Effect of application of several growth regulators and silicon element on greenhouse cucumber in response to tomato leaf curl Palampur virus infection

Tomato leaf curl Palampur virus (ToLCPalV) is a destructive bipartite begomovirus which recently is responsible for huge losses to tomato and cucurbits production in Iran. In this research, the effect of the silicon element, growth regulators including salicylic acid (SA), methyl jasmonate (MJ), brassinosteroids (BR), silicon element (Si) and their interactions to response of ToLCPalV infection of the greenhouse cucumber was studied. The study was performed as factorial experiment based on randomized complete block design and carried out under greenhouse conditions in pots. Before planting, cucumber seeds were presoaked separately in SA (0.5 millimolar), MJ (5 micromolar) and BR (1 micromolar). Subsequently, two or three-leaf stage of cucumber seedlings was sprayed by Si solution (1 ml/lit), one week before agroinoculation with ToLCPalV infectious clone. To analyze morphological and chemical characteristics, plant growth parameters including fresh weight and plant height parameters and amount of the catalase, peroxidase, polyphenol oxidase, ascorbate peroxidase and guaiacol peroxidase enzymes were assessed 30 days post agroinoculation with ToLCPalV infectious clone. Results indicated that, SA and combination of MJ+Si and BR+Si treatments resulted in raising the enzyme levels which leads to delay in appearance of ToLCPalV symptoms and decrease fresh weight and plant height parameters of plants. Based on the results of this research, application of plant growth regulators with or without silicon element including SA, MJ, MJ+Si and BR+Si could be resulted in increasing resistance in greenhouse cucumber against ToLCPalV infection.