A novel environment-induced genic male sterile (EGMS) mutant in indica rice
SummaryMale-sterile mutants were isolated from M2 and M3 generations of indica rice variety 26 Zhaizao, dry seeds of which had been exposed to 60Co-γ rays at a dose of 290 Gy. The mutants were planted in early season and ratooned in late season for two successive years for identification of fertility conversion in different growing seasons. One of the mutant lines was further observed in a growth chamber and in the field. Results showed that daily average temperature might be the major factor conditioning the male fertility conversion at a moderate daylength. The critical temperature for the male fertility conversion of the mutant grown under 12.5 h and 14.0 h daylength is about 23°C, below which the plant becomes completely male sterile. Its male fertility conversion character differs from other EGMS lines so far developed. The performance of the hybrids between the mutant and some other indica varieties demonstrated its good combining ability and its potential value in hybrid rice production. The obtained mutant line still sheds KI-stainable pollen grains under male sterilizing conditions. Nevertheless, pollen grains shed from the male sterile plants were much more vulnerable than from normal plants. At sucrose concentration below 1.5 M, the pollen grains from the mutant grown under male sterilizing conditions almost completely broke down, while above 1.5 M they became plasmolysed and shrunken. This is indicative of poor development of the membrane and walls of the pollen grains from the male sterile mutant, causing the pollen grains to be unfunctional. NBT test also clarified the abortion of the pollen grains from the mutant, which were formed in the male sterilizing environment.
Cytogenetic Analysis of Thermosensitive Genic Male Sterility (TGMS) Recovered from a Pennisetum glaucum (L.) R. Br.×P. violaceum (Lam.) L. Rich Cross
One male-sterile plant was recovered from a cross between pearl millet (Pennisetum glaucum) and its wild progenitor P. violaceum. The behavior of male sterility was temperature dependent, as the development of pollen mother cells to pollen grains was found to be dependent on temperature. The plant showed sterility at lower temperatures while it was fertile at higher temperatures during seasonal variations. This thermosensitive male sterility trait was found to be genetically controlled based on the segregation data of backcross generation. Segregation was observed for ca. 50% of the population expressing this trait. These TGMS plants exhibited transition from fertility to sterility when mean daily temperature reduced to ca. 20°C or below, and fertility was restored above this temperature. The period of 4 to 5 d prior to anthesis was found to be most sensitive to temperature variations. Chromosomal studies on the parent plant as well as segregants showed 2n=14 with regular meiosis during non-sensitive phase (period exhibiting male-fertility) ruling out aneuploidy and/or gross chromosomal structural aberrations as a cause of male sterility. Fertility characters were also studied for TGMS and non-TGMS plants during sensitive and non-sensitive phases. Pollen grains shed from the TGMS plants were much more vulnerable than from normal plants during sensitive phase indicating poor development of the membrane and walls of the pollen grains during sterility inducing conditions. Transition characteristics from male sterility to male fertility during sensitive and non-sensitive phases for TGMS and non-TGMS plants are discussed.
Preparation and performance evaluation of swine manure bio-oil modified rubber asphalt binder
Abstract In order to study the effect of the preparation process of swine manure bio-oil modified rubber asphalt binder on the rheological properties of the binder, the matrix asphalt and asphalt rubber were used as the control group, and swine manure bio-oil modified rubber asphalt binders were obtained by three preparation processes. Then the rheological properties of five binders were evaluated by rotational viscosity, DSR, MSCR and BBR tests. The results show that the addition of swine manure bio-oil to asphalt rubber is beneficial to the workability, but cause negative effect on its high temperature performance, fatigue performance and low temperature crack resistance. The preparation method of premixing bio-oil and rubber powder can reduce the degradation of high-temperature performance of asphalt rubber caused by addition of swine manure bio-oil to a certain extent. The fatigue properties of the three bio-binders are close, and the critical temperature is less than 25 °C. The process of premixing bio-oil and rubber powder will increase the creep stiffness and reduce the low-temperature performance. However, the low-temperature performance of the binder obtained by this process is still better than that of the matrix asphalt and can meet the requirements of use. Therefore, it is recommended to use the preparation process of premixing bio-oil and rubber powder to prepare swine manure bio-oil modified asphalt rubber.