Gdd for flowering verasion new model van leeuwen
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Gdd for flowering verasion new model van leeuwen

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Gdd for flowering verasion new model van leeuwen Gdd for flowering verasion new model van leeuwen Presentation Transcript

  • General phenological model to characterize thetiming of flowering and veraison of Vitisvinifera L.Un modèle phénologique pour caractériser la floraison et la véraison deVitis vinifera L.Parker A., García de Cortázar-Atauri I.,van Leeuwen C. and Chuine I.Australian Journal of Grape and Wine Research 17, 206-216, 2011
  • The timing of phenology is a majorquality factor in viticulture• Too late ripening -> green and acidic wines• Too early ripening -> unbalanced wines lackingaromas• Ideally, complete ripeness is achieved at theend of the season :– September / October Northern hemisphere– March / April Southern hemisphere
  • Growers can influence the timing ofripeness• By choosing early orlate ripeningvarieties
  • Adaptation of plant material andviticultural practices to obtain the righttiming of phenology• Can be assessed through trial and error• Can be assessed through phenologicalmodelling
  • Potential applications of phenologymodelling• Adaptation ofplant material toclimaticvariations insidea growing region• Adaptation ofplant material toclimate changeSource : Bois 2007Source : meteo France
  • Existing phenological models• Growing Degree Days (Winkler)• Huglin Index
  • Existing models can be improved• Larger data bases– In this study 4030 phenology observations from :• 123 locations (France, Switzerland, Italy, Greece)• 81 varieties• 48 vintages• Meteo data < 5 km in distance ; < 100 m inaltitude• Improved modelling techniques based on themathematic Metropolis algorithm andcomputational power– Phenology Modelling Platform (I. Chuine)
  • 4 models were tested• Spring Warming (~ GDD) starting at 1st ofJanuary– 3 parameters• Spring Warming with unfixed parameters– 3 parameters• UniFORC– 4 parameters• UniCHILL– 7 parameters
  • Model performancesModel: SW SWt0 = 1 JanuaryUniFORC UniCHILLFloweringEF 0.80 0.75 0.76 0.79RMSE 5.4 6.1 6.0 5.6VeraisonEF 0.74 0.57 0.72 0.69RMSE 8.0 10.2 8.2 8.7EF = EfficiencyRMSE = Root Means Squared Error
  • Effect of base temperature (Tb) onmodel performances (veraison prediction)0510152025300 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Base temperature (°C)RMSE(days)-2,5-2-1,5-1-0,500,51EFRMSEEF
  • Effect of t0 on model performances(veraison prediction; Tb unfixed)t0 (DOY)0 20 40 60 80 100EF0.500.550.600.650.700.75
  • This new phenology model is calledGrapevine Flowering Veraison Model (GFV)• Summation of daily averagetemperatures• Counting starts at DOY 60 (1st ofMarch)• Base temperature 0°C• Remains easy to use
  • Comparison with GDD modelFlowering VeraisonGFV model GDD model GFV model GDD modelt0 60 1 60 1Tb 0C 10C 0C 10CEF 0.76 0.73 0.72 0.14RMSE 5.9 6.3 7.7 14.3
  • Model validation for 50% floweringa) Cabernet francObservation (DOY)100 120 140 160 180 200 220 240Prediction(DOY)100120140160180200220240 b) Cabernet-SauvignonObservation (DOY)100 120 140 160 180 200 220 240Prediction(DOY)100120140160180200220240c) ChardonnayObservation (DOY)100 120 140 160 180 200 220 240Prediction(DOY)100120140160180200220240 f) MerlotObservation (DOY)100 120 140 160 180 200 220 240Prediction(DOY)100120140160180200220240
  • Classification for veraisonF* = thermal summation at veraisonVariety F*Chasselas 2374Pinot noir 2511Sauvignon blanc 2528Chardonnay 2547Riesling 2590Syrah 2601Merlot 2636Cabernet-Sauvignon 2689Cabernet franc 2692Grenache 2761Ugni blanc 2799
  • Portugese varieties• We do not have a lot of data onPortugese varieties• We would be happy to receive phenologydata with corresponding daily climaticdata, particularly for:– Touriga nacional– Touriga franca
  • Work under progress• We are currently testing the model forripeness• We are also working on a classificationfor a broad range of varieties (~ 100)and we would be very hapy to includePortugese varieties
  • Conclusion• GFV phenology model– easy to use– performs better than existing models– Generic model across varieties• t0 : DOY 60• Tb : 0°C• Powerful tool for the classification of the precocityof grapevine varieties• Matching grapevine varieties to local climaticvariations• Matching grapevine varieties to a changing climate