Physiological adaptation and recovery of eggplant plug seedlings to low temperature and low-intensity light during storage

The effects of low temperature (9 degrees C) and low-intensity light (5 h photoperiod; photosynthetic photon flux density, 24 mu mol m(-2) s(-1)) on physiological changes in eggplant (Solanum melongena L.) plug seedlings during storage, and on the recovery of these plants after removal from storage, were investigated. Growth of the stored eggplant plug seedlings was suppressed significantly compared to that of control plants. The concentrations of chlorophylls a and b in treated plants (Tr) decreased by 6.2% (P > 0.05) and 13% (P < 0.05), respectively, during storage. Chlorophyll concentrations exhibited a decline during the first 5 d of storage, but increased slightly thereafter. Carotenoid concentrations in Tr seedlings increased by 55% (P < 0.05) in the first 5 d of storage, then decreased by 40% (P < 0.05) after 15 d of storage. Meanwhile, the triphenyltetrazolium chloride (TTC) deoxidisation capacity of the roots of Tr seedlings decreased by 14%, only 57% of that in control plants, after 15 d of storage. The activities of superoxide dismutase (SOD) and peroxidase (POD) in the leaves of Tr seedlings increased by 154% and 126%, respectively, during the first 10 d of storage (P < 0.05). SOD activity then decreased by 12% (P < 0.05) and the activity of POD decreased by 10% (P > 0.05) during the last 5 d of storage. Malondialdehyde (MDA) concentrations reached a peak of 1.7 mu mol g(-1) FW at day-15 of storage in Tr seedlings. After removal from storage and transplanting, the rates of photosynthesis and transpiration in Tr plants showed a rapid and steady recovery, compared to those of control plants.