Effect of Tryptophan and Nano NPK Fertilizer on The Flowring Growth of Two Cultivars of Narcissus Spp

Abstract

The experiment was conducted in the wooden canopy of the Department of Horticulture and Landscape Engineering, College of Agriculture and Forestry, University of Mosul, during the period (2023-2024). The study aimed to examine the effect of spraying with different concentrations of the amino acid Tryptophan at three levels (0, 100, 200 mg L⁻¹) and the addition of NPK nano-fertilizer at three concentrations (0, 0.75, 1.25 mL L⁻¹), as well as the interaction between them, on the vegetative and floral growth, and the production of bulbs and bulblets of two types of Narcissus tazeta L., namely "Semper Avanti" with white flowers and "Red Devon" with yellow flowers. The experiment employed a randomized complete block design (RCBD) in a factorial arrangement with three replicates, resulting in 18 experimental units per replicate and 7 plants per unit. The results indicated that the yellow cultivar Red Devon recorded the highest values in some studied traits, such as the time required for flower opening (115.454 days), flower stalk length (38.713 cm), and flower diameter (67.71 mm). Meanwhile, the white cultivar Semper Avanti recorded the highest values in the following traits: number of flowers (1.572 flowers plant⁻¹) and flower stalk diameter (6.826 mm).