Study on nitrogen mobilization of senescence leaves under different nitrogen rate in winter rapeseed (B. napus L.)

摘要

Leaves of rapeseed are not only a main photosynthetic organ before flowering, but also a organ for N storing. Data from field experiments conducted on a fertile sandy-loam soil in rapeseed growing season of 2001/2002 and 2002/2003 at experimental farm of Yangzhou university in the People's Republic of China were used to analyze the changes of nitrogen and soluble protein concentration in senescence leaves in winter rapeseed (B. napus L). The N concentrations per unit area of long-stalk, short-stalk and non-stalk leaves and soluble protein concentrations per unit area of short-stalk and non-stalk leaves were measured respectively. The main results were as follows. (1) The concentration of nitrogen (N) and soluble protein in leaves decreased gradually as the senescence of leaves. The changes of N concentration per unit area and the days after flowering in senescence leaves could be expressed as cubic curve. (2) The ratio of soluble protein N to total N increased gradually as the senescence of leave. (3) The concentration of N and soluble protein and the amounts of N mobilized increased, but the proportion ofN mobilized to the total N of leaves decreased (from 83.21% to 76.73% in short-stalk leaves and from 73.49% to 62.21% in non-stalk leaves respectively) as the increasing of N fertilizer application (from 0 to 360kgN/ha). (4) The amounts of N mobilized in long-stalk,short-stalk and non-stalk leaves were about 85%, 80% and 70% respectively during their senescence.