Study on the Culture Conditions for Hairy Roots of Aconitum coreanum( Levl.) Raipaics

[Objective]This study aimed to investigate the culture conditions for hairy roots of Aconitum coreanum（Levl.）Raipaics and optimize the amplification culture conditions in bioreactors,thus providing basis for large-scale production of A.coreanum hairy roots.[Method]The effects of different p H,culture modes and culture vessels on the growth of hairy roots were compared to obtain the optimal culture conditions for A.coreanum hairy roots.Moreover,the effects of medium volume and inoculation mode on bioreactor culture of A.coreanum hairy roots were investigated to analyze the feasibility of amplification culture of hairy roots in bioreactors.[Result]After autoclaving,medium p H was reduced slightly and the clarity of medium varied.To be specific,A.coreanum hairy roots cultured in medium at p H 5.80 exhibited the best growth.A.coreanum hairy roots cultured in liquid medium displayed more rapid growth than hairy roots cultured in solid medium.Medium p H and electrical conductivity（EC）varied with the extension of culture time.The yield and propagation coefficient of A.coreanum hairy roots were positively correlated with the size of culture vessels.The growth of hairy roots cultured in bioreactors were influenced by medium volumes and inoculation modes.[Conclusion]The growth of A.coreanum hairy roots were significantly influenced by medium p H,culture modes and culture vessels.A.coreanum hairy roots cultured in bioreactors exhibited high yield and large propagation coefficient.According to the results,the relationship between ventilation volume and hairy root density is crucial to the amplification culture of A.coreanum hairy roots.

Weed-Suppressing Effect and Mechanism of Allelopathic Rice Accessions

Two allelopathic rice accessions, PI312777 and Allelopathy1, significantly suppressedthe growth of associated weeds in the field. Moreover, their weed-suppressing effectswere correlated with the cultivation patterns. The weed-suppressing effects of throwingand transplanting were more effective than that of direct seeding. Furthermore, theamounts of allelochemicals (resorcinols, flavones and hydroxamic acids) produced andreleased from two allelopathic rice accessions were much higher than that from a non-allelopathic rice variety Hua-Jing-Xian1, and reached the maximum concentration at the6th leaf stage. Differences in the weed-suppressing effects of rice accessions appear toresult from the accessions producing and releasing different amounts of allelochemicalsin the field. Further research confirmed that in PI312777 plants, allelochemicals weresynthesized by the above-ground parts, and then secreted through the root tissues. Roottissues of PI312777 plants never produced the allelochemicals. Root exudates fromPI312777 could significantly inhibit the growth of E. crus-galli surrounding rice plantsin water culture. However, when activated carbon was added to the culture solution, whichcould absorb allelochemicals from root exudates, the growth of E. crus-galli was nolonger significantly inhibited. Weed-suppressing effects of rice accessions depended onallelopathy, cultivation patterns and other factors in rice fields, while allelopathywas one of important factors. Interestingly, the amounts of allelochemicals produced andreleased from allelopathic rice plants may be induced by the presence of E. crus-galli.This suggests that there is a possible chemical recognition between rice and E. crus-galli.