질산태 질소의 공급수준에 따른 알팔파의 건물, 질소의 분포 및 저장영양소의 축적

Abstract

To investigate the effects of the exogenous N supply level on the nitrate assimilation and growth during the vegetative growth stage, and on the accumulation of organic reserves during the successive regrowth period, dry matter (DM), the amount of nitrogenous compounds, total N and starch in alfalfa plants grown hydroponically with 0.2, 1.0 and 3.0 mM KN was estimated, respectively, during vegetative growth period and two cycle of regrowth. When compared with DMs and N contents in various N compounds in the organs grown with 1.0 mM N , N starvation symptoms were found in 0.2 mM and a depressive effect was observed in 3.0 mM after 10 weeks of vegetative growth. Total starch content in root system gown with 0.2, 1.0 and 3.0 mM N during the first regrowth was 50.96, 15.47 and 6.37 mg plant, respectively. Starch was contained mainly in taproots. The starch content was not significantly changed by 24 days of the second regrowth with 1.0 mM N N0. Total nitrogen content in root system grown with 0.2, 1.0 and 3.0 mM N during the first regrowth was 6.66, 8.43 and 11.09 mg plant , respectively. Nitrogen was contained mainly in lateral roots; 80% (in 0.2 mM), 74% (1.0 mM) and 76% (3.0 mM) of total nitrogen in root system. Total N content in root system at the end of the second regrowth also closely affected by the N supply level during the first regrowth. These results suggest that the level of N may strongly influence the accumulation of organic reserves in root system, and that the initial level of organic reserves for the successive regrowth was one of the determinants for shoot regrowth.