Studies On Practical Application Of Four Short Photoperiod And Low Temperature Sensitive Genic Male Sterile Lines (Oryza Sativa L.)

The genic male sterile rice induced by short photoperiod and low temperature is a new type of germplasm, which is sterile under the conditions of short photoperiod and low temperature and fertile under the conditions of long photoperiod and high temperature, contrary to original EGMS rice. In this research, four new short photoperiod and low temperature sensitive genic male sterile lines (Hua131S, Hua133S, Hua134S, and Hua135S) from Huazhong Agricultural University and D38S (CK) were used for this study, we have observed basic growth characteristics, major agronomic traits and fertility performance (temperarure and photoperiod traits of fertility transfer) of these male sterile lines under natural conditions in Wuhan and Hainan, and analyzed the combining ability performances of main agronomic and grain quality traits of F₁ combinations from above sterile lines and two groups of restorer lines adopting the incomplete diallel cross design in 2007 and 2008 at Hainan and Wuhan. In order to further acquire the combination ability and obtain some hybrid combinations with superior heterosis, these 4 new sterile lines and 86 restorer lines have been mated. The main results were as following:1. All of 4 male sterile lines showed fertile in the period from July to early October in Wuhan. In this period, the average seed setting ratio of Hua133S was 32%, while that of Hua131S, Hua134S and Hua135S was more than 56%. All of them can reproduce themselves in Wuhan in Autumn.2. The tendency of fertility alteration of four male sterile lines in Hainan displayed as follows: sterile stage-fertile stage-sterile stage. The stable sterile periods of 4 male sterile lines in Hainan region were different. The stable sterile period of Hua131S was less than 30 days, that of Hua133S, Hua134S and Hua135S was 106, 85 and about 60 days, respectively. It means that the seed productions of Hua133S, Hua134S and Hua135S are relative safe and reliable, but more risks for Hua131S at Hainan region.3. The sensitive stage to temperature for fertility alteration in four sterile lines was all on the period of 5-25d before heading, but their critical point of temperatures (CTP) of fertility alteration was different. The CPT of Hua131S and Hua135S was below 23.5℃and below 24.9℃, respectively; while that of Hua133S was ranged from 25.5 to 25.9℃, and about 25.5℃for Hua134S.4. Under the conditions of natural high temperature in Wuhan, shortage of photoperiod treatments can cause a significant reduction of fertility. The result shows that the four lines had the fertility/sterility alternation characteristic that short photoperiod and low temperature induced male sterility while long photoperiod and high temperature induced male fertility. The low temperature can strengthen sterility, while high temperature can weaken the sterility. On the base of the experimental critical point of day length (CPDL) of fertility alteration, CPDL of Hua133S was above 13h, that of Hua131S and Hua135S was ranged 11.5h-12.5h, but the CPDL of Hua134S was unknown, it need for further research.5. The sterility of Hua133S, belonging to recessive inheritance, was controlled by nuclear genes, the genetic segregation of fertility in most F₂ and BC₁F₁ populations accorded with genetic model of two pairs of independent genic major genes, and probably involving the modification of many minor genes.6. In this study, the general combining ability (GCA) and specific combining ability (SCA) variance of most agronomic traits of hybrid combinations and parents were statistically significant difference (P<0.05 or 0.01). The additive and non-additive effect of the majority of trait loci played an important role, and GCA variance was greater than SCA variance, which means that the majority of traits are controlled by genetically additive effect mainly. There was no apparent correlation between the GCA effects from parents and SCA effects from hybrid combinations. Combining ability analysis showed GCA effects of agronomic traits of some male sterile lines were different, Hua131S showed higher GCA effect in spikelets per panicle and yield per plant, Hua133S showed higher GCA effect in 1000-grain weight and brown rice rate, Hua134S showed higher GCA effect in spikelets per panicle, filled grains per panicle and head rice rate; and D38S showed the highest GCA effect in 1000-grain weight, length/width ratio, while showed minimum GCA effect in chalky rate and chalk area.7. Two combinations Hua133S/Huakang394 and Hua133S/C60448 with high heterosis were selected among tested combinations.