Synergistic effects of pigments, morphology, and physio-biochemical parameters reveal petal coloration differences in eight rose cultivars

As a key ornamental plant, the core value of rose (Rosa spp.) resides in its petals. Variations in petal development and physio-biochemical parameters among cultivars exhibiting divergent floral coloration could significantly influence their horticultural performance and commercial viability. To address this, we systematically analyzed eight common rose cultivars from Nanning Botanical Garden, measuring petal color parameters, pigment content, morphological structure, antioxidant capacity, nutrient and mineral element content. Our objectives were to: (1) characterize coloration features, (2) identify key drivers of color variation, and (3) identify superior cultivar. Our study revealed that: Petal coloration is primarily regulated by pigment content (chlorophyll, carotenoids, anthocyanins, and flavonoids), enabling classification into deep-toned and light-toned groups. Morphological and physio-biochemical parameters collectively drive color variation: deep-toned cultivars (R4, Rosa 'Golden Scepter'; R5, Rosa 'Brass Band'; R7, Rosa 'Sheherazad'; R8, Rosa 'Hiogi') are synergistically regulated by petal thickness and width ratio (TWR), phenylalanine ammonia-lyase (PAL) content, malondialdehyde (MDA) content, superoxide dismutase (SOD) content, and phosphorus (P), boron (B), and calcium (Ca) content, whereas light-toned cultivars (R1, Rosa 'Icecap'; R2, Rosa 'Scepter'd Isle'; R6, Rosa 'Pink Fan') are synergistically regulated by soluble sugar (SS), catalase (CAT) content, nitrogen (N), and zinc (Zn). The blue hue (R3, Rosa 'Shinoburedo') is specifically regulated by elevated pH and Ca. Membership function analysis identifies R4 as the top-performing cultivar, demonstrating superior landscape applicability and comprehensive development potential.