Studies On The High-yield And High-purity Seed Production Techniques For Combinations Of Two-line Hybrid Rice Pei'ai64S

The success of two-line hybrid rice research is a new way to utilize the heteroses of rice. The fertility expression of the P(T)GMS line is genetically controlled by the nuclear genes, so the compatibility is higher and it is more effective to breed high yielding hybrid combinations.Pei'ai64S is a PGMS line which has the largest number both on making hybrid combinations and the acreage of utilization. The research systematically studied the seed production techniques with high yield and high purity of the combinations of Pei'ai64S and the main results as follows:1.To guarantee the seed purity, the sensitive stage of fertility reversing of peiai64S should be within the period from 15 July to 25 August, and in south part of Hunan is more safe due to the different length of male sterile stage of the S line under different ecology condition.2.The blooming time of Pei'ai64S after initial heading is earlier than that of the R-line. The standard of synchronization should be that Pei'ai64S headings 1-2 d earlier than R-line. The emerged spike-lets rate of Pei'ai64S is about 63.3% when its male is sterile. The spike-lets blooming time of Pei'ai64S is earlier and longer than R-line. The stigma exertion rate of Pei'ai64S is high but the stigma size is smaller and its viability is weaker.3.The GA3 should be sprayed when Pei'ai64S has 3-5% hills to heading. The seed set rate of out crossing could be higher while the dosage of GA3 is increasing. The maximum dosage used in this study is 35 g/667 m2. The dosage for lower kernel smut and higher out crossing seed set would be further studied.4.Pei'ai64S has strong tillering ability but lower panicle bearing rate. Some fertile pollen has been obeserved from the late tillers. The seedlings with tillers heading uniformly and the panicles bearing more spike-lets. The suitable row ratio is 2:18 when the seedling quality of R-line is better, otherwise 2:16 is more suitable. Intermediate fertilizer lever is recommended.5. Lightly clipping can increase the out crossing seed set.6.For control the kernel smut, it is the effective ways to reduce the amount of nitrogen fertilizer, control the unproductive tillers and the length of the flag leaf, apply GA3 at optimal time and lightly clipping the flag leaf.