• Korean Journal of Plant Resources
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• v.31 no.6
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• pp.684-694
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• 2018

This study describes the successful establishment of a cryopreservation protocol for Citrus limon cultivars: 'Frost Eureka limon' and 'Cook Eureka limon', using a droplet-vitrification method. The shoot tips that were excised from in vitro grown seedlings of the two cultivars were preserved in liquid nitrogen (LN) and successfully regenerated into whole plants. Excised shoot tips were pre-cultured for 1 or 2 days in 0.3 M and 0.5 M sucrose solutions at $25^{\circ}C$ and incubated in a loading solution (LS) composed of 17.5% glycerol + 17.5% sucrose in Murashige and Skoog (MS) medium for 40 min at $25^{\circ}C$. Prior to direct immersion in LN for 1 h, the shoot tips were dehydrated with plant vitrification solution 2 (PVS2) at $0^{\circ}C$ or PVS3 at $25^{\circ}C$. The frozen shoot tips were re-warmed and unloaded with 1.2 M sucrose in $\text\tiny{^1/_2}$ MS for 30 min at $25^{\circ}C$. Shoot tips were post-cultured overnight on survival medium and then micrografted onto 'trifoliate orange' (Poncirus trifoliate (L.) Raf. seedling rootstocks for recovery and to produce whole plants. The highest regrowth rates were 53.5% and 50.3% for cryopreserved shoot tips of 'Frost Eureka limon' and 'Cook Eureka limon', respectively, when pre-cultured in 0.3 M and 0.5 M sucrose concentrations in a sequencing manner, with LS and treated with PVS2 for 60 min at $0^{\circ}C$. We also investigated whether the ammonium ion concentration on post-culture medium affected the viability of the cryopreserved Citrus shoot tips. The viability of cooled samples, following culturing on woody plant media (WPM) containing $\text\tiny{^1/_4}$ ammonium nitrate overnight before micrografting, was the highest (70.3%) in 'Frost Eureka limon'. The study described here is a cost-effective and safe method to conserve Citrus fruit cultivars, for the improvement and large-scale multiplication of fruit plants and for breeding disease resistance.

• Korean Journal of Environmental Agriculture
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• v.35 no.3
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• pp.175-183
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• 2016

BACKGROUND: There's a long rainy season during the Summer in Northeast Asia, including Korea. Heavy rainfall during this season causes harm to tree's root, and damped injury in the pear has been continuously reported. Pear Research Institute is breeding damp resistant rootstocks and investigating their mechanisms to relieve damped damages in the pear.METHODS AND RESULTS: Seedlings of Pyrus betulaefolia and P. calleryana were divided into two groups: control and damped, respectively. Damped group was treated by constant irrigation for 77 days and control group was maintained to keep the soil moisture pressure between 0 and -10 kPa. After the treatment, we analysed trees' growth rate, chlorophyll content, amino acids and total phenolic compounds. As a result, P. betulaefolia was sensitive to damped treatment while P. calleryana did not have significant differences between the control and damped treatment. It was observed that total contents for phenolic compounds were dramatically increased in P. betulaefolia while trees' growth rate, chlorophyll b and general amino acid contents were lowered by damping treatment.CONCLUSION: In some pear cultivars, growth habit is suppressed by damped damage. Pyrus calleryana displayed tolerances to damped damage in growth rate and some organic compound contents compared to P. betulaefolia. So we recommend to exploit P. calleryana as a pear rootstock rather than using P. betulaefolia.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.364-370
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• 2014

The nutrient and irrigation management of scion and rootstock can alleviate stress on grafted transplants after grafting and promote the growth. This study investigated the effects of nutrient and irrigation management of scion and rootstock on the graft-take and growth of grafted pepper transplants. Before grafting, the scions were subjected to different water potential regimes in media by controlling the irrigation frequency and time. The scions were subirrigated 0, 1(two days before grafting), 1(one days before grafting) or 2 times for five days before grafting. The irrigation frequency and time influenced the water potential of media and the growth of scion and grafted transplants. At 13 days after grafting, fresh and dry weight of transplants which were irrigated once at two days before grafting were greater by 29 and 34% than those without irrigation during five days before grafting. This suggests that mild water stress on scion prior to grafting by controlling water management alleviate water stress on grafted transplants after grafting and improve the growth. Before grafting, the rootstocks were subjected to different nutrient regimes by controlling nutrient solution application. The rootstocks were supplied with nutrient solution 0, 1, 2, or 4 times. The nutrient application frequency and time influenced the electrical conductivity (EC) and pH of media. Accordingly, the growth and mineral contents of rootstock and grafted transplants were also affected. At 13 days after grafting, fresh and dry weight of transplants with four times of nutrient application increased by 30 and 20%, respectively, than those without nutrient solution supply during seven days before grafting. Therefore, it is recommended that nutrient solution be supplied more than four times during seven days before grafting for the production of high quality transplants.

• Horticultural Science & Technology
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• v.33 no.1
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• pp.70-82
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• 2015

This study was conducted to establish an efficient screening system to identify melon resistant to Fusarium oxysporum f. sp. melonis. F. oyxsporum f. sp. melonis GR was isolated from infected melon plants collected at Goryeong and identified as F. oxysporum f. sp. melonis based on morphological characteristics, molecular analyses, and host-specificity tests on cucurbits including melon, oriental melon, cucumber, and watermelon. In addition, the GR isolate was determined as race 1 based on resistance responses of melon differentials to the fungus. To select optimized medium for mass production of inoculum of F. oxysporum f. sp. melonis GR, six media were tested. The fungus produced the most spores (microconidia) in V8-juice broth. Resistance degrees to the GR isolate of 22 commercial melon cultivars and 6 rootstocks for melon plants were investigated. All tested rootstocks showed no symptoms of Fusarium wilt. Among the tested melon cultivars, only three cultivars were susceptible and the other cultivars displayed moderate to high resistance to the GR isolate. For further study, six melon cultivars (Redqueen, Summercool, Superseji, Asiapapaya, Eolukpapaya, and Asiahwanggeum) showing different degrees of resistance to the fungus were selected. The development of Fusarium wilt on the cultivars was tested according to several conditions such as plant growth stage, root wounding, dipping period of roots in spore suspension, inoculum concentration, and incubation temperature to develop the disease. On the basis of the test results, we suggest that an efficient screening method for melon plants resistant to F. oxysporum f. sp. melonis is to remove soil from roots of seven-day-old melon seedlings, to dip the seedlings without cutting in s pore s uspension of $3{\times}10^5conidia/mL$ for 30 min, to transplant the inoculated seedlings to plastic pots with horticulture nursery media, and then to cultivate the plants in a growth room at 25 to $28^{\circ}C$ for about 3 weeks with 12-hour light per day.

• Journal of Bio-Environment Control
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• v.30 no.3
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• pp.196-205
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• 2021

This research was conducted in order to analyze the difference in yield through the changes in growth and measuring the photosynthesis efficiency in cherry tomatoes. Seedlings of cherry tomato 'Nonari' were used as scion and non-grafted control, while 4 different grafted tomatoes 'Powerguard', 'T1', 'L1', and 'B.blocking' were used as rootstocks. Plants grafted onto 'B.blocking' produced the highest fruit yield (417.5 g plant^-1), whereas non-grafted plant 'Nonari' had the lowest fruit yield, (354.2 g plant^-1) at the latter period of cherry tomatoes in May. The flowering position in May, plant grafted onto 'B.blocking', showed 14-17 cm, whereas non-grafted plant 'Nonari' showed 10-14 cm. The growth strength on May 15, non-grafted plant 'Nonari', showed 8.43 mm which was the lowest value among the treatments. Grafted plants kept the growth balance until the end of the harvest that led to an increase in fruit yield, while non-grafted plant weakened the vigor earlier that led to a decrease in fruit yield. Grafted plants showed higher values of chlorophyll fluorescence variables than the values of non-grafted plant. These results indicate that grafting influenced fruit yield which was observed as maintaining growth balance for longer and an increase in photosynthesis efficiency compared to non-grafting.

• Journal of Bio-Environment Control
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• v.32 no.1
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• pp.40-47
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• 2023

There are many different types of cultivation in tomatoes for year-round production. One of them, semi-forcing cultivation is characterized by growing seedlings in winter season. If grafted seedlings are used in winter season that energy cost can be reduced, because they have tolerance to cold stress. This study was conducted to analyze the rootstock performance by measuring the growth, yield, and leaf-macronutrient content of cherry tomatoes grown in semi-forcing hydroponics. Three domestic rootstocks 'HSF4', '21LM', '21A701', and a control cultivar 'B-blocking' were grafted onto jujube-shaped cherry tomato (Lycopersicon esculentum L.) commercial cultivar 'Nonari'. The total yield per plant with grafted cherry tomato '21A701' was 3,387g, which was 11%, 22% and 24% higher than the yield with 'B-blocking', non-grafted one and 'HSF4'. The stem diameter of '21A701' was thick with 8.26mm, whereas non-grafted one was thin with 7.23mm at 160 days after transplanting. The flowering position of '21LM' was 34% and 47% higher than the flowering position of 'B-blocking' and non-grafted one at 153 days after transplanting. The NO₃-N concentration in petiole sap of '21LM' was the highest with 1,746mg·L^-1 and non-grafted one and 'HSF4' were the lowest with 1,252mg·L^-1 and 1,245mg·L^-1 at 167 days after transplanting. The results indicated that rootstock/scion combinations in cherry tomatoes can affect the plant growth, yield, and the concentration of different NO₃-N in leaves at the late growth stage. Both '21A701' and '21LM' have vigorous root system, which influence the growth and yield increased.

• Korean journal of applied entomology
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• v.48 no.3
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• pp.319-325
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• 2009

Woolly apple aphid, Eriosoma lanigerum, overwintered as adult or nymph stage on rootstocks, and crown- and root sucker in the soil. In an un sprayed apple orchard, the number of E. lanigerum colony started to increase from mid-April, showed the 1st peak between late June and early July, thereafter decreased followed by the 2nd peak in late July, and then again peaked in late September as the size in the 1st peak. In this orchard, the number of E. lanigerum colonies per tree did not exceed 3.5 colonies during the peak occurrence period, and was maintained around 2 colonies throughout seasons. In all seasons, parasitism of Aphelinus mali on E. lanigerum was much lower on root colonies than on aerial colonies that located on shoots and tree trunks above the ground. The parasitism of E. lanigerum was high in most orchards examined, showing parasitism of > 70% in maximum in most cases. In the laboratory bioassay for the mortality effects of several insecticides on E. lanigerum, fenitrothion, dichlorphos, machine oil, methidathion, thiacloprid, and imidacloprid showed 97.8, 96.8, 95.4, 91.5, 26.7, and 7.8% morality, respectively. Also, the adult emergence rates from A. mali mummies were 51.2, 72.6, 14.2, 3.5, 72.2, and 85.4% in the treatment of the above insecticides, respectively. Insecticides belong to neonicotinoid, which are newly developed to control aphids, showed low mortality against E. lanigerum. Fenitrothion and dichlorphos were effective on E. lanigerum control and had a low toxic to A. mali. Consequently, the insecticides should be useful in integrated pest management system for E. lanigerum in apple orchards.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.3
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• pp.151-161
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• 2016

This study was conducted to find out influence of dormancy level and carbon concentration on freezing hardiness in bourse shoot of 'Fuji' apple tree. Bourse shoot of 'Fuji' adult apple tree grafted on M.26 and M.9 rootstocks were used as experimental materials. Dormancy levels of bourse shoot were categorized according to the periods as follows the internal dormancy (late January), the early days after internal dormancy breaking (early February), the late days after internal dormancy breaking (late February), the bud break (late March), and the full bloom (late April). Chilling temperatures with bourse shoot were ranged from 0 to $-40^{\circ}C$. Also, the freezing hardiness according to carbon concentrations were investigated on 'Fuji'/M.9 apple tree that defoliated severely by Marssonina blotch (defoliation) and that of below the average 20 cm in shoot length through heavy crop load (weakness). Results showed that freezing hardiness of bourse shoot may become weaker after internal dormancy breaking. There was no differences in the carbon concentration of bourse shoot of 'Fuji' apple tree grafted on M.9 and M.26, so may be resulted in no difference in freezing hardiness both of bourse shoot grafted on M.9 and M.26 rootstock. Carbon concentration in bourse shoots with weakness and C/N ratio in bourse shoots with defoliation were lower than that of healthy. It may be shown that the freezing hardiness of defoliation and weakness were weaker than that of healthy.

• Horticultural Science & Technology
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• v.17 no.3
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• pp.329-332
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• 1999

The objective of this study was to determine the influence of grafting timing, rootstock cut timing and leaf removal with promalin ($GA_{4+7}+BA$) treatments on the maiden tree growth, lateral development and flower bud initiation. In mid-March 1997, two-year-old M.9-T337 rootstocks selected with trunk diameter over 1 cm were planted in the field. Chip budding with 'Fuji' scion on M.9-T337 rootstock budded in mid-April was earlier in sprouting than chip budding in mid-June. Late cutting chip budding (LCCB) with 'Fuji' scion on M.9-T337 rootstock was lower in the failed budding percentage with 14% than that of early cutting chip budding (ECCB). Especially, ECCB in April was not suitable for scion growth such as uniformity with high percentage of failed tree. Grafting timing in mid-June and rootstock cutting timing of LCCB induced more branches and flower buds than other treatments. Removal of 8 to 10 uppermost immature leaves on central leader stem and application of Promalin 250 mg/L after every 30 cm of terminal growth produced a 189 cm tall tree with 9 flower buds and 14.2 short lateral shoot from 30 to 35 cm long in length in 1998. Promalin increased branching on second-season growth and, when combined with leaf removal, resulted in uniform distribution of branches along the central leader stem.

• Horticultural Science & Technology
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• v.34 no.4
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• pp.564-577
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• 2016

Salinity stress limits plant cultivation in many areas worldwide; however, persimmon (Diospyros spp.) has high tolerance to salt. Five accessions of Diospyros [three of Diospyros lotus (accession numbers 824, 846, and 847); one of Diospyros kaki var. sylvestris (869); and one of Diospyros virginiana (844)] were chosen for analysis of salinity stress. We compared the effects of salt stress on plant growth, relative water content (RWC), malondialdehyde (MDA), electrolyte leakage (EL), hydrogen peroxide content ($H_2O_2$), and antioxidative enzyme activities (superoxide dismutase, SOD; catalase, CAT; peroxidase, POD; and ascorbate peroxidase, APX) in leaves of healthy potted seedlings from each of the five accessions after salt treatment for 25 days. Salt stress affected the growth of plants in all five accessions, with all three D. lotus accessions showing the most severe effect. Salt stress increased membrane lipid peroxidation in all accessions, but a stronger increase was observed in the three D. lotus accessions. Moreover, accumulation of $H_2O_2$ was faster in salt-sensitive D. lotus compared to salt-tolerant D. virginiana 844. The activities of all antioxidant enzymes increased in D. virginiana 844 and in D. kaki var. sylvestris 869; the activities of SOD, CAT, and APX were at similar levels in D. virginiana 844 and D. kaki var. sylvestris 869, but POD activity was stimulated to a greater extent in D. virginiana 844. The activities of all antioxidant enzymes (except POD) decreased in D. lotus 824 and increased (except for SOD) in D.lotus 846. The activities of SOD and APX decreased in D. lotus 847, whereas POD and CAT activities both increased. Relative water content decreased significantly in D. lotus. No significant changes in lipid peroxidation or relevant antioxidant parameters were detected in any of the accessions in controls treated with 0.0% NaCl. D. virginiana 844 had higher antioxidant capacity in response to salinity compared to other persimmon rootstocks. These results indicate that changes of these key physiological variables are related to salinity resistance in different accessions of persimmon.