苹果幼树新梢生长期^(14)C同化物的种类和运转特性

Compositions and Translocation Characters of ^(14)C-assimilates at the Shoot-growing Stage in Young Apple Trees

对苹果幼树新梢生长期^(14)C同化物的种类和运转特性研究结果表明:(1)苹果叶片^(14)C同化物主要是糖,以山梨醇含量最高,蔗糖次之,葡萄糖和果糖很少;叶合成的氨基酸主要有天冬氨酸、丝氨酸、丙氨酸和天冬酰胺。(2)山梨醇输出叶片速度大于蔗糖,向所在新梢以上发育部位短途输送以山梨醇为主,向其它器官长距离供应,蔗糖占优势。(3)叶片同化物在一昼夜内即完成地上地下部循环。根系上运物质主要是氨基酸,以谷酰氨,天冬酰胺和天冬氨酸为主。它们在地上部各器官的分配受代谢强度调节,无严格对应关系。

The compositions and the translocation characters of 14 C-assimilates at theshoot-growing stage in pot-cultured young Liao Fu'apple trees were studied during 1986-1987. The results have shown that the major compositions of 14 C assimilates in apple leaves are sugar, sorbitol content is the maximum, sucrose the second, glucose and fructose only a little. The amino acids synthesized in leaves are mainly aspartic acid, serine' alanine and asparagine. The export rate of sorbitol out of leaves is higher tnan that of sucrose. Sorbitol is dominant in short-distance transport from the natured leaves up to the developing parts, but sucrose is mainly transported in long distance to other organs. At the shoot-growing stage of young apple trees, carbon assimilates can finish the leaf-root-top cycle within 24 hours. Parts of sugar imported in roots are transformed into organic acids and amino acids, for example asparagine, glutamine and aspartic acid, then translocated back to the top of tree. The distribution of the substance among the top parts is strictly regulated by metabolism.