Artificial selection of the Green Revolution gene Semidwarf 1 is implicated in upland rice breeding

Semidwarf breeding has boosted crop production and is a well-known outcome from the first Green Revolution. The Green Revolution gene Semidwarf 1(SD1), which modulates gibberellic acid(GA) biosynthesis, plays a principal role in determining rice plant height. Mutations in SD1 reduce rice plant height and promote lodging resistance and fertilizer tolerance to increase grain production. The plant height mediated by SD1 also favors grain yield under certain conditions. However, it is not yet known whether the function of SD1 in upland rice promotes adaptation and grain production. In this study, the plant height and grain yield of irrigated and upland rice were comparatively analyzed under paddy and dryland conditions. In response to dryland environments, rice requires a reduction in plant height to cope with water deficits. Upland rice accessions had greater plant heights than their irrigated counterparts under both paddy and dryland conditions, and appropriately reducing plant height could improve adaptability to dryland environments and maintain high grain yield formation. Moreover, upland rice cultivars with thicker stem diameters had stronger lodging resistance, which addresses the lodging problem. Knockout of SD1 in the upland rice cultivar IRAT104 reduced the plant height and grain yield, demonstrating that the adjustment of plant height mediated by SD1 could increase grain production in dryland fields. In addition, an SD1 genetic diversity analysis verified that haplotype variation causes phenotypic variation in plant height. During the breeding history of rice, SD1 allelic mutations were selected from landraces to improve the grain yield of irrigated rice cultivars, and this selection was accompanied by a reduction in plant height. Thus, five known mutant alleles were analyzed to verify that functional SD1 is required for upland rice production. All these results suggest that SD1 might have undergone artificial positive selection in upland rice, which provides further insights concerning greater plant height in upland rice breeding.

Advances and prospects of super rice breeding in China

Super rice breeding in China has been very successful over the past 3 decades, and the Chinese government has made great efforts to support breeding and cultivation of both conventional and hybrid super rice. In this review, we focus on the progress in and potential of super rice breeding. After the establishment of the breeding theory and strategy of ＂generating an ideotype with strong heterosis through inter-subspecies hybridization, by using gene pyramiding to combine elite traits through composite-crossing to breed super rice varieties with both ideotype and strong hybrid vigor＂, a series of major breakthroughs have been achieved in both conventional and super hybrid rice breeding. A number of new genetic materials with ideotype have been created successfully, and the Ministry of Agriculture of China has approved 156 novel super rice varieties and combinations for commercialization. During the Developing the Super Rice Varieties Program, great attention has also been paid to the integration and demonstration of the rice production technology. Collaboration between industry and university researchers has led to technological innovations and initiation of a demonstration system for super hybrid rice. With widespread cultivation of super rice with higher quality and yield, as well as resistance or tolerance to abiotic or biotic stresses, the yield of rice production per unit has reached a new level. In addition to increased quality and yield, hybrid rice breeding has also led to improvements in many other agronomic traits, such as resistance to pests and diseases, resistance to lodging, and optimized light distribution in population. Achievements in super rice breeding and innovation in rice production have made major contributions to the progress in rice sciences and worldwide food security.

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.

Research progress on the breeding of japonica super rice varieties in Jiangsu Province,China

In this study we report the results of a decade-long breeding program for japonica super rice made by Nanjing Branch of Chinese National Center for Rice Improvement in Jiangsu Academy of Agricultural Sciences. We concluded that selection of parents with good comprehensive traits and complementary advantages and disadvantages of both parents in the hybrid combination, and early selection of high heritability traits in earlier segregating generations could significantly improve the breeding efficiency. The use of closely-linked functional markers in pyramiding of multiple genes could greatly increase breeding efficiency, avoiding time-consuming and laborious steps that were used in traditional breeding program. It is also important to coordinate the yield components with variety characteristics such as yield stability, wide adaptability, lodging resistance, and an attractive grain appearance during late growth stage of rice.

Breeding Methodology and Practice of Super Rice in China

To meet the growing demand for rice production, the Ministry of Agriculture, P. R. China initiated a nationwide project on the development of super rice in 1996. Through efforts in research, super rice breeding in China has gained significant advances in the aspects of breeding theories, creation of breeding materials and selection and promotion of elite rice varieties. A creative super rice breeding path of the construction of harmonious plant type combined with the utilization of heterosis was proposed. Super rice plays more and more important roles in rice production. Totally, 71 super rice varieties in China have been successfully developed and released to production. These varieties have 12 t/hm2 yield potential in on-farm demonstration fields, 8% to 15% higher than the check varieties with high resistance to pest and medium to high level of grain quality, the total growing area of which has reached 23.7 million hectares, and rice grain production increased by 17.7 million tons from 1996 to 2009. This paper reviewed the development and achievements of super rice breeding in aspects of the breeding methodology and breeding practices, summarized the successful experience of super rice breeding in China and proposed the developmental strategies of super rice for the future.

Plant Ideotype at Heading for Super High-Yielding Rice in Double-Cropping System in South China

The newly released super high-yielding hybrid rice combinations, Yueza 122, Fengyou 428, Peiza 67, and the super high-yielding conventional cultivars, Guangchao 3 and Shengtai 1, were grown in both early and late seasons. The morphological characters of each population were investigated at the heading stage, and the data were analyzed by using ANOVY and other statistic methods. The plant ideal morphological characters at the heading stage were established as follows： 1 ） for the early-season cropping, 90-105 cm plant height; 11-12 tillers per plant; 35-40 em length and 2.1-2.2 cm width of flag leaf; 46-50 cm length and 1.8-2.1 cm width of the second leaf from the top （L2）; 59-64 cm length and 1.4-1.9 cm width of the third leaf from the top （L3）; 7°-14°, 18° and 200-33° for the ideal leaf angles of the flag leaf, L2 and L3, respectively; 2） for the late-season cropping, 90-100 cm plant height; 9-15 tillers per plant; 30-41 cm length and 1.8-2.0 cm width of flag leaf; 53-61 cm length and 1.3-1.8 cm width of L2; 52-58 cm length and 1.2-1.5 cm width of L3; 9°-19°, 15°-37° and 16°-49° for the ideal leaf angles of the flag leaf, L2 and L3, respectively. The main physiological characteristics of these varieties were also analyzed.

Study on Plant Morphological Traits and Production Characteristics of Super High-Yielding Soybean

Super high-yielding soybean cultivar Liaodou 14, soybean cultivars from Ohio in the United States, and the common soybean cultivars from Liaoning Province, China, with similar geographic latitudes and identical pod-bearing habits were used as the study materials for a comparison of morphological traits and production characteristics to provide a theoretical basis for the breeding of improved super high-yielding soybean cultivars. Using a randomized block design, different soybean cultivars from the same latitude were compared under conventional and unconventional treatments for their production characteristics, including morphological traits, leaf area index （LAI）, net photosynthesis rate, and dry matter accumulation. The specific characteristics of the super high-yielding soybean cultivar Liaodou 14 were analyzed. The results showed that the plant height of Liaodou 14 was significantly lower than that of the common cultivars from Liaoning, whereas the number of its main-stem nodes was higher than that of the cultivars from Ohio or Liaoning. A high pod density was observed in Liaodou 14 under conventional treatments. Under both conventional and unconventional treatments, the branch number of Liaodou 14 was markedly higher than that of the common cultivars from Liaoning, and its branch length and leaf inclination angle were significantly higher than those of common cultivars from Liaoning or Ohio. Only small changes in the leaf inclination angle were observed in Liaodou 14 treated with conventional or unconventional methods. Under each treatment, Liaodou 14 exhibited the lowest amplitude of reduction in SPAD values and net photosynthesis rates from the grain-filling to ripening stages; the cultivars from Ohio and the common cultivars from Liaoning exhibited more significant reductions. Liaodou 14 reached its peak LAI later than the other cultivars but maintained its LAI at a higher level for a longer duration. Under both conventional and unconventional treatments, Liaodou 14 produced a higher yield than the other two cultivars, with significant differences from the Ohio cultivars. In summary, super high-yielding soybean cultivars have several main features： suitable plant height, high pod density, good leaf structure with strong functionality, and slow leaf senescence at the late reproductive stage, which is conducive to the accumulation of dry matter and improved yield.

Changes in Some Physiological Characteristics After Full Heading Stage in Flag Leaves of Super High-Yielding Inbred Rice

In a field experiment, rice cultivar Shanyou 63 was used as a check cultivar to investigate the changes in activity of peroxidase and contents of malondialdehyde and soluble protein after full heading stage in flag leaves of two super high-yielding inbred rice, including Shengtai 1 and Yuxiangyouzhan. The results showed that the peroxidase activities and soluble protein contents in the leaves of the three cultivars tended to increase gradually to peak values and thereafter descended during stage after full heading. Moreover, both the peroxidase activities and soluble protein contents of Shengtai 1 and Yuxiangyouzhan peaked at 8 days after full heading, which was compared with that of Shanyou 63 at 4 days later. Meanwhile, the malondialdehyde contents in the leaves of the three cultivars increased gradually after full heading stage. In addition, activities of peroxidase and contents of malondialdehyde and soluble protein in different cultivars were various at the same time. In general, for Shengtai 1 and Yuxiangyouzhan, the peroxidase activities and soluble protein contents were higher than those of Shanyou 63, whereas the malondialdehyde contents were lower compared with that of Shanyou 63. And these features could make the senescence of leaf become later and slower and photosynthetic product was more in Shengtai 1 and Yuxiangyouzhan than that in Shanyou 63.

Super Rice Breeding in China

1. Dernand for super high yield rice in ChinaRice is one of the main staple food in China. Theperformance of rice sector in production and yield had been

Breeding of New Japonica-indica Hybrid Rice Combination Chunyou 284

Chunyou 284 is a medium- japonica hybrid combination,as well as an indica-japonica subspecific hyrbid with super-high yield,which was developed from Chunjiang 23A,a thermo-sensitive CMS line with very early anthesis time,and C84,an indica-japonica intermediate type restorer line with wide compatibility.This combination has the advantages of high yield potential,early maturity,excellent comprehensive agronomic traits and wide adaptability.It was approved by Jiangsu Provincial Crop Variety Approval Committee in June,2018.The breeding process,main characteristics,cultivation techniques and seed production points of the combination were introduced.

南粳系列超级稻品种灌浆期光合产物的分配特性

【目的】研究南粳系列超级稻灌浆期光合产物转运和分配及相关基因表达量的变化特性及其与对照品种的差异,总结南粳系列超级稻高产的生理优势,为优质高产粳稻的培育提供理论依据。【方法】采用南粳5718、南粳晶谷、南粳3908和南粳5055为研究对象,以淮稻5号为对照,在孕穗期、开花期以及开花后每隔7 d至成熟期测定剑叶光合速率、地上部干物质分配和转运,以及剑叶和籽粒发育不同时期物质转运相关基因的表达量,统计产量差异。【结果】南粳系列超级稻产量和千粒重高于淮稻5号,其剑叶净光合速率在孕穗期和花后28 d显著高于淮稻5号。在物质转运方面,南粳系列超级稻开花后茎叶干重、叶片输出量、输出率和转运率显著高于淮稻5号,其中南粳5718叶片输出量和输出率最高。南粳5718剑叶中与淀粉降解和糖类代谢相关基因(OsSPS1,OsSUT2,OsGWD1)的表达比其他品种启动早,最高表达量也高于其他品种。籽粒中SWEET基因在灌浆早期的蔗糖转运过程中扮演重要角色,中后期OsPK3、OsSUT1、OsSUT2基因在糖类的运输卸载中发挥重要作用,OsAGPL2和OsDPE1基因在中后期淀粉合成中发挥重要作用,南粳5718、南粳晶谷、南粳3908籽粒中与淀粉合成和糖类运输的相关基因在不同时期的表达量显著高于淮稻5号。【结论】南粳系列超级稻较高的产量在物质转运方面主要有以下特征:茎秆和叶片物质积累量多,穗积累量大,叶片和茎秆物质转运率高;叶片中蔗糖代谢和转运相关基因表达量高,有利于蔗糖在源端的合成、装载和转运;籽粒中蔗糖转运和淀粉合成相关基因表达量高,有利于蔗糖在库端的卸载及籽粒中淀粉的合成。

优质超级稻新品种荃优212的选育与应用

荃优212是福建省农业科学院水稻研究所利用自育的优质抗稻瘟病恢复系福恢212与安徽荃银高科种业股份有限公司选育的荃9311A配组育成的中籼杂交稻新品种,米质达部颁一等优质食用稻品种品质标准,2018年通过福建省农作物品种审定,2021年被农业农村部确认为超级稻品种,是目前福建省选育的超级稻品种中首个米质达部颁一等优质食用籼稻品种品质标准的品种,2023年荃优212通过国家农作物品种审定。介绍了恢复系福恢212的选育过程和配制杂交稻荃优212的种植表现。

A historical review of hybrid rice breeding

The development of germplasm resources and advances in breeding methods have led to steady increases in yield and quality of rice (Oryza sativa L.). Three milestones in the recent history of rice breeding have contributed to these increases: dwarf rice breeding, hybrid rice breeding, and super rice breeding. On the 50th anniversary of the success of three-line hybrid rice,we highlight important scientific discoveries in rice breeding that were made by Chinese scientists and summarize the broader history of the field. We discuss the strategies that could be used in the future to optimize rice breeding further in the hope that China will continue to play a leading role in international rice breeding.

我国大规模生猪养殖全要素生产率的时空差异——基于Malmquist指数和超效率SBM模型

我国是最大的猪肉生产国,生猪养殖业是我国农业生产中的支柱产业之一,猪肉在城乡居民肉类食品消费中占据重要地位。本文基于Malmquist指数和超效率SBM模型,依据2011—2021年26省份的生猪生产数据,对大规模生猪养殖的生产效率和全要素生产率及其时空差异特征进行评价分析。结果表明:从生产效率和全要素生产率综合来看,10年间我国大规模生猪养殖的生产效率呈现波动上升态势,生猪养殖技术效率年均值为0.812。从全要素生产率来看,全要素生产率年均增长率为0.5%,呈现周期波动趋势,主要依赖效率变化的增长(1.3%),生猪全要素生产率具有明显的区域性差异,中西部地区适合发展规模化生猪养殖,而东部沿海不太适合大规模生猪养殖。未来中西部应不断完善基础设施并加强技术引进与创新,在东部地区发展小规模生猪养殖,优化生产要素与资源的合理配置,调整养殖结构。

Innovation of Super Early-Mature Millet Germplasm with Sweet-Stem and Multi-Spikes

A new millet (Setaria italica Beauv) variety, super early-mature millet No.1, was bred by means of gene bank breedingmethod of target characters. This variety has the following outstanding characters. (1) Super early-mature. This varietyonly needs 1550C effective accumulated temperature and can normally maturate in the Bashang Region in Hebei Provinceof Chi na, which can break through the limit zone of millet cultivation and move the cultivation zone northward greatly. (2)Multi-spikes, in addition to the effect tilling at the top, the nodes in the low-middle part also can produce spikes. (3) Sweetstem have high sugar content. The contents of whole-sugar, soluable sugar and deoxidized sugar are 74.8, 200.5, 237.2%higher than the regular varieties respectively. (4) High gross protein content. The content of gross protein is higher thanthe regular varieties by 3.9-30.4%. (5)Changeable grain color. The grain color of super early-mature millet No.1 is red inShijiazhuang, but yellow in the Bashang region. In addition, this variety is characterized by good quality, high yield, andgood synthetic traits

稻田除草剂应用现状与抗除草剂水稻育种研究进展

在水稻生产中,杂草是影响稻谷产量和品质的主要原因之一,而除草剂是目前最有效的除草手段。近年来,市场供应的稻田除草剂商品种类庞杂,常用除草剂使用量逐年增加,单一除草剂长期大量使用带来的杂草抗药性问题和除草剂残留引起的食品安全、农田生态环境问题日益严重,难以有效解决。创制抗除草剂水稻品种是解决稻田杂草危害重、防控难的一种较好选择。本文从稻田杂草及其发生规律入手,介绍了水稻直播和移栽种植模式下杂草的治理措施、稻田常用除草剂应用现状及挑战,重点研究了最新的抗除草剂水稻新品种育种进展和应用情况,展望了生物育种技术在抗除草剂水稻创制中的发展前景,旨在为提高稻田杂草防控水平,促进抗除草剂水稻育种研究和扩展生物育种技术应用范围提供参考。

Relationship between leaf photosynthetic function at grain filling stage and yield in super high-yielding hybrid rice (Oryza sativa.L)

The characteristics of dry matter production before and after heading and the relationships between photosynthesis of flag leaves and dry matter accumulation in panicles were investigated on super high-yielding rice cv. Xieyou 9308 (the yield of up to 12 t/ha) with rice cv. Xieyou 63 as a control. The results showed that (i) the capacity of dry matter production before and after heading in Xieyou 9308, i.e. biomass and daily dry matter production, was remarkably higher than that in Xieyou 63, especially after heading; (ii) CO2 assimilation capacity in flag leaves in Xieyou 9308, namely Leaf Source Capacity (LSC), was also significantly higher than that in Xieyou 63, and the supply of photosynthate in leaves and the demand of grain filling were completely synchronous in Xieyou 9308, but photosynthetic function in flag leaves in Xieyou 63 declined sharply 20 days after heading and it was not enough to meet the demand of grain filling. These results confirmed that high efficient photosynthetic function in leaves after heading and its complete synchronization with grain filling are the key approaches to super high yield of rice.

Breeding strategies for increasing yield potential in super hybrid rice

Super hybrid rice breeding is a new breeding method combining semi-dwarf breeding and heterosis breeding using germplasm and gene-environment interactions.This paper reviews the breeding strategies of super hybrid rice breeding in China,focusing on the utilization of heterosis of indica and japonica subspecies,construction of ideal plant architecture and pyramiding of disease resistant genes in restorer lines.To develop super hybrid rice,considerable effort should be made to explore genes related with high yield,good quality,resistance to pests and diseases,tolerance to stresses.Molecular breeding methods in combination with crossing techniques should be adopted in super hybrid rice breeding.

超甜玉米新品种鄂甜玉9号的选育

鄂甜玉9号是湖北蔬谷农业科技有限公司以自交系shB227为母本、shB202为父本于2013年组配而成的超甜玉米单交种。该品种生育期适中,湖北省低山平原地区春播,出苗至采收83 d左右,商品性好、甜度高、食用品质好、产量稳定,667 m^(2)产鲜穗854.48 kg、适应性强。可作为鲜食和加工两用超甜玉米,适宜在湖北省低山平原及相似生态区春秋两季种植。