Fertilized Non-fertilized P-vlue Irrigtion x Fertiliztion Fertilized, nonirrigted c 1.70 c Irrigted, nonfertilized Fertilized nd irrigted Control c P-vlue z Mens within the sme column with different letters re significntly different, Duncn s multiple rnge test (P 0.05). 57

9 Tle 3. Chlorophyll fluorescence in sycmore mple grown with different irrigtion nd fertiliztion tretments. Tretment 28-June July-2005 Irrigtion Irrigted 0.78 z 0.77 Non-irrigted P-vlue Fertiliztion Fertilized Non-fertilized P-vlue Irrigtion x Fertiliztion Fertilized, nonirrigted Irrigted, nonfertilized Fertilized nd irrigted Control P-vlue z Mens within the sme column with different letters re significntly different, Duncn s multiple rnge test (P 0.05). 58

10 Growth nd gs exchnge responses of two field-grown mple tree species to three reference evpotrnspirtion sed irrigtion regimes Thyne Montgue Dept. Plnt nd Soil Science, Texs Tech University, Luock, Index words: Acer x freemnii Autumn Blze, A. trunctum, Reference Evpotrnspirtion, Irrigtion Significnce to Industry: For mny nurseries, wter conservtion is top priority. However, while reducing the mount of wter used in nursery production is crucil, little dt exists which quntifies the mount of wter needed to produce field-grown trees, or methodology to estimte tree wter requirements. This reserch suggests clculting irrigtion levels sed upon estimted tree root re nd reference evpotrnspirtion my provide sufficient wter for growth, yet void over irrigting nd wsting resources. In ddition, this reserch indictes irrigtion volume will influence gs exchnge nd growth of field-grown mple tree species, ut proper irrigtion volume cn conserve wter nd produce stisfctory growth. Nture of Work: Drought nd depleted wter tles hve incresed the numer of ordinnces (often without regrd to plnt wter requirements) in mny municiplities nd irrigtion districts. These ordinnces often limit the mount of wter nurseries cn use to irrigte trees (1). Even though reserch on wter conservtion in nurseries is currently ongoing (3), little reserch hs een conducted to inform growers, municiplities, nd irrigtion districts the mount of wter required to produce field-grown (FG) tree species (2). To help determine the influence of limited irrigtion on FG tree species, this reserch investigted gs exchnge nd growth of two FG mple tree species sujected to three reference evpotrnspirtion sed irrigtion regimes in semi-rid climte. Reserch ws conducted t field nursery in Luock, TX. Selected species were: Autumn lze (Acer x freemnii Autumn Blze ) nd Shntung (A. trunctum) mple. During Spring 2002, nine continerized (3 gl) trees of ech species were plnted in rndomized lock design. Irrigtion regimes were sed upon estimted soil surfce re ove the tree s root system (in 2 ) nd locl reference evpotrnspirtion (ETo (in)). During the dormnt period fter ech growing seson root re ws estimted y removing soil from severl trees. Climtic dt ws collected from n on site wether sttion. Irrigtion regimes were: 100, 60, nd 30% of ETo (high, medium, nd low, respectively). Trees were irrigted through drip irrigtion system. Ech tree hd 3, 2, or 1 emitters (1 gl hr -1 ) plced t the se of the tree nd trees were irrigted n equl mount of time twice ech week. If precipittion occurred, precipittion ccumultion ws sutrcted from ETo. Trees were not fertilized or pruned during the experiment. During the 2002 growing seson, ll trees were irrigted 59

11 t 100% ETo. Irrigtion tretments egn Spring 2003 nd continued through the 2005 growing seson. On severl occsions ech growing seson gs exchnge dt (pre-dwn lef wter potentil nd mid-dy stomtl conductnce) were collected. Growth dt (trunk cliper increse, shoot elongtion, nd totl lef re) were collected t the end of ech growing seson. Dt were sujected to ANOVA pproprite for rndomized lock design. If tretment differences were found, mens were seprted y Fisher s LSD. Due to pge limittions nd similrity of dt etween growing sesons, 2004 dt will e presented. Results nd Discussion: Climtic dt from the growing seson (1 April through 30 Septemer) indicte precipittion totl ws 7.9 inches nd totl ETo ws 46.5 inches. For ech irrigtion tretment, totl irrigtion volume pplied to ech tree rnged from to 138 gllons (low irrigtion regime) to 462 gllons (high irrigtion regime) (dt not shown). Pre-dwn lef wter potentil nd mid-dy stomtl conductnce mesurements during the growing seson were vrile (dt not shown). For Shntung mple, pre-dwn lef wter potentil nd stomtl conductnce mesurements vried etween irrigtion regimes. However, trees receiving the gretest mount of irrigtion generlly where under less stress (less negtive pre-dwn lef wter potentil nd greter stomtl conductnce mens) when compred to trees receiving less irrigtion. For Autumn lze mple, pre-dwn lef wter potentil nd stomtl conductnce mens lso vried etween irrigtion. However, on severl occsions trees receiving low nd medium irrigtion hd greter stomtl conductnce nd lower pre-dwn lef wter potentil thn trees receiving the high irrigtion tretment. Dt indicte irrigtion tretment lso influenced growth of ech species. When compred to the low nd medium irrigtion tretments, shoot growth nd lef re of Shntung mple trees receiving the high irrigtion tretment hd greter growth (Fig. 1). However, there ws no difference for cliper increse etween irrigtion tretments. Similr growth trends were not found for Autumn lze mple. For ech growth prmeter, Autumn lze mple trees receiving the medium irrigtion tretment hd similr or greter growth when compred to trees receiving the high irrigtion tretment nd generlly greter growth thn trees receiving the low irrigtion tretment (Fig. 2). This reserch indictes irrigtion volume cn influence gs exchnge nd growth of these FG, mple vrieties. It is interesting to note tht the gretest gs exchnge nd growth ws not necessrily ssocited with trees receiving the gretest mount of irrigtion volume. In ddition, despite limited irrigtion ll trees survived nd were of similr esthetic qulity. Therefore, it ppers for some tree species irrigtion volume my e reduced nd produce similr growth when compred to trees receiving greter irrigtion volume. In ddition, it ppers the influence of irrigtion volume on growth of these FG trees is plnt structure nd species specific. Dt lso suggests irrigtion of FG trees sed upon soil surfce root re nd locl ETo mesurements my e mens to conserve irrigtion wter nd produce FG trees with cceptle growth. However, 60

12 continued reserch on the influence of reduced irrigtion on FG tree species is needed. Literture Cited 1. Mthers, H.M., T. H. Yeger, nd L. T. Cse Improving irrigtion wter use in continer nurseries. HortTechnology. 15: Montgue, T., R. Kjelgren, R. Allen, nd D. Wester Wter loss estimtes for five recently trnsplnted lndscpe tree species in semi-rid climte. J. Environ. Hort. 22: Wrren, S.L. nd T. E. Bilderck More plnt per gllon: Getting more out of your wter. HortTechnology. 15: Shntung mple growth (2004) 7 Low irrigtion Medium irrigtion High irrigtion c Shoot growth (inches) Cliper increse (inches) Lef re (inches 2 ) Figure 1. Shoot growth, cliper increse nd totl lef re for field-grown Shntung mple trees sujected to three irrigtions regimes (100, 66, nd 33% reference ET (high, medium, nd low, respectively). Different letters indicte significnt effects of irrigtion regime (P 0.05). 61

13 Autumn lze mple growth (2004) 7 Low irrigtion Medium irrigtion High irrigtion c Shoot growth (inches) Cliper increse (inches) Lef re (inches 2 ) Figure 2. Shoot growth, cliper increse nd totl lef re for field-grown Autumn lze mple trees sujected to three irrigtions regimes (100, 66, nd 33% reference ET (high, medium, nd low, respectively). Different letters indicte significnt effects of irrigtion regime (P 0.05). 62

14 Investigting wter requirements of select, field-grown tree species in semi-rid climte Thyne Montgue Dept. Plnt nd Soil Science, Texs Tech University, Luock, Index words: Acer uergernum, A. cmpestre, Quercus muehlenergii, Q. rour x Q. icolor Asjes, reference evpotrnspirtion, irrigtion Significnce to Industry: For mny nurseries, wter conservtion is top priority. However, while reducing the mount of wter used in nursery production is crucil, little dt exists which quntifies the mount of wter needed to produce field-grown trees, or methodology to estimte tree wter requirements. This reserch suggests clculting irrigtion levels sed upon estimted tree root re nd reference evpotrnspirtion my provide sufficient wter for growth, yet void over irrigting nd wsting resources. In ddition, this reserch indictes irrigtion volume will influence field-grown mple tree species, ut proper irrigtion volume cn conserve wter nd produce stisfctory growth. Nture of Work: Recent droughts nd depleted wter tles cross mny regions hve elevted the necessity to irrigte field-grown (FG) nursery trees. At the sme time, ordinnces restricting nursery irrigtion volume hve een implemented, often without regrd to plnt wter requirements. These ordinnces often limit the mount of wter nurseries cn use to irrigte trees (1). Even though reserch on wter conservtion in nurseries is currently ongoing (3), little reserch hs een conducted to inform growers, municiplities, nd irrigtion districts the mount of wter required to produce FG tree species (2). To help determine the influence of limited irrigtion on FG tree species, this reserch investigted growth of two FG mple nd two FG ok tree species sujected to three reference evpotrnspirtion sed irrigtion regimes in semi-rid climte. Reserch ws conducted t field nursery in Luock, TX. Selected species were: Acer uergernum (trident mple), A. cmpestre (hedge mple), Quecus muehlenergii (chinkpin ok), nd Q. rour x Q. icolor Asjes (English ok). During Spring 2002, nine continerized (3 gl.) trees of ech species were plnted in rndomized lock design. Irrigtion regimes were sed upon estimted soil surfce re ove the tree s root system (in 2 ) nd locl reference evpotrnspirtion (ETo (in)). During the dormnt period fter ech growing seson root re ws estimted y removing soil from severl trees. Climtic dt ws collected from n on site wether sttion. Irrigtion regimes were: 100, 60, nd 30% of ETo (high, medium, nd low, respectively). If precipittion occurred, precipittion ccumultion ws sutrcted from ETo. Trees were irrigted through drip irrigtion system. Ech tree hd 3, 2, or 1 emitters (1 gl hr -1 ) plced t the se of the tree nd trees were irrigted n equl mount of 63

15 time twice ech week. Trees were not fertilized or pruned during the experiment. During the 2002 growing seson, ll trees were irrigted t 100% ETo. Irrigtion tretments egn Spring 2003 nd continued through the 2005 growing seson. Trunk cliper increse nd shoot elongtion (10 rndomly selected shoots from ech tree) were collected t the end of ech growing seson. Dt were sujected to ANOVA pproprite for rndomized lock design. If tretment differences were found, mens were seprted y Fisher s LSD. Due to pge limittions nd similrity of dt etween growing sesons, only 2005 dt will e presented. Results nd Discussion: Climtic dt from the 2005 growing seson (1 April through 30 Septemer) indicte totl precipittion ws 9.1 inches nd totl ETo ws 43.4 inches. For ech irrigtion tretment, totl irrigtion volume pplied to ech tree rnged from to 123 gllons (low irrigtion regime) to 410 gllons (high irrigtion regime) (dt not shown). Dt indicte irrigtion tretment influenced growth of ech species. When compred to high nd medium irrigtion tretments, shoot nd cliper growth of ech mple species ws gretest for trees receiving the lest mount of irrigtion (Figs. 1 nd 2). For ok species, growth vried etween species nd irrigtion tretment. Chinkpin ok hd greter shoot nd cliper growth when trees were irrigted t the high irrigtion level (Fig. 3). However, for English ok there ws no difference for shoot growth etween high nd low irrigtion tretments (Fig. 4). Cliper increse for English ok ws gretest when trees received the low irrigtion tretment. This reserch indictes irrigtion volume cn influence gs exchnge nd growth of these FG tree species. It is interesting to note tht for severl species the gretest nd growth ws not necessrily ssocited with trees receiving the gretest mount of irrigtion volume. In ddition, despite limited irrigtion ll trees survived nd were of similr esthetic qulity. Therefore, it ppers for some tree species irrigtion volume my e reduced nd produce similr growth when compred to trees receiving greter irrigtion volume. In ddition, it ppers the influence of irrigtion volume on growth of these FG trees is plnt structure nd species specific. Dt lso suggests irrigtion of FG trees sed upon soil surfce root re nd locl ETo mesurements my e mens to conserve irrigtion wter nd produce FG trees with cceptle growth. However, continued reserch on the influence of reduced irrigtion on FG tree species is needed. 64

16 Literture Cited 1. Mthers, H.M., T. H. Yeger, nd L. T. Cse Improving irrigtion wter use in continer nurseries. HortTechnology. 15: Montgue, T., R. Kjelgren, R. Allen nd D. Wester Wter loss estimtes for five recently trnsplnted lndscpe tree species in semi-rid climte. J. Environ. Hort. 22: Wrren, S.L. nd T. E. Bilderck More plnt per gllon: Getting more out of your wter. HortTechnology. 15: Low irrigtion Medium irrigtion High irrigtion Hedge mple c Shoot growth (inches) Cliper increse (inches) Figure 1. Shoot growth nd cliper increse for field-grown hedge mple trees sujected to three irrigtions regimes (100, 66, nd 33% reference ET (high, medium, nd low, respectively). Different letters indicte significnt effects of irrigtion regime (P 0.05). 65

17 5 Low irrigtion Medium irrigtion High irrigtion Trident mple Shoot growth (inches) Cliper increse (inches) Figure 2. Shoot growth, cliper increse, nd totl lef re for field-grown trident mple trees sujected to three irrigtions regimes (100, 66, nd 33% reference ET (high, medium, nd low, respectively). Different letters indicte significnt effects of irrigtion regime (P 0.05). 5 Low irrigtion M edium irrigtion High irrigtion Chinkpin ok Shoot growth (inches) Cliper increse (inches) Figure 3. Shoot growth, cliper increse, nd totl lef re for field-grown chinkpin ok trees sujected to three irrigtions regimes (100, 66, nd 33% reference ET (high, medium, nd low, respectively). Different letters indicte significnt effects of irrigtion regime (P 0.05). 66

18 5 Low irrigtion M edium irrigtion High irrigtion English ok Shoot growth (inches) Cliper increse (inches) Figure 4. Shoot growth, cliper increse, nd totl lef re for field-grown English ok trees sujected to three irrigtions regimes (100, 66, nd 33% reference ET (high, medium, nd low, respectively). Different letters indicte significnt effects of irrigtion regime (P 0.05). 67

19 Effect of Nitrogen Source on Trunk Cliper Growth of Field- Grown Zelkov Jmes A. Roins University of Arknss, Horticulture Deprtment, Little Rock, AR Index Words: nursery production, plnt nutrition, fertilizer Significnce to the Industry: Field-grown zelkov trees were fertilized with different nitrogen sources. Regrdless of N source, there ws no significnt difference in trunk cliper fter one or two growing sesons. Dt from the Arknss Delt region suggest tht N source, when pplied in the spring, hs miniml effect in field production of zelkov trees. Nture of Work: Limited dt re ville on the effect of nitrogen (N) rte on the growth of field-grown shde trees reltive to continer-grown ornmentls (8). Specific results re dependent on the N rte, time of ppliction nd species involved (3, 5, 6, 9). While nitrogen source hs een extensively studied for greenhouse crops (2, 4, 7), less is known out the effect of nitrogen source on the growth of field-grown shde trees. The ojective of this reserch ws to evlute the effect of N source on the growth of field-nursery grown shde trees in the Delt region of Arknss. The reserch ws conducted t commercil field shde-tree nursery in Hrrisurg, AR. Zelkov serrt Green Vse trees were plnted s reroot (BR) plnts on 5 Mrch 2005 y the nursery owner. Plnts were wtered s needed y drip irrigtion. Tree spcing within row ws on 6 ft. centers nd tree density ws pproximtely 560 trees/cre. Nitrogen fertilizer tretments were pplied on Mrch 30, 2005 nd Mrch 15, 2006 which is typiclly two to three weeks efore ud rek for northest Arknss. Ure (46-0-0) nd mmonium nitrte (AN; ) were rodcst y hnd to the soil surfce in n re 1 ft 2 within the tree trunk. The month controlled relese fertilizer PolyOn (N-P 2 O 5 -K 2 O nlysis; Pursell Technologies, Sylcug, AL), ws pplied on Mrch 30, 2005 using the drill nd fill method (1). Tretments were ssigned in completely rndomized design. Tretments were pplied to single plnts, which represented one replicte; the totl numer of replictions ws 17. Every yer in June the soil ws tested to estlish P & K levels. Soil ws smpled to depth of 4-6. No dditionl P or K ws required in 2005 or 2006 s indicted y the soil test. Tree growth ws evluted y mesuring the trunk clier 1 m (~3 ft.) ove the soil surfce nd tree height on 1 Novemer 2005 nd 30 Octoer Dt ws nlyzed y ANOVA procedures nd men seprtion y Tukey s HSD (p=0.05). 68

20 Results nd Discussion: Nitrogen source did not hve significnt effect on the trunk cliper of Green Vse Zelkov during the first nd second sesons following BR plnting in field nursery in the Delt region of Arknss (Tle 1). Nitrogen in ny form, when pplied t 100 l N/A for two growing sesons, did not increse cliper growth reltive to n unfertilized control. The fct tht nitrogen hd miniml effect on cliper growth of field-grown shde trees is consistent with reserch conducted on other tree species in this region. Bsed on these dt, it would pper tht N input for Arknss Delt field nurseries should e miniml, thus reducing nutrient input (fertilizer) costs. Literture Cited: 1. Bilderck, T. et l Drill nd fill nd other field nursery fertilizer ppliction techniques. Proc. SNA Res. Conf. 48: Crer, R.I., R.Y. Evns nd J.L. Pul The uptke of nitrte nd mmonium y greenhouse roses. Act Hortic.424: Chong, C Response of little-lef linden nd honey locust to rtes of orgnic nd minerl nitrogen. HortSci. 35: Conover, C.A. nd R. T. Poole Nitrogen source effects on growth nd tissue content of selected folige plnts. HortScience 21(4): Cripps, R.W N fertiliztion of field-grown woody ornmentls. Proc. SNA Res. Conf. 37: Rose, M.A Nutrient use ptterns in woody perennils: implictions for incresing fertilizer efficiency in field-grown nd lndscpe ornmentls. HortTechnology 9: Steinkmp, K. et l Nitrogen form ffects folige plnt growth: A summry of reserch t CFREC-Apopk. S. Nursery Digest. June , 38-39, Struve, D.K A review of shde tree nitrogen fertiliztion reserch in the United Sttes. J. of Aror. 28(6): Wrren, S.L., et l Optimizing shde tree production: groundcover, nitrogen rte nd timing of nitrogen ppliction. Proc. SNA Res. Conf. 38: Acknowledgements: The uthor is extremely pprecitive of the dontion of production spce y Lwrence Reddmnn Frms, Hrrisurg, AR. Support for this reserch ws provided y the Arknss Fertilizer Tonnge Fee. 69

21 Tle 1. Trunk cliper for Zelkov serrt Green Vse fertilized with different N sources t field shde tree nursery in Hrrisurg, AR. Men seprtion y Tukey s HSD (p=0.05) N Fertilizer Tretment z Men Trunk Cliper (cm) Ure; 50 l N/A Ure; 50 l N/A AN; 50 l N/A AN; 50 l N/A PolyOn y ; 100 l N/A Unfertilized check Unfertilized check z N ws pplied on Mrch 30, 2005 nd Mrch 15, AN = mmonium nitrte (NH 4 NO 3 ) y PolyOn , month controlled-relese fertilizer pplied with drill nd fill method 70

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