| Annual apple seedlings of M.hupehensis Rehd and M.micromalus Makin and 7-year-old trees of M.domestica Borkh var.Red Fuji/ M.hupehensis Rehd were used as materials to study the ultraweak luminescence(UWL) and its physiological and biochemical mechanism. The relationship between drought-resistance and UWL of the two apple seedlings was evaluated. Moreover, the changes of UWL and some relative physical characters during apricot florescence and peach fruit softening were also probed. The main results were as follows:1.The UWL intensity of leaf and root was increased with the growth of seedlings and the sequence of UWL intensity was new leaf > cotyledon > root. The UWL intensity of middle leaf on the young tree was the highest, top young leaf took the second place and basal leaf the lowest.2. Under water stress, UWL intensity of both seedling leaf and root was down. The higher level of stress, the more extent UWL declined. The changing range of UWL was different in different position leaf of young tree: the UWL intensity of mature leaf with strong chloroplast's function was the highest and the decreasing range was the smallest. On the contrary, the UWL intensity of young leaf and old leaf with weak chloroplast's function was low and the decreasing range was large. UWL intensity was positively correlated to the energy metabolism represented by ATP at the 0.01 level and positively correlated to the relative water content of leaf and root activity at the 0.05 level. While there was a negative significant correlation between UWL intensity and O2 production rate and plasma membrane permeability. The drought resistance of the two apple seedlings reflected by UWL and other physiological characters were consistent. The UWL intensity of Mainsmicromalus with strong drought resistance was higher than that of M.hupehensis which was at the same age of Malus micromalus.3. The changes of active oxygen production rate and MDA content were smooth before the peak season of blossom during the florescence of apricot (Ameniaca.vulgaris Lam.). The UWL intensity and ATP content were both rising and the respiration rate also mainly showed the trend of rise at the same time. After the peak season of blossom, the respiration rate and ATP content declined rapidly while the UWL intensity went down slowly, but the active oxygen production rate increased rapidly. The protein content increased at first and then decreased during the florescence of apricot. The change hi MDA content was similar to the change in active oxygen production rate, which rose rapidly after the peak season of blossom. The result showed that the UWL was closely related to the energy level symbolized by ATP content and was affected by active oxygen metabolism in the apricot flower. The ATP content was the main factor to lead to the rise of UWL before the full bloom stage while the action of active oxygen on UWL appeared just after the peak season of blossom.4. There was a marked peak of UWL during the Fei-Cheng peach (Prumis persica c.v. Fei-Cheng)fruit softening whether in room temperature or in low temperature (0) storage. The peaks of UWL and ethylene production rate appeared almost at the same time and the changing trends of them were also similar no matter what conditions or treatments. When fruits were treated with 2-aminoethoxyvinylglycine (AVG), an ethylene synthesis inhibitor, the rate of ethylene production decreased, but the intensity of UWL did not decrease. When fruits were treated with ethrel, an ethylene release reagent, the rate of ethylene release increased, but the intensity of UWL did not increase. This indicates that the rates of change in UWL and ethylene production were not interdependent. The appearance of UWL peak may be the reflection of the active metabolism during fruit storage.5. The UWL intensity of mitochondria suspension was positively correlativeto its concentration (0-100 mg/ml). The UWL intensity of mitochondriasuspension stimulated by the exogenous active oxygen increased significantlyand the duration of high U...
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