1. WELCOME Expert Panel on Maize-Model Improvement: Phenology - Results December 2012 Agenda Introductions (new attendees only) Overview of thermal methods and data sets used for evaluation Objective 1 Presentation followed by discussion Objective 2 Presentation followed by discussion Next meeting on leaf area expansion Request for leaf area expansion and senescence routines

2. Attendance Last Name First Name Institute/company Y* Andrade Fernando INTA, Balcarce, Argentina Y Boote Ken Univ. of Florida, Gainesville, FL N Cairns Jill CIMMYT, Harare, Zimbabwe Y* Castiglioni Paolo Dow, Davis, CA N Edmeades Greg Cambridge, New Zealand Y Hammer Graeme Univ. of Queensland, Brisbane, Australia Y* Hatfield Jerry USDA-ARS, Ames, IA N Holland Jim USDA-ARS, NC State Univ., Raleigh, NC N Hoogenboom Gerrit Washington State Univ., Prosser, WA Y Jones Jim Univ. of Florida, Gainesville, FL Y Kemanian Armen Penn State, University Park, PA Y* Kim Soo Univ. of Washington, Seattle, WA N Kiniry Jim USDA-ARS, Temple, TX Y Kumudini Saratha Monsanto Co., RTP, NC Y Lizaso Jon Univ. of Madrid, Madrid, Spain Y Nendel Claas Leibniz, Germany N Otegui Maria Univ. of Buenos Aires, Buenos Aires, Argentina. Y* Sala Rodrigo Monsanto, Jerseyville, IL N Singh Upendra IFDC, Muscle Shoals, AL N Stöckle Claudio Washington State Univ., Pullman, WA N Tardieu Francois INRA, Toulouse, France Y Timlin Dennis USDA-ARS, Beltsville, MD Y Tollenaar Thijs Monsanto Co., RTP, NC Y Vyn Tony Purdue Univ., West Lafayette, IN Y* Wallach Daniel INRA, Toulouse, France N Westgate Mark Iowa State Univ., Ames, IA Y* Yang Haishun Univ. of Nebraska, Lincoln, NE

3. Objectives 1.Determine the thermal accumulator that is most consistent in predicting maize development:  Compare thermal accumulators using large Monsanto and public data sets.  Does the precision of thermal accumulators vary across different phases of development (i.e., planting to anthesis vs. silking to maturity) and/or different Relative Maturity (RM) groups? 2.Quantify response of RM groups in terms of thermal methods:  Effect of photoperiod?  Influence of RM group on proportion of pre-silking period and GFP

4. Overview of Thermal Methods

5. Linear Thermal Methods GDD 10,30 Tbase = 10 O C IF T < 10 O C THEN T = 10 O C IF T > 30 O C THEN T = 30 O C Tmean = (Tmax + Tmin)/2 GDD = GDD + (Tmean – Tbase) GDD 8,34 If T 34 O C, 1-h T estimated from sine wave (CERES-Maize) Tbase = 8 O C IF T < 8 O C THEN T = 8 O C IF T > 34 O C THEN T = 34 O C Tmean = (Tmax + Tmin)/2 GDD = GDD + (Tmean – Tbase) GDD3-h T estimated from sine wave between Tmax and Tmin (APSIM)0 O C =< T =< 44 O C IF 18 O C > T > 0 O C THEN GDDR = 10 * T/18 IF 34 O C > T > 18 O C THEN GDDR = T – 8 IF 44 O C > T > 34 C THEN GDDR = 26 * (44 – T)/10 GDD = GDD + GDDR/8

6. CERES-Maize, IXIM, and Hybrid-Maize [GDD (34,8) ]

7. APSIM

8. Non-Linear Thermal Methods β-Function 1-h T estimated from sine wave between Tmax and Tmin (MAIZSIM) 0 O C = < T = < Tceil Topt = 32.1 O C ; Tceil = 43.7 O C; Rmax = 0.53 HR = Rmax * (Tceil – T)/(Tceil –Topt) * (T/(Topt) Topt/(Tceil-Topt) TLU = TLU + HR/24 β-Function β-Function (MAIZSIM), but: Topt = 31 O C (TLU) Tceil = 44 O C Rmax = 0.58 GTITmean = (Tmax +Tmin)/2 GTIRV = 0.043177 * Tmean 2 – 0.000894 * Tmean 3 GTIRR = 5.3581 + 0.011178 * Tmean 2 IF DATE < SILK THEN GTIR = GTIRV ELSE GTIR =GTIRV GTI = GTI + GTIR CHUCHU (Day) = 3.33 * (Tmax – 10 ) - 0.084*(Tmax – 10) 2 CHU (Night) = 1.85 * (Tmin – 4.4) CHU = [CHU(Day) + CHU(Night)]/2

9. β Function Yan and Hunt, 1991 MAIZSIM, (Kim et al., 2012) TLU β 44 Rmax0.580.530.58 Topt31.032.131.0 Tceil41.043.744.0

10. GTI vs. GDD (30,10) [Pre-silking phase] GDD (30,10) GTI (Stewart et al., 1998)

11. GTI GDD (30,10) GTI vs. GDD (30,10) [Post-silking phase] (Stewart et al., 1998)

12. Crop Heat Units (CHU)

13. Data sets used Monsanto – 2 data sets 1.118 Commercial hybrids grown 2007-2011 in 45 locations throughout the NA Corn Belt 2.>3,000 hybrids grown 2007-2012 at a single location (~RM 100-zone) in the NA Corn Belt Nielsen and Thomison, 2002 3 hybrids grown at 3 planting dates in four locations (IN and OH) from 1991 to 1994 Andrade (various publications) Various hybrids grown from 1989 to 2012 at Balcarce, Argentina Kiniry, 1982 3 hybrids grown at 2 planting dates at two location in 1978 and 1979 in MO Weather for all except Andrade studies : http://www.ncdc.noaa.gov/cdo-web/

14. OBJECTIVE 1

15. RMObs.DaysGDD 10,30 CERESAPSIM MAIZ SIM TLU β 44GTICHU (no.) ------------ CV (% ) for duration from planting to anthesis (silking) ------------------------------ 76-85 121 10.3 (9.9) 9.5 (9.8) 9.3 (9.7) 7.8 (7.9) 9.0 (9.2) 7.8 (7.9) 7.6 (7.7) 7.0 (7.0) 86-95 205 10.0 (9.5) 9.7 (10.4) 9.5 (10.2) 7.6 (8.1) 9.2 (9.8) 7.8 (8.3) 7.6 (8.0) 6.8 (7.1) 96-105 346 9.4 (9.1) 6.4 (7.0) 6.5 (7.2) 6.0 (6.4) 6.2 (6.8) 5.7 (6.2) 5.7 (6.2) 5.7 (5.9) 106-115 578 10.4 (10.2) 6.3 (6.6) 6.9 (7.3) 5.4 (5.7) 6.0 (6.3) 4.7 (5.0) 4.7 (5.1) 4.6 ( 4.7) 116-119 152 10.2 (10.0) 6.3 (6.5) 6.8 (7.4) 5.2 (5.7) 5.8 (6.2) 4.6 (4.8) 4.5 (5.1) 4.7 ( 4.4 ) Coefficient of variation for duration from planting to anthesis (silking) of commercial hybrids within each of five RM (Relative Maturity) groups grown in the Corn Belt from 2007 to 2011.

16. RMObs.DaysGDD 10,30 CERESAPSIM MAIZ SIM TLU β 44GTICHU No.----- CV duration from silking to black layer (%) ------ 76-85183 9.08.28.07.17.66.56.2 6.0 86-95 417 9.49.39.18.38.67.4 6.8 96-105 777 8.59.49.38.38.77.1 6.0 106-115 1481 9.99.69.38.18.97.27.1 5.8 116-122 288 9.611.811.59.610.99.07.7 7.3 Coefficient of variation for duration from silking to black layer of maize hybrids within each of five RM (Relative Maturity) groups grown at a single location in the Corn Belt from 2007 to 2012.

17. Planting date PhaseDaysGDD 10,30 CERESAPSIM MAIZ SIM TLU β 44GTICHU --------------------------- CV (% ) ---------------------------------- EarlyPre-silk 5.65.76.47.26.15.55.7 4.7 GFP 8.6 11.312.814.012.612.0 8.6 10.5 MidPre-silk 8.94.75.56.25.04.3 4.5 3.8 GFP 11.19.110.311.210.19.7 7.6 8.9 LatePre-Silk 11.34.55.36.04.84.14.4 3.5 GFP 9.38.59.310.29.18.6 6.9 8.1 CV for duration from planting to silking (first row) and from silking to black layer (second row) of three maize hybrids planted at four locations ( n = 36 ) in Indiana and Ohio at three planting dates from mid April to mid June from 1991 to 1994 (Nielsen et al., 2002).

18. Planting date Phase No. Obs DaysGDD 10,30 CERESAPSIM MAIZ SIM TLU β 44GTICHU -------------------------------------- CV (% ) ---------------------------------- May Pre- silk 12 11.311.411.711.211.310.710.6 10.3 GFP11 13.16.1 5.5 6.56.17.17.6 8.4 June Pre- Silk 12 7.5 8.79.38.98.78.1 8.27.7 GFP12 22.711.2 10.9 11.511.211.9 13.213.4 CV for duration from planting to silking (first row) and from silking to black layer (second row) of three maize hybrids planted at two locations in Missouri during May and June in 1978 and 1979(Kiniry and Keener, 1982).

19. Planting month PhaseObs.DaysGDD 10,30 CERESAPSIM MAIZ SIM TLU β 44GTICHU (no.) -------------------------------------- CV (% ) ---------------------------------- Sept. Pre- silk 6 5.4 8.27.76.77.67.0 6.96.8 GFP 6.7 5.5 4.6 4.84.9 5.1 Oct. Pre- silk 41 6.7 6.16.56.46.25.9 6.3 5.4 GFP 12.5 12.412.812.612.412.1 12.7 11.6 Nov. Pre- silk 12 9.0 8.48.68.58.48.2 8.3 8.0 GFP 18.7 10.8 10.0 11.610.611.6 13.413.1 Dec-Jan Pre- silk 16 12.5 9.7 9.810.0 9.7 9.9 10.010.5 GFP 11.0 8.48.3 7.5 8.28.0 8.18.6 CV for duration from planting to anthesis (first row) and from silking to black layer (second row) of maize hybrids planted at different dates near Balcarce (Argentina ) from 1989 to 2012 (Andrade et al.).

20. Conclusion For the Monsanto data sets, non-linear methods were better than the linear methods and APSIM is close to the non-linear methods. In general, CHU was the best. It also appeared that those functions that have a greater response at lower temperatures are generally more consistently predictive of development (e.g. APSIM, and CHU), especially during the post-silking phase. Results were more variable for the public data sets. CHU and GTI were best in the Indiana/Ohio data set that consisted of 36 observations (means). Variability was large among data sets with less than 20 observations.

21. Quantification of RM in terms of heat units.

22. Thermal time from planting to anthesis for 118 commercial hybrids grown 2007-2011 either at a single location or in multi- locations in their area of adaptation

23. CHU pre-anthesis vs. days between 21 June and silking (Nielsen et al., 2002) Days between 21 June and silking Crop Heat Units

24. CHU pre-anthesis vs. days from 21 Dec. to silking (Andrade et al., 1989-2012) Days between 21 Dec. and silking Crop Heat Units

25. Thermal time from silking to physiological maturity (black layer) of >3,000 maize hybrids grown between 2007-2012 at a single location in the NA Corn Belt

26. CHU GFP vs. Photoperiod at Silking (data from Nielsen et al., 2002) Crop Heat Units

27. GFP CHU vs. days from 21 Dec. to silking (Andrade et al., 1989-2012)

28. Relationships between CHU and RM pre-anthesis and GFP (data from >3,000 hybrids grown during the 2007-2012 seasons at a single RM100-zone in the Corn Belt)

29. Relationships between GDD 8,34 (CERES-Maize) and RM pre-anthesis and GFP

30. Relationships between GDD 10,30 and RM pre-anthesis and GFP

31. Conclusion When grown at one location, duration of developmental phases is linearly related to Relative Maturity (RM) classification. When compared across environments, duration of developmental phase is not linearly related with RM. Photoperiod was associated with the duration of phases of development, in particular, the grain-filling period. Quantification of the relative proportion of the pre-silking period and GFP is dependent on the thermal method used.

32. Next Expert Panel Meeting Leaf Area Expansion and Leaf Senescence François Tardieu will give presentation All maize modelers are invited to send us a one (or 2)-page summary of their routines for leaf area expansion and leaf senescence. Proposed time: Mid/late January 2013