Studies On The Effect Of Habitate To Key Enzymes Which Influence Texture Of Sweet Orange [Citrus Sinesis(L.)Osbeck] Fruit And The Change Of The Key Enzymes Activation

Applying two different orange varieties Robertson Navel Orange[Citrus sinesis(L)Osbeck] and Valencia Orange [Citrus sinesis(L)Osbeck] as testing materials, which had grafted on tangerine[C.reiculata] rootstock for 10 years. Using the methods of combining field biological and ecological investigation and indoor analysis, the activity changes of key enzymes related to sweet oranges texture during fruit growth, the activity changes of key enzymes which effect on texture of the peel and pulp, the comparisons of key enzymes related to Navel Orange texture in different habitats, the effects of ecological factors on key enzymes related to Navel Orange texture were studied, the result showed:1. During the course of fruit developing and maturating, Polygalacturonase (PG) activity of sweet orange rose constantly in the same habitat. PG activity of navel orange pulp reached maximum earlier than Valencia Orange about one month. Cellulase(Cx) activity of sweet orange peel rose firstly and then decreased rapidly during fruit growth. But Cx activity of navel orange peel reached maximum earlier than Valencia Orange about one month and Cx activity of sweet orange were increased at young stage.2. During the course of fruit developing and maturating, Cx activity of sweet orange pulp were low at young stage. Cx activation of navel orange pulp is higher than Valencia Orange from 85days after anthesis to 220 days after anthesis.3. Cx and PG activation of pulp is higher than peel during navel orange fruit growth. Cx activation of peel rose while Cx activation of the pulp is the lowest at young stage. From 85 days after anthesis to 115 days after anthesis, PG activation of pulp reached maximum while Cx activation of pulp began to rise, which indicated that Cx and PG activation of pulp play an important role at expand stage. Especially the function that PGof pulp effect on hydrolysis of pectin is particularly important. Cx activation of pulp rose constantly and reached maximum froml30 days after anthesis to 175 days after anthesis.4, In different habitats, PG activation of navel orange pulp showed much difference each other. In different habitats, PG activation of navel orange pulp reached maximum at expand stage. From 115 days after anthesis to 220 days after anthesis, PG activation of navel orange pulp keep the same with the texture index of navel orange in different habitats. PG of the navel orange pulp is one of the enzymes effect on the texture index of navel orange.5, In different habitats, Cx of navel orange pulp had a significant difference in activity. After 100 days after anthesis, Cx activation of navel orange pulp at Hong'ge is higher than Jiang" an and Ming'shan notably. In different habitats, Cx activation of navel orange pulp is one of the main factors of influencing the remarkable difference of fruit digest residue at fruit ripening stage.6, In different habitats, PG of navel orange peel had a significant difference inactivity. From 115 days after anthesis to 190 days after anthesis, PG activation of navel orange peel keep the same with the texture index of navel orange in different habitats. It indicated that PG of the navel orange peel is one of the enzymes effect on the skin thickness of navel orange in different habitats.7, Through the gray system analysis of 3 ecological factors to the key enzymes activity, the results showed that the factors which influenced the key enzymes activity were more seriously were sunshine and temperature. Sunshine is the greatest factor influencing the activation of PG and Cx of navel orange pulp at fruit expand stage. Temperature is the greatest factor of effect key enzymes activity at fruit ripening stage. Mean relative humidity is not the important factors influencing the activation of PG and Cx of navel orange pulp during fruit growth. But from 40 days after anthesis to 130 days after anthesis, mean relative humidity is the important factors influencing the activation of PG of navel orange peel. This maybe one of the reasons Hong'ge navel orange peel is thick.