• Horticultural Science & Technology
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• v.33 no.4
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• pp.459-469
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• 2015

The effects of elevated spring temperatures on the growth and fruit quality of the mandarin hybrid 'Shiranuhi' [(Citrus unshiu ${\times}$ C. sinensis) ${\times}$ C. reticulata] were investigated in plastic greenhouses, to develop a cropping system to improve the quality of the fruit and increase the income of growers on Jeju Island, South Korea. Under conditions of elevated temperature I ($25/15^{\circ}C$, day/night) and elevated temperature II ($28/18^{\circ}C$, day/night) during early spring, budburst was advanced by 11 and 15 d, and full bloom by 22 and 45 d, respectively, compared to those of the plants grown at ambient air temperature in a plastic greenhouse. Elevated temperatures decreased the number of spring shoots but increased mean spring shoot length and leaf area. Growing 'Shiranuhi' trees at elevated temperatures resulted in increases in mean fruit weight and fruit L/D ratio (> 1.0). In addition, fruit color development was significantly advanced in trees grown under elevated temperatures during early spring, which allowed the fruit to be harvested 1-2 months earlier than trees grown under ambient air temperature. Fruit soluble solids content (SSC) and titratable acidity (TA) at harvest were similar between elevated temperature I and ambient air temperature, but were significantly higher than at elevated temperature II. Considering fruit quality, harvest time, and yield, the elevated temperature treatment regime of $25/15^{\circ}C$ (day/night) during early spring could be useful for cultivation of the mandarin hybrid 'Shiranuhi' to increase the income of growers.

• Journal of Bio-Environment Control
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• v.6 no.1
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• pp.27-33
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• 1997

This experiment was carried out to investigate the effects of limited nutrient supply during 21 days before and after pollination stage on the growth, fruit quality and nutrient uptake of muskmelon in rockwool culture. Muskmelon, cv. Earl's Favorite seeds sowed on rockwool cube and transplanted on rockwool slab($90\times15\times7.5cm$) when 2 to 3 true leaf appeared on Sep. 6, 1991. Three kinds of nutrient composition recommended by Shizuoka university, combinated with the composition of Otsuka house A and composition Shizuoka III. One half of calcium nitrate(Ca(NO$_3$)$_2$.4$H_2O$) for limiting nitrogen supply during 21 days was treated and then fertigated the nutrient composition recommended by Shizuoka university up to harvest time. Trickling nozzles(Netafim Co. Israel) were used for fertigation of nutrient solution and noncirculating system was employed. Temperature was maintained $18^{\circ}C$ in night but 23 to $25^{\circ}C$ for 10 days after pollination for softening the fruit. The drainage ratio of nutrient solution was adjusted 20 to 30 percent. Fertigated and drained amount, and the pH and EC of nutrient solution were recorded. The concentrations of mineral elements including N, P, K, Ca, and Mg were analyzed and compared among treatments. In both autumn and winter cultivation, the limitation of nutrient supply by adjustment of nutrient composition(NO$_3$-N : 8meㆍ$\ell^{-1}$) caused the nutrient deficiency in muskmelon plant due to the limited nutrient supply. After pollination nutrient limitation by the lowering the nitrate retarded the over thickening of upper leaves of muskmelon but plant height and fresh weight of fruit were higher in the plot of nonlimited nutrient supply. The phenomena were attributed to the differences of the amount of nutrient uptake due to the limited time of nutrient solution, duration of nutrient supply and concentration of nutrient solution. These results suggested that increasing nutrient supply in the pollination stage was favorable for better appearance of fruit and improving fruit quality. Further trials would be required for the incre-ment of sugar degree of muskmelon grown in rockwool.

• Human Ecology Research
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• v.53 no.1
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• pp.17-27
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• 2015

This study was performed to investigate the antioxidative properties of sea buckthorn (Hippophae rhamnoides L.; leaf, fruit and stem) and the quality characteristics of brown rice sulgidduk prepared using a powder of sea buckthorn leaves. First, the antioxidative activities of sea buckthorn were measured to choose the most effective part of this plant. By analyzing the measured values, we concluded that the effective part of sea buckthorn was its leaves. The $IC_{50}$ value of the DPPH radical scavenging activity and the ABTS radical scavenging activity in sea buckthorn leaves were $7.78{\mu}g/mL$ and $264.04{\mu}g/mL$, respectively. The total polyphenol and total flavonoid contents of sea buckthorn leaves were 3.80 mg/mL and .19 mg/mL, respectively. Therefore, the brown rice sulgidduk was prepared using a powder of sea buckthorn leaves in the weight ratio of 0%, .5%, 1.0%, 1.5%, 2.0% and 2.5%. For analyzing the quality characteristics of the prepared sulgidduk, proximate compositions, color and texture profiles were measured and a sensory evaluation was conducted. With an increase in the added content of the sea buckthorn leaf powder (SBLP), the L-value significantly decreased while the a-value and the b-value increased. In the case of texture profiles, the control group (control A) had a higher score for hardness than the case groups in which the SBLP was added. However, springiness, chewiness and adhesiveness were not significantly different among the groups. In the sensory evaluation, the sample containing 1.5% SBLP yielded the best results. Therefore, we suggest that the powder of sea buckthorn leaves is a good ingredient for increasing the consumer acceptability and functionality of sulgidduk.

• Horticultural Science & Technology
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• v.18 no.3
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• pp.399-403
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• 2000

Recently, abnormal leaf chlorosis has been observed in jujube trees of the major production area in Kyongbuk province. To determine possible causes for the observation, physico-chemical properties of the orchard soil and nutrient contents in the jujube trees were investigated. The chlorosis symptoms were categorized into three types based on the site of chlorosis initiation; leaf center, petiole, and intravein. Of the three, leaf center chlorosis was the most common. The symptom occurred more frequently in Ihyeon, Gyuam, and Geugrag soil series with previous history of apple orchard. In general, the soil and the tree showing leaf chlorosis had lesser nutrient contents than normal except P, Fe, and Zn. In particular, Mg contents in leaf, branchlet, and fruit of the tree were as much as 4 times lesser than those in normal tree; the soil also had 7.8 times lesser Mg contents. The results indicate that the abnormal leaf chlorosis in jujube tree may be caused by nutrient deficiency in soil and could be cured by proper fertilization.

• Journal of Korean Society of Forest Science
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• v.42 no.1
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• pp.1-38
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• 1979

The woody species of Genus Ilex which are endemic to Korea are distributed on limited area due to solely temperature factor. There is some differences according to species, however in general, the evergreen Ilex are found along southern coastal area of Korean Peninsula and near islands where the cold index does not exceed $-5^{\circ}C$. But Ilex macropoda and the variety, only deciduous ones, are grown in temperate zone of the peninsula and some islands. The list of Ilex species of Korea are as follows. Ilex cornuta Lindley et Pax., I. crenata Thunb. var. microphylla Max., I. crenata Thunb., I. rotunda Thunb., I. macropoda Miq., I. macropoda Miq. var. pseudo-macropoda Loensner, I. integra Thunb. The author surveyed the populations of Ilex species as many as possible and data of some characters such as leaf shape, spine, fruit shape, stomata density, sex ratio in natural communities, etc. are collected. Almost all the Ilex species in Korea show sporadic distribution. This means quite small sized populations isolate distantly each other eliminating the change of gene exchange in between. Particularly Ilex conuta and I. crenata show the morphological differentiation among populations as well as significant individual variation within a population. These were true with such characteristics, leaf shape, leaf dimension, leaf margin, fruit shape, spine, and stomata density. The founded are that the fruit length and the stomata density counted on the beneath surface of leaves of Ilex cornuta increased with the decrease of latitude. These are naturally closely related with the cold index values. The table shown below indicates the correlation between mean stomata density per $0.3642mm^2$ and cold index values. These relation however were not observed on Ilex crenata. The most dominated natured in relation to individual variation were outline of leaf, the number of marginal spine, the shape of leaf cross section and the degree of luster of the upper leaf surface. As shown in photos 5~7, these variations are agreed at a glance. There are reports that the development of marginal spines in some Ilex species is associated with the juvenility and topophysis. In present study, these two factors were neglected because of the intended sampling procedure. Of Ilex rotunda, population difference with the characteristics of leaf length is recognized but not for leaf width, petiole length, and fruit size. However, individual variations within a population were significantly large. In case of Ilex integra, only individual differences within population were calculated statistically for such characteristics as leaf length, leaf width, and petiole length. As to natural population, the sex ratio was 1:2 (female to male) for Ilex cornuta, and 1:1 for Ilex crenata. The tendency of more male than female in I. cornuta was agreed to other observations. Preparing the tip cutting of length 10cm, and treating with IBA, then attaching earth ball to the cut end, very successful rooting percentages were obtained. Asexual propagation has the advantages of maintaining the heterozygosity of existing varieties and overcoming the difficulties of delayed seed germination frequently encountered with Ilex species. Considering a great deal of variation in morphological traits, a good possibility of selection breeding for decorative and ornamental purposes exists. At present, these evergreen Ilex are ignored by local people as nuisance weedy shrubs. So the proper protection measures should promptly be taken.

• Horticultural Science & Technology
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• v.33 no.6
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• pp.820-828
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• 2015

This study was carried out to determine the effects of vernalization, temperature, and soil water deficit (SD) on mesophyll cells, growth, and yield of Chinese cabbage (Brassica campestris L). The palisade parenchyma and spongy tissues of Chinese cabbage were observed under full irrigation and two weeks of SD treatment. These cells were severely collapsed by four weeks SD treatment. The SD treatment had the greatest influence on the growth of Chinese cabbage among the tested treatment factors (vernalization, temperature, and SD), growth significantly decreased by severe drought treatment (four weeks SD treatment). In addition, the relative growth rate, unit leaf rate, leaf area ratio, specific leaf area, and leaf weight ratio were significantly affected by SD treatment; however, other individual factors and their combined treatments did not influence the analyzed growth parameters. The yield under vernalization after high temperature and full irrigation treatments was 3,056 kg/10 a, which was the greatest among all the tested treatments, while four-week SD treatment significantly reduced the yield. Head formation of Chinese cabbage was not altered under SD treatment, and vernalization treatments did not induce bolting. Our results indicated that collapsing mesophyll cells and reduced growth and yield were induced by SD treatment. Thus we suggest that optimal irrigation system should be install to avoid or overcome crippling drought conditions in the open field.

• Journal of Bio-Environment Control
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• v.7 no.2
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• pp.151-158
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• 1998

This study was carried out to evaluate the effect of substrates and nutrient solution supplying methods in the media culture using perlite and its mixtures with rice hull, carbonized rice hull. cocopeat on the growth and fruit qualify of hydroponically grown cucumber. Three substrates. Perlite(70%) +rice hull(30%) perlite(70%) +carbonized rice hull(30%) and perlite(70%)＋cocopeat(30%) were compared with perlite medium. Supplying methods of nutrient solution were composed of drip irrigation, modified drip irrigation(covered with cheesecloth between drip hose and substrate) and mist system Leaf area of cucumber Plants was lowest in perlite medium while it was highest in mixture of perlite and cocopeat. NAR was higher in the plot of mixture with cocopeat. and same trend was observed in LAI and CGR. T/R ratio was higher in Perlite and perlite mixture with rice hull. Fruit Yields increased in the plot of modified drip irrigation system. When perlite mixture with rice hull used as a substrate. mist system was recommended. Perlite mixture with carbonized rice hull was observed favored in conventional drip irrigation system. Marketable yield and the number of fruit per plant increased and the malformed fruit decreased in the plot of modified drip irrigation system with the mixtures of Perlite and cocopeat.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.486-494
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• 2021

Watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) is sensitive to low temperature and shows retarded growth under 10℃. Although early transplanting guarantees higher returns, it requires cost and labor to maintain the appropriate temperature for plant growth. Therefore, cultivars tolerant to chilling stress is necessary to reduce the cost and labor requirements. The purpose of this study is to analyze data on plant growth and fruit enlargement under continuous chilling night temperature to develop new cultivars tolerant to chilling temperature. Two cultivars expected to have chilling tolerance and another cultivar sensitive to chilling temperature were grown in greenhouses with chilling and optimal night temperature conditions. In the early growth stage after transplanting, the cultivars expected to have chilling tolerance showed better vine length, fresh weight and dry weight. However, one of the tolerant cultivars showed significantly lower vine length, leaf length and width, and petiole length than the sensitive cultivar during pollination period and later growth stage, showing genotype specific responses. The fruit length, width, and weight were also significantly lower in the tolerant cultivar. The fruit set ratio was significantly higher in the chilling sensitive cultivar than the two tolerant cultivars. These results suggest that the present chilling tolerant cultivars in watermelon were selected based on their performance in the early growth stage, and further studies on chilling tolerance in different growth and development stages are required to develop cultivars adapted to various forcing cultivation systems.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.773-786
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• 2016

Grape cultivar "Campbell Early" account for 70% of table grape in Korea and Leaf Spot Disease caused by Pseudocercospora vitis is one of a major disease in greenhouse and field grown area during late summer season in both of organic and conventional grape farm. Leaf spot disease can cause lowing of sugar content in fruit and vine growth and very difficult to control especially in organic field. Photosynthesis ability and chemical components are compared between leaf spot disease infected leaves with degree of necrotic area. With increase of disease necrotic area, $CO_2$ differential value, water use efficiency and $CO_2$ assimilation and respiration ratio are decreased proportionally and on the other hand, stomatal conductance value is not affected by disease necrotic area. Chlorophyll contents are also decreased by 50% in heavily infected leaves and imply decrease of chlorophyll contents is a major source of photosynthesis ability decline. With increase of disease necrotic area in leaves, total nitrogen and phosphate contents are decreased and on the other side, total carbon, potassium, calcium and magnesium contents are increased. From this research, we can infer that not only chemical control program is important in control of leaf spot disease but also fertilizing program is significant especially in organic agronomical control of fungal disease in grape cultivar "Campbell Early".

• Korean Journal of Environmental Agriculture
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• v.32 no.3
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• pp.201-206
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• 2013

BACKGROUND: Kiwifruit, which was introduced to Korea in late 1970s, is a warm-temperate fruit tree, whose leaves are easily damaged by wind because of their large size. To produce high quality fruits, efficient windbreak is necessary to protect leaves until harvest. In Korea, typhoons from July onwards usually influence the production of kiwifruit. Damages from typhoons include low fruit quality in the current year and low flowering ratio the following year. This study was conducted to investigate the effect of early defoliation of kiwifruit vines from July to October on the regrowth of shoot axillary buds the current year and bud break and flowering the following year. METHODS AND RESULTS: Scions of kiwifruit cultivar 'Goldrush' were veneer grafted onto five-year-old Actinidia deliciosa rootstocks, planted in Wagner pots (13L) and grown in a rain shelter. Kiwifruit leaves in the proximity of leaf stalk were cut by lopping shears to simulate mechanical damage from typhoon since only leaf stalks were left when kiwifruit vines were damaged by typhoons. Kiwifruit vines were defoliated from July 15 to October 14 with one monthintervals and degrees of defoliation were 0, 25, 50, 75 and 100%. All experiments were conducted in the rain shelter and replicated at least five times. Defoliation in July 15 resulted in a high regrowth ratio of 20-40% regardless of degree of defoliation but that in August 16 showed only 5.8% of regrowth ratio in the no defoliation treatment; however, more than 25% of defoliation in August 16 showed 17-23% of regrowth ratio. In September 15, regrowth ratio decreased further to less than 10% in all treatments and no regrowth was observed in October 14. Percent bud break of all defoliation treatments were not significant in comparison to 64.7% in no defoliation except for 42.1% and 42.9% in 100% defoliation in July 15 and August 16, respectively. Floral shoot in the no defoliation treatment was 70.2% and defoliation of 50% or less resulted in the same or increased floral shoot ratio in July 15, August 16, and September 15; however, defoliation in October 14 showed no difference in all treatments. In flower number per floral shoot, 2-3 flowers appeared in no defoliation and only 1 flower was observed when the vines were defoliated more than 50% in July 15 and September 15. In October 14, contrary to the floral shoot ratio, flower number decreased with increased defoliation. CONCLUSION(S): Therefore, it is suggested that dormancy of 'Goldrush' axillary buds, was started in August and completed in October. The effect of defoliation on bud break of axillary buds the following year was insignificant, except for 100% defoliation in July 15 and August 16. From July 15 to September 15, floral bud ratio was significantly reduced when more than 50% of leaves were defoliated compared to no defoliation. Also, the number of flowers per flower-bearing shoot the following year decreased by less than 50% when compared to no defoliation, and this decrease was more prominent in September 15 than July 15 and August 16.