Studies On The Sucrose-metabolizing Enzymes In Navel Orange Fruit From Different Habitats

Applying 9 to 12-year old Roberson navel orange trees(Citrus sinensis Osbeck) grafted on Citrus tangerine as testing materials, using the methods of combining field biological and ecological investigation and indoors analysis ,the activity changes of enzymes related to sugar metabolism during fruit growth and their relationships with the sugar accumulation, the comparisons of enzymes related to sugar metabolism in different habitats, the effects of ecological factors on sucrose-metabolism enzymes were studied, the result showed:Sugar content increased during development of navel fruit. At the of stage inflation, inverse activity were high, but with the development of fruit, it decreased quickly ; Sucrose synthase(cleavage dirction) activity increased with fruit growing; sucrose phosphate synthase (SPS)Activity kept a low level; sucrose synthase(synthetic direction) increased to max at 45d after flowering, then reduced. SS(cleavage direction) were the most important enzyme at the stage of inflation. From 90 to 150d after flowering, the activity of SPS increased were in relation of sugar content. From 150 to 195d after flowering, SS(synthetic direction) were the most important enzyme. In the stage of mature, the activity of sucrose-metabolism enzymes reduced a low level when sugar content slowly increased, the sugar in fruit mainly came from leaf. Sucrose metabolism were controlled by sucrose-metabolism enzymes at the same time. So the net activity of sucrose-metabolism enzymeswere very important to sugar metabolism.Sugar content were different in different habitats. Hongge>Changning>Mingshan. In different habitats, the activities sucrose-metabolism enzymes were different. At the stage of inflation, the activity difference of SS(cleavage direction) and AI in different habitats were the cause of sugar content. From 90-150d after flowering, the different activity in different habitats controlled sugar accumulation. From 90 to 195d, SS (synthetic direction) were the most important enzyme in different habitats. In different habitats, the activities of sucrose metabolism enzymes were higher than Changning and Mingshan, among of them, Mingshan were the lest.SS(cleavage direction),SS(synthetic direction) and SPS played main role in sugar accumulation in different habitats. Though the gray system analysis of ecological factors to the activity of SS(cleavage direction), SS(synthetic direction) and SPS, the result showed that average temperature and sunshine rate were mainly ecological factors, espectly the average temperature and the rate of sunshine in the main stage of sugar accumulation. Thus, they became the key indexs for navel orange ecological ivisions.