Effects Of Salicylic Acid On Respiratory Pathway Of Ya-li Pear (Pyrus Bretschneideri Rehd.cv.Yali)

Respiration is an important process of fruits associated with fruit quality decline. Therefore, it is very crucial to maintain the respiration rate at a minimum level as much as possible to prolong the storage life of fruits .Temperature is one of the key environmental factors that influence fruit respiration process. Salicylic Acid (Salicylic Acid, SA) in plants has a variety of important physiological functions, and it was considered as a new kind of endogenous hormones. It will be helpful to reveal the inherent mechanism of respiration by studying the effect of salicylic acid on fruit physiological and biochemical characteristics, which also provides a reference for the postharvest storage theory. In this study, the effect of Salicylic acid treatment on the total respiration rate, respiration pathway, the key enzyme and climacteric respiration of'Ya Li'pear both at room temperature and cold storage was studied. The main results were as follows:1. SA treatment decreased the respiratory intensity of Ya-li Pear. SA at 0.02 mmol/L had better effect at room temperature, SA at 0.002 mmol/L had significant effect at 0～2℃and 8～10℃, while SA at 0.2 mmol/L had better effect at 12～14℃.2. Activities of Embden-Meyerhof-Parnas (EMP), Tricarboxyfic acid cycle (TCA),Phosphopentose pathway (PPP),Cytochrome Pathway, alternative Pathway, enzyme activities were all reduced with the treatment of SA at different concentration. It appeared that SA regulated the respiratory intensity of respiratory pathway by regulating the enzyme activities of relevant-respiratory pathway.3. SA treatment decreased content of O2-of Ya-li pear. SA at 0.02 mmol/L had significant effect at 26～28℃, SA at 0.002 mmol/L had better effect at 0-2℃and 8～10℃, SA at 0.2 mmol/L had better effect at 12～14℃. A positive correlation was found between content of O2-and respiratory intensity.4.,'Ya Li'pear appeared climacteric respiration at room temperature .When there is the climacteric and the peak of light respiration, the pear fruit respiration pathway changed, EMP and a proportion of alternative pathway raised, while TCA ,PPP and the cytochrome pathway decreased.5. The content of O2- has declined with the increase of cyanide-resistant respiration. Cyanide-resistant respiration was significantly negatively correlated with the content of O2- . It proved that "antioxidant" theory of the alternative pathway is correct .6. After being treated by different concentrations of exogenous SA at different temperature, the respiration rate of Ya-li fruits at storage stepped down, and the respiration climacteric was postponed or even inhibited. The trend of respiratory Pathway was regulated, which contributed to defer the fruit senescence storaged at 0～2℃.7. Different storage temperature caused changes in respiration pathway, and low- temperature could increase the proportion of PPP and the alternative pathway, as well as reduced the proportion of EMP, TCA, and cytochrome pathway.