棉花枯萎病抑菌土成因初探Ⅰ棉根系分泌物对棉花枯萎菌的影响

INITIAL STUDYS OF PATHOGEN SUPPRESSIVE SOIL TO FUSARIUM WILT OF COTTONⅠ. EFFECTS OF ROOT EFFUSION OF COTTON ON THE FUSARIUM OXYSPORUM F. SP. VASINFECTUM

试验表明，随着棉花抗病品种连作时间的增长，土壤中棉枯萎菌的数量和致病力由高逐渐降低，土壤的抑菌作用逐渐积累而形成抑菌土。土壤带菌量（ｘ）与连作年代（Ｎ）的关系为：ｘ＝１８４４．２７－１５２．８９Ｎ。抗病品种根系分泌物对棉枯萎菌小孢子萌发没有显著影响，但对病菌菌丝的生长、厚坦孢子形成和萌发的抑制作用较为明显。用紫外分光光度计测定结果表明，不同抗性棉花品种根系分泌物的吸光值不同。

The changof inoculum number and pathogenity of different soils sample on monoculture of rises-tens cotton varites (MCRCV)has been studed. As MCRCV is increasing in years the inoculum numberand pathogenity aregeting less and less. It is demonstrated that there are suppressive factore in the soilsof MCRCV. The line equation between inoculum(X)and years of MCRCV(N)is X=1844.27-152.89N, r=-0.9114. Hyphea growth of and numbers of chlamydospore of Fusarium oxysporum f.sp. vasinfectum is inhibited in the effusion of risestent cotton root(RCR), and the later is less in normalsoils then in those of MCRCV. Analysis result using the UV-200 spectrophotometer indicated ab-sorbancy of effusion of RCR is 1.92 in 280 nμ, but absorbancy of effusion of susceptible cotton vari-aty is 0.55. It shows that there some differences in protein structure beween the effusion of risestentand susceptible. May be the effusion of RCR is im porta nce for forming suppressive soil.