WaltersGardensTotalGrowLightTesting
TestSummary:
Thepotentialfora2/3powerconsumptionreductionbyreplacing1000Whighpressuresodiumlightswith150WTotalGrowTG15AlightswastestedandprovenbycomparinggrowthcharacteristicsofseveralWaltersGardensperennials.Eightcharacteristicsweremeasuredon11varietiesofplantsin2growthstagesusing3lightintensitiesrepresentinglesser,equivalentandgreaterthancurrentWaltersGardenslightinglevels.
Plantstested:
MonardaLeadingLadyPlum(showandproduction,3lightintensities) EchinaceaJulia(show,3intensities) Heucherella(show,3intensities) AgaveQWT(production,3intensities) CarexBananaBoat(production,3intensities) CoreopsisMoonbeam(production,3intensities) CoreopsisZagreb(production,3intensitieslostfrominadequatewatering) DianthusFireStar(production,3intensities) GeraniumRozanne(production,mediumintensity) EchinaceaKimsKneeHigh(production,mediumintensity) HakonechloaAureola(production,mediumintensity)
GrowthDataCollected:
Height(all10varieties) Diameter(6varieties) Largestleaflength&width(7varieties) Branching(Monarda) Totalshoots(6varieties) LeafCount(6varieties) RootScore(all10varieties)
ResultsSummary:
TheTotalGrowlightingstrategytestedrequiresonlyonethirdofthepowerconsumptionofthe1000WHPSlightingsystemwhileconsistentlyyieldingstatisticallyequalgrowth.Mostvariationinthedataisbetterattributedtouncontrolledvariablesthantothelighting,especiallydifferingsoilmoisturelevelsduetovaryingamountsofairflowandoccasionallyinconsistentwatering.Whencombiningdatafromallvarieties,alltraitswerewithinonestandarddeviationofdifferencebetweenlightingtypeswithonlyheightandbranchingdifferingbymorethan0.5standarddeviations(greaterinTGduetogreaterMonardashowplantsizes).Averagelightintensitiesweretargetedat25%higherunderHPStotesttheabilityoftheTotalGrowspectrumtobeequallyeffectiveatalowerlightintensity.Averagelight
intensities,measuredinmole*m2*s1PAR,were21%higherunderHPSareasthanTotalGrowareaswhenmeasuredwithanOceanOpticsUSB2000spectrometerandamobileintegratingsphere.Rootgrowthandqualityappearedtobethecharacteristicmoststronglycorrelatedwithlightintensity,showingimprovementathigherintensitiesregardlessoflightingtype.
Resultsindetail:
Evaluatingeachdatacategorybynumberoftrialswithgreatervaluesfromeachlightingtypeandaveragemagnitudeofvariation,measuredbystandarddeviations(SDs):
HeightTGgreaterin16/29trials(.6SDs)o GreatestforTGinMonardaandHeucherellashowplantsandAgaveandGeranium
productionplants,greatestforHPSinCoreopsisMoonbeamandDianthus DiameterTGgreaterin9/19trials(.1SDs)
o GreatestforTGinMonarda,EchinaceaandHeucherellashowplants,greatestforHPSinDianthus
LargestleaflengthandwidthTGgreaterin10/18trials(.2SDs)o GreatestforTGinMonardaandHeucherellashowplants,allothersverysimilar
MainBranches(Monardashowplantsonly)TGgreaterin2/3trials(.9SDs) TotalShootsHPSgreaterin13/20trials(.3SDs)
o GreatestforHPSinMonardaproductionplantsandCarex LeafCountHPSgreaterin12/17trials(.1SDs)
o GreatestforTGinMonardashowplants,greatestforHPSinMonardaproductionplantsandEchinaceaKimsKneeHigh
RootScoreHPSgreaterin16/29trials(.3SDs)o GreatestforHPSinCarex,CoreopsisMoonbeamandEchinaceaKimsKneeHigh,all
othersverysimilar
Foreachcharacteristic,therewasanear5050splitoftrialswithgreaterresultsbetweenthetwolightingtypes.Combinedwiththesmallmagnitudeoftheaveragevariationsbetweentreatments,theseresultsstronglysuggestthatthelightingusedwasaninsignificantsourceofvariation.
Focusingonlightingintensity,itwasexpectedthatthemediumlightintensitywouldproducethemedianvalueforeachgrowthcategories.Inreality,mediumlightlevelsactuallyproducedthesmallestaveragenumbersforhalfofthedatacategoriesinbothlightingtypes.Thisisbestexplainedbythegreaterimpactoftheothervariablesinfluencinggrowth.Thismediumlightinglevelisthemostrelevant,however,asitrepresentstheamountoflightcurrentlyprovidedinthegreenhouses.Also,flatstestedundermediumlightlevelsweremostsimilarlypositionedrelativetofansandthusshouldhavesimilarlevelsofmoisture.Everyplantalsohadatleastonemediumlightingtreatmentflatwhile3productionplantsdidnothaveloworhighintensityflats.Height,diameter,largestleaflength&width,leafcount,andMonardasbranchingallweregreateronaverageunderTGlighting(0.5,0.9,0.5,3.0and2.0SDsofaveragedifference,respectively)whiletotalshootsandrootscorewereaslightlygreaterunderHPS(0.3and0.3SDsofaveragedifference,respectively).
Rootdatawasalsoselectivelyanalyzed.Rootscoresweredeterminedbytakingpicturesofeachplantsrootsandgivingascorebetween05relativetotheotherplants.Thiswasthusthemostsubjectiveofthedatacategoriestaken.Especiallydryorwetsoilwasnotedaswellasseverityofboltinginfloweringplants.Bothlightingtreatmentsproducedthebestresultsunderhighlightingwithmediumlightslightlyoutperforminglowlight.Boltinghadinconsistenteffects.WetanddryconditionsappearedtoadverselyaffectrootdevelopmentaswellexceptfordryandnormalconditionshavingequalresultsforHPS.Overall,HPShadaslightadvantageinaveragerootsscores.Byobservation,itappearedthatTGplantsoccasionallyhadlarger,whiterrootsthanHPSwhileHPSplantshadagreaternumberofsmaller,brownercoloredroots.
Discussion:
Plantsgrownunder1000WHPSandtheeffectiveequivalentamountof150WTG15Alightsdidnotdemonstrateanyconsistentsignificantdifference.Occasionalvariationswithinthesmallsamplesizesofindividualplantvarietiesandlightintensitieswerebetterattributedtouncontrolledvariablesthantolightsourceastheyfavoredeachlightsourcerelativelyequally.Forexample,MonardaandHeucherellashowplantsunderTotalGrowlightsrelativelyconsistentlyoutscoredHPStrials,butDianthusandCarexplantsunderHPSlightsshowedsimilartrendsovertheirTGequivalents.
Whencombiningallresults,thereappearstobeaslighttrendofTGplantshavinggreaterabovegroundgrowthandHPSplantshavinggreatergrowthinrootsandnewshoots.ThismaybeduetotheradiantheatofHPSlightsthatdriesoutsoilmorequickly.TheresultsshouldbedriersoilsunderHPSplantsthanTGplantswhichwouldfavorrootdevelopmentoverabovegrounddevelopment.GrowingunderTGlightsmightallowreducedwateringneedstomaintaindriersoilsandbetterrootgrowthwhendesired.
Rootgrowthalsoappearedtobethecharacteristicmostdirectlyimprovedbyincreasedlightingintensities,especiallyunderTGlighting.Averagerootscoresimprovedby0.6(ona05scale)forbothlightingtypeswiththeincreasefromlowtohighlightingintensity.Itwastheonlycategorythatincreasedbothfromlowtomediumintensityandmediumtohighintensityunderbothlightingtypes.Again,thismaybeconfoundedbyincreasingsoiltemperaturesanddrynessunderincreasedlights,butrepresentsanopportunitytorefinegrowingstrategiestoimproverootgrowthwhenthatisapriority.
Figures:
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Figure1TotalGrowPARoutput(mole*m2*s1).Squaresrepresentonesquarefoot.RedareasrepresentlowerthannormallevelsofequivalentsupplementallightingforWaltersGardensgreenhouses,greenrepresentsnormalrangesandyellowrepresentsincreasedlevels.Blueboxesshowactualareasusedfortestingtheselightlevels.DarkgreenareasareidealtestareasduetocomparableairflowlevelstodarkgreenareasunderHPSlighting(seefigure2).Thickoutlinesrepresentfixturelocations.
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96 91 88 88 91 96 ## ## ## ## 92 85 80 76 75 74 74 75 76 80 85 92 ## ## ## ## 96 91 88 88 91 96 Figure2HighPressureSodiumoutput(mole*m2*s1).Squaresrepresentonesquarefoot.RedareasrepresentlowerthannormallevelsofequivalentsupplementallightingforWaltersGardensgreenhouses,greenrepresentsnormalrangesandyellowrepresentsincreasedlevels.Blueboxesshowactualareasusedfortestingtheselightlevels.DarkgreenareasareidealtestareasduetocomparableairflowlevelstodarkgreenareasunderTGlighting(seefigure1).Thickoutlinesrepresentfixturelocations.
0.000.200.400.600.801.001.201.40
Averages(AllPlants)
TotalGrow
HPS
Figure3Normalizedaveragesforthe8measuredcategoriesofgrowthforallplantsundereachlightingtreatment.Errorbarsrepresentonestandarddeviationgreaterorless.
0.000.200.400.600.801.001.201.401.60
LightIntensityAverages(AllPlants)
TGLow
TGMed
TGHigh
HPSLow
HPSMed
HPSHigh
Figure4Normalizedaveragesforeachgrowthcategoryseparatedbybothlightingtypeandlightintensity.Errorbarsrepresentonestandarddeviationgreaterorless.
Figure5TotalGrowtestareaattheendofthetest.
Figure6TotalGrowfinishingplantstestsatweek1andweek8.
Figure7TotalGrowproductionplantstestatweek1andweek8.Moreplantvarietieswereaddedasthetestprogressed.