Autotoxicity In Panax Notoginseng Of Root Exudates And Their Allelochemicals

Sanqi [Panax notoginseng (Burk.) F.H. Chen] was known of traditional herbal medicine in the Guangxi province of China, and had several hundred years of cultural history. In Guangxi, Sanqi was called Tianqi. Sanqi continuous planting was easy to cause serious succession cropping obstacle problem in the same field. This research on autotoxicity of root exudates was to study of succession cropping obstacle, and the results provided theoretic basis to solve the succession cropping obstacle problem.(1) Succession cropping soil significant autotoxicity against seed germination, and also showed a certain impact on the growth of Sanqi. With the increasing of time of harvest, autotoxicity went from strength to weakness. The soil conditions began to recover in six to nine years after harvest.(2) In the hydroponic conditions, the autotoxicity of Sanqi were investigated in hydroponics either with or without activated charcoal (AC) addition. The result showed that the root fresh weight and dry weight in the hydroponic condition with AC were significantly higher than the other. The CAT and POD activities and MDA content were lower than the other without AC, but the difference was not significant.(3) Based on GC/MS analysis results from new soil, rhizosphere soil and root exudates of Sanqi. The study found that there are lots of organic acids and esters in rhizosphere soil than new soil. The four kinds of chemical substances were found from the rhizosphere soil and root exudates of Sanqi, respectively benzoic acid, phthalic acid, palmitic acid and stearic acid. The four kinds of allelochemicals were selected to study their effect on the germination and growth. The test found that the higher concentration, the stronger of the autotoxicity of Sanqi. The greatest effect on the root growth of Sanqi. the 4 substances of three seven autotoxicity the storage of them was in the order as phthalic acid> palmitic acid> benzoic acid> stearic acid.