| Three-line system hybrid rice is the most popular type of cultivated rice in China for planting area. Developing elite cytoplasmic male sterile (CMS) lines are key step in three-line system hybrid rice breeding program. Five new CMS lines, Hua108A, 62048A, 62066A, 62046A and 1623A. which were developed by Huazhong Agricultural University, were used in the studies. Growth characteristics, fertility performance, flowering habit and major agronomic traits were investigated in natural field at Wuhan and Hainan, respectively. Five CMS lines were crossed with two group restorer lines as NCII desigen. The combining ability of main agronomic and quality traits were analyzed at Wuhan in 2007 and 2008, respectively. Hual08A was crossed with 100 restorer lines for selecting superior heterosis combinations.The main results are as follows:1. Investigating to growth characteristics of five CMS showed that the duration from seeding to heading Hua 108A was the shortest, 59-63 days, with a least leaves leaves on main stem. It could be classed as an early type of indica CMS line in Yangze Valley; The growth duration from seeding to heading in other four CMS lines were longer than Hua 108A, with more number of leaves on main stem. They could classified as the medium matured indica CMS lines.2. The results of inspecting pollen sterility and spikelet self-sterility of five CMS lines showed that both the pollen sterility and spikelet self-sterility of Hua 108A were not very stable, with near 99.5%. 62048A was very stable, completely sterile for pollen and spikelet. Pollen sterility of 62066A was 100%, spikelt self-sterility was about 99.5% or more, both the pollen sterility and spikelet self-sterility of 62046A and 1623A were over 99.5 %, showing stable sterility.3. The results of investigating flowering habit of five CMS lines showed that Hua108A and 1623A had a relatively long flowering duration over single plant and panicle. Full flowering stage of five CMS lines began on the second days after heading, lasting for 2-5 days; the flower time of 62048A and 62046A were more concentrated in a day, but Hua108A and 1623A were relatively dispersed; the exsertion rate of the stigma of Hua108A was highest with 56.43%, and with the lowest rate of the wrapped spikelet, 20.42%, the distance of opened glume tips and the spikelet opening angle, were 0.41mm and 26.25°, respectively; 1623Ahad a longest of the spikelet opening time, 181.67min.4. Both the general combining ability (GCA) and specific combining ability (SCA) variances were significant at 5% or 1% levels for most rice grain quality and agronomic traits. The additive effect and non-additive effect played an important role in most traits. The parental general combining ability variances were greater than specific combining ability variances, which showed that additive effect was more important genetically for main traits. General combining ability effects were not correlated with specific combining ability effects in parental traits. The performances of general combining ability effects were some different between two group test among five CMS lines for several traits, Hua108A had a highest general combining ability effect for yield per plant; total grains per panicle, the brown rice rate and ratio of length to width were the highest general combining ability effect for 62048A; chalky rice rate and chalkiness degree of general combining ability effect were the minimum, the transparency of general combining ability effect was the highest for 62066A; amylase content of the general combining ability effect was the minimum for 62046A.5. Several heterotical combinations were selected from among test crosses and combining ability analysis. Hua 108A/YR6068-18,Hua 108A/Huahui 150 and Hua 108A/Huahui 237 showed higher competitive heterosis.
|
PDF Full Text Request