Science and Industry of Persimmon in the Republic of Korea

Transcription

1 Science and Industry of Persimmon in the Republic of Korea Won-Doo Song Sweet Persimmon Research Institute Gyeongnam ARES, Gimhae Korea Tae-Choon Kim College of Life Science and Natural Resources Wonkwang University Iksan Korea Yeun-Dae Choo Sang-Ju Persimmon Experiment Station Gyeongbuk ATA, Sangju Korea Seong-Mo Kang Department of Horticulture Gyeongsang National University Jinju Korea Keywords: Diospyros kaki, breeding, cultural practice, fruit quality, postharvest physiology Abstract Production of fruits in general and persimmon in particular are introduced, along with the recent changes in socioeconomic circumstances in Korea. Fruit growing area has increased almost two-fold in the past 20 years, persimmon being the most widely grown fruit crop at present. Most recently, however, fruit growing area is either not obviously changing or even decreasing for some fruit crops. Health-conscious consumers demand, and are willing to pay more, for safe and high quality fruits; growers understand their survival would depend on how successfully they can answer to this demand. On the other hand, aging populations in farming communities have been uneasy by the global free-trade policy and the reductions in their income in the past several years. There is a nation-wide consensus to help improve the infrastructure of fruit industry. For example, fruit handling centers, equipped with up-to-date facilities and equipment, are being established to handle the fruits produced in large areas. There are two research institutions in Korea that specialize in persimmon. Important areas of research include the breeding of new cultivars, stable production of high quality fruits, environment-friendly pest control, efficient storage of fresh and processed fruits, and fruit marketing as well. Some of recent findings are highlighted. FRUIT INDUSTRY IN KOREA Current Status of Fruit Production Table 1 shows the total arable land and the changes in its use for horticultural crop production from 1980 to Out of about 2 million hectares of arable land, the proportion being utilized for growing horticultural crops has been stable at about 20% (MAF, 2004). However, the changes in growing area for fruit crops are noteworthy. There has been almost a 2-fold increase in fruit growing area in the past two decades. Such an increase in the proportion of fruit crops indicates their growing importance in Korean agriculture. Fruit crops were grown in 40% of the land being utilized for horticultural crops in Changes in annual productions of major fruit crops show some interesting development in Korean fruit industry (Table 2). Since 1990, production for apples has declined dramatically (MAF, 2004), while those for pears, grapes, persimmon, and citrus have increased 2- to 3-fold over The statistics for the production in 2003 show a decline for pears, grapes, and especially persimmon, due in part to a severe typhoon. However, recent decline in growing area for these crops (Table 1) is another reason for the decline in production. Proc. III rd IS on Persimmon Eds. Y.M. Park & S.M. Kang Acta Hort. 685, ISHS

2 Persimmon Production and Export The growing area and production of persimmon rapidly increased from 1990 (Table 3). Sweet persimmon peaked in 2000, followed by a decline to about 20,000 hectares in 2003 (MAF, 2004). The dramatic decline in sweet persimmon production in 2003 reflected the damage by a typhoon. While the acreage for astringent types constitutes less than 30% of the industry, it has been increasing gradually. In 2000, sweet persimmon production was about 80% of the total. Basically all of sweet persimmon fruits are consumed fresh at the table. Fuyu accounts for 81.6% (MAF, 2004). About 4,000 tons of fresh fruits were exported in 2001 and 2002, mostly to southeast Asian countries including Malaysia, Hong Kong, Singapore, and Thailand (Fig. 1). In 2003, 44 tons of sweet persimmons were exported for the first time to the United States. Recent Changes in Socioeconomic Environment Recent changes in socioeconomic environment of the country have affected Korean fruit industry. Some are important for the development of persimmon industry not only for now but for the future. A survey done at Gyeongbuk Agricultural Technology Administration indicates that young people do not like persimmon as much as the people in their fifties and older. The young are not accustomed to handling the knife to peel the fruits. Also, compared with other fruits, fresh persimmon is available for a rather limited period of time, so that they are not so much exposed to persimmon as they are to apples, for example. How to comply with the taste of young people is of some importance for the future success of persimmon industry. Persimmon fruits are not easily handled at large cafeterias of schools and army; the development of minimal processing technology warrants serious attention. It is obvious that the decline in consumption will translate into the decline in growing areas. The proportion of aging population has been continuously increasing in farming communities, and this causes many problems in coping with the changing agricultural and social environment and in accommodating new technologies. On the other hand, the demand for safe and high quality fruits by health-conscious consumers has never been this high in the history of Korean fruit growing. It is not uncommon to observe as much as a 10-fold difference in price between special- and low-grade fruits. Understanding this kind of changes in socioeconomic conditions is important in formulating future directions for persimmon industry. RESEARCH ACTIVITIES ON PERSIMMON Institutions for Persimmon Research Korea has two research institutions specifically for persimmon, both of which are administered by provincial governments. One is Sangju Persimmon Experiment Station, established in 1995 with a 10-hectare farm for the research on astringent types. The other one, Sweet Persimmon Research Institute at Jinyeong, was established 10 years ago with a 6-hectare farm to deal primarily with sweet persimmon. Researchers at the two institutes have their own programs as well as some other projects executed cooperatively with those at the universities in the nation. Breeding Efforts for the development of new cultivars have been made at Sangju Experiment Station and Sweet Persimmon Research Institute. At Sangju Experiment Station, 297 accessions are being evaluated. Important goals of breeding programs for astringent types are to select or develop (a) early-maturing, seedless, and juicy fruits for red-ripe soft persimmon, (b) more productive, high sugar fruits suitable for vinegar production, and (c) high quality clones of Sangjudoongsi persimmon. Developing a mass propagation system has been another important subject. Development of new cultivars has also been a top priority at Sweet Persimmon Research Institute. More than 22

3 100 accessions have been collected, and a few promising lines from the collections and the crosses are being evaluated. Cultural Practices Production of nursery trees with better root system has been made possible by using non-woven fabric sheet (Kim et al., 2002). A Y-trellis training system was compared with the traditional modified-leader system to increase early production and to save labor (Choi et al., 2005). To meet the demand for high quality fruits, the adjustment of crop-load at the earliest time possible has been emphasized (Park et al., 2000). Cutting back the secondary shoots on vigorous trees, done in late July, increased fruit growth in the year of treatment and the proportion of bearing shoots the following year (Park et al., 2003). Park (2002) reported that different level of irrigation combined with nitrogen supply at the final stage of fruit growth could affect growth and soluble solids of the fruit. With the changing climate in recent years, some disorders like calyx separation and green blotch have frequently occurred. Recent results indicated that the occurrence of calyx separation depended on the abrupt changes in soil water, number of seeds per fruit, and crop-load (Choi et al., 2002). In addition, the determination of the optimum size and angle of mother branches, the development of training techniques for low-stature trees, and the evaluation of various tree supplements to improve fruit quality, have all been important areas of research. On the other hand, severe leaf loss by typhoons in early autumn has been a problem in persimmon growing. Choi et al. (2002) concluded that thinning some proportion of the fruits was a key practice to ensure the quality of the remaining fruits and the accumulation of reserves. Control of Diseases and Pests One of the important areas of research has been the control of diseases and pests in an efficient manner. Although mycological characteristics of circular leaf spot disease in Korea have been documented (Kwon, 1997), the disease is still prevalent, quite severely in some years depending on climatic conditions. Plant pathologists at Gyeongnam ARES periodically monitor ascospore scattering of circular leaf spot and then provide the growers with that information for appropriate measures. Other diseases of importance include anthracnose and powdery mildew. Gall-forming thrips, reported in Korea for the first time in 2000, are being widespread (Lee et al., 2002; Shin et al., 2004). Sting bugs and persimmon fruit moth have also been serious pests depending on climatic conditions of the year. Postharvest Management of Fruits Keeping quality of fruits has always been an important area of research in persimmon. There are some significant losses from various disorders during storage and marketing. Recent results indicate that browning disorder is due to low oxygen combined with high carbon dioxide, while skin blackening is due to high oxygen and high humidity which would increase phenol oxidation in the skin (Ahn et al., 2001). Fruit softening is caused by ethylene when cold-stored fruits are marketed at relatively high temperature (Ahn et al., 2004). Traditionally, five Fuyu fruits are packed in a polyethylene film bag for low temperature storage. To maintain optimal oxygen and carbon dioxide concentrations within the bag, Lee (2004) reported the equations to determine the optimal thickness of polyethylene film dependent on fruit size. Ahn and Lee (2004) have done some work on respiration of sweet persimmon depending on temperature and air composition. Low oxygen combined with high carbon dioxide reduces fruit respiration, and this effect is greater as temperature increases. Efforts to understand postharvest physiology of persimmon fruits have led to the development of a packing technology for individual fruits, instead of traditional five, based on fruit respiration, permeability of various packing materials, and the mechanism involved in the occurrence of various physiological disorders of the fruits. Department stores prize the fruits that are packed individually. 23

4 Processing of Dried Persimmons Techniques in various forms have been developed to maintain the quality and marketability of dried and ripe-frozen astringent-type persimmons. Drying the peeled fruits at right temperature and humidity to optimum tenderness is nothing but an artistic venture. Dried persimmons are one of the most popular gift items in the country. They are dried by two methods depending on localities. A traditional method is to hang the peeled fruits on a string. Fruits are about 10-cm apart to keep mould from growing; when two fruits are too close each other or many are in clusters, humidity increases around them. The other way to make dried persimmons in some areas is to tie two fruits together at their stalks and then put them on a long bamboo stick. This is more time-consuming for preparation than the string method, but fruits dry faster. CHALLENGES WITH WHICH PERSIMMON INDUSTRY IS FACED Summarized are five major challenges that Korean persimmon industry is now faced. First, reducing the size of the trees is an essential ingredient to reduce production cost and to mitigate vicious labor for aging growers. It is not very difficult to find persimmon trees as high as five meters, especially in astringent types. Growing the trees of reduced height is directly related to the second challenge. That is, the production of high quality fruits. Persimmon should now compete not only with a variety of other fruits but with fruit vegetables in the market. Suitable adjustment of crop-load at the earliest time possible, floor and soil management for water and nutrient management, maintenance of tree architecture for better reception of light, and sound and hygienic way to control diseases and pests, all are extremely important areas to meet this demand for high quality fruits. The third challenge is the production of fruits in an environment-friendly way. Production of safe fruits is the only, and the best, way to let the health-conscious consumers believe in persimmon fruits. Consumers are willing to pay more for safe fruits. What is meant by safe, is almost always no chemicals whatsoever. How to cope with this demand is difficult challenge and it will be so more in the future. The fourth challenge has something to do with the size economics of farms and markets. Consumers prefer the fruits sold at large stores to the ones sold at traditional small stores. The statistics for the recent change in consumer preference is quite dramatic: only 8.4% of the fruits were sold at large stores in 1998, but the proportion increased to 42% in 2003 (KREI, 2004). Large stores have the advantage to deal with different kinds of high quality fruits over small stores. Small farms may not be able to meet the demand of large stores that ask for a large quantity of high quality fruits. Increase in farm size is not a small task in a traditional farm community. Therefore, it is important to establish large handling centers equipped with up-to-date facilities and equipment to take joint steps in handling and marketing the fruits produced from large areas. And lastly, the necessity is on the rise to prepare for, or cope with, the changing climate. Global warming is not a theory anymore; it is not uncommon that bud growth and flowering take place at least a week earlier than usual. This could be viewed as positive because this could mean a longer growing season. However, it has not worked that way all the time. Damages by spring and autumn frosts, heavy rains, typhoons, etc. have now become the most important cause for unstable production of persimmon. There is a need to do some important work to cope with this hostile and changing climate. CONCLUSION Reducing the production cost while producing high quality fruits may be hard to achieve; in fact, they may seem mutually exclusive in many instances. However, these are the ultimate tasks that persimmon industry has to overcome. Demand for high quality fruits by health-conscious consumers has been overwhelming; growers understand that their survival depends on how successful they are in answering to this demand. And at the same time, persimmon growing in an environment-compatible way is the one we cannot do without. Socioeconomic conditions with which Korean industry has been faced in 24

5 recent years are presumably the same in most countries, and this is a justification for an active international cooperation among all the parties concerned with persimmon industry. Meeting the challenges is a global business, not a business of any individual country. Literature Cited Ahn, G.H. and Lee, D.S Enzyme kinetics based modeling of respiration rate for Fuyu persimmon (Diospyros kaki) fruit. Korean J. Food Sci. Technol. 36: Ahn, G.H., Song, W.D., Choi, S.J. and Lee, D.S The association of post-storage physiological disorder incidence with respiration and ethylene production in Fuyu persimmon fruits. Korean J. Food Sci. Technol. 36: Ahn, G.H., Song, W.D., Park, D.S., Lee, Y., Lee, D.S. and Choi, S.J Package atmosphere and quality as affected by modified atmosphere conditions of persimmon (Diospyros kaki cv. Fuyu) fruits. Korean J. Food Sci. Technol. 33: Choi, S.T., Kang, S.M., Park, D.S., Song, W.D. and Seo, K.K Thinning effect on fruit characteristics and reserve accumulation of persimmon trees defoliated in early autumn. J. Korean Soc. Hort. Sci. 43: Choi, S.T., Park, D.S., Kim, S.C. and Kang, S.M Factors causing the calyx-end cracking of sweet persimmon fruits. Annu. Res. Rep. of Gyeongnam Agricultural & Extension Services. p Choi, S.T., Park, D.S., Song, W.D. and Kang, S.M Early performance of Uenishiwase persimmon trees on a Y-trellis training system. Korean J. Hort. Sci. Technol. 23. (in press) Kim, S.C., Choi, S.T., Park, D.S. and Kang, S.M Seedling growth and carbohydrate distribution in persimmon (Diospyros kaki L.) as affected by restricting main root growth. Korean J. Hort. Sci. Technol. 20: Korea Rural Economic Institute (KREI) Kwon, J.H Mycological characterization of Mycosphaerella nawae and epidemiology of persimmon spotted leaf casting. PhD Diss., Gyeongsang Natl. Univ., Jinju, Korea. Lee, K.C., Park, C.G., Choo, H.Y., Lee, D.W., Woo, K.S. and Kang, C.H Occurrence of Japanese gall-forming thrips, Ponticulothrips diospyrosi Haga et Okajima (Thysanoptera: Phlaeothripdae) in Korea. Korean J. Appl. Entomol. 41:1-4. Lee, Y.J Optimal dimension of PE film bag according to fruit size in MAP storage of Fuyu persimmon fruit. Korean J. Food Sci. Technol. 36: Ministry of Agriculture and Forestry (MAF) Park, D.S., Choi, S.T., Seo, K.K., Ahn, K.H., Kim, S.C., Song, W.D. and Kang, S.M Shoot growth and fruit characteristics of Fuyu persimmon as affected by the size of bearing mother branches and the time of fruit-load adjustment. J. Korean Soc. Hort. Sci. 41: Park, D.S., Kang, S.M., Choi, S.T., Lim, C.A. and Song, W.D Effect of secondary-shoot prunings on fruit growth and following year s fruit set of Fuyu persimmon. J. Korean Soc. Hort. Sci. 44: Park, S.J Effect of irrigation and N levels on fruit quality and nutrient distribution in Fuyu persimmon tree parts during the final stages of fruit growth. J. Korean Soc. Hort. Sci. 43: Shin, W.W., Lee, H.S., Lee, K.C. and Park, C.G Seasonal occurrence of Japanese gall-forming thrips, Ponticulothrips diospyrosi Haga et Okajima, and its damage pattern. Korean J. Appl. Entomol. 43: Shin, W.W., Lee, K.C. and Park, C.G Spread of Japanese gall-forming thrips, Ponticulothrips diospyrosi, in Korea. Korean J. Appl. Entomol. 42:

6 Tables Table 1. Total arable land of Korea and the changes in its use for horticultural crop production (area in 1,000 ha). Year Total (A) Food Hort crops Fruit crops crops Area (B) A/B (%) Area (C) C/B (%) Other crops ,765 1, ,088 1, ,936 1, Table 2. Changes in production of major fruit species in 1,000 tons. Year Apple Pear Grape Persimmon Citrus Table 3. Production of sweet and astringent persimmon. Year Sweet Astringent Total ha M/T ha M/T ha M/T ,900 66, ,000 13, , , , ,000 31, , , , ,000 27, ,000 Table 4. Cultivation area of sweet persimmon cultivars in ha. Year Fuyu Jiro Nishimurawase Others Total ,972 (81.5) 1 1,400 (10.4) 323 (2.4) 767 (5.7) 13, ,247 (81.6) 2,143 (10.2) 1,106 (5.2) 629 (3.0) 21,124 1 Numbers in parenthesis are percent share of cultivation area. 26

7 Figures Export (ton) Year Fig. 1. Annual export amount of sweet persimmon. 27

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