Evaluation of French Marigold (Tagetes Patula L.) Genotypes for Cold Tolerance Using Multivariate Analysis

Abstract

Low temperature is a major limiting factor affecting flower quality, yield, and spatial distribution in French marigold (Tagetes patula L.). This study, conducted at the Division of Floriculture and Landscaping, ICAR-IARI, New Delhi, evaluated 20 genotypes for cold tolerance using morphological, physiological, and biochemical traits through multivariate analysis. Cold stress significantly influenced physio-biochemical responses, including electrolyte leakage (87.75–96.4%), relative water content (85.86–92.26%), total chlorophyll (6.78–13.92 mg g-1 fwt), superoxide dismutase (14.4–30.54 mmol mg-1 protein min-1), guaiacol peroxidase (3.7–15.19 mmol mg-1 protein min-1), catalase (6.25–30.40 mmol mg-1 protein min-1), protein (1.35–3.17 mg g-1 fwt), malondialdehyde (164.1–498.43 μg g-1 fwt), total soluble sugars (138.26–747.91 mg g-1 fwt), total phenols (0.61–14.82 μmol g-1 fwt), and proline (0.61–14.82 μmol g-1 fwt). Flower yield ranged from 21.16 to 208.20 g per plant. Multivariate analysis comprising Principal Component Analysis, Hierarchical Clustering Analysis, Pearson’s correlation, and Subordinate Function Analysis identified Fr./R-5, Hisar Beauty, and Hisar Jafri as cold-tolerant genotypes based on superior performance under cold stress. Yield showed positive correlation with proline, relative water content, and antioxidant activity and negative correlation with electrolyte leakage and malondialdehyde. These findings highlight the importance of osmolyte accumulation, water retention, and antioxidative defense, positioning these genotypes as valuable resources for breeding cold-resilient marigold varieties.

Keywords: Antioxidant activity, Cold stress, Cold tolerant, French marigold, Multivariate analysis