Roots of Huanglian responded to low phosphorus stress by physiological rather than morphological changes
Objective:To explore the Huanglian root system response strategy to low phosphorus(P)stress,and provide a basis for understanding the mechanism of successive cropping obstacle.Method:Rhizome alkaloid and nitrogen(N),P and potassium(K)contents of biennial Huanglian collected monthly for one year were detected.Biomass,root morphology,organic acid secretion and nutrient element content of Huanglian in hydroponics were determined.Result:The alkaloid content of Huanglian rhizome was linearly positively correlated with P content,but not with N and K content.In the hydroponic experiments,there was no significant difference between the biomass of Huanglian underground at low and normal P levels.The total root length,root surface area,root volume and mean diameter had no difference under two P concentration treatments.The rate of root malic acid and oxalic acid secretion in the low phosphorus treatment was significantly higher than in the normal P treatment,especially malic acid.Root P content in the low P treatment was significantly lower than in the high P treatment,while root zinc content showed the opposite pattem.There was no significant difference in leaf P,K,Fe,Mg and Cu contents between the two P treatments.Conclusion:The roots of Huanglian mainly respond to low P stress through physiological changes.Zn may be an important element affecting the organic acid metabolism of Huanglian roots.
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万方数据
