Flower Color, Color Stability, and Flower Longevity in Red-flowered Elepidote Rhododendrons

Abstract

Red-flowered elepidote rhododendrons (Rhododendron sp.) are favored by consumers, but cold-hardy red-flowered rhododendrons frequently have blue-red flower hue rather than the preferred red flower hue. Flower longevity, color, and color stability over 14 days were studied for the following eight elepidote rhododendron cultivars possessing red flowers: Besse Howells, Burma, Cary’s Red, Firestorm, Francesca, Henry’s Red, Low Red Frilled, and Nova Zembla. The eight cultivars were separated by flower hue into two distinct groups of four cultivars each. Rhododendron cultivars Burma, Firestorm, Francesca, and Henry’s Red produced flowers with red hue and Besse Howells, Cary’s Red, Low Red Frilled, and Nova Zembla produced flowers with blue-red hue. Flower longevity among rhododendron cultivars varied with Francesca blooms lasting the longest at over 14 days, and Besse Howells and Firestorm blooms lasting the shortest at ≈10 days. As flowers aged, hue angle decreased (became bluer), lightness increased, and chroma decreased or remained unchanged. The degree of change in flower color over time differed among cultivars, with ‘Francesca’ demonstrating the least change (ΔE00 ≈ 3) and ‘Besse Howells’ the most change (ΔE00 ≈ 11).