Abstract
Gamhong’ is a midseason, high fresh eating quality red apple (Malus domestica Borkh.) that has high popularity in Korea. ‘Gamhong’ however is prone to bitter pit or russet. Over two growing seasons, different types of calcium (Ca) were applied in either soil or foliar spray to 5 year-old ‘Gamhong’/M.26 apples which had severe bitter pit in 2004. We sprayed calcium chloride (CaCl2), prohexadione-Ca (Pro-Ca) to soil or leaves, and covered fruits with Ca-coated paper bags in 2005. Drenching lime stone liquid or CaCl2 solution on soil were not effective in the reduction of bitter pit, while foliar spraying two times of 0.5% CaCl2 before paper bagging was effective in the reduction of bitter pit while increasing Ca content of peels. Great effect on reduction of bitter pit and on enhancement of Ca content in peels was attained by three different treatments: leaves spraying of 0.5% CaCl2 three times before bagging; Pro-Ca spraying five days after full blooming; and Ca-coated paper bagging 4-5 weeks after full blooming. However, the best result was shown by foliar spraying three times of 0.5% CaCl2 followed by Ca-coated paper bagging.
고두병 발생이 심하였던 5년생 ‘감홍’/M.26 사과나무를 택하여 2004년에 각종 칼슘의 토양관주, 염화칼슘의 수체살포를 실시하였으며, 2005년에는 염화칼슘 엽면살포, 칼슘도포봉지 씌우기 및 proheaxadion-Ca 살포를 행하고 고두병 발생과 과피의 칼슘함량에 미치는 이들의 효과를 검토하였다. 생석회액 또는 염화칼슘액의 토양 관주는 고두병 발생을 감소시키지 못하였다. 봉지 씌우기 전 0.5% 염화칼슘 3회 살포는 고두병 발생 감소와 과피의 칼슘 함량 증가에 효과가 있었다. 봉지 씌우기전에 0.5% 염화칼슘 3회 살포와 만개 5일 후 proheaxadione-Ca을 살포하고 만개 4-5주 후에 과실의 칼슘도포봉지 씌우기는 고두병 발생을 감소시키고 과피의 칼슘함량을 증가시켰다. 그리고 고두병 방지효과는 0.5% 염화칼슘 3회 살포 후 칼슘도포봉지를 씌운 처리가 좋았다.