Crop breeding is the genetic improvement of crops for human benefit. In Korea, crop breeding by hybridization was initiated in the early 1900s. Since the development of the first rice variety ‘Namseon 1’ in 1932, a series of great achievements have been made in most of the crops. Of these, the development of ‘Tongil’ rice, which brought self-sufficiency of the staple food due to its high productivity, was a monumental achievement in Korea’s crop breeding history. Laws for Variety Protection and Seed Industry were established as of June 2013. Until 2018, a total of 7,644 crop varieties were registered for protection in the national variety list that is managed by the Korea Seed and Variety Service. Some Research/Development (R/D) programs for promoting crop breeding studies have been implemented with governmental support. However, domestic seed markets have stagnated for years because of reduced cropping area. Considering the fact that international seed market size has increased at an annual rate of more than 7%, seed export is regarded as a breakthrough measure for the expansion of the Korean seed industry. In order to obtain a competitive power in international seed markets, the Korean seed industry sector should be reinforced with manpower training, R/D investment, an international marketing system, and governmental support. More details are discussed.

The government-led system for seed production and distribution of major crops was developed by enforcement of the Major Crops Seed Law in 1962. The Korea Variety and Seed Service has played a key role in operating the system, in cooperation with breeding institutes under the Rural Development Administration and provincial Basic Seed Centers. In the case of rice, the most important crop in the country, the quality of certified seed has continuously improved from the simply cleaned seed in the 1960s to graded, disinfected, coated seed of the present. Its coverage of the total planted area increased from 14% in 1985 to 60% in 2015. Since its inception in 2010, the Foundation of Agricultural Technology Commercialization and Transfer has been involved in the production/distribution of certified seed of minor crops/varieties, which had not been properly cared for by the mainstream system previously mentioned. Vegetable seed has been produced and marketed by the private sector. In the latter half of 1950s, seed self-sufficiency was attained in major vegetables. Vegetable seed market became totally open by 1991, and since then Korean seed companies have explored overseas production sites to meet the needs of local and export markets. The acquisition of major local seed companies by multinational major companies in the late 1990s has led to opportunities for Korean vegetable seed firms to upgrade their operational plant production and quality assurance practices to global standards. The quality of vegetable seed offered by Korean companies today is at the top level in the world market. The small and ever-decreasing size of the local seed market has been and will be a serious factor limiting the seed business in Korea. It is necessary to develop technologies to overcome the meteorological disasters that are becoming more violent and more frequent due to climate change. Labor-saving technologies are in urgent need in the area of field production. Phytosanitary border control systems need to evolve to more science-based reasonable ones. Seed enhancement technology, such as biological treatment, is becoming an essential part of holistic farm solutions, where seed is not only a carrier of the genetic constitution of a plant variety, but also plays a complementary role in making up for limitations of varieties and/or cultural managements practices. It is necessary to be adaptive and incorporate new sciences and technologies such as artificial intelligence, new breeding technologies, and epigenetics, among others.

The history of development of seed management in Korea can be broadly divided into the periods of pre-enlightenment (Joseon Dynasty), enlightenment, Japanese colonial occupation, after liberation, installation of the National Seed Supply Office, and the Seed Industry Act. During the Joseon Dynasty, quite a few agricultural books had been published. With the signing of the Korea-U.S. Trade Treaty in the late 19th century, the Agriculture and Livestock Experimental Station was established, and subsequently many varieties were introduced from the U.S. and tested in the station. The Agricultural Exemplary Testing Station, founded in Suwon by the Japanese Resident General in 1906 as a national agricultural research facility, was a hub in colonial agricultural research and food production. In order to expand agricultural productivity, the "Regulations on Subsidization of Rice Seed Production" was enacted in 1922. This carried out nation-wide seed production and supply projects, and established a seed multiplication system. After liberation, the seed management system of food crops was enacted under the Major Crop Seed Act (1962). The Agricultural Seeds and Seedlings Act (1962) was enacted for vegetables and other crops, and then the Seedlings Management Act (1973) replaced it. In 1974, the National Seed Supply Office was established as an institution that supplies high quality seeds for food self-sufficiency with support of the FAO and IBRD. Then, by introducing the variety protection system under the Seed Industry Act (1997), Korea was able to reform the national seed management system and prepare an opportunity to join the ranks of developed countries.

The plant variety protection system (PVP), which started in 1968 to protect the rights of breeders, was first launched in Korea in 1998 with 27 species, including rice and barley. In 2008, the forest sector started the PVP system, which was later than the agricultural sector, and included 15 species of chestnut, oak mushroom, etc. It was then extended to all plants species in 2012. The new plant variety protection system protects the rights of the breeder for a new variety when it has novelty, denomination, distinctness, uniformity, and stability. In the past decade, a total of 424 new varieties of forest plant applications have been filed, and 193 new varieties have been registered. The number of applications of new varieties has increased every year, with 18 new varieties applied in the early stages of the forest sector’s PVP system, and 20~30 new varieties are registered each year. In the early stages of the operation of the PVP system, the central and local governments mainly took the applications (82 applications), but recently, due to consulting, promotion of the PVP system and support of breeders, applications to the private sector, such as individual breeders and the seed industry have increased (107 applications). The National Forest Seed Variety Center (NFSV) publishes Test Guidelines (292 books) and DUS test manuals (7 books), and conducts the “PVP system information session” every year of the PVP system settlement. NFSV will continue to implement policies for protecting the rights of breeders and the development of the bio-industry sector. These efforts provide a new provision against the Nagoya Protocol Paradigm with the promotion of the forest bio-industry.

The global area of GM Crops continued to grow in 2018 and reached 191.7 million hectares. Twenty-six countries approved biotech crops for planting and an additional 44 countries (18 + 26 EU countries) officially imported biotech crops for food, feed, and processing, meaning that biotech crops are now commonly accepted in those countries. First-generation GM seed is being commercialized by global agricultural companies in advanced countries such as the United States and parts of Europe. The fact that more than 90% of first-generation GM seeds, which have been commercialized for 20 years, are both insect resistant and herbicide resistant proves that they continue to have an effect on improving agricultural productivity and increasing farmers' incomes. As the effectiveness of GM crops has been proven and technology has been developed, the GM crop development trend has recently changed. In other words, it has moved from being producer-oriented to benefiting both farmers and consumers. In Korea, the National Program for GM Crops (NCGC), one of the Next-Generation BioGreen 21 Programs organized by Rural Development Administration (RDA), was established in 2011 to develop biotech crops that will be used in the future to solve our agricultural problems. To accomplish this mission, the NCGC carried out the exploration of useful functional genes, the development of qualified events, and the safety assessment of developed events. Here, we introduce the current status of GM crop development and commercialization in the world and in Korea.

Research on mutation breeding started in the early 1960s by researchers at the Atomic Energy Research Institute, Rural Development Administration (RDA) and several universities in Korea. The Radiation Agriculture Research Institute (RARI) was established in 1966, and studies of mutation breeding using radiation were actively conducted for a while. RARI was merged into the Korea Atomic Energy Research Institute (KAERI) and RDA in 1973, and radiation breeding research was neglected by the two agencies. In the 1980s, the relevant research department was lost, which resulted in a recession period of radiation breeding research. The Advanced Radiation Research Institute (ARTI), under the KAERI, was established to promote radiation research and the industry in 2005, which led to the activation of radiation breeding research. Then, the Radiation Breeding Research Center (RBRC) at the ARTI was established with support of the Ministry of Agriculture, Food and Rural Affairs in 2013. Recently, the importance of seed and genetic resources has been emphasized in Korea, and many institutes, companies and private breeders are interested in mutation breeding. The RBRC is trying to develop advanced radiation breeding techniques and new genetic resources using mutation techniques combined with bio-tech. This is to deal with the loss of biodiversity due to global climate change and environmental degradation, growing global demand for food and bio-energy, and to strengthen the protection for new plant varieties. Approximately 180 new mutant varieties were developed and registered officially in Korea. Recently, new mutant varieties, especially of flowers and ornamental plants, have quickly increased and are being commercialized, mainly by private company and breeders.

Rice research in Korea during the past 100 years has gone through tremendous changes and improvements as the country underwent a turbulent history of transformation. Full-scale R&D modernization began in the 1970s, when the government focused policy on achieving self-sufficiency in rice in order to establish the foundation for national economic growth. A major landmark was reached by the development of the rice variety “Tongil” and its cultivation technology, which was at the core of the unprecedented Korean “Green Revolution”. Since achieving self-sufficiency in rice, the breeding goal of Korea moved from increasing yield to improving grain quality as more consumers began to seek high quality food products in the 1980s. This change led to the establishment of the high quality rice breeding platform for enhancing the global competitiveness of Korean rice to cope with the opening of domestic rice market in the 2000s. Currently, the major breeding goals in rice are developing premium quality cultivars for table rice and specialized cultivars for boosting processed food industry. To date, the National Institute of Crop Science has released a total of 300 rice cultivars, including 202 table rice and 98 specialized usage cultivars. Diverse technologies have been developed and utilized for breeding new rice cultivars to meet changing needs. In the next 100 years of rice breeding, the convergence of traditional crop improvement technologies and the new breeding technologies utilizing recent advances in biotechnology will play a crucial role in enhancing breeding efficiency.

Barley and wheat are a major food crop of humans, along with rice, soybean and corn. A systematic breeding program for Korean barley began in 1906 with selection and introduction breeding. In 1908, landrace barley was collected, and breeding focused on selection and introduction for high yielding varieties until the 1970s. In the 1980s and 1990s, breeding was carried out for diversity; thereafter, we aimed to improve quality, productivity and lodging tolerance that can be applied to the paddy field in Korea. Since 2010, the major result of breeding was shortening cultivation to approximately 6–12 days, making a double cropping system possible in the paddy field in Korea. Yield has increased by 1.2 times from 438 kg/10 a in the 1960s to 536 kg/10 a in the 2010s, and farm yield has increased by 1.7 times. In addition, as cultivation safety has been enhanced, the varieties have also improved, such as the covered barley used in making tea and other processing products. In case of wheat, up to now forty cultivars have been developed in Korea. In the early stage, we developed a domestic wheat variety that was early maturing and high yielding. As a result, the maturation time of wheat planted in the 1970s to 2010 was shortened (from 13 to 30 days), while productivity increased by 30% from 408 kg/10 a in the 1970s to 532 kg/10 a in 2010. In recent years, there have been remarkable efforts for a more stable production by focusing on increasing disaster and pest resistance due to climate change. In addition, a wheat variety discrimination marker was developed using a variety-specific marker, and selection was made using a trait-specific marker at the early stage of breeding to enhance breeding efficiency. In the 2000s, winter cereals for forage have been promoted to expand forage production and to replace imported feed grains. Therefore, winter cereal that is useful for feed, such as rye, oat, and triticale, have had various varieties and safe production techniques developed. Currently, our research goal for winter cereals for feed is to develop a double-cropping adaptation and abiotic stress tolerance cultivar, and safe production in paddy field. Hence, aggressive action is needed to support the strategic survival of the Korean wheat and barley industry. Barley is a health food that requires a multifaceted effort to improve breeding efficiency, develop varieties that contain large amounts of functional components and are more resistant to stronger biotic and abiotic stresses in response to climate change. It is necessary to recognize the role of wheat and barley as the second main crop after rice, and to improve the self-sufficiency rate of these crops for the health and food industry crisis of Korea.

In Korea, native or open pollinated corn varieties that were not improved before 1960 were cultivated. The 1960s was a step that created the foundation for the development of varieties. In 1962, systematic corn breeding was started when the synthetic type ‘Hwangok 2’ was distributed to farmers. The 1970s was the era of the change from synthetic varieties to hybrid ones, with a focus on the development of single-cross hybrids among the corn hybrids. The single-cross corn hybrid, ‘Suwon 19’, was an epoch-marking variety that had a unit-yield closer to that of advanced countries. The 1980s was a time when the breeding direction was changed from grain corn to silage because the corn cultivation area for silage increased rapidly with the government's livestock promotion policy, and the corn seed supply system of single-cross hybrids was established. In the 1990s, the era of globalization and the launching of imports of agricultural products, the living standards of consumers became more advanced, and the development system of corn varieties was established for various use purposes. As we entered the 2000s, it started the heyday of developing corn varieties, with 29 corn varieties of various use purposes and excellent cultivation stability developed. In the 2010s, the scope of corn variety development expanded from government or universities to private seed companies. Thus, the corn varieties in Korea have changed and developed in response to the situation of the times, and there are currently 110 corn varieties registered with Korea Seed & Variety Service (KSVS). In the future, vegetable corn is expected to be continuously developed, with functional ingredients such as strengthening vitamins, trace elements, and antioxidant components. Specialized grain corn, such as lysine and maltodextrin, will be developed and commercialized in order to improve the value added. In the case of silage corn, there will be varieties of early maturing and late planting adaptability, with no more than 110 days until maturity, suitable for the cropping system, such as second cropping and double cropping, as well as high digestion rate and nutrition varieties with high feed value, and excessive water tolerance corn varieties that adapt well to paddy fields. Furthermore, it is expected that corn varieties that adapt well to Southeast Asia, Latin America, and Africa will continue to be developed and supplied.

The horticultural seed industry in Korea is small but has developed through rapid changes. During the Japanese colonial era, only small seedlings such as radish, cabbage, and Japanese and Chinese crop varieties were introduced. After liberation, horticultural breeding began with the establishment of the first Horticultural Research Institute and Dr. Woo Jang-chun’s activities. Seed companies grew rapidly due to the implementation of new seedling laws and the spread of the first hybrid variety. Through the IMF, multinational companies merged together and merged with domestic seed companies, and domestic seed companies expanded overseas, while there were active startups by professional breeders. Various breeding techniques were used to develop new varieties of vegetables. F₁ hybrid breeding produced hybrids using artificial crosses, self-incompatibility, and male sterility. Haploid breeding techniques using anther culture, microspore culture, and embryo culture were used for chinese cabbage, red pepper, and onion crops. Mutant breeding methods using a diploid breeding technique and mutation using translocation was used for seedless watermelon. New breeding hybrids were cultured through interspesific hybridization, and embryo culture and ovule culture techniques were used to breed interspesific hybrids. Male sterile varieties were raised through protoplast fusion. Recently, molecular markers have been used in all crops for early introduction and purity testing of major traits. In addition, transgenic and genome editing technology has been used to cultivate disease-resistant and physiologically resistant varieties.

Nowadays most parts of vegetable breeding in Korea have been conducted by private seed companies. However, in the beginning stages of breeding research, Horticulture Experiment Station played a crucial role. Major vegetable varieties that are distributed from Korea are produced as F₁ hybrids. Korea has developed leading techniques and human infrastructure for vegetable breeding. Such brilliant developments have resulted from three major factors: changes in the composition of varieties, the establishment of year-round vegetable production, and the development of the seed export market. First, an F₁ hybrid system increased seed performance more than traditional open pollinated (OP) varieties with respect to productivity, uniformity and disease resistance. Moreover, an F₁ hybrid system required repetitive seed production and provision, which increased the economic growth of seed companies. Second, vegetables tend to be consumed fresh instead of dried or processed. Finally, vegetable seed exports have continuously increased with the aid of R&D projects such as the Golden Seed Project (GSP). Therefore, for further progress of the vegetable industry, new varieties that can meet consumers’ demands, as well as the stable provision of fresh vegetables, are required. Contrary to the past, the future focus must be concerned with productivity and cultivation stability, the development of high value, functional, eco-friendly vegetables, and high quality vegetables. To cope with this, every breeding subject, including industry, universities, and institutes, have to collaborate with the aim of advancing vegetable breeding in Korea.

Although small-scaled breeding programs for apples, pears, and grapes were conducted in the 1930s and 1940s, national fruit breeding programs by the Korean government were commenced after the foundation of the National Horticultural Technical Institute on May 20, 1953, and the programs were confined to apples and pears. Peach and grape breeding programs were started after the establishment of Rural Development Administration (RDA), with the Horticultural Experiment Station as its affiliated research organization in 1962. However, because of insufficiencies in breeding infrastructure, manpower, and funds during the 1960s and 1970s, most efforts were devoted to the collection and selection of wild Akebia and Actinidia, local varieties of astringent persimmons, jujube, and apricot, and adaptability tests of foreign fruit varieties. Fruit breeding programs became more activate with the establishment of the Apple Research Institute, the Pear Research Institute and the Citrus Research Institute as subsidiary organizations of the Fruit Research Institute, RDA, in 1991, and with Fruit Experiment Stations for grapes, persimmons, and peaches as affiliated provincial research organizations in early 1990s to cope with the domestic agricultural market opened by Uruguay Round Agreements. The legislation of the Seed Industry Law in 1995 and joining the UPOV in 2002 contributed to fruit breeding activation in the private sector. The results of such breeding programs include the development of the ‘Danbae’ pear as the first fruit variety in 1967, the ‘Yumyong’ peach in 1977, the ‘Hongro’ apple, and the ‘Cheongsoo’ grape. After the Korea-Chile FTA, effective in 2004, research projects for the development of molecular markers linked to disease resistance in fruit trees and seedless grapes have been carried out to improve the competitiveness of the Korean fruit industry. However, the establishment of a molecular breeding system based on genome sequence information and collaboration among research organizations are required for competition in domestic and foreign fresh fruit markets. In this review, we analyze the achievement from the fruit breeding programs operated by central and local autonomous governments since 1945, and propose future directions and strategies.

The number of flower types filed and registered in the Korea Seed & Variety Service has increased each year. Of the 7,731 crops registered to date, flowers account for 53%, with 4,123 cases. This seems to reflect the nature of flowers with their various shapes and colors, as well as rapid change in varieties. The 1980s was seen as the birth of different flower varieties, with a focus on the collection of genetic resources for each flower type, the selection of chrysanthemums and rose varieties, and culturing of trumpet lilies and carnations. The 1990s was an era of globalization and the import of agricultural products, which enabled research on new flower varieties and the mass production of seedlings to develop strategies for export. In 1995, the Seed Industry Act was implemented and the cultivation of varieties actively began with Korea joining the International Union of the Production of New Varieties of Plants (UPOV); research on breeding and producing high quality seedlings for development of flower types such as lilies, carnations, chrysanthemums, roses, hibiscus, gerberas, gladioli, herbaceous flowers, cacti, orchids, and various other novel floral crops were expanded. In particular, support measures to promote private breeding were also devised. In the 2000s, breeding technology was stabilized, which led to the development of many new varieties at national and local levels, even by common citizens. Penetration rates of chrysanthemums, roses, and orchids, whose main focus was breeding, increased from 1% in 2000 to 5.8% in 2008 and 27.3% in the 2010s. Currently, cactus dominates the world market, with domestic varieties accounting for 70% of the world’s trade, while freesias account for 60.4%, showing the high contribution of domestic small area crops. ‘Baekma’ (chrysanthemums), ‘Shiny gold’ (freesia), ‘Deep purple’ (rose), and ‘Woori tower’ (lily) are representative examples of domestic varieties bred in Korea. In the future, the development of varieties tailored to various consumers will be promoted, along with research on the production of virus-free seedlings, genome technology for enhancing breeding efficiency, and adding high value to the flower industry.

Artificial selection of ginseng has been practiced since Hwangsook (with yellow pericarp and a green stalk, and was developed from a landrace parent) and Cheonggyeong (with red pericarp) were selected as breeding lines in 1926. Systematic research into ginseng breeding, however, started in earnest in the 1960s when the Central Research Institute of Monopoly and Technology (CRIMT) was established, and the Korean Ginseng Experiment Station was organized under the CRIMT. Research into variant characteristics, resource collections, and genetic evaluations began around this time. With the establishment of the Korean Ginseng Institute in the 1970s, studies involving pedigree selection, cataloguing of agricultural traits of genetic resources, generation shortening by tissue culture, and heritability assessments were conducted. In the 1980s, regional adaptation tests were carried out on breeding lines, focusing on ginseng-producing districts. In the 1990s, research was performed on seed multiplication for variety diffusion, effective components and processing quality, and cross breeding. Foreign ginsengs were introduced for interspecies hybridization, and studies were conducted using genetic engineering techniques. Since the 2000s, applications have been made to patent different ginseng cultivars. Currently, 32 cultivars are registered at the Korea Seed & Variety Service. Future goals for ginseng breeding include developing climate change- and disaster-resistant, consumer-oriented, high-performance cultivars. Therefore, it is necessary to develop technologies for distributing new cultivars by collecting and evaluating genetic resources, and cross breeding and performing mass propagation using these resources.

Forest tree improvement is relatively a young science and its purpose is to provide guidance for the conservation, management and sustainable utilization of genetic resources of natural and managed forests. In South Korea, forest tree improvement programs started in 1956. The programs had two main aims: to guarantee the genetic origin of the forest reproductive materials used in afforestation and reforestation, and to develop genetically improved individuals and varieties of some commercially important trees. Since the launch of the forest tree improvement programs, biomass production has been the major improvement target, together with overall adaptability to different sites. Further improvement targets have recently been added, including wood quality traits, and more specific targets linked to adaptation to abiotic and biotic factors in response to new socioeconomic needs and global changes. Additionally, since the early 1970s, forest genetic resource conservation and forest fruit and nut tree breeding have progressed in South Korea. Molecular breeding techniques based on omics information are being developed to enhance the efficacy of selection and to accelerate forest tree breeding cycles. Genetic engineering, including gene editing, has also been applied, but is currently limited to research purposes. Forest tree improvement will be an integral part of the bioeconomy in securing the production of good quality raw materials in large quantities, and will play a significant role in sequestering carbon dioxide and decelerating climate change in the long term.

Studies on forest tree breeding (FTB) in South Korea started in the 1950s and have achieved remarkable outcomes through various techniques and methods such as selective breeding, cross breeding, introduction breeding, and biotechnology. Despite these outstanding achievements, no attempt has been made to objectively and quantitatively evaluate the results of domestic FTB research. Here, we quantitatively analyzed past research trends using keywords of published journal papers and compared the current domestic research level of FTB with the international level. Using various keywords in this field, we searched for research articles published in the Journal of Korean Society of Forest Science, the Korean Journal of Breeding Science, and the journals listed on the Science Citation Index from 1962 to present. The analysis of these studies showed that the research on FTB has grown quantitatively in Korea, and has been conducted on various subjects. Research topics from Korea, in terms of purpose and species, are not significantly different from those of foreign countries. The genus Pinus has been the major subject of FTB studies both domestically and internationally. However, in foreign FTB research, the trees used for research have diversified each year, while they were not diverse in Korea. The FTB research capacity of Korean national institutions, such as the National Institute of Forest Science, continues to dramatically increase, while the research capacity of universities is relatively low. Based on the results of this analysis, it is necessary to establish a concrete and effective policy for future research and development of FTB.