| Peiai64S, a widely-used photoperiod(thermo-)sensitive genie male sterile rice, had a characteristic of dormancy.In this experiment, its dormancy was studied systemically, and the main results were as follows.1 The seed of Peiai64S had a character of deep dormancy, and the dormant periods of seed, which was ripe in different climate and different regions, were different.The dormant period (its germination percentage was 80%) of seed multiplicated in Hainan, was about 60 days, and the completely dormant period (its germination percentage was the maxium) was about 105 days.However, the dormant period of the same seed multiplicated in summer from hunan, was only about 45 days, and the completely dormant period was about 77 days. The dormant period of the former was longer than of the latter.2 The dormant periods among Peiai64S seed, Peiliang-you-288 and Peiliang-you-288 seed produced at the same region and period, had not significant difference. The results showed that the dormant gene of Peiai64S seed controlled the dormant character of hybrid rice seed.3 The absorbing-water rate of Peiai64S seed, which's in dormancy, was more rapid in water than that of in Qianglvjing solution.And the difference of the rate between in water and in Qianglvjing solution had a significant graph with ascent, stable and descent. Moreover, the relation between the absorbing-water rate and the dormancy of Peiai64S seed wasn't significant.4 The germination percentage of seed wasn't significantly changed as compared to the check after the seeds being treated with 0℃ and 5℃ for 5, 10 and 15 days.5 The germination percentage of Peiai64S seed was increased significantly as compared to the check after the seeds being treated with higher temperature such as 40℃ or 50℃ for 2,4 and 6 days respectively. Theresults showed that higher temperature could effectively break the seed dormancy.6 The dormancy of Peiai64S seed could be broken to some extent after being treated with an available concentration of GA3 solution.Especially, the result of being delt with GA3 for 200ppm and 150 ppm, reached a significant level.But there was no significant difference in the treatment of 24, 36, 48, 60 and 72 hours.7 The treatments of H2O2 for 15% and 20% were both effective, and reached significant level in comparison with the Check.But the difference, between the treatment with 25% and the Check, wasn't significant .The difference among the treatments of time wasn't significant as well.8 The results of removing dormancy of seeds of Peiai64S and two hybrid combinations Peiliang-you-288, Peiliang-you-500, treated with three kinds of solution concentration of Qianglvjing, reached extremely significant level in comparison with the check, and the best one was 1:250.There lied no significant difference among the treatments of time. So it was the most economical, convenient and reliable to immerge seed with Qianglvjing, and had a greatly popularizational prospects.9 The amylase activity of Peiai64S seed, including a-amylase and a +B amylase, was much lower in dormancy (the germination percentage was 20%) than in undormancy(the germination percentage was 90%).The amylase activity was negatively correlated to the dormancy of Peiai64S seed.10 The result of this study showed that the dormancy of Peiai64S seed was caused by physiological factors, not the dank and ventilative obstacle of seed chaff or seed capsule. And the dormant cause was worth to be further studied. The research result supported the theorical basis both for detecting exactly germination percentage periods of Peiai64S and its hybrid combination seed, and for identifying seed purity. Moreover, the best method of removing seed dormancy was found in this study.
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