Breeding lines with neutral genes to improve fertility of intersubspecific hybrid rice

Since the sterility-neutral allele S~n has been incorporatedinto indica or japonica varieties, many intersubspecifichybrids have been released commercially. These hybridsshowed high heterosis, but some of them exhibited unstableseed setting rate under low temperature. When the hybridsflowered at low temperature, the fertility of female gamete

The Breeding of New Indica-japonica Intersubspecific Hybrid Rice Combination Chunyou 84

Chunyou 84 is an indica-japonica hybrid rice combination developed from Chunjiang 16A, a late japonica CMS line with early anthesis time, and C84, an indi-ca-japonica intermediate type restorer line with wide compatibility. It has the charac-teristics of high yield potential, high seed production, excel ent agronomic characters, good resistance and wide adaptability. It was registered and released by Zhejiang Provincial Crop Variety Appraisal Committee in March, 2013. The breeding proce-dure, characteristics, major techniques of cultivation and seed production of Chunyou 84 were introduced in this paper.

Source-Sink Relationship in Intersubspecific Hybrid Rice

Three indica restorer lines （Mianhui 725, Shuhui 527, Shuhui 881）, an American rice variety Lemont and a javanica rice variety Xiangdali were crossed with japonica Kitaake, and five F1 hybrids were obtained to study the photosynthetic and agronomic traits. The data on photosynthetic characteristics indicated that the net photosynthetic rate （Pn） of the five F1 hybrids was significantly higher than that of their parents （or one of them） under high photosynthetic flux density （PFD）; while the overall performance of hybrids was better than their respective parents in apparent quantum yield （AQY）, carboxylation efficiency （CE） and CO2 compensation point （CCP）. Moreover, the photosynthetic performance of the five F1 were different due to the variation in heredity and the typical indica-japonica hybrids, Mianhui 725/Kitaake and Shuhui 527/Kitaake, were better than the others on this aspect. The agronomic traits revealed that the five F1 exhibited different heterosis, with Shuhui 881/Kitaake the largest sink followed by Mianhui 725/Kitaake, Shuhui 527/Kitaake, Lemont/Kitaake and Xiangdali/Kitaake. The production potential of indica-japonica hybrids was higher than that of the other two hybrids, which was consistent with the performance of Pn. However, the superior trait of indica-japonica hybrids on sink size has not been fully turned into high yield because of abnormal seed setting. Therefore, attention should be paid to the proper genome coordination and appropriate genetic distance so as to achieve super high yielding.

Alternatingly stacked thin film electrodes-based compact aqueous hybrid electrochemical capacitors for hundred-volts AC line filtering

Filtering capacitor with compact configuration and a wide range of operating voltage has been attracting increasing attention for the smooth conversion of the electric signal in modern circuits.Lossless integration of capacitor units can be regarded as one of the efficient ways to achieve a wider voltage range,which has not yet been fully conquered due to the lack of rational designs of the electrode structure and integration technology.This study presents an alternatingly stacked assemble technology to conveniently fabricate compact aqueous hybrid integrated filtering capacitors on a large scale,in which a unit consists of rGO/MXene composite film as a negative electrode and PEDOT:PSS based film as a positive electrode.Benefiting from the synergistic effect of rGO and MXene components,and morphological characteristics of PEDOT:PSS,the capacitor unit exhibits outstanding AC line filtering with a large areal specific energy density of 1,015 μF V^(2)cm^(-2)(0.28 μW h cm^(-2)) at 120 Hz.After rational integration,the assembled capacitors present compact/lightweight configuration and lossless frequency response,as reflected by almost constant resistor-capacitor time constant of 0.2 ms and dissipation factor of 15% at120 Hz,identical to those of the single capacitor unit.Apart from standing alone steadily on a flower,a small volume(only 8.1 cm^(3)) of the integrated capacitor with 70 units connected in series achieves hundred-volts alternating current line filtering,which is superior to most reported filtering capacitors with sandwich configuration.This study provides insight into the fabrication and application of compact/ultralight filtering capacitors with lossless frequency response,and a wide range of operating voltage.

Machine Learning for Hybrid Line Stability Ranking Index in Polynomial Load Modeling under Contingency Conditions

In the conventional technique,in the evaluation of the severity index,clustering and loading suffer from more iteration leading to more com-putational delay.Hence this research article identifies,a novel progression for fast predicting the severity of the line and clustering by incorporating machine learning aspects.The polynomial load modelling or ZIP(constant impedances(Z),Constant Current(I)and Constant active power(P))is developed in the IEEE-14 and Indian 118 bus systems considered for analysis of power system security.The process of finding the severity of the line using a Hybrid Line Stability Ranking Index(HLSRI)is used for assisting the concepts of machine learning with J48 algorithm,infers the superior affected lines by adopting the IEEE standards in concern to be compensated in maintaining the power system stability.The simulation is performed in the WEKA environment and deals with the supervisor learning in order based on severity to ensure the safety of power system.The Unified Power Flow Controller(UPFC),facts devices for the purpose of compensating the losses by maintaining the voltage characteristics.The finite element analysis findings are compared with the existing procedures and numerical equations for authentications.

复杂建设环境下基于Hybrid A^(*)算法的铁路平面线形绿色优化设计

随着“双碳经济下绿色铁路”理念的兴起,将“绿色生态”融入到铁路平面线路优化已成为近年来的研究热点。本文以铁路建设成本与生态破坏成本的协同优化为目标,引入并改进了一种自动驾驶导航算法(Hybrid A^(*)算法),以适应复杂的铁路设计问题,同时考虑最小曲线半径、最大曲线半径、最短曲线长度、最短夹直线长度、缓和曲线长度等铁路线形约束。研究结果表明:(1)改进后算法以离散网格方式整合外部环境因素,实现渐进式全局探索,获取接近全局最优的铁路线路设计结果;(2)该方法在复杂外部环境约束下,无需预设水平交点位置和数量,可自动生成符合线路-环境耦合约束的优化平面线路方案。

Solutions to Insecurity Problems in Seed Production of Two-line Hybrid Rice

The insecure problems of seed production have seriously hampered the healthy and sustainable development of two-line hybrid rice.The safety issues on seed production of two-line hybrid rice and current research situation were pointed out in this paper.The three main reasons for unsafety in seed production of twoline hybrid rice were unsuitable site selection,high critical sterility-inducing temperature and the drift of critical temperature.In this paper,strategies and measures were put forward based on many years of practice.It could minimize the risk in seed production of two-line hybrid rice by selecting dual-purpose genic male sterile line with lower critical sterility-inducing temperature and long lower temperature resistant time.Based on the climate data and climatic demands of the ＂three safe-periods＂ in seed production,a new idea for determining appropriate bases and periods for seed production was proposed by using computer technology,which solved the aimless selection of sites and periods for the seed production of two-line hybrid rice.Besides,we established a system of single plant selection and identification method and original seed propagation with cyclic cold water,which could reduce the generation number of original seed propagation in seed production and avoid the drift of critical sterility-inducing temperature.This paper improved the seed production safety in the three aspects of seed nature,seed source and seed production site.

Study on Agronomic Characters and Storage Durability of a New Line of Endurable Storage Hybrid Rice Chucangyou No.1

[Objective] The aim of this study was to investigate the storage durability of a new line of endurable storage hybrid rice Chucangyou No.1 selected by endurable storage genes of Yunhui 290.[Method] Agronomic characters of the new line and the control II you 838 and Shanyou 63 were comparatively studied,and storage durability of the new line and indica,japonica or hybrid rice were also comparatively analyzed by the accelerated ageing test.[Result] Agronomic characters of the new line were excellent,and germination rate in the artificial accelerated ageing test was significantly higher than those in other materials.[Conclusion] Chucangyou No.1 has the better storage durability,which can be used in large scale of extention.

Analysis of Heterosis, Combining Ability and Heritability of Cadmium Content in Brown Rice of Three-line Indica Hybrid Rice

Five cytoplasmic male sterile （CMS） lines were used as parents in an incomplete diallet cross and six restorer lines of rice design （Nc II design）. Thirty hybrid combinations with the same growth period were selected as experimental ma- terials to investigate the heterosis, combined ability and heredity of Cd content in brown rice of indica hybrid rice. According to the results, Cd content in brown rice showed a significantly negative heterosis; the general combining ability and specific combination ability of Cd content in CMS and restorer lines both reached extremely significant level （P〈0.01）, indicating that both genetic improvement of parents and e- valuation of combinations are important to the breeding of hybrid combinations with low accumulation of Cd; the broad-sense heritabitity and narrow-sense heritability of Cd content were both relatively high with slight differences, which respectively reached 97.73% and 80.10%, indicating that Cd content in brown rice mainly de- pends on the additive action of genes; in addition, parent improvement showed bet- ter effect on the selection of early generation.

High-yielding Seed Production Techniques of Disease-resistant and High-quality Hybrid Rice Sterile Line Rong 18A

Rong 18A, bred by Crop Research Institute, Chengdu Academy of Agri- culture and Forestry Sciences is a new blast-highly resistant and high-combining ability hybrid rice sterile line. It is currently one of the male sterile lines in Sichuan Province which combine well high grain quality and rice blast resistance. More than 20 combinations of Rong 18A have passed the national and provincial variety iden- tification. Combined with the climate conditions in Chengdu, the key points of high- yielding seed production techniques for Rong18A are analyzed and summarized in this paper.

Combining Ability Analysis on Yield Traits of Recombinant Inbred Lines in Hybrid Rice

A population of 140 recombinant inbred lines at F8 generation were obtained after seven successive generations of self-pollination using single seed descent（SSD） method from the F2 hybrids of three-line restorers Luhui 8258 with high combining ability and Yanghui 34. Then, the 140 inbred lines obtained above and their parents Luhui 8258 and Yanghui 34 were crossed with three different types of cyto-plasmic male sterile（CMS） lines（Gang 46 A, Ⅱ-32 A and Lu 98A） according to NCⅡ design. The resulting 426 combinations were planted at Deyang and Suining bases to test the combining ability and inheritance of five yield traits： yield per plant, panicle number per plant, filled grain number per panicle, seed setting rate and 1 000-grain weight. The results showed that the variances of both general and specific combining abilities of the five traits all reached a significant or extremely significant level at the two sites. The broad and narrow heritability of the yield traits（except 1 000-grain weight whose broad and narrow heritability were both over70%） were all below 50% at the two experimental bases, suggesting that the four traits were easily subjected to environment influence. Very significant positive correlation of general combining ability was found between yield per plant and other traits except 1 000-grain weight. The general combining ability variance showed a normal distribution among the recombinant inbred lines at two sites, right in line with inheritance of quantitative traits. So, the genes controlling rice general combining ability can be targeted by QTL mapping.

Effect of Enhanced UV-B Radiation on Seed Setting Rate and 1 000-grain Weight of Indica Hybrid Rice Restorer Lines

[Objective] This study was to investigate the effect of enhanced UV-B radiation on seed setting rate and 1 000-grain weight of hybrid rice combinations. [Method] The seed setting rate and 1 000-grain weight of 10 new sterile indica restorer lines planted in pots under enhanced UV-B radiation and fluorescent lamps （control） were respectively measured, and the differences were compared. [Result] The enhanced UV-B radiation significantly reduced the seed setting rate of indica restorer lines, and the differences between that UV-B radiation treatment and control all reached extremely significant level. In addition, the enhanced UV-B radiation reduced the 1 000-grain weight of most indica restorer lines, and compared with that of control the difference achieved significant or very significant level. However, the effect of enhanced UV-B radiation on seed setting rate and 1 000-grain weight differed to different indica restorer lines, and the differences among restorer lines tested were significant or very significant, which indicated the possibility to screen antiUV-B radiation rice materials and combinations. Finally, the indica restorer lines 09R-14, Luhui 37 and 10R-7703 which were strongly resistant to UV-B radiation were screened out. [Conclusion] This study laid foundation for breeding hybrid rice varieties resistance to UV-B radiation.

Breeding and Application of Indica PTGMS Line Yan 161S and Its Hybrid Yanliangyou 1618 in Rice

In 2006, the indica photoperiod- and thermo-sensitive genic male sterile （PTGMS） line Yan 161S was successful y bred by crossing the Guangzhan 63S （♀） and the medium indica breeding material Yan 229 （♂）, which was bred by the Institute of Agricultural Sciences in Coastal Region of Jiangsu Province, after years＇ and generations’ selection in different areas. It passed the identification by Jiangsu Provincial Crop Variety Appraisal Committee in 2013. Crossing the Yan 161S with Yanhui 888, a new high-yielding and high-quality two-line hybrid rice combination Yanliangyou 1618 was developed, and it passed the variety identification in 2014. This paper introduced the breeding processes and characteristics of Yan 161S and Yanliangyou 1618 and the cultivation and seed production techniques of Yanliangyou 1618.

Characterization and evaluation of rice blast resistance of Chinese indica hybrid rice parental lines

The development of resistant varieties and hybrid combinations has been the most effective and economical strategy to control blast disease caused by Magnaporthe oryzae.However, the distribution of major R genes and blast resistance characterization in hybrid rice parents has not been well investigated, resulting in their limited use in hybrid rice blast-resistance breeding. In the present study, 88 elite indica hybrid rice parental lines were evaluated with 30 isolates of M. oryzae collected from the main planting area of indica hybrid rice in China and were characterized for the presence of 11 major resistance genes using molecular markers. The pathogenicity assays showed that four types of hybrid rice parent line showed some resistance to M. oryzae. However, the proportions of highly resistant lines and the mean resistance frequency(RF) varied among the four types, with resistance in decreasing order shown by three-line restorer lines, three-line maintainer lines, two-line sterile lines, and two-line restorer lines. All 88 hybrid rice parental lines carried more than one R gene, but none carried the R genes Pi1 and Pi2. Although Pid3 and Pi9 were present only in three-line restorer lines and Pigm only in three-line maintainer lines, the remaining six R genes(Pib, Pid2, Pi5, Pia, Pi54, and Pita) were present in the four types of hybrid rice parent with significantly different distribution frequencies. The correlation between R genes and resistance reactions was investigated. The results are expected to provide useful information for rational utilization of major R genes in hybrid rice breeding programs.

Studies on Seed Setting Stability in Associated with Temperature for a Two-Line Hybrid Rice,Liangyoupeijiu

When being planted in wide areas in southern China (23°23' - 33°23' N, 98°35' - 120°19' E, sea level above 2.7 - 1285 m), Liangyoupeijiu (LYPJ), a two-line hybrid rice combination, showed a seed setting rate of 75.2 - 77.2%, which was lower by 4.3 - 7.5 percent point than that of an indica hybrid rice Shanyou 63 (CK), with similar values of grain yield and coefficients of variation to CK. Sowing during 5-25th of May in Nanjing (32°3' N, 118°48' E), China, LYPJ headed before 4th September, and gave a seed setting rate of 75 - 90%, and grain yield over 1 kg/m2. If the sowing date was delayed to 14 - 15th, June, its heading date would be as late as 17th - 21st September, and seed setting rate would be declined by 10 - 15% in comparison with that on a suitable sowing date. When flowering took place at an average daily temperature range of 13.7 - 28.5℃ for five days, the spikelet fertility (SF) would be increased by 1.9- 10.7%, for each increment of 1℃. The suitable (SF≥90%) and safe (SF≥75%) temperatures for flowering stage were indicated to be 26.5℃ and 22.9℃, respectively. To get a high and stable seed set in cultivating LYPJ, it was recommended that LYPJ would be planted in the areas south of 34癗, and the favorable average daily temperature during flowering stage should be at 26 - 28℃.

Thoughts and Practice on Some Problems about Research and Application of Two-Line Hybrid Rice

The main problems about research and application of two-line hybrid rice were reviewed, including the confusing nomenclature and male sterile lines classification, the unclear characteristics of photoperiod and temperature responses and the unsuitable site selection for male sterile line and hybrid dce seed production. In order to efficiently and accurately use dual-purpose genic male sterile lines, four types, including PTGMS （photo-thermo-sensitive genic male sterile rice）, TGMS （thermo-sensitive genic male sterile rice）, reverse PTGMS and reverse TGMS, were proposed. A new idea for explaining the mechanism of sterility in dual-purpose hybrid rice was proposed. The transition from sterile to fertile was involved in the cooperative regulation of major-effect sterile genes and photoperiod and/or temperature sensitive ones. The minor-effect genes with accumulative effect on sterility were important factors that affected the critical temperature of sterility transfer. In order to make better use of dual-purpose lines, the characterization of responses to photoperiod and temperature of PTGMS should be made and the identification method for the characterization of photoperiod and temperature responses of PTGMS should also be put forward. The optimal ecological site for seed production could be determined according to the historical climate data and the requirements for the meteorological conditions during the different periods of seed production.

Resistance Evaluation of Some Chinese Leading Rice Maintainer, Restorer lines and Their Hybrids to Magnaporthe grisea

Six isolates of Magnaporthe grisea were selected to inoculate on 10 Chinese leading maintainer lines (B-lines), 14 restorer lines (R-lines) and their F1 hybrid plants. In the tested rice materials, R-lines were proved to be more resistant to blast than B-lines. The resistance frequency of about 25% F1 hybrid plants was less than their parents. In addition, 26 isolates of M. grisea collected from different rice growing areas of China were inoculated on 13 new improved hybrid rice combinations. The resistance frequencies of 5 improved hybrids were better than those of the controls and leading varieties in rice production of China.

Molecular characterization of LMW-GS genes from a somatic hybrid introgression line Ⅱ-12 between Triticum aestivum and Agropyron elongatum in relation to quick evolution

In order to exploit the evolution and find novel low-molecular-weight glutenin subunit （LMW-GS） for improvement of common wheat quality, thirteen variants from a somatic hybrid introgression line II-12 between Triticum aestivum cv. Jinan 177 （JN177） and Agropyron elongatum were characterized via genomic PCR. Four clones were pseudogenes because they contained an internal stop codon. The remaining nine variants contained intact open reading frames （ORFs）. Sequence alignment indicates that the proteins deduced from the nine ORFs have similar primary structure with LMW-GS cloned from its parents previously. However, they have some unique modifications in the structures. For example, EU292737 contains not only an extra Cys residue in the C-terminal domain but also a long repetitive domain. Both EU 159511 and EU292738 start their first Cys residue in the N-terminal repetitive domain, but not in the N-conserved domain traditionally. These structural alterations may have positive contributions to wheat flour quality. The results of phylogeny showed that most LMW-GS variances from 11-12 were homologous to those from parent JN177 and other wheat lines. The reason for quick evolution of LMW-GS in 11-12 was discussed.

New Temperature Sensitive Genic Male Sterile Lines with Better Outcrossing Ability for Production of Two-Line Hybrid Rice

An investigation was carried out with three newly developed temperature sensitive genic male sterile （TGMS） lines for their floral traits, seed production potential and outcrossing ability in ten cross combinations. In the TGMS lines, fertile pollens had an average diameter of 0.89 mm while the sterile pollens was with 0.02 mm diameter.TS-29-150GY produced the biggest fertile pollens with 0.92 mm and other two lines produced relatively smaller pollens with 0.91 and 0.85 ram. Pollen fertility during the fertility reversion period was an average of 60.7%. TS-29-150GY had the maximum of 66.9% spikelet fertility whereas other two lines （TNAU18S and TNAU60S） had relatively lower spikelet fertility of 27.8% and 26.7%, respectively. Average of 17.00 g of seed yield was obtained in the TGMS lines during the fertility reversion period. TS-29- 150GY had the highest value of 21.20 g of seed yield while TNAU18S and TNAU60S produced 16.6 g and 13.2 g of seed yield, respectively. The low seed production ability of these three TGMS lines was attributed only to the environmental conditions prevailing during the period. All three TGMS lines had considerable outcrossing potential of 41.2%, 24.6% and 25.0%, respectively. The cross combinations viz. TNAU18S/IET21508 （36 g/plant）, TNAU18S/IET21044 （13 g/plant）, TNAU18S/IET21009 （26.5 g/plant）, TNAU60S/CB-09-106 （26.2 g/plant）, TNAU60S/IET21009 （14 g/plant） and TS29-150-GY/DRR 3306 （39.2 g/plant） showed perfect synchronization with acceptable hybrid seed yield, indicating suitability of TGMS system under Indian condition. Based on the outcrossing related traits viz. panicle exertion, angle of glume opening, stigma length and pollen size, TNAU18S was identified as the best, followed by TS-29-150GY.

Utilizing Dominant Early Maturity Genes of Sterile Line UP-3s in Hybrid Rice Breeding to Avoid High Temperature Season

A new sterile line UP-3s, which carries the Dominant Early Maturity Gene (DEMG), was bred on the farm of University of Arkansas at Pine Bluff (UAPB). UP-3s and two check sterile lines, Jin23-A and Xie-A which do not carry the Dominant Early Maturity Gene, were crossed with a group of different maturity restorer lines, PB-1R, PB-5R,PB11, PB-13R, PB-20, PB-21, PB-22R, and PB-23R. Eighteen new hybrid rice combinations of these crosses were then tested at UAPB in 2012 and 2013. The results showed that panicle differentiation (PD) of hybrids from female parent UP-3s (DEMG) crossed with the 8 male parents, were earlier than the hybrids from female parent Jin23-A or Xie-A crossed with the 8 male parents. The PD of these earlier hybrids was before Jun 25 and heading was before July 20. Early PD and heading avoided the high temperature (over 34&degC) period which usually occurs after July 20 in Arkansas. The yields of these earlier maturity hybrids with female parent UP-3s were higher than those of the late maturity hybrids thatwereF1 progeny of sterile lines Jin23-A or Xie-A (these two female parent checks with non-DEMG). These results showed that the DEMG sterile line UP-3s can be adopted in making crosses with later maturity restorer lines to obtain earlier maturity hybrids to avoid the high temperature period in Arkansas.