The influence of controlling temperature during apple (Malus domestica Borkh.) maturation on sugars, fruit maturity, and watercore occurrence was investigated in watercore-susceptible `Himekami' and `Fuji' apples. The incidence of watercore at 13/5 and 23/15C was greater than at 33/25C or ambient temperatures in `Himekami' apples in 1991 and was greater at 18/10C than at other temperatures in `Fuji' apples in 1990. In 1992, the extent of watercore increased as fruit temperature decreased from 28 to 14C and 23 to 9C in `Himekami' and `Fuji' apples, respectively. Watercore occurrence affected by fruit temperature was not related to fruit maturity, as judged by ethylene evolution. The effect of fruit temperature on sorbitol was relatively small compared with that on other sugars, and no relationship was found between watercore development and sugars. These results suggest that fruit temperature affects watercore expression independently of fruit maturity or sorbitol metabolism in the fruit in watercore-susceptible apple cultivars.
Hisashi Yamada, Hirokazu Ohmura, Chizuru Arai, and Makoto Terui
Sadao Komori, J. Soejima, Y. Ito, and H. Bessho
Cross-incompatible combinations among the main cultivars in apple are rarely reported in Japan. Recently, however, most new Japanese cultivars are progenies of `Ralls Janet', `Delicious', `Golden Delicious', `Jonathan', and `Indo'. Cross incompatibility in apple, therefore, will become a serious problem in the near future. Since the analysis of the S-allele genotypes were not performed, especially in Japanese apple cultivars, the fruit set percentage were examined in several combinations of `Hatsuaki' (`Jonathan' × `Golden Delicious') and `Iwakami' (`Fuji' × `Jonathan') progenies using back crossings. As a result, we found that `Golden Delicious' and `Jonathan' had no common S-allele, while `Fuji' and `Jonathan' had one common S-allele. These facts were used as basics for the S-allele genotype analysis, and fruit set percentage and seed number per fruit were investigated on a large scale. The cross seedlings between `Delicious' and `Jonathan', `Ralls Janet' and `Jonathan', `Iwakami' and `Golden Delicious', `Golden Delicious' and `Delicious', `Hatsuaki' and `Fuji', `Hatsuaki' and `Delicious', `Hatsuaki' and `Jonathan', and `Hatsuaki' and `Golden Delicious' were analyzed. In addition, incompatibility between `Redgold' and `Kinesei' (`Golden Delicious' × `Ralls Janet'), `Senshu' (`Toukou' × `Fuji') and `Iwakami', and progenies of `Northern Spy' also were analyzed. As a result, we have found the existence of six alleles and 15 genotypes, and we have established S-allele standard cultivars and strains as follows: (Sa, Sb) = `Golden Delicious'; (Sa, Sc) (4)-354, (4)-425; (Sa, Sd) = `Toukou'; (Sa, Se) = `Redgold', `Kinsei'; (Sa, Sf) = `Narihokou', (4)-4195; (Sb, Sc) = `Hatsuaki', `Kuifua', `Sekaiichi'; (Sb, Sd) = `Tsugaru', (4)-300; (Sb, Se) = (4)-150, (4)-743; (Sb, Sf) = `Northern Spy', M.9, `Umezawa'; (Sc, Sd) = `Jonathan', `Himekami'; (Sc, Sf) = `Fuji', `Shinkou'; (Sd, Se) =; (Sd, Sf) = `Senshu', `Iwakami'; (Se, Sf) = `Ralls Janet'.
Hiroshi Iwanami, Shigeki Moriya, Nobuhiro Kotoda, Sae Takahashi, and Kazuyuki Abe
’ × ‘Shinsekai’, ‘Senshu’ × ‘Shinsekai’, ‘Senshu’ × ‘Kotaro’, ‘Fuji’ × ‘Megumi’, ‘Fuji’ × ‘Orin’, ‘Fuji’ × ‘Tsugaru’, ‘Fuji’ × Morioka 57, ‘Kitaro’ × ‘Tsugaru’, and ‘Hatsuaki’ × ‘Megumi’); ( B ) seven crosses (‘Fuji’ × ‘Himekami’, ‘Senshu’ × ‘Himekami’, ‘Fuji
Keiko Sekido, Yusaku Hayashi, Kunio Yamada, Katsuhiro Shiratake, Shogo Matsumoto, Tsutomu Maejima, and Hiromitsu Komatsu
cross combinations (‘Jonathan’ × ‘Pink Pearl’, ‘Himekami’ × ‘Pink Pearl’, ‘Megumi’ × ‘Pink Pearl’) exhibited an ≈1:1 segregation ratio of red:white flesh, suggesting that the red flesh trait of progenies seemed to be inherited by mainly a single dominant