Research On Physiological Changes Of Different Muskmelon Cultivers During The Senescene Period

The physiological changes about qulity,protective enzyme,MDA,polyamine,peel cell structure of three major muskmelon cultivars("huanghemi","yujinxiang","yingdi") in Gansu was analysised after storaged at the different temperature, in order to make clear the mechanism of senescence, and provide the theoretics basis for the storage technology of muskmelons.The results showed as fellows:1.The physiological changes of three cultivars during the senescene period The SSC of three cultivars was rising ;the firmness was droping ;the water was dissipating. The respiratory intensity was changed regularly,belong to the spring fruit. The enzyme activity of PAs,MDA changed regularly,which could be suggested to determine the criterion of ripening and senescene.The content of Spm was more than Put and Spd .Spm was droping during the whole storage period.The cell structure gradually becomed looser during the senescene period,the cell gap gradually becomed wider, the lignin obviously accumulated. The colour change of isozyme expiained the POD activity becomed higher,especially yindi and yujinxiang.2. The physiological difference among three cultivars during the senescene period The drop of firmness and the change of the loss of water were related to the characters of cultivars, droping extent of firmness in the longer-storage cultivars was smaller, whereas in the shorter-storage cultivars.The change of respiratory intensitiy was positively related to the characters of cultivars. Yujinxiang, a shorter-storage cultivar, the respiratory intensitiy was highest of all. Huanghemi, a longer-storage cultivar, lowest of all.The PAs,MDA changed regularly among three cultivar. which could be suggested to determine the criterion of ripening and senescene.The change of Spm content are related to the characters of cultivars. The content in longer-storage cultivar was higher than in shorter-storage cultivar. The difference of colour and band of isozyme expiained the difference of POD activity among the different cultivars.3. The physiological changes of different cultivars storaged at the different temperatureThe droping speed of firmness becomed slower,the SSC was rising ,the loss of water was droping storaged at the low temperature.it was helpful to maintain the quality of fruit.Storage temperature have a obvious influence on respiratory intensity,storaged at the low temperature not only reducd the respiratory intensity,but also put off the appear of respiratory apex,prolong the storage life of fruit. There was obvious change in the enzyme activity of PAs storaged at the low temperature, and there was obvious change in shorter-storage cultivar, tiny change in longer-storage cultivar .The MDA content was reduced storaged at the low temperature.There was obvious influence for content of polyamine storaged at the low temperature,that is Spm content was higher than storaged at the normal temperature. the colour change of isozyme expiained that the rising of POD activity was restrained storaged at the low temperature.At the same time it was helpful to maintain the cell structure,reduce aggradation of the lignin.