Background : Boxthorn has been cultivated by conventional fertilization and irrigation methods that can be characterized by applying a great deal of fertilizers and a small amount of water compared to the other crops. With increasing rain shelter greenhouses, there were significant needs for developing new fertigation and irrigation methods. In this study, several prescribed fertigation methods for balanced fertilizer application and a few irrigation start methods based on soil moisture tension has been tested to confirm the fruit quality and productivity for Boxthorn growers. Methods and Results : In the experiment, ‘Cheong-un’ cultivar was grown in the rain shelter greenhouses for the tests. Plots were set by randomized block design. According to the growth investigation on the ‘Cheong-un’ cultivar which is supplied with four different formulated fertigation, the formulation N 15 me/ℓ increased the size and weight of fruit leading to 17% increased yield than the others. Additionally, on the amount of annual supply of fertigation with the concentration of N 15 me/ℓ, the treatment applied with 10kg/10a during the cultivation period facilitated overall growth of ‘Cheong-un’ cultivar and increased the yield as well. In the irrigation experiment ‘Cheong-un’ cultivar was grown in the four differently planned treatments that start irrigation at –20, -40, -50 and -100kPa soil moisture tensions. According to the investigation, the irrigation treatment starting at -50kPa enhanced the number of fruit bearing and productivity of Boxthorn consistently during two years. Conclusion : Therefore, the newly developed fertigation and irrigation methods could enhance the annual income of Boxthorn growers by increasing growth and yield.

Background : Fruit picking is the most labor consuming procedure for Boxthorn (Lycium chinense Mill.) growers. Recently fruit harvesters were invented and improved in the efficiency to fulfill the expectation of farmers through field demonstration tests. Additionally, T-type hedge cultivation method harmonized well with fruit picking machine, but it also needed to be improved in its’ pruning methods for the efficiency of fruit collecting procedure. Methods and Results : In this experiment, ‘Cheong-un’ cultivar and local variety were grown in the rain shelter greenhouses for the tests. Plots were set by randomized block design. There were two types of previously developed harvesters. One vibrates it’s harvest rod right and left (A type) and the other shakes it’s rod back and forth (B type). Among two harvesters A type was superior to B type in efficiency and convenience in use and it was able to harvest eleven times more fruits than manual picking in simple comparison test. In field comparison test, A type harvester performed 4.6 to 5 times more fruits than manual fruit picking. T-type hedge cultivation method is the proper way of enhancing efficiency of harvester. In the test, wiry perpendicular branches formed by once pruning method hindered moving forward of fruit collector. However installing collecting net with velcro along the edge under the field increased the efficiency and handiness of fruit harvester and well harmonized with T-type hedge cultivation. Conclusion : From the above results, the newly developed fruit harvester could increase the annual income of Boxthorn growers by reducing fruit picking labor and time.

Background : When ginseng seeds were gathered, the seeds were unripe. To grow immature embryo definitely, special treatment called dehiscence must be performed. Even though dehiscence is completed, most ginseng seeds are on enforced dormancy. The breaking seed dormancy is generally achieved using cold treatment. Also it is reported that gibberellin treatment can replace the treatment. It is very time consuming process in order to develop new ginseng cultivar because ginseng flowers after 3 years of growth. To shorten the ginseng breeding period, it is necessary to establish fast generation progress. Therefore, this study examined the possibility of breaking seed dormancy of ginseng using GA3 treatment and alternating temperature. Methods and Results : Seeds were obtained from local variety fruit which is not inbred. Gibberellin of 100 ppm was treated at seeds for 24 hours. Fixed cold condition was treated on both –2℃ and 2℃. Alternating cold condition was treated on 2℃ and then –2℃, finally 2℃. Fixed and alternating temperature was continued for 15, 30, 45, 60, 90 days that 15 days of alternating temperature is first 2℃ for 5days and then -2℃ for 5days, finally 2℃ for 5days. The other treatment periods such as 30, 45, 60, 90 days mean 10, 15, 20, 30 days respectively. Each of 48 seeds were sowed on tray in greenhouse at 3 replication. Experimental plot was completely randomized. Conclusion : Seeds untreated with GA3 were germinated little and there is no difference between 2℃ and –2℃. Alternating temperature until 60days made no difference with fixed temperature but germination rate increased up to 70.8% when seeds were treated for 90days. Germination of seeds treated with GA3 is much higher than untreated seeds especially combined with alternating temperature.

Background : Management of air temperature are known to primarily affecting on physiological properties and yield in plant. Methods and Results : The effect of air temperature on characteristics of photosynthesis and chlorophyll fluorescence in Schisandra chinensis Baillon were investigated under controlled temperature using growth chamber. Net photosyntheis rate, transpiration was measured at 1,000 μmol m-2 s-1 of photon flux density and chlorophyll fluorescence was analyzed by OJIP method. Net photosyntheis rate and transpiration rate was higher in treatment of 25℃. As results of chlorophyll fluorescence by OJIP analysis, maximum quantum yield (Fv/Fm) of photosystem II (PSII) and PIabs was higher in treatment of 25℃ which reflects the relative reduction state of PSII. But in treatment of 35℃ the relative activities per reaction center such as ABS/RC, DIo/RC were higher than in treatment of 25℃ which implied that the relative reduction of electron transport at PSI and increasement of photo inhibition at reaction center. Conclusion : This result implies that 25℃ of air temperature may be a adequate temperature to improving the efficiency of photosynthesis through controlling a photosystem in Schisandra chinensis Baillon.

Background : Most ginseng seedlings are cultivated in conventional shading facility. However, due to recent climate changes and soil-related bacterial issues, the production of healthy ginseng seedling with its rhizome weigh more than 0.8g has greatly dwindled. Hence, growing seedling system that raises ginseng on nursery soil in greenhouse is being more highlighted. Nevertheless, there are no sufficient researches conducted to study the growth stability after transplantation of ginseng seedling grown at nursery (GSGN). Methods and Results : After categorizing GSGN produced in 2014 according to individual weight (0.5-0.6g, 0.6-0.7g, 0.7-0.8g, 0.8-0.9g), those GSGN with 0.8-0.9g conventional ginseng seedling (CGS) have been transplanted on preparation field in 17, March of the following year. It has turned out that there were no significant differences about seedling emergence rate and weights between GSGN and CGS both same seedling weight of 0.8-0.9g in 25, June after 100 days transplantation. The 2-year-old ginseng growth of transplanted GSGN according to weight has shown strongly positive correlation between the weight of ginseng seedling and their growth. Especially the leaf area and weight have shown significant correlations represented as Y=212.15-567.32X+499.5X2(R2=0.9988) and Y=4.9-12.9X+11.17X2(R2=0.9788), respectively. Meanwhile, there was no significant correlation noticed treatment plot in relationship between seedling emergence rate and chlorophyll content. Conclusion : With the same root weight of GSGN and CGS, it can be judged that the growth of the 2-year-old GSGN is stable.

Background : Ginseng is a semi-shade plant which prefers cool temperature and mild lighting, and artificially installed shading facility is required from preventing photo-oxidation occurrence when ginseng is exposed to direct sunlight. High temperature damages are commonly noticed due to recent global warming although more farmers are using aluminum foil and blue light-proof screen instead of 4-layered polyethylene shade net (blue 3 + black 1) to prevent the rise in temperature and influx of rainwater, there are insufficient research conducted. Methods and Results : In mid-March, 2015, we have installed steel A type shading facility after transplanting 2-year-old domestic variety ginseng in 7 lines, 10 rows per 3.3㎡. We have prevented the excessive influx of direct light by fixing 4-layered shade net, aluminum foil and blue light-proof screen as shading materials on facilities and adding 2-layered black polyethylene shade net. During July and August with high temperature, light transmission rates have shown varying according to shading materials used: blue light-proof screen (8.4%) > aluminum foil (5.9%) > 4-layered shade net (3.3%). In case of the highest temperature reached, the order followed blue light-proof screen (42.3℃) > 4-layered shade net (40.8℃) > aluminum foil (38.3℃), and in case of average temperature it followed blue light-proof screen (48.7%) > 4-layered shade net (37.6%) > aluminum foil (33.2%). Although there were no difference about leaf area among the shading materials, ginseng leaf grown in aluminum foil has lower chlorophyll content than the other two treatment plot because of photooxidation by light damage. The 3-yr-old ginseng root weight harvested in end of October increased as follows light-proof screen (14.4g) > 4-layered shade net (11.9g) > aluminum foil (9.8g). Conclusion : Aluminum foil showed greater influx of light but lower temperature than 4-layered shade net due to its materialistic character. However the front side of foil can reflect light and cause photo-oxidation of rear-planted ginseng leaves, so it is a need for improvement. In case of blue light-proof screen, although it had higher inside temperature, the root weight of ginseng was the heaviest because of less influx of light and destruction of chlorophyll.

Background : The ginseng cool-season and semi-shade plant undergoes photosynthesis smoothly at low temperature in the morning but its efficiency falls at high temperature in the afternoon. Therefore, if it is possible to control light transmission rates (LTR) every day, it will be able to draw an ideal result in the ginseng growth by attracting a lot of lights before 11am and attracting few lights after 11am which is the affect point of the photosynthetic efficiency. Methods and Results : While installing the sun shading facility that could control the light environment based on 11am and surveying the ginseng's growth and photosynthetic characteristics. The photosynthetic efficiency increased 2.81 times compared to conventional practices without the change of the chlorophyll content although LTR was high because of the low temperature in the morning. The aboveground part growth of the ginseng which adapted to the light environment increased to influence the root weight, when the ginseng was 4 years old, the fresh root weight was averagely 33.3g per plant which increased by 81% than 18.4g of conventional practices. Conclusion : If the light environment management according with the photosynthetic nature of the ginseng is conducted based on 11am, it will be possible to produce a large capacity and excellent-quality ginseng.

Background : This study was conducted to determine the optimal conditions of growth medium, temperature, and light quality for efficient propagation of Pyrrosia petiolosa spores. Methods and Results : P. petiolosa spores were collected from Andong-si area in February 2015, and the spores were subjected to a careful selection process. The selected spores were stored at the Korea National Wild Plant Seed Bank (4℃, RH 40%) and used as our experimental materials (GR0000182302). The spore germination rate and prothalium development were high in Knop media (24.5%), which had low mineral content. The germination rate increased with the increase in temperature and reached its maximum, 24.5%, at 25°C. The germination rate was also measured under different light conditions, and the highest rate of 28.7% was observed under LED blue light compared to fluorescent lights (24.5%). The germinated spores developed into heart-shaped prothallia under LED blue light; however, 3 weeks after sowing, prothallium development decreased compared to fluorescent lights. Conclusion : In conclusion, the optimal P. petiolosa In vitro propagation method include spore germination on Knop medium at 25°C under LED blue light, and the change in light source to fluorescent light 3 weeks after sowing for prothallium formation and proliferation.

Background : The research is designed to investigate the optimal cultivation technology and the growth of above-ground and below-ground sections as well as the photosynthetic characteristics for new ginseng variety “K-1” by differentiating the planting density under the conditions of transplanting and direct seedling. Methods and Results : The K-1 variety and hybrid variety (Jakyungjong) were selected for the research and the ginseng varieties were transplanted and directly sown in Yeoncheon area in 2013. The transplanting was made in the form of 5 lines × 9 rows (45 plants), 6 lines x 9 rows (54 plants), 7 lines × 9 rows (63 plants) and 8 lines × 9 rows (72 plants) in each lot (1.65㎡) while the direct seedling for testing was conducted three times in randomly blocked design in the form of 11 lines × 14 rows (154 plants), 12 lines × 14 rows (168 plants), 13 lines × 14 rows (182 plants). Various measures were collected from the 4-year transplanted ginseng and 3-year direct seedling ginseng in 2015 to find out the growth features and photosynthesis of above-ground section (rate of germination, leaf length, leaf width, stem length and leaf area index (LAI)) and the below-ground section (length, diameter, weight and class of roots). Conclusion : After the planting of the ginseng, the germination rate of K-1 for the transplanting was 85.1 ~ 92.0% across different plantation densities while that for the direct seedling was 67.7% ~ 77.9% across plantation densities, thus showing no significant difference between the two planting methods. LAI was higher for the higher planation density for both transplanting and direct seedling. As for the photosynthesis speed, the form of 6 lines × 9 rows showed the higher speed in transplanting while the form of 12 lines x 14 rows showed the higher speed in direct seedling. The photosynthesis of K-1 was higher than that of Jakyungjong. In the 4-year ginseng cultivated under the transplanting, diameter of roots, number of branch roots and weight of raw ginseng were the highest in the plantation density of 5 lines × 9 rows. The distribution of root weight was high with 23.3% and 20.0% for the 51~70g group and the 71g or above group, respectively, for the 4 year transplanted plants in the form of 5 lines × 9 rows. The growth for above-ground and below-ground sections for K-1 was better than that for Jakyungjong. As a result, it was found that the proper plantation density for the 4-year root in the transplanted K-1 was 5 lines × 9 rows considering the growth of the above-ground section, quantity and distribution of root weight.

Background : Acreage of rain-shelter plastic greenhouse to prevent anthrax is being gradually increased according to growing importance of safe Boxthorn production. But When Boxthorn is grown in the hot season in rain-shelter plastic greenhouse, quantity of Boxthorn decreases. therefore the research was carried out to investigate Fertilization mode. Methods and Results : Chungwoon was very strong self-incompatibility. Chengyangjaerae, Chengyang18 and CBP11542-206 was self-compatibility. Artificial fertilization rate was slightly higher in roof and side vents than in side vents of rain-shelter plastic greenhouse in hot season. Pollen sterility due to high temperature is not critical because artificial fertilization rate was high in side vents of rain-shelter plastic greenhouse in hot season. Airborne fertilization rate was significantly lower in all varieties. Open fertilization rate was higher in roof and side vents than in side vents of rain-shelter plastic greenhouse Conclusion : Roof and side vents was good in compared to side vents in rain-shelter plastic greenhouse of Boxthorn because of high Airborne and open fertilization rate. Self-compatibility varieties were better than self-incompatibility varieties in rain- shelter plastic greenhouse because of high open fertilization rate.

Background : The purpose of this study was to evaluate methods to high quality medicinal vegetables, thereby increasing farm income. This study investigated the effects of different organic fertilizer and applicated cultivation on stable foliage production in Peucedanum japonicum Thunberg. Methods and Results : method of application with organic fertilizer were conducted under nine condition compose to control(non application), N-P2O5-K2O (20-12-10)㎏․10 a−1, Hyphal incubation compost(HIC) applied at 851㎏․10 a−1, Hangawi organic compost(HOC) applied at 547㎏․10 a−1, Fermented mixed oil cake compost(FMOC) applied at 380㎏․10 a−1, 60% and 40% of basal fertilizer in March 12, top dressing were four application in April 12, May 12, June 13 and July 12, respectively. Sowing dates were March 23, 2015. Plants were spaced 15 ㎝ apart in rows 15 ㎝ apart with open cultivation. Conclusions : chemical fertilizers < hyphal incubation compost < hangawi organic compost < fermented mixed oil cake compost application, top dressing than 60% in order of 40% additional fertilizer, aerial part as a result were so many such amount of growth as number of leaf per plant, etc., Green leaf yields is untreated control plot (875 kg․10 a−1) compared to 12% from using chemical fertilizers, HIC application 18% higher, HOC application 20% higher, and FMOC application increased to 28% of the most.

Background : The purpose of this study was to evaluate methods to high quality medicinal vegetables, thereby increasing farm income. This study investigated the effects of different covering material and weed eliminating on stable foliage production in Peucedanum japonicum Thunberg. Methods and Results : method of weed elimination with covering material were conducted under four condition compose to Non covering(4～6 times by manual weed control), Barley straw cutting covered with 700㎏․10 a−1, Rice straw cutting covered with 500㎏․10 a−1, Rice husks covered with 1,000㎏․10 a−1. Fermented mixed oil cake compost applied at 380㎏․10 a−1, 60% of basal fertilizer in March 14, 40% of top dressing were four times application in April 14 ～July 15. Sowing dates were March 25, 2015. Plants were spaced 15 ㎝ apart in rows 15 ㎝ apart with open cultivation. Conclusions : Rice husks covering < Barley straw covering < Barley straw covering cultivation this order, aerial part as a result were plenty amount of growth. Weed the rates was 12 to 29% lower incidence. Green leaf yields is uncovering control plot (915 kg․10 a−1) compared to 2% from covering rice husks, barley straw and rice straw covering increased to 18%, 20%, respectively.

Background : Angelica gigas N., one of the herbs has been used most frequently with Glycyrrhiza uralensis. It is usually cultivated in semi-alpine of more than 400m in North Central province of South Korea. However its production is becoming more unstable due to the climate change especially abnormally high temperature. In particular, the environmental change may cause not only a change in production but also a change in active ingredient of Angelica gigas N. This study was performed to investigate these problems. Methods and Results : This study was carried out in temperature gradient tunnel(TGT) in Pyeongchang, Gangwon province. Temperature conditions were maintained the ambient+0~2℃ (T1), ambient+2~4℃(T2), ambient+4~5℃(T3) throughout the year. We planted and grown one year old seedlings of Angelica gigas N. from mid-April to early November. As a result, there was no difference in early growth of Angelica gigas N. among the temperature range but there was a difference between each treatment region from the survey in June. Average length of soot in T1, T2, T3 was the largest(36cm), medium(27cm), smallest(19cm) respectively. This trend was similar to a survey in September and November. Each of death rate was 0%(T1), 19%(T2), 71%(T3). There was no bolting according to the temperature. The yield of a plant of Angelica gigas N. was 476g(T1), 76g(T2), 26g(T3), respectively. Production of Angelica gigas N. is foreseen 84.7% and 94.5% reduction if the temperature rises to 3±1℃ and 4±1℃ more than it is at present based on temperature in Pyeongchang 2015. Total amount of Decursin was reduced at higher temperatures. Conclusion : The results of this study show that quality and production of Angelica gigas N. is expected to decline significantly if the temperature rise than the current. Therefore development of various techniques is required to response to climate change.

Background : Usually, planting and harvest time is around the middle of April. A labor shortage deu to her planting time as harvest time and some farmers were late planting culture. After planting until take rooting It will take more than one month when late planting growth is bad. Seedling cultivation, just taking rooting is agricultural growth promotion. Methods and Results : So did design the optimum nursery days and number of plants. Nursery days were 30 days and 45 days and number of plants 1, 3, 5 plants. Plant length was longer in less number of plants while Root length was longer in more number of plants of Temporary planting seedling, Leaf number was a big increase but number of plants was not a big shift. In post-havest survey, plant length was longer in 3 number of stem and root length was longer in one number of stem. 45 days and 3 number of stem seedling was the most good in number, weight and length of tuberous root. Yield of 45 days and 3 number of stem seedling was higher 7% than 1 number of stem seedling and higher 5% than 5 number of stem seedling. 45 days and 3 number of stem seedling was 1,789 thousand per 10a in income was the most. Conclusion : Result of this study, for rasing healthy seeding nursery days 45 days and number of plants 3 plant

Background : Plants of Taraxacum spp. are widely used in medicine, but some of them have some problems related to propagation, such as strong dormancy and inactive germination. This study investigated the effects of temperature, gibberellic acid (GA3), and potassium nitrate (KNO3) on seed germination in Taraxacum ohwianum. Methods and Results : The seeds (NIBRGR0000135524) were exalbuminous, and their length and width were 4.25 ± 0.118 mm and 0.89 ± 0.062 mm, respectively. Among various temperatures (15, 20, 25, and 30℃), the optimum temperature for germination was found to be 20℃ (31.3%). High temperature (30℃) induced off-type in seedlings (thickened and crumpled cotyledons, and restricted root system). GA3 treatments increased germination percentage and speed, but germination percentage was higher with KNO3 treatment. Under KNO3 treatments (50 to 200 mg·L-1), germination percentage exceeded 80% after 12 days, with 50 mg·L-1 KNO3 being notably effective (91.2%, after 15 days). Conclusion : Seeds of T. ohwianum showed germination ability at low temperature. The best method for germination was pre-soaking in 50 mg·L-1 KNO3 (4℃, dark, 24 h) and incubating at 20℃ for 15 days.

Background : The Ginseng has been one of the crops that represents Korea, and the main export items in the 1960s, Now it occupies the first exports of agricultural products. The Eco-friendly cultivation of Ginseng was difficult for various reasons. But the cultivation in Green House can be suppressed disease occurrence, when utilizing an environmentally friendly materials has the advantage that can dramatically increase the income by possible organic production. For other crops, it made up a lot of studies on water management, But the studies on water management of ginseng is somewhat lacking. Therefore, this study was conducted to establish appropriate soil- moisture-management-systems within the house of ginseng cultivation. Methods and Results : The type of house is a double steel structure. The first layer was PE film, the second layer was the blue shading net and 75% black shading net. The Soil texture was silt loam and the Soil Series was YEONGOK Series. Install the house on the adjacent paddy soil and upland soil, and planting on April 30, 2011 which was cultivated by the straw mulching. The irrigation start point was the 40, 30, 20kpa, and the end point was treated with 15, 10kpa. Soil moisture measurements were determined by tension meter(Jet Fill) depth 20cm in soil. Growth and Yield Survey was conducted in accordance with the Rural Development Administration (RDA) standard research. Statistical analysis of the results were analyzed using the Microsoft's Excel 2003. Conclusion : In a survey due to differences in soil traits and Irrigation point, from 2 years to 4years of root weight and yield of Ginseng were heavier in the upland, especially 30kpa irrigation point treatment was heaviest than the other treatments. From 5year to 6 Years of ginseng has showed heavier in paddy soil, the most treatment was 30kpa- 15kpa irrigation point. This trend was the same in upland soil. Soil moisture management in the case of silt loam, the humid-state-control was more advantageous than dry-state control in upland and paddy soil.

Background : Liriope platyphylla Wang et. Tang is a species of Liliaceae and its tuber is used as medicinal herbs. This medicinal plant is mainly cultivated in Cheongyang and Buyeo of Chungcheongnam-Do and Miryang of Gyeongsangnam-Do. It is necessary to establish a cultivation techniques for stable production to solve the problems that are found on farms. These farm surveys were carried out to obtain the basic data on soil environment and cultivation conditions at main producing areas of Chungnam-Do in Liriope platyphylla Wang et. Tang. Methods and Results : The surveys were investigated from 37 farmers in Cheongyang and 32 farmers in Buyeo who cultivate Liriope platyphylla Wang et. Tang. There were slightly differences in the local characteristics between Cheongyang and Buyeo. The rate of successive cropping for more than 3 years were 19% at Cheongyang and 41% in Buyeo. The reason may be due to the a small-owned field. It has grown 28% at Cheongyang and 59% at Buyeo in paddy fields. The injury by successive cropping that farmers argued were the increasing pest/disease occurrence, degradation of tuber quality and yield reduction. Crops planted after the harvest of L. platyphylla were mostly Pepper or soybean in upland. It is necessary to reduce the injury of successive cropping. The results of 112 soil analysis data were classified by 8 soil series. There are many acidic soil, lack of organic matter, excess phosphate. However, it did not analyzed the influences on the growth and yield of the crop as affected by different soil conditions. Conclusion : From the above results, it is necessary to develop cultivation techniques on the reduction of injury of successive cropping, such as cropping system, seedling transplanting cultivation, cultivation methods for good agricultural practices(GAP) and soil improvement.

Background : Liriope platyphylla Wang et. Tang is a perennial plant and its tuberous root is used as herbal medicine. Liriope platyphylla is grown throughout a year from April to April of next year. Recently, the production was lowered because of severe drought/rainfall and injury by successive cropping. The ridge height affected the growth of shoots and roots as affected by drought or rainfall. It is necessary to establish the cultivation techniques for stable quantity per unit area and good tuber’s quality. This experiment was carried out to select a cultivar of good tuber quality and to determine the ridge height for high-yielding. Methods and Results : It were investigated the characteristics of roots and tubers depending on different ridge heights in four varieties of Liriope platyphylla Wang et. Tang. There was not significantly different in shoot growth by different ridge heights. The tubers distribution in less than 10cm soil depth at the surface was decreased about 6.6% in the 15cm ridge height compared to 5cm. So, the mean distributed position of tubers was deepened at higher ridge. The cultivars that tubers were mainly distributed in the 10cm depth from surface was Seoungsu and Cheongyang natives’s lines. The no. of tubers per a plant and the ratio of marketable tubers were increased about 13.2% and 20.1% in the 15cm ridge height compared to 5cm. Considering the tuber sizes and ratio of marketable tubers, Cheongshim and Maekmundong 1 has good quality than Seoungsu or Cheongyang natives’s lines. The tuber yield increased about 19.5% in the 15cm ridge height compared to the 5cm. So, high ridge was advantaged to increase the yield. Conclusion : From the above results, the quality and quantity of tubers of Liriope platyphylla Wang et. Tang was good in the higher ridge. We recommended Cheongshim cultivar because of the large tuber sizes and high ratio of marketable tubers.