Morpho-physiological and biochemical screening of African marigold (Tagetes erecta L.) genotypes for heat stress tolerance

Krishna Singh Tomar

doi:10.56093/ijas.v96i11.179828

Authors

Krishna Singh Tomar College of Horticulture, Banda University of Agriculture and Technology, Banda -210 001 Uttar Pradesh

https://doi.org/10.56093/ijas.v96i11.179828

Keywords:

Correlation, Heat tolerance, Heritability, African Marigold, Path analysis,

Abstract

Climate change-induced heat stress significantly impairs growth, flowering, and flower quality in African marigold (Tagetes erecta L.), one of India's most important ornamental crops. To identify heat-tolerant genotypes, twenty-two African marigold genotypes were evaluated based on morpho-physiological and biochemical parameters during the rainy and summer seasons of 2024–25 at ICAR–IARI, New Delhi, using integrated morphophysiological, biochemical, and multivariate analyses. Pooled ANOVA revealed significant variability among genotypes along with all sources for genetic variation, seasonal and genotype × season interaction effects for all traits. High heritability coupled with high genetic advance as percent of mean was observed for relative water content (97.91%), flower diameter (91.55%), stalk length (90.12%), hydrogen peroxide (90.45%), and malondialdehyde (85.04%), indicating the predominance of additive gene action and the effectiveness of selection. Correlation analysis revealed that heat stress-induced oxidative damage adversely affected flower yield through increased hydrogen peroxide and malondialdehyde accumulation, whereas membrane stability index and relative water content were negatively associated with oxidative stress markers. Antioxidant enzymes, including superoxide dismutase, guaiacol peroxidase, and catalase, exhibited coordinated responses that mitigated oxidative damage and enhanced stress tolerance. Path coefficient analysis identified relative water content (9.79), membrane stability index (8.87), and number of flowers per plant (5.91) as the major positive direct contributors to flower yield under heat stress, while total soluble sugars and catalase exerted important positive indirect effects. The study highlights relative water content, membrane stability index, number of flowers per plant, total soluble sugars, and catalase activity as reliable selection criteria for the development of high-yielding and heat-tolerant African marigold genotypes under changing climatic conditions.

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Author Biography

Krishna Singh Tomar, College of Horticulture, Banda University of Agriculture and Technology, Banda -210 001 Uttar Pradesh

Assistant Professor (Floriculture and Landscaping), Department of Floriculture and Landscape Architecture,
College of Horticulture, Banda University of Agriculture and Technology, Banda -210 001 Uttar Pradesh

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