Study On Continuous Cropping Obstacle Of Astragalus Membranaceus

Continuous cropping obstacle always lead to poor growth, declining quality and yield reduction on crops,which making a serious effect on agricultural sustainable development. Astragalus membranaceus is a Legume plants of astragalus linn, it is a famous vagina Chinese crude drug,which is the tonification drug,not only contains many amino acids,microamount elements and polysaccharides that is essential for human body,but also has higher nutritive value and health protection function, especially reinforce organism immunity and boost human body disease resistance. However, Astragalus membranaceus always was cultivated using continuous cropping method because of market supply and demand and cultivated area.This method usually has a bad effect on declining quality and aggravated root rot because it was mainly affected by self-allelopathy, allelopathy and soil microoranganism imbalance.As a result,the development of Astragalus membranaceus industry was restricted seriously.The studies on Astragalus membranaceus now were mainly focus on chemical composition analysis and pharmacological effects,but had a little reported on self-allelopathy, allelopathy and soil microoranganism imbalance effects.The widely cultivated Astragalus membranaceus in Dingxi city,Gansu Province was selected as reportor, and the mainly local Chinese medicina herbs and crops were selected as donor materials for extracting the infusion of different organs of 17 species plants.The agar plate method and hanging drop method were applied for bacteriostatic test on two dominant species of Fusarium oxysporumt and Fusarium solani which causing the root rot of Astragalus membranaceus. The plant infusions which had a obviously inhibitory effect was screened as donor materials on the basis of bacteriostatic test, and Astragalus membranaceus was selected as the test material for carrying out bioassay. The field test was also carried out in the study.The order of the study included three aspects as follows:â‘ The influencing factors for Continuous cropping obstacle of Astragalus membranaceus would be concluded.â‘¡A theory basis for field rotation of Astragalus membranaceus would be concluded.â‘¢The basis on development of botanical fungicides could be determined. The main results based on the study as follows.1. Continuous cropping obstacle could speed up the rate of root rot incidence of Astragalus membranaceus in a long time. The analysis on the isolation,purification and identification of root rot pathogen in the study showed that several fungis could lead to root rot on Astragalus membranaceus,and Fusarium oxysporum schlecht and Fusarium solani were dominant species.2. The methods of growth rate and hanging drop,and the donor meterials from 17 plants infusion were used for the bacteriostatic test of colony growth and spore germination on Fusarium oxysporum schlecht and Fusarium solani.The results showed that 12 plants(Alliumcepa L., Triticum aestivum L., Zea mays, Solanum tuberosum, Sophora alop ecuroides, Radix et rhizoma rhei, Herba ephedrae, Radix sophorae flavescentis, Chinensis franch, Fructus xanthii, Radix isatidis and Radix glycytthizae) infusion had a siginificant inhibitory effect on the growth and spore germination for Fusarium oxysporum schlecht and Fusarium solani,and the inhibitory rate declined with the declination of mass concentration.However,both of the infusion of Ston leek Allium satirum and Allium tuberosum rattler had a promoting effect on the growth of the two fungis at the lower concentration.3. The mixture confected by different plant infusion according to proportion had a higher inhibitory rate than that of single plant infusion on the two fungis. Both the two plants infusion mixed by Radix glycytthizae,Radix sophorae flavescentis and Radix sophorae flavescentis,Chinensis franch according to a certain proportion had a higher inhibitory rates on the growth and spore germination of the two fungis.The three plants infusion mixed by Radix glycytthizae,Radix sophorae flavescentis and Herba ephedrae or Radix glycytthizae,Radix sophorae flavescentis and Alliumcepa L according to a certain proportion had a significant inhibitory effect(inhibitory rates were over 80%) on the two fungis. However, the mixture of the other plants infusion had a weak inhibitory effect on the two fungis.4. Both of various donor materials had allelopathy effect on Astragalus membranaceus.The 12 donor materials screened on the basis of bacteriostatic test both had allelopathy effect on Astragalus membranaceus,of which the Radix et rhizoma rhei infusion had a promoting effect on the seed germination and seedling growth,and both of other donor materials had a inhibitory effect and concentration-dependent on the seed germination and seedling growth.5. The mixture also had allelopathy effect on seed germination and seedling growth,but had no siginificant difference compared with that of single dose.6. Various tillage method had a different influence on the seedling survival rate and Astragalus membranaceus growth,and rotation cultivation method had a better effect on seedling survival rate and Astragalus membranaceus growth than that of continuous cultivation method. Astragalus seedling transplanted on the field that Alliumcepa L., Zea mays , Solanum tuberosum , Sophora alop ecuroides, Radix et rhizoma rhei , Radix sophorae flavescentis and Radix isatidis grew at current year had a better survival rate and growth than that of continuous cultivation,and also had a lower root rot rate than that of continuous cultivation.According to the results as above, the infusion of various plants which had a obviously antibacterial effect could be configured to different concentrations so as to develop botanical fungicide to control root rot of Astragalus membranaceus.On the other side, rotation cultivating with the plants which had a obviously antibacterial effect could be applied because of better quality,better yield and lower rate of root rot on Astragalus membranaceus.