تغییر پاسخ دفاع القایی گیاه در مقابل توالی حمله دو گیاه‌خوار از طریق کاربرد PGPR در توت فرنگی

Herbivores with different feeding modes can have strong effects on each other’s population by changes in induced defense response of the common host plant. Plant-growth-promoting rhizobacteria (PGPR) can have adverse effects on herbivores through upregulation of induced plant defense system. The present study examined the effects of three PGPR species in comparison to chemical nitrogen fertilization and control in two sequential attacks of herbivores (first aphid or mite infestation) on population abundance of both herbivores and, growth, chemical and physiology measures of strawberry plants. The studied treatments included three species of rhizobacteria, which are Azotobacter chroococcum, Azospirillum brasilense, and Pseudomonas brassicacearum, along with nitrogen treatment (no PGPR+NPK) and control (no PGPR and NPK). The results showed that interactions between both herbivores of mite and aphid were negative, regardless of treatment effect and the first infestation by each one (mite or aphid) would decrease the abundance of another one (aphid or mite). In the clean plants treated with chemical nitrogen fertilization, the mite population was overflowed and the plant growth measures were declined. Application of PGPR decreased the population abundance of herbivores in both attack sequences as compared to herbivores feeding on chemically fertilized and the control plants. Total leaf phenol concentration in the Pb-treated plants earlier infested with mite was significantly more than that in other treatment combinations. Higher photosynthesis, leaf nitrogen content and leaf area in the PGPR-treated plants in comparison to chemically treatment and control indicate that the PGPR-treated plants have less damaged by herbivory. Overall, the effect of herbivore attack sequences in herbivores' population abundance and, plant growth and physiology in PGPR treatments specially Pb and Ac treatments was lower.