Abstract: By inducing frequency, intensity and duration of low temperature in the middle and last ten-day periods in August in China′s southern rice-growing area, increasing temperature for safe seed production of two-line hybrid rice was defined as 2℃. During the fertility sensitive period, the characters of panicle height and canopy structure of a TGMS rice, Pei'ai64S, were measured. Results showed that the temperature changes caused by irrigation in field was below 40 cm of rice plant, and heating effect was significant at 20 cm, as increased by 3.1℃. From the present study, irrigation techniques were putted forward: the water depth at 15-20 cm, current water, irrigating at 17:00 and bailing at 10:00 at sunny or cloudy weather, irrigating for all the day at shade or rainning weather, increasing inflows and outflows in large fields. In the present experiment, pollen fertility and self-fertilized seed setting rate approved that the techniques were feasible and effective for safeguarding seed production of two-line hybrid rice.

Key words: Two-Line Hybrid Rice, Low Temperature, Seed production, Purity, Irrigation