YO assesReducing sucrose loss in sugarbeet storage

Controlling sucro e loss in sugar-beet storage has been an industrygoal since the 1950s. Sugarbeet

roots utilize sucrose for energy tomaintain them el es.

Dessication from wind and sun orroo much rain and microbial activitycan negatively influence stored roots,increasing respiration and the buildupof impurities.

Factors such as scalping, impactsand wounding during harvest andtransport, mud and weed in piles, andunusually high and low temperaturecan also lead to ucro e loss.

Disease and drought stress duringproduction can al 0 predispose rootsto ucrose loss in storage.

In particular, rhizomania cau edby Beet necrotic yellowvein virus

FIG. 1. Suqarbeet cultivars being compared forstorability on top of an indoor storage pile in Paul,Idaho, Each bag contains roots from a different cultivarproduced in a commerciallield infested With naturallevels of rhizomania. Cultivars that retained the mostsucrose had rhizomania resistance and the least fungalgrowth and weigh! loss.

has been shown to compromise thestorability of roots allowing for signifi-ca.nt sucro e losses in storage by earlyDecember.

Sucrose losses over 90 percent havebeen documented in long-term stor-age (142 days) with cultivars that lacktorability, Thus, developing a cultivar

selection program for storage could beof considerable benefit to the sugar-beet industry.

Trial RunsHealthy roots in storage lose 0.2 to0.51b sucrose per ton roots per day.Thus, losses of 8 to 17 percent wouldbe expected for healthy roots after 100days in outdoor storage under ambi-

18 I SugarProducerJune/July 2009

ent condition. Lo se in roots fromrhizomania infested fields could beconsiderably higher.

In an effort ro develop a cultivarselection program for storage, experi-ments in Idaho were conducted withroots from commercial sugarbeet fieldsinfested with natural levels of rhizoma-nia.

From each plot the center two rowwere harvested to determine tonnageand two 8-beet amples were collectedto determine percent sucrose.

Additional8-beet samples fromeach plot were collected to determinesucrose yield after storage.

The storage root amples were heldin nylon mesh onion bags, and placedinside outdoor piles and on top ofindoor piles (Fig. 1).

The outdoor piles were subject toambient condition while the buildingholding the indoor pile had a set pointof 35 degrees F.

After 142 days (Oct 2006 to Feb2007) in torage inside a commercialoutdoor pile, sucrose losses rangedfrom 13 to 32 percent depending oncultivar.

When roots from the same plotswere stored over the same periodunder warmer conditions on top of anindoor commercial pile, losses rangedfrom 13 to 90 percent depending oncultivar (Fig. 2).

Some cultivars lost twice as muchsucro e as other cultivars. The experi-ment was repeated the next year andafter 159 days (Oct 2007 to Mar 2008)of torage inside a commercial out-door pile, ucro e loss ranged from 28to 60 percent depending on cultivar.

Indoors, losses ranged from 57 to100 percent depending on cultivar,More consistent cultivar separationwas achieved with the samples heldindoor, which should provide a reli-able means of cultivar selection forstorability.

Best PerformanceIn previous research the ability toseparate cultivars for storability withhealthy sugarbeet roots was problem-atic since variation in the data madeit difficult to separate cultivars. Usingour indoor storage system with roots

10 ERS-Feb07 • ERS-Qct06 I

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FIG. 2. Estimated recoverable sucrose (lb/A) is shown at harvest in October 2006 (ERS-Oet06 in black) and laterafter 142 days in storage in February 2007 (ERS-Feb07 in yellow) with roots from 32 commercial sugarbeet culti-vars, The roots had been produced in a commercial sugarbeet field with natural ievels of rhizomania and held in acommercial indoor storage facility in Paul. Idaho; with a temperature set point of 35 degrees F. Some cultivars lostas little as 13 percent sucrose (left side) and others lost gO percent of their sucrose (right side) in storage.

from a rhizomania infested field, theranking of cultivar was the same asstorage with healthy roots outdoors,but the eparation between cultivarsw-asgreater and could be proven statis-tically.

In Fig. 2, some commercial cultivarslost more than twice as much sucroseas other cultivars emphasizing thepoint that storability can be an impor-tant economic trait. Cultivars that per-formed the best in storage possessedrhizornania resistance, and had theleast fungal growth and weight los.

These storage data collectedthrough thi indoor/rhizomaniacultivar selection method should al-low grower group seed committees tomake informed decisions on cultivarsfor storability, The potential for reduc-ing los es in storage is considerableand can now be addressed with repeat-able methods.

Separate OutGiven the negative impact that diseasesin the field such as rhizomania, curlytop, Aphanomyces root rot and otherdiseases can have on storability-grow-ers should also consider segregatingroots at harvest.

Roots from fields with heavy diseasepressure or other production issuecould be placed in piles targeted forearlier processing since it is clear thatcompromised roots will not store well.

For piling grounds with multiplepilers, segregating roots should be apossibility.

TraditionGrowers have traditionally only beenconcerned with percent sucrose andtonnage at harvest. For companies thatare grower owned cooperatives, thoseare notju t roots sitting in those piles.

Those roots are the grower's moneysitting there. In Idaho only one-thirdof the crop i direct processed throughthe factory during harvest.

Another one-third of the crop isheld in hart term storage « 90 days)and one-third is held in long term stor-age. As noted above, the recoverablesucrose at processing can be a lot lessthan that determined at ha.rve L

Roots from some cultivars maintainthemselves considerably better in tor-age than roots from other cultivars.Thus, selecting cultivars for storabiliryhas the potential to have major impacton the sucrose saved or lost.

Combining cultivar selection fortorabiliry along with segregating roots

at harvest could lead to considerableeconomic benefit for sugarbeet grow-ers. _

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Editor's note:Strausbaugh is USDA-ARS, Research Plant

Pathologist/Lead Scientist, Kimberly,Idaho. He can be reached via email toCarl. Strausbaugh@ars. usda.gov.

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