Dynamic Changing Of Nonstructural Carbohydrates Through A Growing Season In The Leaves And Rhizomes Of Lymus Chinensis And The Affects Of Soil Salt-alkalization On It

The salt-alkalization of soil and the deterioration of vegetation are the main ecologicalproblem of grassland in our country. Then the recover of vegetation is important to resolvethe problem. The flourish of Leymus chinensis grassland is decided by the productivity andpopulation reproducibility of Leymus chinensis population. The non-structural carbohydrate isclosely related with the reproducibility and physiological estate of Leymus chinensispopulation. The non-structural carbohydrates in the Leymus chinensis include fructan andsome dissolubility small molecule sugars such as sucrose etc. The fructan is a main depotpolysaccharide, and the dissolubility small molecule sugars not only have storage function,but also decide the physiological state or the metabolism level of Leymus chinensis asmetabolic substrates. Therefore, an investigation on dynamic changing of nonstructuralcarbohydrate in Leymus chinensis and the effects of soil salt-alkalization on it has doublesignificances in theories and practicality. It is advantageous to clarify the regulation andrelation between soil salt-alkalization and the degeneration of Leymus chinensis grasslandtheoretically, and also provide the theoretical basis for recovering the ecosystem of Leymuschinensis grassland.According to the present conditions of degenerated Leymus chinensis grassland, foursampling sites with different extents of salt-alkalization were selected in the Institute ofGrassland Science of Songnen located in Changling County. The leaves and rhizomes ofLeymus chinensis were taken as sample to mensurate the contents of the non-structuralcarbohydrates that include sucrose, fructose, solubility total sugar and fructan. Samples weretaken termly overall a growing season at each sampling site. The all shoots and roots werecollected in a unit area to measure total biomass in mid-July. At the same time, soil sampleswere taken from 1-15 cm soil layer. The electric conductivity rate, buffer capacity and pHvalue of the soil samples were measured. The statistical analysis of data was performed. Thenthe seasonal changing regulation of nonstructural carbohydrate contents in the different partsof Leymus chinensis was investigated. The effects of soil salt-alkalization on the changeregulation of nonstructural carbohydrate in Leymus chinensis were analyzed. The resultsshowed as follows:(1) The component and distribution of non-structural carbohydrates in the leaves andrhizomes of Leymus chinensis were obvious different. In rhizomes, the content of fructan wasmarkedly higher than that of other components, and twice higher than that in leaves.Therefore, it could be considered that the fructan was the main form of depot substance forLeymus chinensis.(2) The seasonal changing of the non-structural carbohydrates was closely related withthe physiological state of the leaves or rhizomes of Leymus chinensis. The contents ofdissolubility saccharide did not significantly changed through a growing season in therhizomes of Leymus chinensis. But the content of fructan increased gradually over a growingseason, and reached to top at the end of growing season. The total amount and the contents ofevery component of dissolubility saccharide in leaves trended rising slowly through a growingseason. Opposition, the content of fructan was smoothly decreased through a growing season.(3) The extent of soil salt-alkalization did not affect obviously on the components ofnon-structural carbohydrates in dry material of Leymus chinensis. But it is closely related withthe total content in a Leymus chinensis population growing on a unit area. The total amount ofnonstructural carbohydrates and the contents of each component all decreased obviously withaggravating the extent of soil salt-alkalization. The total amount of non-structuralcarbohydrates in a Leymus chinensis population was the foundation of material and energythat decided the viability and expands reproducibility of population. Therefore, it could betaken as an ideal index to evaluate deteriorated vegetation and its trend of development.(4) The results of statistical analysis showed that there were highly significant negativerelativity between the total amount of nonstructural carbohydrates in population and each soilindex including pH value, buffer capacity, and electric conductivity. In other word, theextents of soil salinization and alkalization all were the dominant factors that affected thenonstructural carbohydrates of Leymus chinensis population.