| Due to the importance of sugarcane as a raw material for sugar industry, sucrose quality of sugarcane plays a key role in the development of sugar industry. In field production, sucrose quality of sugarcane is affected by inheritable characters of the cultured varieties and culture environment. For a long time, researchers have been in an endeavor to the breeding of new varieties with high yield and brix genotype, obtaining sugarcane with high sucrose quality through breeding and improving the culture environment. Traits (phenotype) of sugarcane are the results of interactions between the genotype and environment, and only through a variety of biochemical and metabolic reactions in sugarcane, the effects of both genes and environmental factors on these traits can display.The objective in this study was to reveal the physiological indices indicating high sucrose quality traits of sugarcane. Laboratorial experiments were conducted on nine varieties:Co-331, Co-419, GT-11, YZ89-151, MT69-421, YT93-159, YZ71-388, and ROC-20. At the early mature stage of sugarcane, i.e. from the late November,5 consecutive collections of+1 leaves from normal plants with the interval of 20 d were conducted. To investigate the effects of major enzyme systems and endogenous hormones on the sugarcane yield and quality, the activities of three enzymes, acid invertase, neutral invertase and diastase, and four hormones, auxin, gibberellin, cytokinin and abscisin in the middle tissue of leaf were assayed, and the cane quality and sugar content were measured. All data were analyzed with SPSS.The results indicated that in the course of the sugarcane maturing and sugar accumulating, the content of sugar in cane increased gradually, activities of acid invertase and neutral followed the trend of low-high-low-high, diastase activity decreased continuously, auxin activity decreased rapidly from the high to the low level, the activity of gibberellin varied along the low-high-low route, and the activities of cytokinin and abscisin decreased slowly at the bigginning and then increaed slowly.Correlation analysis suggested that sugar accumulation correlated extremely significantly positively with the activity of acid invertase and neutral invertase, and negatively with diastase respectively; while correlated positively with cytokinin and abscisin, negatively with auxin and gibberellin. Furthermore, the four endogenous hormones were found interplaying in the mature stage of sugarcane. The activity of abscisin was extremely significantly correlated negatively with gibberellin, positively with cytokinin, and significantly positively correlated with auxin. The activity of cytokinin was extremely significantly correlated negatively with gibberellin, and positively with auxin. The enzymes including neutral invertase and diastase also interplayed with the hormones such as auxin, gibberellin and abscisin. The activity of gibberellin correlated positively with diastase at extremely siganificant level, abscisin activity correlated positively with neutral invertase and was affected negatively by diastase, while auxin activity correlated negatively with neutral invertase at extremely siganificant level. In the present study, the relationship between the sugar accumulation and the interactions among acid invertase, neutral invertase, diastase, auxin, gibberellin, cytokinin and abscisin in the mature stage of sugarcane was documented at physiological level. Stimulative or inhibitive effects through interactions between invertase, neutral invertase, diastase and auxin, gibberellin, cytokinin and abscisin were found in this study. The results also suggested that decreasing the activities of endogenous auxin and gibberellin, increasing the activity of abscisin could decrease the activity of acid invertase and diastase, and then increase the activity of neutral invertase; while these further variations could be in favor of maturing of sugarcane and improve sucrose quality. |
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