Studies On The Effects Of Habitat To The Texture And Texture Composition During Development Of Sweet Orange [Citrus Sinesis (L.) Osbeck] Fruit

According to Sichuan province three different habitate: the Southern subtropical dry hot and more sunshine of Jinsha River and Yalong River zone of TongzUin (1098 meters above sea level)and Hong'ge town(1476 meters above sea level),Yanbian County; the Middle-subtropical wet hot and more sunshine region of Yile town and Anle state farm, Jiang'an County(420 meters above sea level); the north-middle- subtropical wet hot and less sunshine region, Pujiang (505 meters above sea level),Ya'an(612 meters above sea level) and Mingshan(645 meters above sea level).Applying two different orange varieties (Robertson Navel Orange [Citrus sinesis(L.) Osbeck] and Valencia Orange [Citrus sinesis(L.) Osbeck]) as testing materials, which above 10 years old on tangerine[C.reticulata] rootstock. Samples were got in orientation and regular date, at the same time the field ecology and biology periodical inspection were made. The cell wall hydrolytic enzyme activities of polygalacturonase (PG, EC 3.2.1.15), pectinmethylesterase (PME, EC 3.1.1.11) and carboxymethlcellulose (CX-cellulase, EC 3.2.1.4) were detected during development of orange fruit in 2002. The changes of main texture indexes and the composition of cell wall were studied during fruit growth and maturation as well. The result showed:1. During the course of fruit developing and maturating, main texture indexes of orange had changed. The water pectin (WP) increased significantly with the development of fruit; meanwhile the HC1 soluble pectin (HP) and total pectin were declined. The content of fibers on the young stage was highest then declined sharply correlated with the days of anthesis. The content of ADF and NDF in Valencia Orange were higher than in Robertson Navel Orange during development of fruit The content of hemicelluloses were less than ADF and NDF. And the changes of hemicelluloses were little either. CX, PME and PG were existed in two different habitate during development of fruit but two ecotypes and two varieties differ greatly in enzyme activity. Naval orange fruit had a strong enzyme activity but Valencia weaker. The CX relative activity of naval orange and Valencia fruit were low at young stage and the expand stage. To time of pre- maturation the CX relative activity was inclined prompt, and then to full- maturation stage the activity was declined. Valencia PME relative activityinclined little during fiuit development and different ecotype changed little, activity differs minor. Navel orange PME relative activity showed a distinct "U" character trend, meaning two-tail(young stage and maturation stage) had stronger activity, between (expand stage) tend to weaker. In addition, the PME activity of mature stage rising bear relation to ecotypes. During young stage and expand stage the PG activity and relative activity were higher than PME. During maturation period the PG activity went steadily up; and deep maturation period fall. Thus, PG had no obvious low valley.2. The effect of ecotypes on orange pulp and fiuit texture.Different habitate had difference effect on Navel orange and Valencia fruit; Such as water content, shape index of fruit, peel thickness, TSS, fruit weight, and so on; texture and digesting residue degree differ greatly. The degree of fruit digest residue had been influenced by the PME, CX and PG chiefly. The fruit texture and digest residue degree had an effect on each other. If the fruit taste more brittleness, possibility the digest residue was accepted more reasonable. And probably the more TSS was, the more brittleness texture tasted. CX relative activity was significant correlated with digest residue positively. CX coordination with PG acted on pulp. And CX must take effect on Valencia fruit pulp then the digest residue can be tasted well. However, navel orange fruit was combined action by PME, PG and CX.Less than three different eco-environment of experimental region, the fruit of navel orange whose PG activity, protein content and the CX relative activity of pulp was remarkable negative correlated with fruit texture di...