Studies On The Relative Physiological And Biochemical Characters In Sugarcane During The Growth Of Internodes

Eight sugarcane (Saccharum officinarum L.) genotypes were employed in three experiments. They were Badila (Saccharum officinarum L.), Saccharum spontaneum L. , three sugarcane varieties (Saccharum spp. hybrid), i.e. middle-thin cane variety NL8, middle cane variety ROC16, middle-thick cane variety YT86-368, and three other F, clones whose parents were Co419XYN73-204 named Clone One, Clone Two and Clone Three according to their cane diameter from thin to thick. There were three experiments in our research. Experiment One and Experiment Two were main experiments. Experiment One employed NL8, ROC16 and YT86?68 as materials. Experiment Two employed Saccharum spontaneum L., Badila and three Fi clones as materials. Experimemt Three was complementary experiment which employed the ratoon plants as the plant materials whose varities were the same as those in Experiment One. Different internodes and leaves were sampled at the elongating stage and the technical maturing stage. Some physiological and biochemical characters of the different internodes or leaves were assayed. Those characters included the content of the total soluble sugar, reducing sugar, soluble protein, ionically-bound protein and covalently-bound protein in the cell wall, the superoxide anion radical, chlorophyll, carotenoid , and activities of the soluble Mg²⁺-ATPase, ionically-bound Mg²⁺-ATPase and covalently-bound Mg²⁺-ATPase in the cell wall, the soluble peroxidase, the ionically-bound peroxidase and covalently-bound peroxidase in the cell wall, the soluble superoxide dismutase, soluble polyphenol oxidase and some parameters of chlorophyll fluorescence. The length of internodes and leaves, the leaf width and internode diameter were determined. The results were as follows.1. During the growth of the internodes down the stalk of sugarcane, changes of the physiological and biochemical characters in different internodes and leaves were similar in many aspects although the stalk diameter was quite different among the genotypes.At the early elongating stage, contents of the soluble protein, the ionically-bound protein and the covalently-bound protein in the cell wall, and activities of the soluble Mg²⁺-ATPase, the ionically-bound Mg²⁺-ATPase and the covalently-bound Mg²⁺-ATPase in the cell wall decreased rapidly from InternodeThree to Internode Five and then slowly from Internode Five to Internode Eight. The content of the superoxide anion radical and the activities of soluble superoxidase dismutase in leaves increased gradually from Leaf Two to Leaf Five and Eight. The parameters of chlorophyll fluorescence such as Fo, Fm decreased gradually from Leaf One to Leaf Three and Five.At the middle elongating stage and technical maturing stage, changes of the physiological and biochemical characters in different internodes and leaves were similar, but still there were some difference in many aspects during growth of the internodes down the stalk of sugarcane. Contents of the soluble protein, superoxide anion radical, and activities of the soluble Mg²⁺-ATPase, peroxidase, superoxide dismutase, polyphenol oxidase, the ionically-bound peroxidase and the covalently-bound peroxidase in the cell wall decreased rapidly from Internode Three to Internode Five. Activities of the soluble Mg²⁺-ATPase, peroxidase, polyphenol oxidase, the ionically-bound peroxidase and the covalently-bound peroxidase in the cell wall decreased gradually and they were very low even not available below Internode Five. But contents of the soluble protein, superoxide anion radical and activities of the superoxede dismutase showed a trend of increasing gradually below Internode Five. At the same internode from the top, contents of the soluble protein and activities2+of the soluble Mg²⁺-ATPase were higher, but the activity of the superoxide dismutase was lower at the technical maturing stage than at the middle elongating stage. Activities of the soluble peroxidase, polyphenol oxidase and superoxide dismutase in maturing internodes were higher at the m...