关键词: 缺钾, 根系形态, 氮吸收, 氮同化

Abstract: In order to investigate the relationship between potassium nutrition and nitrogen absorption and assimilation ability of flue-cured tobacco, and make clear the possible pathway of interaction between potassium nutrition and nitrogen assimilation, so as to provide a theoretical basis for rational application of potassium fertilizer, this paper took flue-cured tobacco K326 as experimental material, and analyzed the changing of nitrogen and dry matter accumulation in different plant organs, root morphology, root NO-3 absorption rate and root nitrate reductase (NR) activity after potassium deficiency under nutrient solution culture condition. The result showed that dry matter accumulation in stems and leaves decreased significantly under potassium deficiency condition, but there was no significant change in dry matter accumulation of root system. Potassium deficiency shortened the total root length, and reduced root surface area and root volume, but the average root diameter did not change much. Potassium deficiency brought down the nitrogen accumulation in stems and leaves, increased the N allocation rate in root system and decreased the N allocation rate in stems. Potassium deficiency increased the root NO-3 absorption rate, thus the NR activity in root system was significantly increased. In conclusion, the main reason for the decrease of nitrogen accumulation in flue-cured tobacco under potassium deficiency is that the reducing of plant nitrogen demand due to the decrease dry matter accumulation.

Key words: potassium deficiency, root system morphology, nitrogen absorption, nitrogen assimilation