Effects Of Salicylic Acid On Respiratory Pathway Of Postharvest Huang-guan Pear (Pyrus Bretschneideri Rehd.)

Postharvest Huang-guan pear(P. pyrifolia. cv. Whangkeumbae) were used as the experiment material with different concentrations of SA solution. The effects of SA on respiration had been studied. Measurement of respiratory intensity of respiration, content of superoxide anion, while respiratory intensity and activities of key enzymes were studied at Embden-Meyerhof-Parnas pathway (EMP), Tricarboxyfic-acid-cycle pathway (TCA), Phosphopentose pathway (PPP) and electron transport respiratory chain. Relationships among content of superoxide anion(O2-.), respiratory intensity of each respiratory pathway and respiratory intensity of respiration were studied, relationships between each respiratory pathway and respiratory enzyme were investigated, which provides the theoretical foundation for change of nutrition components and storage of post-harvest fruit. The main results were as follows:1. SA at different concentration decreased the respiratory intensity of respiration of Huang-guan pear. SA at 0.02 mmol/L and 0.2 mmol/L had significant effect, respiratory intensity of respiration was decreased by 64% and 54% after 10 days of treatment.2. The respiratory intensity of EMP, TCA, PPP was decreased significantly, and enzyme activities of Phosphohexoisomerase, succinic dehydrogenase, Glucose -6- phosphate dehydrogenase and 6-Phosphogluconate dehydrogenas with 0.02 mmol/L SA. The trend in respiratory intensity of EMP, TCA, PPP was coincided with the enzyme activities of EMP, TCA, PPP, and respiratory intensity of EMP, TCA, PPP was positive correlation with enzyme activities of EMP, TCA, PPP.3. SA at different concentration decreased the respiratory intensity of alternative pathway, and SA at 0.02 mmol/L had significant effect. Respiratory intensity of Cytochrome pathway was positive correlated with Cytochrome oxidase. The trend in respiratory intensity of Cytochrome pathway was coincident with the enzyme activity of Cytochrome oxidase, and respiratory intensity of alternative pathway was positive correlated with rate of EMP, TCA, PPP .5. SA at different concentration regulated of respiratory intensity of each glucose metabolism by enzyme activity of relevant-respiratory pathway, respiratory intensity of alternative way was regulated by respiratory intensity of EMP, TCA, PPP, while Cytochrome Pathway was regulated by activity of Cytochrome Oxidase.5. SA at different concentration decreased content of O2-. of Huang-guan pear. SA at 0.02 mmol/L and 0.2 mmol/L had significant effect. A positive correlationship was found between content of O2-. and respiratory intensity of respiration.6. After treatments of SA, decreases of total respiration intensity, respiration intensity of EMP, TCA, PPP and alternative pathway, and activities of repective key enzymes as well as content of O2-. contribute to deferment of fruit and as a result extend the storage period.