Fig. 4.

Varietal differences for high temperature-induced spikelet sterility in the phytotron assay system. A Spikelet fertility of nine rice cultivars under 35 °C/29 °C for 3 days. B Relationship between spikelet fertility at 35 °C/29 °C and at 34 °C/28 °C of eight cultivars except for N22. C Panicle temperature of nine rice cultivars under 35 °C/29 °C. Panicle temperature indicated was the average of 10:00–16:00 of stable range. The data are the mean ± SE (n = 3–5). The same letters on the chart are not significantly different at the 5% level by the Tukey–Kramer test