• 한국환경농학회지
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• 제42권2호
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• pp.104-111
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• 2023

As apple trees mature, it is important to maintain good light distribution within the canopy to produce marketable fruits. Tree thinning is the selective removal of a proportion of trees growing in the orchard to provide more growing space and a good light environment for the remaining trees. This study was conducted over 3 years (14-16 years after planting) to investigate the influence of tree thinning on vegetative growth, yield, fruit quality, and blooming in the 14 years old slender spindle 'Fuji'/M.9 apple trees planted with the tree space of 3.2×1.2 m. The trees were placed in a control group (no thinning; 260 trees per 10 a) or a tree thinning group (thinned 50% of the control; 130 trees per 10 a). The tree thinning successfully improved light penetration, yield per tree, fruit red color, and yield efficiency for 3 years, and the tree thinning controlled the occurrence of biennial bearing. However, tree thinning significantly decreased accumulated yield per 10 a compared with the control. The vegetative growth, yield per tree, soluble solid contents, and blooming were not clear by the occurrence of biennial bearing in the control. These results indicated that tree thinning was a good method for improving light penetration and preventing biennial bearing in the old 'Fuji'/M.9 high-density apple orchards.

• 한국환경농학회지
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• 제42권3호
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• pp.239-252
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• 2023

Most apple trees in South Korea are grafted on M.9 and M.26 rootstocks; however, these rootstocks are susceptible to fire blight. Although M.7 rootstocks are moderately resistant to fire blight, they tend to exhibit excessive vigor, which is unsuitable for high-density planting, unless weak cultivars are used. This study investigated the vegetative growth, yield, and fruit quality of apple trees grafted onto M.7, M.9, or M.26 rootstocks to assess the feasibility of establishing high-density apple orchards domestically using the M.7 rootstock a period of seven years (1-7 years after planting). Rootstocks were tested using three cultivars with contrasting induced vigor and harvesting times: vigorous and late-maturing 'Fuji,' moderate vigor and middle-maturing 'Hongro,' and low vigor and early-maturing 'Sansa.' The planting density was maintained constant, with 190 trees per 10 a. Primary thinning (leaving only the king fruit on clusters) was performed, whereas secondary thinning (controlling crop load) was not. Vegetative growth, accumulated yield per 10 a, and yield efficiency varied depending on cultivars and rootstocks; however, the cultivars had a more notable effect on fruit quality than the rootstocks. Biennial bearing often occurred in the M.26 rootstock. 'Fuji'/M.7 was overly vigorous for high-density planting. The fruit quality and accumulated yield per 10 a of M.7 were similar to those of M.9 with the 'Hongro' and 'Sansa' cultivars. In particular, 'Hongro'/M.7 did not show tree vigor reduction due to heavy crop load, and the degree of biennial bearing in 'Sansa'/M.7 was not particularly high. These results indicated that high-density apple planting using the M.7 rootstock was achievable using the 'Hongro' and 'Sansa' cultivars.

• 한국환경농학회지
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• 제42권4호
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• pp.297-310
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• 2023

M.7 rootstock is moderately resistant to fire blight. However, M.7 is generally too vigorous for high-density apple systems, but it can be grafted onto cultivars that exhibit weak tree growth, such as 'Sansa'. This study investigated the vegetative growth, yield, and fruit quality of 'Sansa' apple trees grafted on M.7 or M.9 rootstocks to assess the feasibility of establishing domestic high-density apple systems using M.7 and to determine the optimum exposure length for rootstocks. Trees were planted with exposed rootstock lengths of 5, 10, and 15 cm. The vegetative growth of apple trees grafted onto M.7 was greater than that of M.9 and vegetative growth tended to decrease as the exposed length of rootstock increased. However, the differences in yield per tree, average weights, soluble solids contents, and titratable acidity due to the rootstock and its exposure length varied. The accumulated yield over a 10 year period and the yield efficiency of M.7 were lower than that of M.9 and the yield efficiency tended to decrease as the exposed length of rootstock increased. When apple trees were grafted onto M.9, biennial bearing and tree vigor weakening occurred if the exposed length of the rootstock was over 10 cm. Conversely, when apple trees were grafted onto M.7, vegetative growth was excessive if the exposed length of rootstock was below 10 cm. Based on the results from this study, the optimum M.7 and M.9 exposure lengths for 'Sansa' were 15 cm and 5 cm, respectively.

• 원예과학기술지
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• 제33권1호
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• pp.1-10
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• 2015

본 시험은 성목기 '후지'/M.9 사과나무의 재식밀도별 적정 착과수를 조사하고자 영양생장, 생산량, 과실품질 및 이듬해 개화율을 3년(재식 7-9년차) 동안 조사하였다. 시험재료는 $3.5{\times}1.5m$(190주/10a), $3.5{\times}1.2m$(238주/10a), $3.2{\times}1.2m$(260주/10a)로 심어 세장방추형을 목표수형으로 관리하고 있는 '후지'/M.9 사과나무이었다. 목표 착과수 범위는 주당 55-64과, 65-74과, 75-84과, 85-94과, 95-104과의 5수준이었다. TCA 증가, 총 신초장, 이듬해 개화율, 주당 생산량 및 수량 효율은 재식밀도가 낮을수록 증가하는 경향이 있었고, 과중과 가용성고형물 함량은 목표 착과수준이 낮을수록 증가하는 경향이 있었다. 착색은 신초생장이 감소할수록 증가하는 경향이 있었다. 해거리는 238주과 260주 재식구의 주당 과실수가 각각 85-94과, 75-84과 이상이 되면 발생하였다. 그러나 190주 재식구는 주당 95-104과 정도 되어도 해거리가 발생하지 않았다. 누적 생산량은 재식밀도 및 목표 착과수준이 높을수록 많아지는 경향이 있었으나, 해거리가 발생한 착과구들 간의 차이는 없었다. 결론적으로 190주로 재식된 '후지'/M.9 사과나무의 성목기 적정 결실량은 95-104개, 238주 재식구는 75-84개, 260주 재식구는 65-74개 범위가 적당할 것이라고 판단되었다.

• 생물환경조절학회지
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• 제17권4호
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• pp.306-311
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• 2008

본 연구는 2001년부터 2003년까지 '후지'/M.9가 재식된 밀식사과원에서 적정 수세와 적정 착과량을 조사하였다. 엽과비는 평균 과중(y=1.715x+205.02, $R^2=0.66^{**}$)과 수량(y=-35.156x+5963.7, $R^2=0.44^{**}$)에서 고도로 유의한 상관이 있는 것으로 나타났고, 주당엽수와 평균 과중 또한 상관이 있었다. 그러나 착과량에 따른 수체생육, 과실품질 요인중 당도 및 착색도에서는 처리간 차이가 없었다. 격년결실이 발생하지 않으면서 300g 이상의 과실을 생산하는 기준은 엽과비는 55 수준에서 착과량이 주당 약 $55{\sim}64$개의 수준이 적합하였다. '후지'/M.9 밀식재배시 성목기의 안정된 수세 기준은 평균 신초장이 $20{\sim}25cm$, 신초 정지율이 95% 이상수준을 보여야 되는 것으로 판단되며, 보다 세부적으로는 2차 생장이 거의 발생되지 않으며 과대지 비율은 적어도 $20{\sim}30%$ 정도 되어야 할 것으로 판단되었다.

• 한국환경농학회지
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• 제38권3호
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• pp.145-153
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• 2019

BACKGROUND: The 'Gamhong' cultivar, middle season apple with big fruit size and high soluble solid content, has been bred in Korea. However, it was hard to cultivate the cultivar in Korea by serious bitter pit. The relationships between shoot growth, fruit size, and bitter pit may be affected by crop load. This study was conducted for 2 years (7~8 years after planting) to investigate vegetative growth, fruit quality, bitter pit incidence, return bloom, and gross income for optimum crop load of 'Gamhong'/M.9 adult apple tree. METHODS AND RESULTS: The crop load was assigned to 4 different object ranges as follow: 45~64, 65~84, 85~104, and 105~124 fruits per tree. The vegetative growth, average fruit weight, percentage of fruits heavier than 375 g, soluble solid content, and return bloom increased significantly at the crop load range of 45~64 fruits. However, the lowest total gross income per tree may have been caused by the highest bitter pit incidence and the lowest yield per tree in any other crop load range. The total gross income and yield per tree increased significantly at the crop load range of 105~124 fruits and return bloom dropped to 40%, and hence it was possible to occur biennial bearing. It was 85~104 fruits that biennial bearing did not occur and total gross income was as high as the crop load range of 105~124 fruits. Also, the yield of high grade fruits per tree, with fruit weight of 400~499 g and none bitter pit on fruit surface, was highest at the crop load range of 85~104 fruits, compared to other crop load range. CONCLUSION: In considering fruit size, bitter pit incidence, return bloom, and gross income, the optimum crop load range of 'Gamhong'/M.9 adult apple tree in high density orchard was 85~104 fruits per tree.