Effect Of Autotoxicity On The Growth Of Rehmannia Glutinosa Libosch

Rehmannia glutinosa Libosch (Scrophulariaceae) is a perennial herb which has important medicinal value. Its roots and processed products were called fresh rehmannia, radix rehmannia and prepared radix rehmannia respectively. The effect of autotoxicity on the growth and development of Rehmannia glutinosa Libosch was investigated. The main results were shown as follows:1. The growth of R. glutinosa was markedly inhibited by its leaf extract. Injury degrees were related to the leaf extract concentrations, Moreover, the rooting ability was inhibited severely and the seedlings got wilting and withered when the concentration reached to 10 g/L, which indicating that the material extracted from its leaves has toxic effects on the growth and development of R. glutinosa.2. The seedling length, fresh weight of R. glutinosa and the absorption of nutrients were inhibited significantly when treated with the root extract. Lower concentration of extract of its root promoted the root development of R. glutinosa, however, when the concentration was high, the roots were injured, such as partially decay. All these suggest that the extract of its root has autotoxic effects on the growth and development of R. glutinosa.3. The seedling length, fresh and dry weight of shoots and roots were also inhibited significantly when treated with higher concentration of phenolic acids. The activities of CAT, SOD and APX decreased with the increase of phenolic acids, however the opposite trend presented in PPO. While the activities of POD increased in the beginning and then decreased with the increase of phenolic acids.4. The pH, the conductivity of the solution and the absorption of K+ decreased with hydroponics under P-deficient conditions.5. The concentrations of phenolic acids decline in different degrees after eight kinds of beneficial bacteria were cultured in nutrient solution which contained phenolic acids. Moreover, these types of bacteria can not produce phenolic acids themselves, so we concluded that they could alleviate the autotoxic effects by utilizing or decomposition the phenolic acids.In conclusion, the extract of its roots and leaves has toxic effects on the growth and development of R. glutinosa. The accumulating secretion of root in soils can cause soil acidification and imbalance of microenvironment, especially under P-deficient conditions. The beneficial bacteria can alleviate the autotoxicity of the secretion of roots and leaves by utilizing phenolic acids, which provided an effective way to solve the continuous cropping obstacle of R. glutinosa.Innovation:1. The comprehensive analysis of the autotoxicity of different parts of Rehmannia glutindsa was made for the first time.2. The beneficial micro-organisms can break down or use the phenolic acids to alleviate damage from the autotoxicity was demonstrated for the first time.