Open access peer-reviewed chapter

Current Scenario of Breeding Approaches in Rice

By Suhel Mehandi, Anita Yadav, Ramanuj Maurya, Sudhakar Prasad Mishra, Syed Mohd. Quatadah, Nagmi Praveen and Namrata Dwivedi

Reviewed: June 7th 2021Published: July 2nd 2021

DOI: 10.5772/intechopen.98744

Downloaded: 117

Abstract

Rice is the predominant crop in India and is the staple food in eastern and southern Indian populations. One of the oldest grown crops is rice. The initial discovery of cytoplasmic male sterile (CMS) three-line system made it possible to produce hybrids that significantly increase rice yields compared to its inbred counterparts. Further genetic and molecular studies help elucidate the mechanisms involved in CMS male sterility. Additional CMS types were also discovered with similar genetic control from wild sources by interspecific hybridization. In India more than 1200 varieties were released for cultivation suitable different ecosystems and out of them 128 varieties have been contributed from NRRI, Cuttack. A list of these varieties are furnished below with their duration, grain type, yield potential, reaction to major disease and insects grain quality and tolerance to different adverse situations. Recent advances in molecular approaches used in modern rice breeding include molecular marker technology and marker-assisted selection (MAS); molecular mapping of genes and QTLs and production of hybrids and alien introgression lines (AILs). Genomic selection (GS) has been projected as alternative to conventional MAS. GS has huge potential to enhance breeding efficiency by increasing gain per selection per unit time. Due to the adaptation of semi dwarf high yielding varieties, combined with intensive input management practices, the country witnessed an impressive rice production growth in the post-independent period. Rice production was increased four times, productivity three times while the area increase was only one and half times during this period. The projected rice requirement by 2025, in order to keep up with increasing population, is about 130 m.t. The challenge of growing rice production is made more difficult by declining trends in HYV’s yields, decreasing and degrading natural resources such as land and water and a severe labour shortage.

Keywords

  • Rice
  • Hybrid
  • Heterosis
  • Marker Assisted Selection
  • Genomic Selection

1. Introduction

Rice (Oryza sativaL.) is one of the most important staple foods that feed more than half of the world’s population; Asia and Africa are the major consuming regions [1]. For at least half of the world’s population, rice is the most significant source of calories. As a result, many countries have developed strategies to achieve rice self-sufficiency by growing the area under cultivation or increasing yield per unit area. In case of rice, however, grain quality is just as critical as yield. Heterosis is the ability of F1 offspring to outperform either parent and it is the only way to achieve full hybrid vigor in crop plants. For decades, this has been a factor in the production of superior cultivars for many crops in agriculture and enthusiastic geneticists [2]. In a hybrid compared to HYVs, the appropriate combination and manipulation have produced benefits [3]. Since the discovery and growth of the cytoplasmic male sterile (CMS) source in the middle of the twentieth century, heterosis was possible due to its self-pollinating existence (0.3–3.0% outcrossing). Nanyou 2, the first indica rice hybrid, was released for cultivation in China in 1974.

Subsequently, relatively heterotical hybrid rice (HR) breeding approaches were adopted, such as two-line system and super hybrids, which complemented Chinese food security and liveling standards significantly in India. In 1989, the Indian Council of Agricultural Research (ICAR) launched a special goal-oriented and time-bound project for rice called “Promotion of Research and Development Efforts on Hybrids in Selected Crops,” which included 12 network centres. Around four years of intensive research (1989–1993) paid off handsomely, and India became the second country after China to grow and commercialize hybrid rice. APRRI, Maruteru, launched the first hybrid variety APRH-1 in 1993–1994 for Andhra Pradesh. So far, 117 rice hybrids (36 from public organization and 81 from private sector) have been produced, with duration ranging from 115 to 150 days and a total area of 3.0 mha, accounting for 7.0 percent of India’s total rice acreage [4]. As a result, breeding for consumer-favored grain qualities has become a major target for breeding programs all over the world. Grain quality must be clearly identified and the genes underlying their regulation deciphered before it is possible to breeder for fastidious customer preference. Rice is a staple food crop that accounts for more than a fifth of all calories consumed by humans [5]. Since rice is the most common cereal crop in most Asian countries and is the staple food for more than half of the world’s population, even a small increase in rice grain micronutrient content could have a major effect on human health. Hybrid rice is the product of a cross between two rice parents with genetically different traits. When the right parents are chosen, the hybrid can outperform both parents in terms of vigor and yield. Higher yields, increased vigor, and increased resistance to diseases and insect resistance are all advantages of hybrid rice [6].

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2. Hybrid rice breeding program in India

Rice is the predominant crop in India and is the staple food in eastern and southern Indian populations. One of the oldest grown crops is rice. The two cultivated species of rice are (i) Oryza sativa- Asian rice Cultivated Species of Rice (A) Asian Rice (Oryza sativaL.). It is predominant species which has spread to different part of world. (B) African Rice (Oryza glaberrimaL.) [7]. It’s also only found in Africa’s tropical region. Based on morphological and physiological characteristics as well as geographical adaptation, Asian rice is divided into three ecological forms. 1.Indica: Grown in tropical climate such as India, Sri- Lanka, China, Thailand, Malaysia, Taiwan 2. Japonica: Japan and Korea have a temperate climate 3. Javanica:Indonesian hybrid of Indica and Japonica (Table 1).

S.No.YearRemarks
11926Heterosis in rice reported
21964China started hybrid rice research
31970China discovered a commercially usable genetic tool for hybrid rice (male sterility in a wild rice = Wild Abortive)
41973PTGMS rice was found in China
51974First commercial three-line rice hybrid released in China
61976Large scale hybrid rice commercialization began in China
71979IRRI revived research on hybrid rice
81981PTGMS rice genetics and application was confirmed
91982Yield superiority of rice hybrids in the tropics confirmed (IRRI)
101990s- India and Vietnam started hybrid rice programs with IRRI
111991More than 50% of China rice land planted to hybrids
121994First commercial two-line rice hybrid released in China
131994–1998Commercial rice hybrids released in India, Philippines Vietnam

Table 1.

Brief history of hybrid rice.

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3. IRRI’s hybrid rice program

Germplasm, parents and hybrids are being developed through new breeding and seed technology by researcher. Currently scientists are working for the hybrids rice production with the Collaboration of NARS and private sectors.

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4. Wild species

The genus Oryza contains tweny valid species, two of which are cultivated, namely Oryza sativaand Oryza glaberrima.There are nine diploid species among the remaining 18 species (Table 2). Six of them are tetraploid. Some of the wild species utilized in breeding programme are Oryza perennis- Co 31 GEB 24 x O. perennis[8, 9, 10].

Botanical NameChromosome No.GenomeOrigin
O. sativa24AAAsia
O. nivara24AAAsia
O. meridionalis24- Australia
O. longistaminata24AAAfrica
O. rufipogan24AAAsia
O. glumaepatula24America
O. grandiglumis48CCDDAmerica
O. glaberrima24AAAfrica
O. barthii24AAAfrica
O. australiensis24EEAustralia
O. latifolia48CCDDAmerica
O. alata48CCDDAmerica
O. eichingeri24, 48CC, BBCCAfrica
O. minuta48BBCCAsia
O. punctata48BBCCAsia
O. officinalis24CCAsia
O. granulata24Asia
O. meyeriane24Asia
O. ridleyi48Asia
O. longiglumis48New Guninea
O. brachantha24FFAfrica
O. schlechterNew Guninea

Table 2.

Wild species of Rice.

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5. Breeding component and system in hybrid rice development

For breeding technique, there are three approaches (1) the three-line method also known as CMS (cytoplasmic male sterility) system (2) the two-line method also known as the PTGMS (photo/temperature sensitive genic male sterility) system and (3) the one-line method, also known as the apomixis system. Inter-varietal hybrids, Inter-sub-specific hybrids and inter-specific or intergeneric hybrids are three ways to increase the degree of heterosis (Table 3).

5.1 Two-line hybrid rice

The two-line hybrid rice research began in China and was successfully scaled up in 1995. The thermo-sensitive male sterile lines (TGMS) lines are those whose sterility expression is regulated by temperature, whereas photoperiod-sensitive male sterile (PGMS) lines are those whose expression is controlled by day-length duration. Backcrossing has successfully transferred the PGMS trait to many Indicaand Japonicarice cultivars in China. In China, rice hybrids produced by this male sterile system are being tested in multiple locations. The degree of heterosis in two-line hybrid rice is close to that of three-line hybrid rice, but the technique methods is different. Unlike three-line hybrids, the male parent of two-line hybrid is not limited by restorer genes, allowing us to use both good restorer lines with high combining potential and good traditional varieties without restorer genes as male parents. Since restorer genes are not limited, there’s a better chance of breeding elite hybrids [12]. The developed PTGMS lines such as PA64S, GZ63S, Zhun S, etc. have many advantages for hybrid combinations, such as larger freedom for crossing, higher yielding, better quality and diseases resistance. The yield of improved two-line hybrid rice combinations is usually higher than of three-line hybrids used as controls. Meanwhile, seed processing and cultivation techniques for two-line hybrids have advanced to the point that they can be used in commercial production. Breeding of elite restorer lines is the key for matching heterotic combinations [13] (Table 4).

Sl. No.Rice HybridsYear of ReleaseDurationDeveloped byRecommended for
1DRRH- 32010131DRR, HyderabadAndhra Pradesh, Gujarat, Madhya Pradesh, Odisha, Uttar Pradesh
2US - 3122010125–130Seed Works International, Hyderabad.Andhra Pradesh, Bihar, Karnataka, Tamil Nadu, Uttar Pradesh, West Bengal.
3CRHR-322010125CRRI, Cuttack, OdishaBihar, Gujarat.
4INDAM 200–017 (IET 20419)2011120–125Indo-American seeds, HyderabadOdisha, Chhattisgarh, Gujarat Maharashtra, Andhra Pradesh.
527P112011115–120PHI Seeds (P) Ltd.Karnataka, Maharashtra.
6VNR 2245 (VNR-204)201190–95VNR Seeds Pvt. Ltd., RaipurChhattisgarh, Tamil Nadu.
7VNR 2245 (VNR-202)2011100–105VNR Seeds Pvt. Ltd., RaipurUttar Pradesh, Uttarakhand, West Bengal, Maharashtra, Tamil Nadu.
8Shyadri-5 (Hybrid)2011110–115RARS, Karjat (BSKKV)Konkan Region of Maharashtra.
9CO (R) H-42011130–135TNAU, CoimbatoreTamil Nadu.
10Hybrid CO 42012130–135TNAU, CoimbatoreTamil Nadu.
11US 3822012125–130Seed Works International Pvt. Ltd., HyderabadTripura, Madhya Pradesh, Karnataka.
1227P312012125–130PHI Seeds Pvt. Ltd. HyderabadJharkhand, Maharashtra, Karnataka, Tamil Nadu, Uttar Pradesh, Bihar, Chhattisgarh.
1327P612012132PHI Seeds Pvt. Ltd. HyderabadChhattisgarh, Gujarat, Andhra Pradesh, Karnataka, Tamil Nadu.
1425P252012110PHI Seeds Pvt. Ltd. HyderabadUttarakhand, Jharkhand, Karnataka.
15Arize Tej (HRI 169)2012125Bayer Bio Science Pvt. Ltd., HyderabadBihar, Chhattisgarh, Gujarat, Andhra Pradesh, Tamil Nadu.
16PNPH 242012120–130Nuziveedu Seeds Limited, A.P.Bihar, West Bengal, Odisha.
17PNPH 924–12012125–135Nuziveedu Seeds Limited, A.P.West Bengal, Assam
18NK 52512012NANATamil Nadu, Karnataka, Andhra Pradesh, Maharashtra, Gujarat.
19VNR 22452012120–125VNR Seeds Pvt. Ltd., RaipurChhattisgarh, Tamil Nadu.
20VNR 2355 Plus2012130–135VNR Seeds Pvt. Ltd., RaipurUttar Pradesh, Uttarakhand, West Bengal, Maharashtra, Tamil Nadu.
21CR Dhan 7012012140–145NABihar, Gujarat.
22JKRH 33332013135–140JK Agri Genetics Ltd., Hyderabad- 16.West Bengal, Bihar, Chhattisgarh, Gujarat, Andhra Pradesh.
23RH- 15312013118–125Devgen Seeds & Crop Technology, HyderabadMajor Hybrid rice growing regions (Madhya Pradesh, Uttar Pradesh, Andhra Pradesh, Karnataka, Maharashtra).
24CO 4 (IET 21449)2013NATNAU, CoimbatoreTamil Nadu, Gujarat, Maharashtra, Uttarakhand, Uttar Pradesh, Bihar, Chhattisgarh, West Bengal.
25Arize Dhani2013NABayer Bio-Science, HyderabadOdisha.
2627P522013NAPHI Seeds Pvt. Ltd. Hyderabad- 82.Andhra Pradesh, Chhattisgarh, Gujarat, Odisha, Uttarakhand.
2727P632013NAPHI Seeds Pvt. Ltd. Hyderabad- 82.Andhra Pradesh, Chhattisgarh, Karnataka, Uttar Pradesh.
28KPH - 1992013NAKaveri Seed Company Limited, SecunderabadAndhra Pradesh, Chhattisgarh, Madhya Pradesh.
29KPH - 3712013NAKaveri Seed Company Limited, SecunderabadChhattisgarh, Jharkhand, Karnataka, Kerala.
30VNR 2375 PLUS2013NAVNR Seeds Pvt. Ltd., RaipurBihar, Karnataka, Punjab, Maharashtra, Uttarakhand.
31US 3052013NASeed Works International Pvt. Ltd., HyderabadAndhra Pradesh, Tamil Nadu, Maharashtra.
32US 3142013NASeed Works International Pvt. Ltd., HyderabadAndhra Pradesh, Bihar, West Bengal, Uttarakhand.
33Ankur 74342014NAAnkur seed Pvt. Ltd.Chhattisgarh.
34PAC 8072014NAAdvanta India Ltd. HyderabadChhattisgarh.
35PAC 8012014NAAdvanta India Ltd. HyderabadUttar Pradesh.
36CSR 432014NAUttar Pradesh.
37JKRH-4012014NAJK Agri Genetics Ltd., Hyderabad- 16.Uttar Pradesh.
38Arize 6444 Gold2015130–135Bayer Crop Science, HyderabadAssam, Chhattisgarh, Odisha, Uttar Pradesh, Bihar Meghalaya, Karnataka, Tamil Nadu.
39SAVA 1272015115–120Savannah seed Pvt. Ltd.Uttar Pradesh.
40Arize Tej (HRI 169)2015120Bayer Crop Science, HyderabadBihar, Chhattisgarh, Gujarat, Andhra Pradesh, Tamil Nadu, Jharkhand.
4127P312015NAPHI Seeds Pvt. Ltd. Hyderabad- 82.Jharkhand, Maharashtra, Karnataka, Tamil Nadu, Uttar Pradesh, Bihar, Chhattisgarh, Madhya Pradesh, Odisha.
42PAC 8012015NAAdvanta India Ltd., HyderabadUttar Pradesh, Jharkhand.
43NK 165202016132Syngenta India Ltd., SecundrabadChhattisgarh, Uttar Pradesh, Bihar, Jharkhand, Odisha, Telangana.
44KPH 4672016126Kaveri Seed Company LimitedChhattisgarh, Madhya Pradesh, Maharashtra.
45KPH 2722016126Kaveri Seed Company LimitedTelangana, Karnataka, Tamil Nadu.
4637P222017126PHI Seeds Pvt. Ltd. HyderabadPunjab, Haryana.
47GK 50222017123 (Aerobic)Ganga Kaveri Seeds Pvt. Ltd., HyderabadBihar, Chhattisgarh.
4827P362017NAPHI Seeds Pvt. Ltd. HyderabadBihar, Madhya Pradesh, Jharkhand.
49NPH 88992017168 (Boro)Kaveri Seed Company LimitedUttar Pradesh, Bihar, Assam.

Table 3.

List of hybrid Rice released/notified in India during 2010–2017.

NA = Not available.


Source: [11].

Sl. No.VarietyEcologyYear of releaseDurationGrain typeRecommended for
1PhalguniIrrigated2010117LSOdisha
2Reeta (CR Dhan 401)Shallow low land2010150MSOdisha
3Luna Suvarna (CR Dhan 403)Coastal Saline2010150MSOdisha
4Luna Sampad (CR Dhan 402)Coastal Saline2010140SBOdisha
5Nua Chinikamini (Aromatic)Shallow low land2010145–150SBOdisha
6CR Dhan 501Semi-deep2010152LBUP, Assam
7CR Dhan 701Shallow low land2010142MSBihar, Gujarat, Odisha
8CR Dhan 601Boro2010160MSOrissa, WB and Assam
9CR Dhan 500Deep Water2011160MSOdisha, UP
10Satyabhama (CR Dhan 100)Upland2012110MSOdisha
11Pyari (CR Dhan 200)Aerobic2012115–120SBOdisha
12Hue (CR Dhan 301)Irrigated2012135LSOdisha
13Improved LalatIrrigated2012130LSOdisha
14Improved TapaswiniIrrigated2012130SBOdisha
15Sumit (CR Dhan 404)Shallow lowlands2012145LBOdisha
16Poorna Bhog (CR Dhan 902)Shallow lowlands2012140LSOdisha
17Jalamani (CR Dhan 503)Deep Water2012160MSOdisha
18Jayanti Dhan (CR Dhan 502)Deep Water2012160MSOdisha
19Luna Barial (CR Dhan 406)Coastal Saline2012150SBOdisha
20Luna Sankhi (CR Dhan 405)Coastal Saline2012110MSOdisha
21CR Dhan 907 (Aromatic)Irrigated Late2013150MSChhattisgarh, Odisha, Andhra Pradesh, Gujarat
22CR Dhan 300Irrigated2013140LSMaharashtra Gujarat Odisha, Bhar
23CR Dhan 303Irrigated2014125SBMP, UP, Odisha
24CR Dhan 305Irrigated2014125SBJharkhand, Maharashtra and Andhra Pradesh
25CR Dhan 304Irrigated2014130SBOdisha and West Bengal
26CR Dhan 201Aerobic2014118LSChhattisgarh and Bihar
27CR Dhan 202Aerobic2014115LBJharkhand and Odisha
28CR Dhan 407Rainfed shallow lowland2014150LBOdisha and West Bengal
29CR Dhan 505Deep water2014162MSOdisha and Assam
30CR Dhan 204Aerobic2014120LBJharkhand and Tamil Nadu
31CR Dhan 306 (IET 22084)Irrigated2014120–125SBMadhya Pradesh, Bihar, Puducherry
32CR Dhan 205 (IET 22737)Aerobic2014110SBTamil Nadu, Gujarat, Odisha, Madhya Pradesh, Punjab
33CR Dhan 101 (Ankit)Upland2014110MSOdisha
34CR Dhan 203 (Sachala)Aerobic2014110LSOdisha
35CR Dhan 206 (Gopinath)Aerobic2014115SBOdisha
36CR Dhan 307 (Maudamani)Irrigated2014135SBOdisha
37CR Dhan 408 (Chaka Akhi)Shallow lowland2014165 PSLBOdisha
38CR Dhan 310Irrigated2015125MSOdisha, Madhya Pradesh and Uttar Pradesh.
39CR Dhan 207 (Srimati)Aerobic2016110–115MSOdisha
40CR Dhan 209 (Priya)Aerobic2016112–115LSOdisha
41CR Dhan 409 (Pradhan Dhan)Semi-deep2016160–165LSOdisha
42CR Dhan 507 (Prasant)Deep Water2016160MSOdisha
43CR Dhan 800Shallow lowland2016140MSOdisha
44CR Sugandh Dhan 910 (Aromatic)Irrigated Late2016142–145MSOdisha
45CR Dhan 311 (Mukul)Irrigated2016120–126LBOdisha
46CR Dhan 508Deep Water2017187LBOdisha, West Bengal, Assam
47CR Dhan 506Semi-deep2017165MSAssam, Andhra Pradesh and Karnataka.
48CR Sugandh Dhan 908 (Aromatic)Irrigated Late2017145MSOdisha, West Bengal and Uttar Pradesh
49CR Sugandh Dhan 909 (Aromatic)Irrigated Late2017140MSAssam, Bihar, UP, Maharashtra
50Gangavati Ageti (Aromatic)Upland201785LSKarnataka
51PurnaUpland201790SBGujarat
52CR Dhan 309Irrigated2019115LSAssam, Chhatisgarh, Uttar Pradesh
53CR Dhan 801Shallow lowland(for submergence and drought prone areas)2019140SBAP, Telengana, Odisha, UP and WB
54CR Dhan 802 (Subhas)Shallow lowland(for submergence and drought prone areas)2019142SBBihar, Madhya Pradesh
55CR Dhan 510Semi-deep2019160SBWB and Odisha
56CR Dhan 511Semi-deep2019160SBWest Bengal, Odisha
57CR Dhan 312Irrigated2019135–140MSMaharashtra and Chhattisgarh
58CR Dhan 102 (Santha Bhima)Upland2019105–110SBOdisha
59CR Dhan 210 (Sarumina)Aerobic2019110–115LSOdisha
60CR Dhan 410 (Mahamani)Rainfed shallow lowlands2019160–165LSOdisha

Table 4.

Rice varieties developed by ICAR-NRRI, Cuttack during 2010–2019.

Source: ICAR-NRRI [14, 15].

Grain: LS: Long Slender, MB: Medium Bold, MS: Medium Slender, SB: Short Bold, MB: Medium Bold.

5.2 Three-line system hybrid rice

5.2.1 Identification and utilization of cytoplasm male sterility

The role of rice cytoplasm in male sterility was first discovered in 1954 [16]. They studied cytoplasmic differences among rice varieties in 1965 and formed a male sterile line for the first time by transferring the nuclear genotype of rice cultivar Fujisaka [17]. However, due to its instability, poor plant form and photoperiod sensitivity, this cytoplasm male sterility (CMS) line could not be used to breed rice. Yuan Long Ping proposed the concept of using heterosis in rice in 1964, and for the first time in China, hybrid rice research was started. The discovery of WA, a nationwide cooperative program was immediately established to extensively testcross with the WA and screen for its maintainers and restorers. Soon in 1972, the first group of CMS lines such as Erjiunan 1A, Zhenshan 97A and V20A were developed all using WA as the donor of male sterile genes and all using successive backcrossing method. In 1973, the first group of restorer lines such as Taiyin 1, IR24 and IR661 were screened using direct test crossing system. Nanyou 2 and Nanyou 3 hybrids with high heterosis were published in 1974 [18, 19, 20]. In another word, the discovery of WA led to successful breakthrough in hybrid rice production, resulting in the establishment of three-line hybrid rice system. As a result, China became the first country in the world to commercialize hybrid rice for food production. For commercial rice hybrids processing, a three-line hybrid system with the CMS line (A), maintainer line (B) and restorer line (R) is used. The A line cannot produce viable pollen due to the interaction between cytoplasmic and nuclear genes, so called cytoplasmic male sterile, which anthers are pale or white and shriveled. The A line is also known as the CMS line and the seed parent because it is used as a female parent for hybrid seed development. Since the CMS line is male sterile, it cannot replicate itself and requires the assistance of a maintainer. The B line is the maintainer line, and its morphology is very similar to that of its CMS line, with the exception of its reproductive feature. However, the B line has viable pollen grains and normal seed setting, it may pollinate the A line, resulting in male sterile F1 plants. In this way, the male sterility of the A line is maintained, and the A line can be reproduced for further use or commercial purposes. Similarly, the R line will pollinate the A line because it has viable pollen grains and normal seed setting. Unlike the pollination with the B line, the F1 plants from the pollination with R line are extremely fertile, or the male sterility of the A line is restored into fertility in their progeny by R line. As a result, the R line is often referred to as the pollen parent or restoring line [21, 22, 23, 24, 25].

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6. Genetic mechanism of rice heterosis

Heterosis, also known as hybrid vigor, is the phenomenon in which progeny of diverse inbred varieties outperform both parents in terms of yield, panicle size, and number of spikelets per panicle, number of productive tillers, stress tolerance and other factors. This phenomenon has been extensively exploited in crop production as a powerful force in plant evolution. After the successful development of hybrid maize in 1930, other crop breeders, including rice breeders, were inspired to use the concept of hybrid production by exploiting heterosis. In fact, the exploitation of heterosis has been the most practical achievement of genetics and plant breeding research [26]. The impact of this phenomenon can be judged by the fact that the number of grains per square meter in rice varies significantly between (1) wild ancestors with just a few hundred (2) improved inbred varieties with about 40,000, and (3) rice hybrids with about 52,000. Rice heterosis was first reported by Jones (1926) who observed that some F1 hybrids had more culms and greater yield than their parents. Between 1962 and 1967, a variety of proposal came from around the world for commercial exploitation of heterosis to become a major component of national and international rice improvement programs. Rice breeders from Japan, China, United States, India, the former Soviet Union and Philippines, for example, began working on projects to use rice heterosis. However, progress had been hampered by rice’s inability to be strictly self-pollinated crop, as opposed to corn which is needed for hybrid seed development, extremely difficult [27, 28, 29].

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7. Molecular technique to enhance rice breeding activities

Recent progress in molecular biology and biotechnology increases opportunities to use rice genetic tools not addressed in previous programs for rice production. The availability of genomic, phenotypic, geographical, and ecological information among other sequence data, when analyzed together, enables researchers to strategically plan experiments based on established models predicting plant performance [3, 30]. Molecular marker technology and marker-assisted selection (MAS), molecular mapping of genes and QTLs and the generation of hybrids and alien introgression lines [31, 32, 33, 34] are just a few of the molecular approaches used in modern rice breeding. MAS is a form of genomic assisted breeding that uses molecular markers to map QTLs or unique genes linked to phenotypes or target traits in order to select individuals with desirable alleles for desired traits [32]. MAS has many benefits over traditional phenotypic selection, including the fact that it is easier than phenotypic screening, that selection can be performed at the seedling level, and that a single plant can be selected based on its genotype [35].

Breeding for improved grain is complex because many of the quality traits are phenotyped using subjective and or expensive biochemical methods. As a result, scientists have been able to map/clone several QTLs/genes for various quality traits and developed molecular markers to aid in grain quality selection. Co-dominant marker, making it ideal for marker-assisted backcrossing for recessive trait like aroma, since lines carrying the aroma gene can be selected in the heterozygote state without having to screen progeny [36, 37]. Other researchers have produced markers for the 8-bp deletion in exon 7 of chromosome 8. Other alleles in the BADH2 gene, such as a 7-bp deletion in exon 2 [38, 39, 40] and a 3-bp insertion in exon 13 found in aromatic rice varieties from Myanmar [41], have also been functionally identified. Around the world, functional markers for RM 190, a waxy gene SSR and waxy SNPS on intron (In1), exon 6 (Ex6) and exon 10 (Ex10) are used to select for AAC and RVA around the world [42]. The waxy SNP haplotypes have been found to be more effective in selecting for AAC and RVA than the RM 190 haplotype across these three SNPs in the waxy genome [43, 44, 45, 46, 47].

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8. Outstanding elite hybrid rice varieties in India

In India many verities of rice have been released by Indian Council of Agriculture Research (ICAR) institute, state agricultural universities and private seed companies.

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9. Future trends in rice breeding

Rice production would have to double by 2050 to keep up with population growth. If the world’s population grows, so will consumers demands for higher-quality rice. In addition to this challenge, climate change is combining new biotic and abiotic stresses. As a result, when designing new lines, rice breeders must consider a large number of simple and quantitative traits in combination while preserving and enhancing grain quality. MAS has been effective in improving certain biotic, abiotic and quality traits in rice, but it is purposeful on broad impact QTLs/genes and ignores epistatic and genetic context effects. Most traits of interest to rice breeders are regulated by a combination of several small effect and/or major genes rather than a few large-effect genes. The use of genomic selection (GS) as an alternative to traditional MAS has been proposed. By the benefits per selection per unit time, GS has a huge potential to improve breeding efficiency. GS breeding enables breeders to use genome-wide DNA marker data to choose the most suitable parents for the next generation. The association between genome-wide markers and phenotypes of the individuals under selection is used to choose these parents. The major benefits of GS over MAS is that genotyping is not limited to a subset of markers that target genes with significant effects, but instead uses all available marker data to predict breeding value. This aids in the prevention of data loss. Genes with a minor effect can be tracked and chosen based on all of the markers results. As the cost of genotyping decreases, GS will become more efficient method for improving rice breeding performance [48, 49].

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Suhel Mehandi, Anita Yadav, Ramanuj Maurya, Sudhakar Prasad Mishra, Syed Mohd. Quatadah, Nagmi Praveen and Namrata Dwivedi (July 2nd 2021). Current Scenario of Breeding Approaches in Rice, Cereal Grains - Volume 1, Aakash Kumar Goyal, IntechOpen, DOI: 10.5772/intechopen.98744. Available from:

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