Allelopathic Effect Of Between Astragalus Adsurgens Pall And Stellera Chamaejasme L.

Stellera chamaejasme L. is one of naturally occurring poisonous plants and an indicatorfor grassland degradation. The appearance of S. chamaejasme in grasslands indicates along-term reverse succession. It means a process of grassland changeing from healthygrassland to slightly degraded grassland to moderately degraded grassland and finally toseverely degraded grassland. It is an urgent research topic to study how to improve thedegraded grassland as soon as possible in order to bring it back to the healthy grassland. Astragalus adsurgens Pall is a legume pasture of Chinese origin。In degraded grassland,artificial growing of A. adsurgens could inhibit the growth of S. chamaejasme. This thesisreports the study on the mechanism of how A. adsurgens inhibit the growth of S.chamaejasme by A. adsurgens root culture techniques. It is one of the important approachesto renew the degraded grassland. In this thesis the following results are reported: 1. When the seeds of A. adsurgens and S. chamaejasme are co-cultured in same Petridishes with different densities, the germination rate of S. chamaejasme is significantly affected withthe density of A. adsurgens increasing. It also indicates the autotoxicity of A. adsurgens and S.chamaejasme. 2．A. adsurgens root culture filtrates strongly inhibit radicles and coleoptiles elongationof wheat (Triticum aestivum L.) and A. adsurgens, as well as radicle elongation S.chamaejasme. The allelopathy of A. adsurgens root culture under the condition of asepsiscould be certainly sure that the active chemicals originatefrom of the plant. 3．The establishments of root culture exuded from for the compositions of highlyexudation of allelochemicals into culture medium to have the most inhibitive effect on theradicle elongation of A. adsurgens and wheat is that one litre of modified B5 medium of A.adsurgens root culture consists of KNO3 4565.9 mg, (NH4)2SO4 48.1mg, MnSO4·4H2O 5.0mg,inositol 150.0mg, nicotinic acid 1.5mg, vitamin B6 hydrochloride 1.5mg, vitamin B1 15mg,NAA 0.8mg, sucrose 50.0g. 4．The culture period of A. adsurgens root culture is about 24 days. The culture periodcould be divided into three periods: the delaying growing period, the exponential growingperiod and the steady growing period. During the culture period, the strong inhibitive effectof the active chemicals of A. adsurgens root culture filtrates to the test species appears in theexponential period. 5．The allelopathic effect of aqueous extract of A. adsurgens growing in the field onwheat and A. adsurgens shows that the effect of aqueous extract of the leave is stronger thanthat of the stems. During the growth cycle of A. adsurgens in the field, the allelopathic effectof leave and stems is stronger during the nutrition growth period than the florescence growthperiod. 6．The active chemicals of A. adsurgens root culture filtrates to test species and thedifferent part of the same plant has a selective inhibition effect. The same absorption peaksappeared by HPLC analysis between the extracts of A. adsurgens root culture filtrates and theextracts of the whole plantof A. adsurgens under the condition of asepsis.