RESPONSE of APPLE and WINTERPEAR FRUIT QUALITY to IRRADIATION AS A QUARANTINE TREATMENT

Abstract

Irradiation at doses between 0.30 and 0.90 kGy reduced apple firmness. Doses of <0.30 kGy had no effect on apple firmness. Firmness lost due to frradiation was cultivar dependent. Titratable acidity (TA) of ‘Gala’ apples was reduced at irradiation doses of 0.60 kGy and above. No loss of TA due to the irradiation dose was evident, for ‘Fuji’ or ‘Granny Smith’ apples. Irradiation did not influence the external color of apples. but change in the internal color of ‘Gala’ and ‘Granny Smith’ apples due to irradiation exposure was present. ‘Bosc’ pears lost firmness due to irradiation, and the firmness loss was dose dependent. Both, ‘Anjou’ and ‘Bosc’ ripened normally after irradiation exposure. There was an increase in scald for ‘Anjou’ that was dose dependent. Disease incidence of ‘Fuji’ and ‘Granny Smith’ apples caused by P. expansum was reduced from about 80% of wounds with lesions to 30% after irradiation exposure. Irradiation had no effect on number of lesions caused by either B. cinerea or M. piriformis. No effect was observed on decay of ‘Anjou’ pear fruit naturally infected with P. expansum and B. cinerea. However, a reduction in decay was observed in naturally infected ‘Bosc’ pear fruits treated with 0.90 kGy.