Seasonal evolution of the leaf composition of Stipa tenacissima L. in mineral elements and parietal fibers

摘要

The leaf composition of Stipa tenacissima L. in mineral elements and parietal fibers presents a seasonal quantitative variation confirmed by statistical analysis. A principal components analysis showed two essential groups of biochemical variables correlated in spring and summer, translating so the influence of these two seasons on their reworking in the alfa leaves. The first group correlated at the summer seems, making up a biochemical strategy of adaptation to the conditions of summer pause, It is represented by lignin, cellulose, total fibers, potassium and copper. The second group correlated at spring, biological phase where the conditions of growth are optimal, is consisted of pectins, hemicelluloses, nitrogen, magnesium, iron and phosphorus. Comparatively to the mineral matter's weak rate, the parietal fibers, particularly the cellulose and hemicelluloses, are the major compounds in alfa leaves.