• Korean journal of applied entomology
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• v.43 no.1
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• pp.15-20
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• 2004

Leaf damage by apple leafminer, Lyonetia prunifoliella, was surveyed on Fuji apple orchards with seedling rootstock from 1992 to 2001 and with M.9 rootstock from 1999 to 2001. The damage was negligible in apple orchards with seedling rootstock as 0.15% in 1992 and 0.06% in 1993. However it sharply increased to more than 3.39% since 1994, reaching at peak damage of 6.28% to 7.78% in 1996 to 1998. Damages on apple orchards with M.9 rootstock from 1999 to 2001 were higher as 6.09% to 15.3%, compared with those with seedling rootstock in the same years. In seedling rootstock apple, the damage was highest on september but in M.9 rootstock apple, the difference was not significant. Leaf damage showed no differences between cultivars including 4 Korean cultivars and Fuji. These results may explain that increase of M.9 rootstock apple orchards is responsible for the recent outbreak of the leafminer in Korea.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.1
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• pp.59-71
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• 2014

This study was conducted to find out the freezing hardness of apple tree as influenced by dwarfrootstocks, cultivars, and low temperature treatments. The dwarf-rootstocks used were M.9 and M.26, and three cultivars used were early-maturing 'Tsugaru', mid-maturing 'Hongro', and late-maturing 'Fuji'. Chilling temperatures were applied from $0^{\circ}C$ to $-40^{\circ}C$. Checking points of apple tree for freezing hardness were rootstock, trunk, feather, floral bud and foliar bud. Investigations were evaluated by the measure of water loss, electrolyte leaching, and sprouting. The results did not show the differences in water loss, electrolyte leaching, and sprouting by dwarf-rootstocks. Water loss of 'Fuji' was lower than that of 'Tsugaru' and 'Hongro', but sprouting ratio of 'Fuji' was higher than that of 'Tsugaru' and 'Hongro'. Water loss and electrolyte leaching increased as treated by lower temperature, while sprouting ratio decreased. In $-35^{\circ}C$ treatment, sprouting of rootstock and trunk part were higher than that of feather, while sprouting of floral bud was lower than that of foliar bud. Sprouting of bourse shoot at the accumulated low temperature in terms of $-10^{\circ}C$ per day was 100% in the 28 days, and sharply decreased about 50% in the 35 days. In conclusion, there were no differences in freezing hardness between M.9 and M.26, but freezing hardness of late-maturing cultivar was tended to stronger than that of early-maturing and mid-maturing cultivars. Freezing hardness of floral bud was extremely weak $-30^{\circ}C$.

• Journal of Bio-Environment Control
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• v.16 no.2
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• pp.151-156
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• 2007

This work was conducted to investigate the important rooting factors through comparative analysis of a physiological differentiation after layering treatment using four apple rootstocks of different rooting abilities; M.26, M.9, O.3, and Mo.84. Mo.84 showed the highest rooting rate in from rootstocks, while O.3 was the lowest. Mo.84 also found to have the highest indole-3-acetic acid (IAA) content, although the fluctuation of IAA contents was not consistent with layering treatment. In contrast, abscisic acid (ABA) content of Mo.84 which showed highest rooting was lowest among rootstocks regardless of layering treatment. And ABA contents of all rootstocks were decreased after layering treatment than before layering treatment. O.3 which showed poor rooting rate revealed lowest in boron content. Carbohydrate/nitrogen (C/N) ratio of Mo.84 was the highest in all rootstocks. Therefor, we assumed that he IAA contents in layering treated rootstocks were not seemed to be a major rooting factor, but the changes in ABA contents and boron levels limit rooting in dwarf apple rootstocks.

• Journal of Plant Biotechnology
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• v.46 no.3
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• pp.228-235
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• 2019

Apple (Malus pumila) is one of the most economically important fruits in Korea. but virus infection has decreased the sustainable production of apples and caused serious problems such as yield loss and poor fruit quality. Virus or viroid infection including apple chlorotic leaf spot virus (ACLSV), apple stem pitting virus (ASPV), apple stem grooving virus (ASGV), apple mosaic virus (ApMV) and apple scar skin viroid (ASSVd) have been also reported in Korea. In many cases, as apple gets infected with virus and viroid with no specific symptoms, the damage and symptoms caused by the viruses are not detected. In our research, viruses in the rootstock were eliminated for a virus-free apple dwarfing rootstock of M.9 and M.26. The virus elimination methods were apical meristem culture, thermotherapy ($37^{\circ}C$, 6 weeks) and chemotherapy($Ribavirin^{(R)}$). The detection of apple viruses was accomplished by Enzyme-linked Immuno-Sorbent Assay (ELlSA) and reverse transcription-polymerase chain reaction (RT-PCR). RT- PCR method was 10 ~ 30% more sensitive than the ELISA method. The efficiency of virus elimination was enhanced in apical meristem culture method. The acquisition rate of virus-free apple dwarfing rootstocks was 30 ~ 40% higher in apical meristem culture. After the meristem culturing of M.9, the infection ratio of ACLSV, ASPV and ASGV was 45%, 60% and 50%, respectively. In the apple dwarfing rootstock of M.26, the infection ratio of ACLSV, ASPV and ASGV was 40%, 55% and 55%, respectively. Based on this study, the best method for the production of virus-free apple dwarfing rootstocks was the apical meristem culture.

• Journal of Plant Biotechnology
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• v.32 no.3
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• pp.181-186
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• 2005

This work was conducted to evaluate the effects of rooting on tissue cultured M.9 (Malus domestica Bork. cv, tcM.9) after layering in field. We investigated an appearance period of first root in shoot, rooting ratio, contents of indole-3-acetic acid (IAA), abscisic acid (ABA), inorganic matters, sugars, and lignin in rooting areas of stems by layering. First root in shoot of tcM.9 and natural M.9 appeared 25 and 30 days after layering (DAL), respectively. Rooting ratio was much higher in tcM.9 than in natural M.9. The content of IAA was higher in tcM.9 than in natural M.9 before layering, but it was reversed at 20 and 30 DAL. In contrast, the content of ABA was much higher in natural M.9 than in tcM.9 in case of both before and 10 and 20 DAL. The contents of N, B, Mn, and Zn were significantly higher in tcM.9 than in natural M.9 both before and 10 and 20 DAL. The contents of sugars in tcM.9 had the similar pattern of the contents of inorganic materials. There were statistically significant differences in the contents of sucrose and glucose at 30 DAL as well as the content of maltose at 20 and 30 DAL. The content of lignin was significantly higher in tcM.9 than in natural M.9 before layering and 10 and 30 DAL while there was no difference 20 DAL. Therefore, improvement of rooting ability in the tissue cultured root stock M.9 might be due to the changes of inorganic matters or lignin rather than that of sugars and hormones.

• Korean Journal of Plant Tissue Culture
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• v.28 no.1
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• pp.33-36
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• 2001

The experiments were conducted to establish the in vitro culture system of apple rootstock M.9. The meristem tissue of M.9 were pre-treated in antiox: dant solution containing 100 mgL$^{-1}$ ascorbic acid and 150 mgL$^{-1}$ citric acid for 30 minutes, transferred to the MS liquid medium added with 0.1 mgL$^{-1}$ IBA, 0.5 mgL$^{-1}$ GA, and 30 gL$^{-1}$ sucrose, which shaked by 50 rpm for 2 weeks, and then, cultured in same composition of MS agar medium. This treatment stimulated shooting from the tissue, the most favorably, compared with other treatments. All young shoots produced normal roots when they were shake-cultured on the 1/2MS liquid medium added with 0.5 mgL$^{-1}$ IBA, 30 gL$^{-1}$ sucrose and 1,000 times diluted solution of Hormex by 50 rpm for one week, and subsequently transferred to the 8 gL$^{-1}$ agar medium of the same composition as pre-culture medium minus Hormex.

• Journal of Bio-Environment Control
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• v.25 no.3
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• pp.168-172
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• 2016

The effect of different exposed length of M.9 rootstock on growth and yield was tested in the new apple cultivars. The 'Seohong', 'Summer Dream', and 'Hongguem' grafted on M.9 rootstock were planted in March 2010. The trees were planted in such a way that the exposed length of the rootstock to be 10, 20 and 30 cm. The result showed that as decreasing exposure length, TCA of 'Seohong', 'Summer Dream', and 'Hongguem' was increased between $3^{rd}$ and $6^{th}$ year after planting. The TCA of 20 cm and 30 cm exposure length showed respectively 70% and 60% in 'Seohong', 88% and 66% in 'Summer Dream', and 55% and 41% in 'Hongguem' of the TCA with 10 cm exposure length on 6-year-old trees. Tree height, canopy width, shoot length and terminal shoot length were also increased according to decreased exposure length in 6-year-old trees. The cumulative yield of three cultivars was higher in the tree with a lower exposure length between $4^{th}$ and $6^{th}$ year after planting. The cumulative yield of 20 cm and 30 cm exposure length showed respectively 77% and 63% in 'Seohong', 85% and 76% in 'Summer Dream', and 73% and 58% in 'Hongguem' of the cumulative yield with 10 cm exposure length in 6-year-old trees. Considering tree growth and yield, the optimum exposure length of M.9 was 10 cm for 'Seohong', 'Summer Dream' and 'Hongguem'.

• Journal of Life Science
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• v.19 no.6
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• pp.832-835
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• 2009

The main objective of this research was to improve rooting of M.9 apple rootstock through layering time, shading, layering material and water content of the layering part. Among the treatments, rooting was improved by mother plant shading or an earlier covering (layering in shoot length 2 cm) of shoots. Rooting and root growth of sawdust, chaff or vermiculite treatments were significantly higher than those of the control (soil). In the study of layering material water content, -40 kPa treatment increased rooting ratio, number of roots and root growth compared to -60 kPa treatment and control. These results suggest that early-covering, layering with sawdust, chaff, or vermiculite, and keeping the water content in the layering part at -40 kPa could improve rooting and root growth in M.9 rootstock propagation.

• Journal of Plant Biotechnology
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• v.31 no.2
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• pp.133-138
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• 2004

Growth of M.9 (Malus domestica Bark. cv) and M.26 (Malus domestica Bark. cv) of dwarf apple rootstock, cultured on MS agar medium in a vessel with ventilating stopper (VS) and then in vivo rooting and acclimatization under combined-treatment by some materials with IBA, were investigated. Concentration of $CO_2$ and ethylene in the vessel with VS was lower then in the vessel with non-VS. Change of temperature and humidity in the vessel with VS was repeated by light condition. Stomatal pares of tissue in the vessel with VS were immediately closed after plantlets were exposed to room humidity but those in the vessel with non-VS were opened after 20 minutes exposure to room humidity. Leaf area and chloroplast index of tissue in the vessel with VS was higher then in the vessel with non-VS. In vivo rooting ratio and acclimatization ratio of M.9 and M.26 was highest in 300mg/L IBA＋3％ sucrose dip-treatment among other combined- treatments.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.52-52
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• 2018

Apple (Malus domestica) is one of the most economically important fruits in Korea. But virus infection has decreased sustainable production of apple and caused the serious problems such as yield loss and poor fruit quality. Virus or viroid infection including Apple chlorotic leaf spot virus (ACLSV), Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV), Apple mosaic virus (ApMV) and Apple scar skin viroid (ASSVd) has been also reported in Korea, furthermore, its damages and economic losses have increased constantly. In our research, we tried to survey virus infection for commercial nursery trees of major apple cultivars, especially dwarfing rootstocks 'M.9' and 'M.26' as well as scions. Trees were collected from 11 locations which have produced a great amount of apple nursery stocks in Korea. Infection degree was investigated in apple cultivars, 'Hongro' and 'Fuji' using RT-PCR method. In the scion of cultivar 'Hongro', infection ratio of ACLSV, ASPV and ASGV were 100%, 81.8% and 100% respectively. In the rootstock of cultivar 'Hongro', infection ratio of ACLSV, ASPV, ASGV and ApMV were 90.9%, 81.8%, 100% and 9.1% respectively. In the scion of cultivar 'Fuji', infection ratio of ACLSV, ASPV and ASGV were 81.8%, 90.9% and 100% respectively. In the rootstock of cultivar 'Fuji', infection ratio of ACLSV, ASPV, ASGV and ApMV were 81.8%, 90.9%, 100% and 9.1% respectively. Infection of ASSVd was not detected in both cultivars. From our results, it was found that most of apple rootstocks and scions had multiple infections by apple viruses which have caused economic damage in fruit production.