HARVEST INDEXES, STORABILITY, AND POSTSTORAGE REFRIGERATION REQUIREMENT OF SUNRISE APPLE

Starch index and seed color are useful harvest indices for 'Sunrise' a pple (Malus xdomestica Borkh.), Increases in starch index value (appro ximate to 1.4 units per week) and percent brown seed color (approximat e to 27% per week) were linearly correlated with harvest time and para lleled the increase in percent ripe fruit,'Sunrise' was best picked, w ithin a I-week harvest window, at starch index values between 2.5 and 3.5 on a 0-9 scale, percent brown seed color of 30% to 50%, and flesh firmness of 69 to 73 N, Firmness loss was comparable to other apple cu ltivars during harvest (approximate to 5 N per week) and during air or CA storage. However,'Sunrise' fruit lost 18 to 27 N firmness during a 7-d 20 degrees C poststorage shelf-life test, resulting in fruit that was well below 49 N, the minimal firmness for consumer acceptance. Fr uit previously stored at 0 degrees C had a shelf-life of 3 to 4 d at 2 0 degrees C, even though the fruit was picked at the correct maturity and had 70 to 74 N firmness at the end of storage, To ensure good eati ng quality, fruit must be held continuously at 0 degrees C until consu mption. Firmness loss during shelf-life tests was higher for fruit har vested at starch index values between 1.3 and 2.4 and held in 0 degree s C air for 3 to 12 d (13 to 24 N firmness drop) than for fruit left o n the tree and harvested at starch index 2.9 (10 N firmness drop). Fru it held in storage for 1 to 3 months were susceptible to flesh brownin g, flesh breakdown, core browning, stem-end browning, and storage rots . Early-picked (starch index <2.4) fruit held in CA for 1 month develo ped skin disorders resembling those of CO2 injury and scald.