Studies On Practical Application Of Five Indica Rice Photo-thermo-sensitive Genic Male Sterile Lines

Five indica photo-thermo-sensitive genic male sterile lines(PTGMS) newly developed by Huazhong Agricultural University and Pei'ai64S(CK),one of the most popular indica PTGMS in two-line hybrid rice breeding in China,were studied in this paper.The botanical morphology,including growth characterestics,agronomic traits, flowering habits,and floret characters were investigated under natural conditions at Wuhan.The characteristics of fertility alternation were identified under natural conditions at Wuhan and at Lingshui,Hainan Province and in phytotron at Wuhan.PTGMS lines were used as female parents for crossing two-set male parents by NCⅡdesign,one set was composed of six male parents and other composed of five.The general combining ability of female and male parents and the specific combining ability of hybrids were were investigated and analyzed for yield and main agronomic traits in the year 2006 and 2007 at Wuhan.Three PTGMS lines were crossed with 103 restorer lines for selecting heterotic combinations.The main results were as follows:1.Fertility alternation of PTGMS lines had different stages sensitive to temperature and photoperiod.The sensitive stages of Hua888S and Hua890S were ranged from 16 to 22 days before heading date.Hua889S ranged from 16 to 24,Hua891S ranged from 20 to 23, Hua221S ranged from 12 to 23 and Pei'ai64S ranged 12 to 18 days before heading, respectively.2.The results identified in phytotron showed that the critical point temperature(CTP) of fertility alteration in Hua888S and Hua889S were below 23.5℃,and the CTPs of Hua890S,Hua891S and Hua221S were above 23.5℃.3.Flowering kinesis each day in a panicle of Hua888S,Hua889S,Hua890S and Hua891S were better than the control,Pei'ai64S.The flowering periods of Hua888S, Hua889S,Hua891S and Hua221S were more concentrated,while that of Hua890S was relatively dispersed.The stigma exsertion percentage of Hua891S reached as much as 68.25%and Hua221S showed 4.43%of wrapped spikelet,the lowest in six PTGMS lines,. The distance of opened glume tips and the opening angle of spikelet of Hua891S was the largest,3.9mm and 27.86°,respectively,and its spikelet opening time was also the longest,107.5min.The stigma vitality of Hua889S was better than others and showed a longer lasting time.It may obtain higher yield in seed production.4.The results of seed multiplication at Lingshui,Hainan Province showed that the seed setting rate and the grain weight per plant were higher when sowing time was arranged mid-November than other time because of lower temperature in fertility sensitive stages. The seed setting rate of Hua888S,Hua889S and Hua891S showed signifcant difference in different sowing time,but there were a little difference among Hua890S,Hua221S and Pei'ai64S there in diferent sowing time.It implied that arranging a reasonable seeding time is important for increasing seed multiplication yield of PTGMS lines in winter season.5.Both general combining ability(GCA) and specific combining ability(SCA) were significant at 5%or 1%levels for main traits.The additive effects were more important than non-additive effects on panicles per plant.Effects of the GCA and SCA on various characters were not significantly related each other.Hua890S and Huahui2185 showed high general combining ability(GCA) in grain weight per plant.Specific combining abilitys(SCA) among all the combinations were not significant at 5%or 1%levels.6.Several heterotical combinations were selected among tested crosses. Hua891S/Huahui 3 and Hua888S/Huahui2003 showed higher competitive heterosis at Lingshui,Hainan Province,while that of Hua891S/Huakanghui 327 and Hua888S/Huakanghui331 were higher at E'zhou city,Hubei Province.