Early-Maturing Sweet Oranges: Research Update on Earlygold, Itaborai, Ruby, and Westin Sweet Oranges 1

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1 HS920 Erly-Mturing Sweet Ornges: Reserch Updte on Erlygold, Itori, Ruy, nd Westin Sweet Ornges 1 Willim S. Cstle nd Jmes J. Ferguson 2 Erlygold, Itori, Ruy, nd Westin re new sweet ornge selections with vrying comintions of exceptionl juice color, interesting flvor, or good solule solids development erly in the fruit seson. Considering these chrcteristics, these cultivrs hve commercil potentil s juice ornges nd re discussed here. The first trees of these erly-mturing sweet ornges were evluted during the lte 1980s nd erly 1990s in originl Florid field trils t St. Cloud. Descriptions of these selections (nd Verni, n erly mturing Vlenci type ornge), long with some of their performnce chrcteristics, were pulished in the June 1999 issue of Citrus Industry mgzine. Since then, Bureu of Citrus Budwood Registrtion records indicte tht out 1.6 million trees of these selections (including Verni) were propgted from 1999 through The most populr selection hs een Erlygold (59% of the totl) followed y Verni (14%), Westin (13%), nd Itori nd Ruy (7% ech). Dt re no longer eing collected from the originl tril t St. Cloud, ut dditionl trils hve een estlished in commercil groves on the Ridge nd in the Immoklee re. The trees for these trils were propgted using uds from the originl trees ut on other rootstocks not used in the St. Cloud tril. Ridge Site Results (Dundee) This site is locted est of Lke Hmilton on typicl Ridge soil (Cndler snd). Erlygold, Itori, nd Ruy trees on eight rootstocks (Tle 1) were plnted in 1995 t 12 feet x 22 feet nd re irrigted with microsprinklers. This forml tril lso includes norml mture-line commercil Hmlin trees on Swingle citrumelo for comprison. Using uds from the ove forml tril, Erlygold trees on either Benton citrnge or two size-controlling rootstocks (C-35 citrnge nd K x R citrnge) were lso plnted for informl oservtion. Using uds from the originl St. Cloud tril, Westin trees were lso similrly plnted. All trees grew well in the first 7 yers fter plnting. In the forml tril, those on Crrizo nd Kuhrske citrnges re mong the tllest lthough the differences mong trees on different rootstocks re not very gret. However, virtully ll trees of the new selections, except those on C-35 citrnge, re tller thn the Hmlin trees on Swingle. 1. This document is HS920, one of series of the Horticulturl Sciences Deprtment, Florid Coopertive Extension Service, Institute of Food nd Agriculturl Sciences, University of Florid. Puliction dte: My Plese visit the EDIS We site t 2. Willim S. Cstle, professor, CREC-Lke Alfred, Jmes J. Ferguson, professor, Horticulturl Sciences Deprtment, Coopertive Extension Service, Institute of Food nd Agriculturl Sciences, University of Florid, Ginesville, The Institute of Food nd Agriculturl Sciences is n equl opportunity/ffirmtive ction employer uthorized to provide reserch, eductionl informtion nd other services only to individuls nd institutions tht function without regrd to rce, color, sex, ge, hndicp, or ntionl origin. For informtion on otining other extension pulictions, contct your county Coopertive Extension Service office. Florid Coopertive Extension Service/Institute of Food nd Agriculturl Sciences/University of Florid/Christine Tylor Wddill, Den.

2 Erly-Mturing Sweet Ornges: Reserch Updte on Erlygold, Itori, Ruy, nd Westin... 2 Results from the first 4 ering yers indicte tht the new selections in this tril develop juice color superior to Hmlin. Tht dvntge ppers s soon s erly Septemer (Fig. 1 nd Fig. 2). The color numers continue to improve to out 35 or 36 y lte Octoer-erly Novemer depending on the yer. (Note tht color numer is the vlue mesured y the officil colorimeter; color score is the legl 2-digit vlue derived from rounding off the color numer, e.g., color numer of 35.6 = color score of 36.) Juice color lso develops well hed of peel color nd t hrvest, peel color usully chnges from green to yellow. However, if fruit remin on the tree, or cool wether comes erly, the peel cn turn to n ttrctive ornge with hints of red. Figure 1. Chnges in juice color numer of erly-mturing sweet ornge selections on Swingle citrumelo rootstock t the Ridge site during the seson. Figure 2. Chnges in juice color numer of erly-mturing sweet ornge selections on Swingle citrumelo rootstock t the Ridge site during the seson. The verge yield cross ll rootstocks for the seson ws 3.3 oxes/tree for Erlygold, 2.4 oxes for Itori, nd 2.1 oxes for Ruy sweet ornge. The Hmlin trees on Swingle produced out 2 oxes per tree. These yields re slightly down from lst yer, proly reflecting the lower predicted sweet ornge yield of the industry s whole for this seson. Ech yer there hve een only slight, ut consistent differences in yield mong the trees on the eight rootstocks. Cumultive performnces over the erliest 4 ering yers, regrdless of the scion selection, show tht the trees on some rootstocks like Kuhrske nd C-35 citrnges re producing well despite their differences in tree sizes, while others like Smooth Flt Seville re disppointing so fr (Tle 1 nd Tle 2). The Erlygold, Itori, nd Ruy trees on Swingle hve yielded s well s or etter thn the Hmlin trees on Swingle. A more telling story is evident in the cumultive pounds-solids (PS 3 ) dt (Tle 1 nd Tle 2). Agin, the differences mong rootstocks re not lrge, ut Erlygold, Itori, nd Ruy sweet ornge cumultive pounds-solids exceed tht of Hmlin on Swingle y 500 to 2,000 PS/cre fter 4 sesons. This rnge in PS is mostly the result of yield differences of these experimentl cultivrs on different rootstocks, ut note the differences in juice qulity s well (Tle 3, Tle 4 nd Tle 5). Over the lst two sesons, trees of ech selection generlly produced the est qulity juice (rtio nd color numer) when grown on Swingle or C-35. Trees on Smooth Flt Seville produced fruit with reltively poor juice qulity nd were reltively low-yielding (see oxes/tree in Tle 1 nd Tle 2) which explin their low cumultive PS/cre. Westin sweet ornge trees on Benton citrnge re prt of the Ridge site lthough they re younger thn the trees in the forml tril. The Westin trees hve fruited since the seson. Fruit tends to e somewht flttened like grpefruit with etter PS thn Erlygold nd Itori. Westin lso mtures erly, nd its juice color is similr to Hmlin. However, in Brzil, Westin trees hve reputtion for premture fruit drop. In the lst seson (2002) the trees were prticulrly well cropped nd dropped out 5 to 10% of their fruit; this seson the trees were not s well cropped nd dropped very little fruit.

3 Erly-Mturing Sweet Ornges: Reserch Updte on Erlygold, Itori, Ruy, nd Westin... 3 Southwest Site Results (Immoklee) The trees t this site were plnted t out the sme time from the sme tch of nursery trees s those used to plnt the Ridge tril. The trees were not plnted in forml tril, ut in whole eds of ech sweet ornge selection with trees within ed grouped y rootstock. Sesonl trcking dt of juice qulity, yield oservtions, nd tree height mesurements hve een recorded from this site. All indictions so fr suggest tht the trees t oth sites re performing similrly. The trees t Immoklee hve grown well, nd their fruit show the sme sesonl juice color nd PS ptterns s the fruit in the Ridge tril (Fig. 3, Fig. 4, Fig. 5 nd Fig. 6). Figure 5. Chnges in juice color numer of erly-mturing sweet ornge selections on Swingle citrumelo rootstock t the Immoklee site during the seson. The Hmlin fruit were otined from nery, ut different grove. Figure 6. Chnges in juice pound-solids/ox of erly-mturing sweet ornge selections on Swingle citrumelo rootstock t the Immoklee site during the seson. The Hmlin fruit were otined from nery ut different grove. Figure 3. Chnges in juice pound-solids/ox of erly-mturing sweet ornge selections on Swingle citrumelo rootstock t the Ridge site during the seson. Figure 4. Chnges in juice pound-solids/ox of erly-mturing sweet ornge selections on Swingle citrumelo rootstock t the Ridge site during the seson. Grower Cutions Growers re encourged to plnt these new sweet ornges, ut should lso e restrined in their expecttions. As you exmine nd interpret the dt presented, it my e tempting to drw comprtive conclusions out the scion selections or the rootstocks, ut tht would e risky t the moment. It is sfe to conclude tht Erlygold, Itori, nd Ruy hve distinct juice color dvntges over Hmlin, ut it is not timely to conclude tht ny of the new scion selections will otherwise out-perform Hmlin on yield or PS sis. The PS/ox vlues of the new selections my strike some reders s low, ut quick check of the Novemer Florid Agriculturl Sttisticl Service mturity dt ( shows tht these new cultivrs re nerly identicl to Hmlin for erly seson fruit. Hmlin trees cn produce fruit with nerly 6 pounds of solids/ox, ut not ordinrily in Novemer.

4 Erly-Mturing Sweet Ornges: Reserch Updte on Erlygold, Itori, Ruy, nd Westin... 4 The Ridge tril trees re now 7 yers old nd the est comintions re strting to produce 3 or 4 oxes/tree, depending on the rootstock. PS/ox vlues re very similr to Hmlin vlues, ut growers should recognize tht these three selections cnnot e held on the tree into lte Decemer or Jnury like Hmlin. Every yer the Brix/Acid rtio hs either pproched or exceeded 20 y mid-novemer. These sweet ornge selections re very much erly mturing nd must e hrvested erly. For this reson, the use of these selections s resets in Hmlin grove, or to convert Hmlin grove, should e crefully considered. Erlygold hs een the most hevily fvored in propgtion of these selections thus fr. The Ridge site dt tend to support tht decision. However, tke closer look t the Hmlin/Swingle dt. Those dt vry mong the trees included in ech of the res where n experimentl scion selection is eing grown. For exmple, the Hmlin trees growing mong the Ruy trees hve cumultive yield of 6.5 oxes/tree. The Hmlin trees in the Itori re yielded 9.1 oxes. Wht if the Ruy trees hd een plnted where the Itori trees re nd vice vers? The results might e different nd could led to different conclusions. Other fctors could hve ffected these yields. Juvenility One strtegy for introducing new sweet ornges nd other cultivrs into Florid is to otin seeds from promising vrieties grown in different citrus producing regions round the world. Sweet ornge seeds re highly nucellr which mens tht most sweet ornge trees (nd fruit) grown from seed re going to e geneticlly similr to the tree from which they cme. Other citrus scion cultivrs, especilly mndrin hyrids like Roinson, Fllglo, nd Amersweet do not hve high percentge of nucellr seedlings nd seedling trees nd fruit proly will not e identicl to the prent tree. Citrus nurserymen use udwood from mture trees tht re lredy flowering nd fruiting to propgte new nursery trees. This ensures tht trees will come into production s soon s possile nd will not hve to go through juvenile period, s most seedling trees do, efore flowering. In the pst, it ws thought tht seedling sweet ornge trees nd uds tken from these seedling trees would not flower for seven to ten yers. However, in the originl field tril t St. Cloud plnted in the lte 1980s nd 1990s, uds tken from 1-yer old sweet ornge seedling trees nd udded onto Swingle rootstock egn to er fruit fter three to four yers. Yield nd fruit chrcters re lso relted to tree juvenility. The trees t the Ridge nd Immoklee sites re reltively juvenile. They re still vigorous, upright in growth hit, nd thorny which is understndle given tht they were propgted with uds tken from trees only out 6 yers eyond the seedling stge. In contrst, the Hmlin trees in the Ridge tril were propgted from mother trees mny yers wy from the originl Hmlin nd, thus, hve virtully no juvenile tree or fruit trits. The full loss of juvenile trits in the new sweet ornge selections will require time nd cn e ccelerted y seril propgtions. Buds from seedlings (1 st genertion) were used to propgte the originl tril trees (2 nd genertion) t St. Cloud. Buds from these tril trees were then used to produce the Ridge site trees (3 rd genertion). Budwood source trees (4 th genertion) propgted from the Ridge site trees will generlly e less juvenile thn ones produced from the St. Cloud trees. Therefore, s prcticl mtter, growers should lwys inquire out the origin of the ud-source trees used to produce nursery trees nd uy trees propgted from trees s fr removed s possile from the originl trees t St. Cloud. Nursery mngers should lso consider this fctor in sourcing uds for increse locks or nursery trees, or propgting their own mother trees. Trees produced from the ltest genertion mother trees will e more settled nd more like norml grove trees. Growers will notice tht Erlygold, Itori, nd Ruy trees look nd ehve differently thn norml trees. The trees t oth loctions hve reltively dense cnopies resulting in shding tht leds to some fruit drop nd shoot dieck especilly when the trees produce good crops nd the rnches pull down. The fruit hve thicker, corser peel unlike the smooth, thin peel of Hmlin fruit. Those juvenile trits my e prticulrly prolemtic for fresh fruit growers.

5 Erly-Mturing Sweet Ornges: Reserch Updte on Erlygold, Itori, Ruy, nd Westin... 5 Limited experience suggests tht the stiffness of the peel my cuse unexpected oil relese during hndling resulting in oleocellosis dmge (go to for fct sheet on oleocellosis). Rootstocks Smooth Flt Seville ppers to e unsuited for these ornge selections on the Ridge ecuse of low yield nd reltively poor juice qulity. Of the other rootstocks similr to Smooth Flt Seville (Gou tou nd Kinkoji), trees on Kinkoji hve performed the est so fr. Little informtion is ville out Kuhrske citrnge, ut the results from these trils re encourging. Tree size is smller for those on C-35 citrnge s compred with those on other rootstocks, ut excellent juice qulity nd yield for the size of tree continue to encourge the use of this rootstock. Given the juvenile nture of the scion mteril generlly ville, the scion vigor nd size-controlling spects of this rootstock is good mtch. Acknowledgements The continued support of Orie Lee on whose property the originl tril ws conducted, nd the generosity of Hrold McTeer who provides his wisdom nd support for the current tril, re gretly pprecited. Thnks lso to Agtoprof nd Khn Grove Service, nd the Florid Citrus Production Reserch Advisory Council for funding through grnt I. Additionl Notes: 3. Pounds-solids (PS): The mjor determinnts of citrus juice qulity re percent totl solule solids or sugrs (TSS), lso clled degrees Brix, percent titrtle cidity (TA), the rtio etween totl solule solids nd titrtle cidity (TSS:TA or the Brix:Acid rtio) nd percent juice content. Commercilly, when fruit enter processing plnt, the lod is smpled nd PS re determined with stndrd equipment tht mesures the totl solule solids nd percent juice of ech smple. For exmple, field ox of ornges weighs 90 pounds. If 50% of the 90 pounds is juice (50% x 90 pounds=45 ls juice per ox) nd if the TSS re 10% of juice weight, then PS per ox=4.5 ls. PS/ox cn rnge from 4.5 for Hmlins to s high s 9.0 for Vlenci ornges.

6 Erly-Mturing Sweet Ornges: Reserch Updte on Erlygold, Itori, Ruy, nd Westin... 6 Tle 1. Ridge site. Erlygold nd Itori sweet ornge cumultive yields nd PS/cre mesured from 1999 through 2003 (4 sesons), nd tree heights mesured in Novemer 01. Scion Rootstock Cum. yield, oxes/tree Cum. PS/cre Tree ht., ft. Erlygold Benton citrnge 8.5 7, C-35 citrnge 9.7 9, Crrizo citrnge , Gou tou 8.6 6, Kinkoji , Kuhrske citrnge , Smooth Flt Seville 8.0 6, Swingle citrumelo , Hmlin Swingle 7.5 6, Itori Benton 9.1 7, C-35 citrnge 8.1 7, Crrizo citrnge 8.8 7, Gou tou 7.1 5, Kinkoji 7.3 6, Kuhrske citrnge , Smooth Flt Seville 4.7 3, Swingle citrumelo 9.6 8, Hmlin Swingle 9.1 7,589 Estimted. No juice dt for Tle 2. Ridge site. Ruy sweet ornge cumultive yield nd PS/cre mesured from 1999 through 2003 (4 sesons), nd tree height mesured in Novemer 01. Rootstock Cum. yield, oxes/tree Cum. PS/cre Tree ht., ft. Benton citrnge 8.9 8, C-35 citrnge 7.8 7, Crrizo citrnge 9.3 8, Gou tou 6.7 5, Kinkoji 7.5 6, Kuhrske citrnge 9.5 8, Smooth Flt Seville 6.8 5, Swingle citrumelo 6.7 6,

7 Erly-Mturing Sweet Ornges: Reserch Updte on Erlygold, Itori, Ruy, nd Westin... 7 Tle 2. Ridge site. Ruy sweet ornge cumultive yield nd PS/cre mesured from 1999 through 2003 (4 sesons), nd tree height mesured in Novemer 01. Rootstock Cum. yield, oxes/tree Cum. PS/cre Tree ht., ft. Hmlin/Swingle 6.5 5, Estimted. No juice dt for Tle 3. Ridge site. Erlygold sweet ornge juice qulity during the nd sesons. Dt sed on fruit smples hrvested on Novemer 4th or 5th ech yer. Rootstock Yer Rtio Color numer PS/ox Benton citrnge C-35 citrnge Crrizo citrnge Gou tou Kinkoji Kuhrske citrnge Smooth Flt Seville Swingle citrumelo Hmlin/Swingle No juice dt for

8 Erly-Mturing Sweet Ornges: Reserch Updte on Erlygold, Itori, Ruy, nd Westin... 8 Tle 4. Ridge site. Itori sweet ornge juice qulity during the nd sesons. Dt sed on fruit smples hrvested on Novemer 4th or 5th ech yer. Rootstock Yer Rtio Color numer PS/ox Benton citrnge C-35 citrnge Crrizo citrnge Gou tou Kinkoji Kuhrske citrnge Smooth Flt Seville Swingle citrumelo Hmlin/Swingle No juice dt for Tle 5. Ridge site. Ruy sweet ornge juice qulity during the nd sesons. Dt sed on fruit smples hrvested on Novemer 4th or 5th ech yer. Rootstock Yer Rtio Color numer PS/ox Benton citrnge C-35 citrnge Crrizo citrnge

9 Erly-Mturing Sweet Ornges: Reserch Updte on Erlygold, Itori, Ruy, nd Westin... 9 Tle 5. Ridge site. Ruy sweet ornge juice qulity during the nd sesons. Dt sed on fruit smples hrvested on Novemer 4th or 5th ech yer. Rootstock Yer Rtio Color numer PS/ox Gou tou Kinkoji Kuhrske citrnge Smooth Flt Seville Swingle citrumelo Hmlin-Swingle No juice dt for