ศูนย์นวัตกรรมเทคโนโลยีหลังการเก็บเกี่ยว

Preharvest field heat and postharvest fruit response.

Ferguson, I. B.; Snelgar, W.; Bowen, J. H.; Woolf, A. B.;

Acta Horticulturae Year: 1999 Issue: No. 485 Pages: 149-154 Ref: 14 ref.

1999

บทคัดย่อ

Temperatures in the flesh of apple and avocado fruits were measured in the field over diurnal cycles, and the postharvest responses of these fruits to temperature were assessed. In both fruits, flesh temperatures exceeded 35 deg C, and sometimes reached 40 deg C and above, for 2 h or more in direct sunlight, even though air temperatures did not exceed 30 deg C. With night temperatures dropping to 10 deg C or lower, the diurnal range sometimes exceeded 25 deg C. A ubiquitous response to high temperatures in all organisms is the induction of heat-shock protein(s) (hsp) genes and associated protein synthesis. Hsp play a role in thermotolerance. In both fruits, mRNA for hsp were upregulated at temperatures above approx. 33 deg C, and the transcripts remained at an elevated level over the cooler night period. With warming up of fruits, hsp's mRNA levels rapidly declined until temperatures reached inducible levels again. This induction of hsp in fruits in the field indicates that fruits, even under te

mperate conditions, respond daily to temperatures commonly regarded as being in the stress range. Postharvest responses associated with prior high temperature or exposure history of the fruits included exposed sides of apple fruits having higher flesh firmness, and previously exposed avocado fruits having greater resistance to low temperature injury, slower ripening rates and higher thermotolerance. It is concluded that both long-term exposure of fruits and immediate temperature history close to harvest are likely to influence fruit responses to high temperature postharvest treatments and low temperature storage.