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*Fig. 1. Number of spikelets at anthesis per 30 min period on the first (——), second (– – –) and third (······) day of anthesis in IR64 and Azucena at 29.6 °C and 36.2 °C. Bars show SEs for comparing days.*

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*Fig. 2. Spikelet fertility of spikelets of IR64 exposed to temperatures of 29.6, 33.7, and 36.2 °C for 2 h (solid circles and line), and seed-set of spikelets that opened at 29.6 °C either 1 h before (open circles and hashed line) or 1 h after (solid squares and dotted line) the 2 h treatment. Fitted lines: (open circles) y=15.43–0.408x; (filled circles) y=14.30–0.408x; (filled squares) y=3.56–0.062x.*

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*Fig. 3. Spikelet fertility of spikelets of IR64 and Azucena exposed to temperatures of 29.6 (filled cirlces), 33.7 (open circles), and 36.2 °C (filled inverted triangles) for 1, 2, 4, and 6 h. Fitted lines are: IR64 (filled circles) y=2.29–0.0945x; (open circles) y=0.92–0.0945x; (filled inverted triangles) y= –0.69–0.0945x; Azucena (filled circles) y=0.526+0.0116x; (open circles) y= –0.849–0.0116x; (filled inverted triangles) y= –1.029–0.4518x.*

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*Fig. 4. Relationship between spikelet fertility and the proportion of spikelets reaching anthesis exposed to different temperature durations in IR64 (closed squares, open squares) and Azucena (closed circles, open circles) at 29.6 °C (closed symbols) and 36.2 °C (open symbols).*

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**Fig. 5.** Relationship between spikelet fertility and accumulated hourly temperature >33 °C in Azucena. Key: open symbols=33.7 °C; closed symbols=36.2 °C; 2003 (closed diamonds, open diamonds); 2004–duration: (open circles), 1 h; (open squares), 2 h; (open triangles), 4 h; (open inverted triangles), 6 h. Fitted line: y= –6.50–1.67x, r^{2}=0.88.

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