Effect of Thermo-chemotherapy Treatments on Reducing the Population of Crown Gall Agent in Grape Cuttings

In order to effect of hot water and chemical treatments on reducing of bacterium from infected cuttings and some characteristics of rooted cuttings cvs. Sefid Bedaneh and Hossaini, an experiment was conducted in Grape Research Station of Takestan for 3 years. The Experiment was carried out as Split-Split plot design based on CRBD, with 4 replications and 40 samples in plot. Isolation and identification of bacteria isolates was carried out by using common methods such as selective media and test on indicator plants. Treatments were included; cultivars (Main Factor), Hot-Water (sub-plot) and chemical treatments (sub-sub plot). Cuttings were rooted in non-infected media of Perlite, sand and compost soil (v/v) in an isolated nursery. The effect of treatments on infection was evaluated by observation of gall formation and bacterium growing on selective media for 2 years. Analysis of variance was done by MSTAT-C program and means were comprised by LSD method. Agrobacterium tumefaciens characteristicswere observed on the 17 strains of 20 isolates so 3 of it were A. vitis. Effect of combined treatments on vitality and growth characteristics varied with different cultivars and treatments. Variation of the number of healthy rooted cuttings, cuttings survival, roots fresh weight and weight of shoots were observed. However, flower initiation was affected by treatments in the two cultivars. Results showed that agent of crown gall was eradicated or reduced below the level of detection in dormant cuttings of two cvs. of grapes by combined Hot water treatment (50ºC/30 min)× chemical treatment (Streptomycin Sulfate 1000 ppm). Although, a treatment 60 ºC/15 min was more effective, but it killed high number of cuttings. Rooting of cuttings, fruit production and other characteristics were admissible by combined chemical treatment (Streptomycin Sulfate 1000 ppm and 50ºC/30 min).