واثر آن بر ميزان بيماري پژمردگي ورتيسيليومي زيتون در باغ هاي استان گلستان VERTICILLIUM DAHLIAE تاثير شوري بر جدايه هاي

Effect of salinity on Verticillium dahliae isolates and on the level of wilt disease in Golestan olive orchards

Verticillium wilt of olive by Verticillium dahliae kleb. Causes economic losses in olive orchards that are often greater than losses caused by any other diseases or pests. In this study, the effect of major salt of soil, NaCl evaluated on V. dahliae isolates from soil in Vitro. The limits of tolerance to NaCl (0-40 gill) was different among isolates and the isolates from high soil Ec had the highest salt tolerance (p< 0.05). NaCl resistance increased in NaCl - susceptible isolates after 11 times transfering to NaCl-medium and non-NaCl medium. The results show high probability adaptation of V. dahliae to salt changes in environment. To investigate of relationship between V. dahliae populaton in soil and soil EC on wilt severity in olive orchards, the population of V. dahliae in soil, soil EC and percent of disease in 44 olive orchards in Golestan province were assessed. Inoculum density and percentage of disease varied from 6-33 per gram of air-dried soil and 0.2 % - 6.2 % in olive orchards, respectively. The changes of Ec were between 2.5 to 12 mmlcm. The effect of inoculum density (propagules per gram of air-dried soil) and Ec of soils on disease (Y) were significant and fitted a Y=0.0247-0.28 Ec+ 0.163 Ms model with R2-0.66 and Significant F function (P< 0.0001).