Journal of Environmental Biology

Non-invasive imaging and biochemical profiling reveal genotypic variation in Tagetes erecta L. to cold stress

E. Amala¹, K.P. Singh¹*, S. Panwar¹, Namita¹, S. Kumar², P.K. Verma¹ and P. Sangmesh¹     

¹Division of Floriculture and Landscaping, ICAR-Indian Agricultural Research Institute, New Delhi-110 012, India

²Division of Plant Physiology, ICAR-Indian Agricultural Research Institute, New Delhi-110 012, India

Received: 08 March 2025                   Revised: 23 April 2025                   Accepted: 23 July 2025

*Corresponding Author Email : kanwariari@gmail.com                     *ORCiD: https://orcid.org/0000-0002-1173-8428

Abstract

Aim: This study aimed to establish a phenomic-based screening protocol for cold tolerance in African marigold (Tagetes erecta L.) by integrating non-invasive imaging with physiological and biochemical analyses, addressing the gap between field crop and ornamental breeding applications where cold stress significantly constrains cultivation by affecting growth, development, and productivity.

Methodology: Ten marigold genotypes were evaluated under controlled polyhouse and natural cold stress conditions across two growing seasons. High-throughput plant phenotyping utilizing RGB, near-infrared, and thermal imaging quantified key traits including morphological characteristics (via RGB), tissue water content (via near-infrared), and thermal regulation (via thermal imaging), complemented by targeted physiological and biochemical analyses.

Results: Significant genotypic variation was observed, as cold stress caused 70.7% reduction in plant area and 24.3% decrease in the photosynthetic rate. Genotype Af./W-4 exhibited superior cold tolerance through enhanced photosynthetic maintenance, minimal reductions in greenness (4.4%), membrane stability (11%), and photosynthetic rate (14.2%), followed by genotypes PB and Af./W-6. Multivariate analysis indicated that key determinants of cold stress performance include traits like plant area, caliper length, greenness, and photosynthetic rate.

Interpretation: Integration of non-invasive imaging with biochemical analysis successfully differentiated cold-tolerant from the susceptible genotypes. This comprehensive approach provides an efficient screening methodology for identifying climate-resilient genotypes in ornamental crops, potentially accelerating cold-tolerant genotype development for sustainable floriculture production.

Key words: African marigold, Cold tolerance, Genotypic-variation, High through put phenotyping, Tagetes erecta L.

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