Resilience of French Marigold (T<i>agetes patula</i> L.) Genotypes to Cold Stress: Morphological and Biochemical Insights

In this investigation, the impact of cold stress on four French marigold genotypes (Hisar Beauty, Hisar Jafri, Valencia Yellow, and Orange Winner) was studied under open field and polyhouse conditions. Significant reductions in vegetative and floral traits were observed, with genotype and environment interactions significantly affecting the plant performance. Hisar Beauty exhibited the highest cold resilience, with moderate reductions in plant height (12.5%), plant spread (8.6%), and leaf area (12.2%), indicating enhanced stress tolerance. In contrast, Valencia Yellow and Orange Winner showed severe declines. Cold stress also delayed bud initiation and reduced flower yield, with Hisar Beauty maintaining superior flowering traits, including higher number of flowers (61.00), flower weight (3.89 g), and stable flowering duration across environments. Hisar Beauty retained the highest total chlorophyll content (11.17 mg/g FW), with a 15.9% reduction, compared to 32.5 and 35.9% decline in Valencia Yellow and Orange Winner, respectively. Total phenolic content was also highest in Hisar Beauty (687.13 µg/g FW), significantly exceeding that of Valencia Yellow (231.02 µg/g FW) and Orange Winner (226.10 µg/g FW). The PCA indicated that cold tolerance was linked to stable vegetative growth, higher chlorophyll retention and superior flower yield, highlighting Hisar Beauty and Hisar Jafri as promising genotypes for growing in cold-prone regions.