تقويم كفاءة أربع سلالات من بكتيريا رايزوبكتر المنشطة للنمو في تحفيز المقاومة الجهازية إزاء فيروس موزاييك الخيار في نباتات البندورة الطماطم في الزراعة المحمية

الملخص EN

This study was conducted to evaluate two application methods of four strains of plant growth promoting rhizobacter: Pseudomonas chlororaphis MA342, Serratia plymuthica HRO-C48, Bacillus subtillis B2g, B.

subtillis FZB27 to induce systemic resistance in tomato plants against cucumber mosaic virus (CMV) under greenhouse conditions.

In the “treated seed” application, tomato seeds were submerged in a suspension of Pseudomonas chlororaphis MA342, Serratia plymuthica HRO-C48, Bacillus subtillis B2gor B.

subtillis FZB27 (1010 cfu/ml), and in “treated seed + irrigation” application, seeds were treated in the same way as mentioned above, and 10 days after transplanting, every transplant was irrigated with 10 ml of each suspension (109/ml), and 19 days after transplanting were inoculated with CMV.

The time required for initial symptoms development was recorded.

In addition, disease incidence, disease severity and peroxidase enzyme activity were also determined.

Results obtained showed that treatment with the four strains delayed the time needed for symptoms appearance compared with the infected control, and the delay was more in the “treated seed + irrigation” application than in the “treated seed” application.

The treatment with four bacterial strains decreased disease incidence in treated plants which ranged between 36.11-46.65% and 45.00-63.33% 14 and 30 days after inoculation, respectively.

Consequently, the highest reduction in infection rate was with the strain B27 (treated seed + irrigation).

The treatment with bacterial strains reduced infection severity 14 and 30 days after inoculation, and the reduction was higher in the “treated seed + irrigation” application than in the “treated seed” for all the evaluated bacterial strains.

The B27 strain with “treated seed + irrigation” application gave the best effect compared with the other three strains, with reduction in infection rate of 57.14% and 60.36%, 14 and 30 days after inoculation, respectively.

The treatment with bacteria improved the peroxidase enzyme activity in the inoculated treated plants with recorded activity of 0.039- 0.097 n mol and 0.106-0.271 n mol compared with the infected control (0.021 n mol) and the healthy control (0.022 n mol) 14 and 30 days after inoculation, respectively.

The B27 strain in the “treated seed + irrigation” application gave the best result.