Supplementary Information 45.0 40.0 35.0 Temperature, C 30.0 25.0 20.0 15.0 10.0 5.0 0.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Thermocouple position on temperature gradient plate Supplementary Figure S1. Temperatures on the temperature gradient plate, measured with thermocouples placed directly on the surface of the plate (- -) underneath the Petri dishes containing pollen germination medium or in the pollen media itself (). The plate was run twice for each pollen type; once with a 5.6-27.4 °C gradient and once with a 24.6-45.4 °C gradient. Linear regressions for these two gradients were y=-1.67x + 29.68 (R2=0.98) and y=-1.58x+46.04 (R2=0.99) on the plate surface and y=-1.65x + 30.21 (R2=0.98) and y=-1.30x+43.75 (R2=0.96) in the pollen media, respectively. (a) Air temperature ( C) 32 30 28 26 24 22 0:00 6:00 12:00 18:00 0:00 6:00 12:00 18:00 0:00 6:00 Time of day (h:mm) 12:00 18:00 0:00 (b) Relative humidity (%) 100 95 90 85 80 0:00 6:00 12:00 18:00 0:00 Supplementary Figure S2. Diurnal air temperature (a) and relative humidity (b) of field environment from two days before anthesis to anthesis for rice cultivar, N22 (dotted line; on 2-3 August 2011), and for cultivars CG14 and IR64 (solid line; on 15-16 August 2011). Supplementary Table S1. In vitro germination of pollen of rice cultivar IR64 at different concentrations of Ca(NO3)2.4H2O in pollen germination medium. Values are means of four replicates. (SED = 12.5%, 15 degrees of freedom) Ca(NO3)2.4H2O, g l-1 0.030 Germination, % 37.5 (standard error) (10.8) 0.040 39.5 (10.6) 0.050 46.8 (9.9) 0.055 73 (4.2) 0.060 78.2 (5.4) 0.070 52.2 (9.2) Supplementary Table S2. Comparisons of models of pollen germination of three rice cultivars at temperatures between 5.6 and 45.4 °C. Models compared are multiplicative (Mult.) or subtractive (Subt.) probability models with either a linear (Lin.) or an exponential (Exp.) effect of temperature (T) on the variation in maximum temperature limits (sx). The value of the parameter, r, is shown for exponential models. Increases in residual deviances (RD) are shown relative to model (1). Model Effect of T r for Source of variation d.f. Exp. Deviance Deviance Prob- Ad- or sum of or F ratio ability justed squares* R2 4 338437 6958 <0.001 0.9969 77 936.6 … on sx a) CG14 1 Mult. Exp. 1.164 Regression Residual deviance 2 Mult. Lin. … Increase in RD (2-1) 1 60.93 5.01 <0.01 0.9968 3 Subt. Exp. 1.072 Increase in RD (3-1) 1 89.14 7.33 <0.01 0.9967 4 Subt. Lin. … 2 175.4 8.95 <0.01 0.9965 4 399215 70 881.1 … -2.77 Increase in RD (4-1) b) IR64 1 Mult. Exp. 1.045 Regression Residual deviance 7927 <0.001 0.9975 2 Mult. Lin. … Increase in RD (2-1) 1 -34.89 3 Subt. Exp. 1.118 Increase in RD (3-1) 1 171.5 13.6 <0.001 0.9971 4 Subt. Lin. … 2 163.0 6.47 4 1699157 73 3532 … Increase in RD (4-1) ns 0.9977 <0.01 0.9972 c) N22 1 Mult. Exp. 1.164 Regression Residual deviance 8778 <0.001 0.9977 2 Mult. Lin. … Increase in RD (2-1) 1 328.6 6.79 <0.05 0.9975 3 Subt. Exp. 1.067 Increase in RD (3-1) 1 3.11 0.06 ns 0.9977 4 Subt. Lin. … 2 672.0 6.58 <0.05 0.9974 Increase in RD (4-1) ns = not significant (P > 0.05); d.f. = degrees of freedom