بررسی اثر پرایمینگ بذر کلزا با سالیسیلیک اسید در القای مقاومت آنتی زنوزی نسبت به شته مومی کلم در شرایط مزرعه

One of the major pests of rapeseed in the world and Iran is the cabbage aphid (Brevicoryne brassicae L). Due to the attack of this aphid, the growth of infected rapeseed plants is seriously reduced and the formation of the flowers gets highly affected. The plants, mostly, fail to form pods and malformation is occurred. In addition, very few seeds are formed in the pods, in the range of 3 to 5 seeds/pod (compared with 26 to 35 seeds/pod in normal conditions). Salicylic acid (SA), as a natural plant hormone, plays an important role in signaling the plant against the biotic and abiotic stresses. The present study was carried out to evaluate the effect of rapeseed seed priming with SA to induce antixenotic resistance to the cabbage aphid in field conditions. The treatments consisted of 50, 75 and 100 μM SA and control (ethanol + distilled water). The research was carried out in two-leaf and four-leaf-stemming growth stages of rapeseed and in two periods of 24 and 48 hours after the release of the aphid as follows: First, to prepare the desired concentrations, the required amounts of salicylic acid were dissolved in 96% ethanol, by adding distilled water. Rapeseed seeds were immersed in SA for 24 hours (the time needed to activate the enzymatic system). After removing the seeds, the solution was washed with distilled water for three times. The seeds were then placed at room temperature for 48 hours to return to the initial moisture level before planting. To evaluate the antixenotic resistance, seeds were planted at random in four replicates of two concentric circles. The experiment was a completely randomized design. At the two-leaf and four-leaf-stem stages, 100 adult aphids were, simultaneously, released at the center. After 24 and 48 hours, the number of aphids attracted per rapeseed plant was recorded. Data analysis was performed with Minitab16 software and the means were grouped by Tukey's test at 5% significance level. The results showed that, salicylic acid treatments at the two-leaf stage, had a significant difference with control in both the 24 and 48 hours periods. At the four- leaf-stemming stage, the significant difference was observed only at the 24-hours period. The 100 μM SA treatment, with increased number of aphid attraction, in both the two- leaf and four- leaf-stem stages, showed the least antixenotic resistance to the aphid. While, the 75 μM SA treatment, showed the highest antixenosis with the decreased number of aphid attraction, compared with the control and the other treatments. The results of the research might be noticed in the IPM programs of the cabbage aphid.