| Medicago sativa L.,is one of the most important legumes in the world and China,among which root rot disease was the main cause of the decline in quality and yield,and the main pathogen of this disease was Fusarium.In this paper,In order to explore the biological characteristics of Fusarium of alfalfa root rot,the optimal culture conditions for the mycelial growth and sporulation of 4 strains of Fusarium under 6 different culture conditions,such as temperature,light,p H,culture medium,carbon source and nitrogen source,the influence of and select the optimum culture conditions,spore formation and germination condition.It provides a theoretical basis for further systematic study on the regularity of root rot caused by Fusarium.The main results are as follows:1.The 7 strains to be test were provided by Microbiology laboratory,institute of grassland conservation,and mainly from alfalfa planting fields in Linze,Yongchang,Dingxi and Mingle,in Gansu province.The results of morphological identification showed that,the 7 strains were divided into the following 4 species:strains LZ10,LZ22 and LZ30 were Fusarium oxysporum;strains DX27 were Fusarium acuminatum;strains YC21 and YC32 were Fusarium solani;strain ML11 were Fusarium sambucinum.2.The results of different culture conditions indicated that: F.oxysporum grew the fastest in PDA medium,and produced the more spores on OMA and PDB,the optimum temperature for mycelial growth and spored were 25~30 ?and 30~35?,respectively,the optimum p H range were 7.0~10.0 and 6.0~8.0,respectively;The optimum carbon sources for mycelial growth and spored were Lactose and sucrose,the optimum nitrogen sources were KNO3 and Glycine,Light treatment had no significant effect on mycelial growth and sporulation(P>0.05).F.acuminatum grew the fastest in WA medium,and produced the more spores on OMA and SNA,the optimum temperature for mycelial growth and spored were20 ? and 30 ?,respectively,the optimum p H range were 6.0~8.0 and 7.0~11.0;The optimum carbon sources for mycelial growth and spored were maltose and sucrose,the optimum nitrogen sources were Glycine and KNO3,Continuous dark conditions were favorable for the growth of mycelia and sporulation of the strain.F.solani grew the fastest in PDA medium,and produced the more spores on PDA and CMC;The optimum temperature for mycelial growth and spored were 20~25 ? and 30~35 ?,respectively,the optimum p H range were 6.0~8.0 and5.0~6.0;The optimum carbon sources for mycelial growth and spored were Lactose and Glucose,and the optimal nitrogen sources were KNO3;Continuous dark culture was beneficial to the growth of the mycelia,and continuous light culture was beneficial to the spored of the strain.F.sambucinum grew the fastest in PDA medium and produced the greatest amount of spore,and produced the more spores on CMC;The optimum temperature for mycelial growth and spored were30 ? and 25 ?,respectively,the optimum p H range were 8.0 and 7.0;The optimum carbon sources for mycelial growth and spored were maltose and fructose,the optimum nitrogen sources were KNO3.Light treatment had no significant effect on mycelial growth and sporulation(P>0.05).3.The results of the study on spore formation showed that: the four species of Fusarium can produce large and small conidia,and some of them can produce chlamydospores,when cultured on three kinds of liquid medium for 7 days.The number of large-size conidia produced by F.oxysporum on PDB was significantly higher than that of SNA and CMC(P<0.05),and produced the largest number of chlamydospores on SNA.Both F.acuminatum and F.solani produced the largest number of macroconidia on PDB and the largest number of microconidia on SNA,the latter produced more chlamydospores on SNA.The number of macroconidia and microconidia produced by F.acuminatum on PDB and SNA was the highest.The number of macroconidia produced by F.solanum on PDB was the most,the number of microconidia produced on SNA was the most,and the number of placantidospores produced on SNA was the most.The F.sambucinum produced the largest number of macroconidia on CMC,and the number of microconidia produced on PDB was significantly higher(P<0.05)than that of SNA and CMC.4.The results of spore formation indicated that: under the 6 different liquid medium,the conidia of 4 species of Fusarium had a certain degree of germination when cultured for 4~48 h,and the spore germination rate increased gradually from0 ~ 48 h.The spore germination rate of the macroconidia and microconidia of the four species of Fusarium when cultured on SNA for 12~48 h was significantly higher(P<0.05)than under other medium treatment,and secondly the spore germination rate was also higher on PDB.SNA,CMC,PDB three kinds of liquid medium processing of spore germination rate were higher than the other three kinds of carbon source culture medium,the SNA to deal with the spore germination rate is always higher than the other medium,SNA can significantly(P<0.05)promote the Fusarium spore germination. |
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