M.7 사과 대목이 고밀식 ‘후지’, ‘홍로’, ‘산사’ 사과나무의 생산량 및 과실품질에 미치는 영향

Most apple trees in South Korea are grafted on M.9 and M.26 rootstocks; however, these rootstocks are suscep tible to fire blight. Although M.7 rootstocks are moder ately resistant to fire blight, they tend to exhibit ex cessive vigor, which is unsuitable for high-density planting, unless weak cultivars are used. This study in vestigated 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 ap ple orchards domestically using the M.7 rootstock a pe riod of seven years (1-7 years after planting). Rootstocks were tested using three cultivars with contrasting in duced vigor and harvesting times: vigorous and late-ma turing ‘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.