| Nai plum fruit (Prunus salicina Lindl. Var. cordata J. Y. Zhang et al), whichbelongs to rosaceous family, enjoys the reputation as "the king of plum fruit" with the characterof nutrition, good size, attractiveness, delicious and market value. Unfortunately, it is not easy toextend the shelf life of the fresh fruit on the market because it is thin pericarp and juicy and thetemperature was very high during the harvest season, the usual storage methods could hardlysolve the problems of limited shelf life of Nai plum fruit. Low temperature storage could extendstorage time of the fresh fruit efficiently. Nevertheless, to keep the fi-uit at low temperature fortoo long period of time may result in chilling injury.Heat treatment can improve the chilling tolerance of plants. In this study, the effects ofdifferent heat treatment temperature regimes and time (36℃for 4h or 8h; 40℃for 4h or 8h,44℃for 0.5h, 1h, 4h and 8h, respectively) on the chilling tolerance, qualitative andPhysiological attributes of Nai-Plum fruit were investigated. In order to prolong the shelf life ofthe fruit and to increase the preservation efficiency, This paper studied the followingParameters: chilling tolerance, heat shock proteins (HSPs), the endogenetic hormone level,the cell structure, storage quality. The physiological mechanism of improving anti-chillinginjury was discussed, which Provided theoretical bases for the storage of Nai plum fruit.Suitable temperature and time of pre-storage heat treatment couid significantly improve thestorage quality and chilling tolerance of Nai-plum fruits. We found heat treatment for 4h at 40℃was able to get best efficiency of improving chilling tolerance; But too high temperature andtoo long time of heat treatment would lead to heat injury, which the heat injury was occurredwith the characteristic of brown spot on the surface of the fruits after heat treatment for both 4hand 8h at 44℃,Heat treatment for 8h at both 36℃and 40℃was able to induce the production of heat shock proteins (HSPs), but 4h couldn't. Heat treatment for 0.5h or 1h at 44℃could also induceHSPs of Nai-plum fruits. During the cold storage of Nai-plum fruits, the longer they werekept for, the more the species and quantity of HSPs reduced. Heat treatment for 8hinduced more species of HSPs than those for 4h.Heat treatment resulted in the variation of Indole-3-acetic Acid(IAA), GibberellinAcid(GA) and Abscisic Acid(ABA), but it has no significant effect on the production ofZeatin riboside(ZR); Multi-factor regression analysis showed that the Chilling Injury(CI)incidence (70d) with the level of four kinds of phytohormone (0d) was correlatednegatively, and the equation was able to be expressed as CI(%)=30.567—1.057IAA—116.08ABA—0.907ZR—0.1836GA3.Heat treatment was able to maintain the firmness and the integrity of cell structure ofNai-plum fruits, and didn't effect total soluble solid(TSS), but the sugar/acid ratio risedsignificantly. The Membrane Permeability of Nai-plum fruits fluctuate in a certain range, i.e, theconductivity tend to decrease in the prophase of storage, and to increase in the metaphaseand decrease in the anaphase.
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