Basic Studies On The Thermo-sensitive Genic Male Sterile Rice 139S

The temperature sensitive genie male-sterile rice 139S was firstly accredited by Examining and Approving committee of cultivar of Hunan, in Feburary 2003 and this cultivar is applicable in field cropping.Based on the three years continoeus trial of different sowing period under natural ecological condition, in artificial chamber and also in chill pool, a study was undertaken to test the performance of thermo-sensitive genie sterile rice "139S" with the emphasis on its fertility alteration under different growing temperature. Following conclusion could be drawn from this study:1. The initial temperature for fertility alteration of 139S is lower than 23℃ (22.8~ 23.0℃ ) and is therefore one of the cultivars which could alter its fertility at.2. The sensitive phase of fertility alteration is in the 4~6 plase of ear division with 5~6 the most sensitive one. The fertility of cultivar does not change, much treated with average daily temperature 20±2℃ for a days before the third ear leaf division and after 6 ear leaf division phase.3. During the sensitive phase, the sterility of the cultivar does not fluctuate treated in artifical chamber with temperature 20±2℃ for 1 day and do fluctuate for 2 days. But in natural field planting, the sterility of the cultivar does not change or only slightly if the average daily temperature ranges from 22~23℃ for 3 continoens days. The self-fertilization rate is below 1%. This shows that "139S" can tolerate relative low temperature during the sensitive phase of fertility alteration and it is beneficial for purity of seed.4. The fertility of 139S respond relatively sensitive to temperature. The days needed from sowing to heading can be thortened dramatically as the sowing date is postponed, during the sowing season March to July. The accumulative temperature for spring sowing is 700~850℃, and for summer sowing 770~900℃. The accumulative temperature could be set as reference in deciding the sowing date of the parent line.5. The single flower period of 139S lasts 7~8 days and blossoming period lasts 14 days, with the peak blossoming datesform 2~5, 65.97% of flowers are formed during these three days of blossoming. After the peak flowering dates, the blossoming of the cultivar will be dramatically reducell, especially under cold whether. This will strongly influence the fertilization rate of hybridization.6. The exposure rate of 139S pollen is only 50%. But there occurs an obvious pollen exposure peak in 11:00~ 12:00 A.m and this improves the hybridization rate.7. In order to safeguard the safety of the sensitive period of fertility and the period for heading the sowing date of 139S cultivar should be arranged at end of May or beginning of June. In order to increase the output of seeds, although the fertility alteration temperature of 139S is relatively low and can tolerate relatively long lasted low temperature without changing sterility. The sensitive period of fertility of the cultivar is from mid July to beginning August. The heading period is from beginning of August to mid August.8. Since the seeds of 139S are densely grown, and leaves are tighthy close to each other, the humidity of ear is high and easily infected by rice sheath blight and kernel smut. Therefore proper preventive measume should be undertaken in time.