Effect of Nano-Silicon and Imidacloprid Foliar Application on Morpho-Physiological Characteristics of Gerbera Cut Flower and Its Reaction to Whitefly under Greenhouse Conditions

Gerbera (Gerbera jamesonii Bolus ex. Hook f.) is known as the world's fourth cut flower and silicon (Si) is considered the second most abundant element (28%) of the Earth's crust.Silicon deposition in most tissues and organs, such as plant cell wall, the space between the cells of the epidermis, roots, leaves, and reproductive organs causes resistance to environmental stresses, insects, and pathogens into the plant. Greenhouse whiteflies (Trialeurodes vaporariorum) are the most important pests in several crops such as gerbera, which have herbivorous insects with piercing-sucking mouthparts and have 4 to 15 in their generation.

Considering the numerous environmental risks posed by using pesticides in pest control especially under greenhouse conditions,this study was conducted to compare whiteflies control with imidacloprid pesticide and nano-silicon fertilizer (NSF) as a quasi-essential element in plant nutrition and their impacts on improving resistance to pest. This research was designed as a pot experiment in a soilless greenhouse with polyethylene (PE) coated and controlled environmental conditions. Flower quality components, including flower diameter, flowering stem height and vase life, relative water content (RWC), vase solution uptake, the total phenol content,leaf Ca++ and Si+ content and whiteflies contamination (egg, nymph, pupa, and adult) were evaluated using a factorial experiment based on completely randomized design with three replications in a hydroponic greenhouse.

Results

The results showed that NSF caused a significant increase of flower diameter, stem length and vase life of flower compared to imidacloprid. Also, NSF increased total phenol content. Leaf calcium and Si concentration in treatment with NSF showed a significant increase compared to other treatments.In addition, the percentage of whitefly population significantly decreased under applying NSF and imidacloprid compared to the control plants. Spraying imidacloprid despite whitefly control led to the reduction of flower diameter and total phenol content. Also, imidacloprid significantly increased flowering stalk height and the contamination of whitefly nymph with respect to NSF.

According to the results of the present research, foliar application of NSF not only reduced the environmental impact caused by using chemical pesticides but also led to the control of whiteflies population and improved the quality of gerbera cut flower. Therefore, we recommend the use of NSF as a fertilizer-medicine in greenhouse cultivation of gerbera 'Stanza'.