Breeding and Seed Production Techniques of New Aromatic Danxiangyouzhenliang Rice Variety with Good Quality and High Yield

Danxiangyouzhenliang rice is a high-quality rice variety derived from the hybrid breeding of Danxiang 12A and Xianghuixiangmiao R133.Its unique temperature-sensitive three-line characteristics endow it with significant advantages of high and stable yield,and its rice fragrance is exquisite and its taste is delicate.Danxiangyouzhenliang rice showed good resistance to rice blast and bacterial blight.On June 10,2021,Danxiangyouzhenliang rice passed the Guangxi Crop Variety Approval(Guishendao 2021074).Danxiangyouzhenliang rice is suitable to be planted as early and late rice in southern,central and northern Guangxi.This study summarized the breeding process and high-yielding seed production techniques of Danxiangyouzhenliang rice,in order to provide useful reference for rice breeders and growers.

Study on Mechanization Hybrid Rice Seed Production Technology and Combine Breeding Advances

[Objectives]Current hybrid rice seed production mechanization and a new kind of hybrid rice seed production mechanization using Bentazone sensitive lethal genes for mechanized seed production technology are introduced in this paper.[Method]Sensitive Restorer Bentazone lethal dose of filtering,parental and seed weight are bred combinations of several aspects of the system described,and presented mechanized seed technology new research directions.[Results]The method of using Bentazone sensitive lethal genes for mechanized seed production technology is feasible,economic,seed production and combination advantages.[Conclusions] Using Bentazone sensitive lethal genes for mechanized seed production technology is the new study direction of mechanic production.

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.

Research Progress on Mechanized Mixed Sowing Seed Production Technology of Hybrid Rice

Hybrid rice planting has been widely popularized and applied in the world. However, the high cost of seed production and the complicated procedures have become a bottleneck in the development of hybrid rice. The research progress on mixed sowing seed production techniques of hybrid rice was introduced from the aspects of rice resources creation, breeding, sowing seed technology research and cost benefit analysis. The production technology of the new mixed seeding combina- tion ＂Xinhunyou 6＂ was investigated, including the research and validation of benta- zon treatment period and dosage, mixing ratio of male and female parents, and the comparative test of different different sowing methods, which revealed that the mechanization technology of seed production of hybrid rice was mature and feasible and would be one of the most important development trend of technological devel- opment of hybrid rice production.

Effects of Mechanized Transplanting and Fertilization Mode on Population Growth and Development of Male Parent in Seed Production of Hybrid Rice

In order to study the effects of mechanized transplanting and fertilization mode on population growth and development of the male parent in seed production of hybrid rice, three male parents, Huazhan, Shuhui 527 and R9311 were selected as materials. The male parents were transplanted by rice transplanter with two kinds of line spacing design, six lines with equal row spacing （20/25 cm x 30 cm） and wide and narrow spacing （20/25 cm x 40, 20 cm）, and artificial transplanting with equal row spacing （20/25 cm x 30 cm） was set as the control. The three fer- tilization modes were applying for one, two and three times. The flowering stage and panicle-spikelet structure of the male parent were investigated. The results showed that the effects of mechanized transplanting and fertilization mode were little on the duration from seeding to heading; the panicles and spikelets of the three male parents were significantly increased by mechanized transplanting. The tiller number was increased by mechanized transplanting and fertilizing for two and three times. Wide and narrow spacing by machine planting and fertilizing for three times were suitable for Huazhan, which significantly increased the number of spikelets per unit area. Furthermore, the number of spikelets per unit area of Shuhui 527 and R9311 were significantly increased by mechanized transplanting and fertilizing for three times.

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.

High-yielding Seed Production Techniques and Characteristics of Hybrid Rice Yanliangyou 888

According to seed production of Yanliangyou 888, a two-line hybrid rice variety, the research reviewed seed production characters, as follows： to improve outcrossing rate and spike size provided sufficient spikes of female/male parents. The seed production techniques include scientific arrangement of seeding interval, cultivating strong multi-tiller seedlings, scientific arrangement of row ratio of inter- cropping with adequate basic seedlings, scientific water and fertilizer management, improving outcrossing rate by synthesis measures, disease/insect control, and rein- forcing production management.

Seed Production Techniques of Two-line Indica Hybrid Rice Yanliangyou 2208

Yanliangyou 2208, bred by the Jiangsu Institute of Agricultural Sciences in Coastal Areas, is a two-line indica hybrid rice combination characterized with strong heterosis, moderate maturity, wide adaptability, good stability and disease resistance. It was identified as a new variety by the National Crop Variety Approval Committee in 2013. According to the characteristics of parents of Yanliangyou 2208 and com- bined with many years of seed production experience, high-yielding seed production techniques of Yanliangyou 2208 are summed up in this paper.

Study on High-yielding Seed Production Technologies of Japonica Hybrid Rice

[Objective] This study aimed to investigate the high-yielding seed production technologies of japonica hybrid rice. [Method] Key technologies affecting the seed production of japonica hybrid rice were investigated based on manual transplanting experiment, mechanical transplanting experiment, paclobutrazol chemical control experiment, leaf-clipping experiment, gibberellic acid treatment experiment and experiment of different row ratios of male and female parents. [Result] The duration from seeding to heading was significantly shortened with sowing date postponing. The sowing date of mechanical-transplanting parents should be 3 -4 d earlier than that of manual-transplanting parents. Spraying paclobutrazol had significantly control effect on plant height of rice seedlings, and the spraying dose should be determined based on the sensitivities of different parents to paclobutrazol, with an appropriate range of 600-900 g/hm2 . Leaf clipping had certain improving effect on the seed-setting rate. The appropriate spraying dose of gibberellin for japonica hybrid rice was 75-90 g/hm2 . The yield would be relatively high when row ratio of male and female parent was 6∶2. [Conclusion] This study laid the foundation for improving the yield of produced japonica hybrid rice seeds.

Effects of Supplementary Pollination by Single-rotor Agricultural Unmanned Aerial Vehicle in Hybrid Rice Seed Production

In 2012-2015, under the conditions of different natural wind speeds, the single-rotor agricultural unmanned aerial vehicle was used for the supplementary pollination during seed production of 10 hybrid combinations with big parental row ratios in the hybrid rice seed production bases of Hunan, Hainan and Guangdong Province, and the pollination effects were studied through the investigation of pollen density in the field, outcrossing seeding rate of female parent and seed production yield. The results showed that under the parental row ratio of 6：（40-60）, the seed setting rate and yields of the supplementary pollination by single-rotor agricultural UAV could reach and even higher than those of artificial pollination, indicating the single-rotor agricultural UAV could be used in supplementary pollination for hybdd rice seed production, which could promote the whole-process mechanization of seed production.

Research on Theories and Techniques of Irrigation for Safeguarding Seed Production of Two-Line Hybrid Rice

By inducing frequency, intensity and duration of lower temperature in the middle and last ten-day periods in August in the rice-growing areas of southern China, increasing temperature for safe seed production was defined as 2℃. During the sensitive period of fertility, characters of panicle height and canopy structure of TGMS rice, Pei＇ai64S, were measured. Results showed that temperature changes caused by irrigation in fields were below 40 cm of rice plant, and heating effect was significant at 20 cm when the temperature was increased by 3.1 ℃. For the present study, the following irrigation techniques were put forth： the water depth of 15-20 cm, current water used, irrigating after 17：00 and bailing at 10：00 in sunny or cloudy weather, irrigating on whole day, in shady or rainy weather, increasing inflows and outflows in large fields. In the present experiment, pollen fertility and self-fertilized seed setting rate accepted that the techniques were feasible and effective for against lower temperature and safeguarding seed production of two-line hybrid rice.

Seed Production Techniques for a New Two-line Hybrid Rice Combination, Benliangyou 3113

According to seed production practice, the seed production techniques for BenIiangyou 3113, a new two-Iine hybrid rice combination, were summarized. In or-der to obtaln high and stabIe yielding, the seed production of BenIiangyou 3113 re-quires appropriate site seIection, rational sowing period, rational ratio between parental Iines, enhanced water and fertiIizer management, appropriate Ieaf cutting, strict weeding, good artificial poI ination and good pests and diseases controI.

Feasibility Analysis and Policy Recommendations for Production of Hybrid Rice Seed in Foreign Countries

In the economic new normal,production of hybrid rice seed in foreign countries is the necessity for reducing farmland area occupied by seed production,for ensuring national grain security,realizing cost reducing and quality improving of hybrid rice seed,strengthening competitive power at international market,guiding seed industry of China to go out,building transnational seed groups with core competitive power,establishing close relationship with developing countries,promoting the construction of One Belt One Road strategy,serving overall situation of diplomacy,and setting up excellent international image. It is feasible to produce hybrid seed in foreign countries considering( i) high overall national strength of China,( ii) rapid and healthy growth of China's seed industry and increasingly mature hybrid rice seed production technologies,( iii) excellent climatic conditions of foreign host countries of seed production,and( iv) low land and labor price of foreign host countries of seed production. However,there are social and policy risks,technology and trade barrier risks,market,production,and other risks for production of hybrid rice seed in foreign countries. In view of these,it came up with recommendations,including allowing delivering parent seeds of hybrid rice to foreign countries,allowing delivering hybrid rice seed to China,solving the problem of " opening in protection,and protection in opening",and formulating a package of support policies.

The Application of Bentazon Susceptible Gene on Seed Production of Hybrid Rice

The seed production of male and female parent of ‘Hunzhi 1＇ contained bentazon susceptible gene was studied. The result showed that spraying 3. 375 L/hm2 48% bentazon aqua could control the self-pollinated fertilization rate below 1.0% and survival plant rate was 0. The spray of bentazon would not influence MC526 pollen vitality. Seed setting rate of female parent was not obvious different from that of control group with spraying bentazon aqua more than 3. 375 L/hm^2 from the sprouting appearing period to full heading stage. This demonstrated that bentazon aqua had no influence on seed setting rate during florescence of female parent. The weight ratio between male parent seeds and female parent seeds was 1 to 5, then seeds from parents with that weight ratio would be mixedly planted for seed production. With this weight ratio, relative proper structure of panicle and grain would be obtained ,panicle ratio was 1 to 4.3, glumous flowers ratio was 1 to 3.5. Cross seed-setting rate of female parent was 72.6% and seed production per hm^2 was 66 000 kg.

High-yield Production Techniques of High-quality and Early Maturity Hybrid Rice Xiangzaoyou 2017

Xiangzaoyou 2017 is an excellent early maturing variety bred from the combination of Neixiang 3A and the self-fertile restorer QN 2017 by Qiannan Institute of Agricultural Sciences of Guizhou Province,and it has been approved by the Guizhou Crop Variety Approval Committee( Approval No.: Qianshendao 2006001).In order to promote its application in production,the research on the seed production techniques of Xiangzaoyou 2017 was carried out,and the key technical points of high-yield seed production of Xiangzaoyou 2017 were put forward.

Preliminary Discussion on Stigma Vitality of Sterile Line Rong 18A and Its Application in Seed Production

Rong 18A is an Indica three-line sterile line bred with M5B×D Xing B, and has the characteristics of stable sterility, high outcrossing rate, good combining ability and good quality. With Rong 18A as an experimental material and Ⅱ-32A, Jin 23A and Gang46 A as the CK materials, a seed setting rate estimation method by daily pollination was used for measuring its stigma vigor, to comparatively analyze the decreasing rates and lasting time of stigma vigor of various materials under natural condition. According to experimental results and combining with field breeding practice, the application of stigma vigor of sterile lines on hybrid rice seed production was discussed.

Practices and Prospects of Super Hybrid Rice Breeding

The great progress in super rice breeding both in China and other countries has been made in recent years. However, there were three main problems in super rice breeding： 1） the super rice varieties were still rare; 2） most super rice varieties exhibited narrow adaptability; and 3） current breeding theories emphasized too much on the rice growth model, but they were unpractical in guidance for rice breeding. According to the authors＇ experience on the rice breeding, the breeding strategies including three steps （super parent breeding, super hybrid rice breeding and super hybrid rice seed production） were proposed, and the objectives of each step and the key technologies to achieve the goals were elucidated in detail. The super parent of hybrid rice should exhibit excellent performance in all agronomic traits, with the yield or sink capacity reached the level of the hybrid rice control in regional trials. The super hybrid rice combination should meet the following criteria： good rice quality, wide adaptation, lodging resistance, resistance to main insects and diseases, and the yield exceeded above 8% over the control varieties in the national and provincial regional trials. To achieve the goal, the technical strategies, such as selecting optimal combination of the parents, increasing selection pressure, paying more attention to harmony of ideal plant type, excellent physiological traits and all the agronomic traits, should be emphasized. The yield of seed production should reach 3.75 t/ha and 5.25 t/ha for the super hybrid rice combinations derived from early-season and middle-season types of male sterile lines, respectively. The main technologies for raising seed production yield included selecting optimum seed production site, using the male sterile line with large sink capacity and good outcrossing characteristics, and improving the amount of the pollen by intensive cultivation of the male parent. According to the technologies of the three-step breeding on super hybrid rice, two super rice parents, including a male parent 996 and a thermo（photo）-genic male sterile [T（P）GMS] line C815S, were bred. Furthermore, a super early hybrid rice combination, Luliangyou 996, which could be used as a double-season early rice variety in middle and lower reaches of the Yangtze River, China, was bred by using the super rice varlet3, 996 as the male parent, and several hybrid rice combinations with higher yield than control variety in regional trials both of Hunan Province and state were bred with the T（P）GMS line C815S as the female parent.

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.

Identification of a major quantitative trait locus and its candidate underlying genetic variation for rice stigma exsertion rate

Stigma exsertion in male sterile lines of hybrid rice is important for seed yield.In the present study, ZS616 [Oryza sativa subsp.Xian(indica)], a male sterile line with a stigma exsertion rate(SER) as high as 94.5%, was crossed to DS552, a japonica line with almost no exserted stigmas.F3 plants with extremely low and high SER were sequenced to identify SER-associated quantitative trait loci(QTL).A major QTL for SER, qSER-3.1, was identified along with other QTL on chromosome 3 in a 3.9 Mb region.A total of 307 nonsynonymous single-nucleotide polymorphisms(SNPs) and 27 frame-shift insertion/deletions(InDels)differentiating ZS616 and DS552 were identified in the region containing qSER-3.1.Most SNPs(294) and InDels(25) were excluded after further analysis because they were shared by ZS616 and low(<2.0%) SER accessions in the Huazhong Agricultural University(HAU) core rice collection.Association analysis using the full HAU collection identified a 17-bp InDel in OS03 G0689400 as the most likely causal genetic variant underlying qSER-3.1.ZS616-type accessions(n = 54, with the 17-bp insertion) in the HAU collection had minimum(16.5%)and mean(39.6%) SERs significantly greater than those(n = 424) without the insertion(with minimum and mean SERs of 0.2% and 20.6%, respectively).Thus, this study identified a major QTL for stigma exsertion and revealed the mutation in a candidate gene for the QTL.

早熟高产杂交水稻组合两优7871的选育及其高产栽培和制种技术

两优7871是由178S和R71杂交选育的杂交水稻品种,具有早熟、抗倒伏、优质、高产和稳产等特点。本文总结分析了该品种的选育过程、特征特性、高产栽培及制种技术,该品种在2016—2017年长江中下游区域试验中,全生育期130 d,平均产量9.51 t/hm^(2),外观品质优,适口性、抗病性较好;其高产栽培注重培育壮秧,控制无效分蘖,争取有效穗数,促大穗,提高结实率,重点防治稻瘟病、稻飞虱等;制种技术要点包括合理安排播差期,培育壮秧,合理密植,加强田间管理和巧喷赤霉酸生长调节剂等。研究结果为该品种在长江中下游作为一季中稻、麦茬直播稻和再生稻种植提供参考。